'99 Suburban extremely hard on fuel pumps


2subs
10-06-2008, 07:11 PM
Howdy, new member here, I'm beside myself with anger tonight.
1999 K1500 Sub, 186K, Runs great when it runs.

I replaced the fuel pump and sender last December with Delco
parts, and it quit working again mid-August. Drained tank and
replaced again with Delco. Here it is the sixth of October,
I get home from work, and my wife tells me that the truck
won't start again. How can two pumps go bad in such a short
amount of time?

I've done all the work myself, the job isn't too bad, the worst part
is draining the tank. Where are all the grounds located. I have a feeling
that something else is afoot here. Did I miss something?

I also have the telltale dancing fuel needle. Is this a ground issue,
or a sender, or both. Any guidance would be greatly appreciated.

Scott

MT-2500
10-07-2008, 10:14 AM
Wiring and plugin and power and grounds are very importain.
What is failing on the old pumps?

When no start check for 12 volt power and good ground at the wires going to pump.
Have they been run low on fuel in tank?
Dirty fuel or stopped up fuel filter?

2subs
10-07-2008, 01:20 PM
MT,

Thanks for the reply. I'll have to drain again, and check for power
back there. I can't say that I know for sure that the pumps have
failed, I'm just guessing. I get no sign or sound that anything is
alive back there.

Would a bad pressure regulator wear a pump out prematurely?
Does anyone have a schematic of where all the grounds are located?

What drives me nuts is that my '99 5.7 K2500 Sub has no wavy fuel needle, and starts without hesitation.

Let me know if anyone else has bumped into anything unusual. If the pumps keep going out at this rate, I'll have GM back on their feet in no time.

Scott

MT-2500
10-07-2008, 02:39 PM
Are you running the tank low of fuel?
Dirty fuel or stopped up fuel filter?

Fuel pump ground is inside left frame rail near front of transmission.
Relay ground is right rear cylinder head.

Fist check voltage and ground and wires before the get to tank.

Pumps are made to run under normal pressure all time.
Running at high pressure.
Running low of fuel.
Low voltage.
Restricted system and dirty fuel.
Will kill Them dead.

2subs
10-07-2008, 07:11 PM
MT,

I changed the fuel filter last December with a Wix unit. I rarely let
the tank get below 1/2 full because of the gas keeping the pump
cool. I don't know if I have a dirty fuel system, but I don't buy gas
anywhere but "name brand" stations I guess.

Where do I check power to the pump without dropping the tank?

I will check all grounds also. I wonder if the jumpy fuel gauge is indicative
of the pump working too hard to keep pressure, like it's fighting a bad
pressure regulator. I'll keep narrowing down options.

Scott

j cAT
10-07-2008, 07:24 PM
MT,

I changed the fuel filter last December with a Wix unit. I rarely let
the tank get below 1/2 full because of the gas keeping the pump
cool. I don't know if I have a dirty fuel system, but I don't buy gas
anywhere but "name brand" stations I guess.

Where do I check power to the pump without dropping the tank?

I will check all grounds also. I wonder if the jumpy fuel gauge is indicative
of the pump working too hard to keep pressure, like it's fighting a bad
pressure regulator. I'll keep narrowing down options.

Scott


whenever replacing a fuel pump the pump relay should be replaced or opened and inspected for contacts being burned...


on your needle, fuel gauge ...is it wondering or vibrating ? If it vibrates rapidly this is usually the dash console...but could be grounds that look good but have to be removed sanded to bright metal and then re attached....



after the fuel pump is replaced check fuel pressure....this will give info on what maybe causing the pump to fail...

2subs
10-07-2008, 08:18 PM
J cAT,

The needle is vibrating. I couldn't find the ground on the drivers
side near the front of the transmission but I'll keep looking. I found
all kinds of grounds at the rear of the motor on the passenger side.

I'll check fuel pressure after I replace the pump again. All grounds that
I can locate will be cleaned up. I'll replace the relay, and probably
the pressure regulator while it's all apart. It's too nice of a truck to give
up on just yet, but I'll admit I'm frustrated.

Scott

MT-2500
10-08-2008, 09:10 AM
J cAT,

The needle is vibrating. I couldn't find the ground on the drivers
side near the front of the transmission but I'll keep looking. I found
all kinds of grounds at the rear of the motor on the passenger side.

I'll check fuel pressure after I replace the pump again. All grounds that
I can locate will be cleaned up. I'll replace the relay, and probably
the pressure regulator while it's all apart. It's too nice of a truck to give
up on just yet, but I'll admit I'm frustrated.

Scott

Clean and check all grounds.
Also you can run a extra ground on it.

But on your main problem of hard to start always test it out when hard to start.
Could be other ptroblems besides fuel pump or fuel pressure.
Remember proper testing is first thing to do.
Good luck

2subs
10-19-2008, 05:08 PM
Update:

Well, I cleaned up, and rewired the pump ground that runs to the crossmember just in front of the tank. The fuel pump runs again, but
it is throwing a SES that I need to pull.

I hope that's all it was, I have read some past posts where this was the
problem. I hope it continues to run, and I will pull the code and see what's
bugging the ECM.

Scott

MT-2500
10-19-2008, 06:47 PM
Update:

Well, I cleaned up, and rewired the pump ground that runs to the crossmember just in front of the tank. The fuel pump runs again, but
it is throwing a SES that I need to pull.

I hope that's all it was, I have read some past posts where this was the
problem. I hope it continues to run, and I will pull the code and see what's
bugging the ECM.

Scott

Not only in in past post but in this post check the ground was metioned several times,:lol2: :grinyes:
Thanks for posting back how it went

777stickman
10-19-2008, 08:25 PM
If your '99 is an OBS (Old Body Style) (looks like a '95) I may be able to add some tips.

If it's an NBS (New Body Style) (looks like a '00) I'm out.

2subs
10-19-2008, 08:32 PM
MT,

I appreciate the heads up on the grounds. I'm upset at myself for
probably tossing out a perfectly good AC/Delco pump back in
August.

777,

I have the 1999 OBS, last year I believe of the larger Subs. I'll take any
hints and pointers I can get.

Scott

j cAT
10-20-2008, 10:29 AM
MT,

I appreciate the heads up on the grounds. I'm upset at myself for
probably tossing out a perfectly good AC/Delco pump back in
August.

777,

I have the 1999 OBS, last year I believe of the larger Subs. I'll take any
hints and pointers I can get.

Scott


what about that rapidly vibrating fuel gauge????
Did the ground cleaning solve that problem to...? the needle problem has had some give up on repairing..

2subs
10-20-2008, 07:32 PM
j cAT,

Nope, didn't cure the dancing needle. I'm going to check all grounds
under the dash, and see what I come up with. Time to go to Helms
and get the proper FSM. Nice to know where all the grounds and wiring
run.

Scott

j cAT
10-21-2008, 11:09 AM
j cAT,

Nope, didn't cure the dancing needle. I'm going to check all grounds
under the dash, and see what I come up with. Time to go to Helms
and get the proper FSM. Nice to know where all the grounds and wiring
run.

Scott

the dash instrument panel is most likely causing this....as others have also found this to cause their problem...

grounds and conectors in the area..

monskr
10-24-2008, 05:30 PM
Hi All,

New member as well. Having fuel pump issues with my 1999 Suburban K1500, research lead me to this forum. Pump#2 is on the outs in less than 20k miles.

MT - Good tip on the grounds I'll be sure to check them.

I also wanted to share some info I found on this topic that may help.

Federal Mogul (Carter Fuel Delivery Systems) have tec bullitens on failure causes and how to debug them, installation guides, etc.

Check out the bulletines at the bottom of this site using this URL.

http://www.carterfueldelivery.com/fuelpumps/support.php


I have the fuel gage flutter problem as well. I haven't bothered to debug it yet but everything I've read indicates the problems in the dash.

Steve

Schrade
10-24-2008, 08:34 PM
Time to go to Helms and get the proper FSM.

HELMS??? :runaround: You know how many pumps you can buy for the cost of a Helms??? Alot!!!

Books? :lol: With diagnostic procedures? And troubleshootin'??? :lol: :p :grinno:

:nono:

I say see if you can haggle with the suppliers, and get a bulk rate discount on a case of pumps. Bout a dozen or so. Ya' know, change the oil, change the pump.

Checkin' and cleanin' grounds. :lol: Pffft. Grounds are over-rated anyway. Just cut the wire, splice on a couple feet extra, and let it drag like a grounding strap. Works every time uh huh!

j cAT
10-24-2008, 08:58 PM
Hi All,

New member as well. Having fuel pump issues with my 1999 Suburban K1500, research lead me to this forum. Pump#2 is on the outs in less than 20k miles.

Steve
pump #2 was manufactured by who ???????


pumps will fail soon if they don't have suffecient fuel to keep them cool...

as you already know both the supply voltage as well as the ground return must be solid..

fuel filters need to be replaced and if you have a problem with pumps.. cut open and inspect for rust...if you have a rusted metal tank you will require its replacement...or buy a case of pumps ..and change the pump every oil change..

monskr
10-24-2008, 11:57 PM
Thanks for the response.
I believe the second pump is an Airtek. I understand this is not the best.

I inquired about lifetime warranty pumps from the local auto parts suppliers and all no longer offer lifetime warrantees. This was telling as to the failure rates in this application. Thatís when I started researching and it seems Delphi and Carter are the best pumps and interestingly enough both provide a connector kit (connector, butt splices and shrink wrap) with their pumps and strongly recommend replacement. High resistance failures at the OEM connector can cause voltage drop and premature pump failure.

Wasn't aware of these issues when I replaced the pump last rounds. Will check grounds and replace connector this time.

Poly 46 gallon tank. Never run it below 1/3 tank.
It's full now so I need to run some gas out of it before dropping it again.

New fuel filter.

Did some testing today. Pressure gauge at the schrader valve revealed 52PSI when ignition turned on. Should be 60 to 66 PSII believe. Surprisingly the truck started. Pressure remained the same until I shut if off. Pressure then creped up to 60 PSI. I bleed the pressure off to zero through the gauge and tried it again. Same results. Even after 15 minutes the pressure remained at 60 PSI with the ignition off.

Symptoms are vehicle will not start on first try after sitting overnight. If the ignition is cycled 2 - 3 times allowing the pump to run the 2 second intervals each time it finally starts. Seems to be getting worse over time.

Any additional suggestions of what to check?

Steve

MT-2500
10-25-2008, 10:24 AM
Thanks for the response.
I believe the second pump is an Airtek. I understand this is not the best.

I inquired about lifetime warranty pumps from the local auto parts suppliers and all no longer offer lifetime warrantees. This was telling as to the failure rates in this application. Thatís when I started researching and it seems Delphi and Carter are the best pumps and interestingly enough both provide a connector kit (connector, butt splices and shrink wrap) with their pumps and strongly recommend replacement. High resistance failures at the OEM connector can cause voltage drop and premature pump failure.

Wasn't aware of these issues when I replaced the pump last rounds. Will check grounds and replace connector this time.

Poly 46 gallon tank. Never run it below 1/3 tank.
It's full now so I need to run some gas out of it before dropping it again.

New fuel filter.

Did some testing today. Pressure gauge at the schrader valve revealed 52PSI when ignition turned on. Should be 60 to 66 PSII believe. Surprisingly the truck started. Pressure remained the same until I shut if off. Pressure then creped up to 60 PSI. I bleed the pressure off to zero through the gauge and tried it again. Same results. Even after 15 minutes the pressure remained at 60 PSI with the ignition off.

Symptoms are vehicle will not start on first try after sitting overnight. If the ignition is cycled 2 - 3 times allowing the pump to run the 2 second intervals each time it finally starts. Seems to be getting worse over time.

Any additional suggestions of what to check?

Steve


Airtex pumps have a high fail rate.
Some will not make it out of the shop and some run a week and die and some may hang on a while longer.
On fuel pumps that come with the connecter plugin kit.
Pitch the butt connectors in the trash can and solder the wire splices and use heat shrink and wire sealer for a good tight water proff splice.

Guide lines for testing a fuel pump.
Always check/test old pump and replacement pump.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.



On testing a fuel pump here is the guide lines.

j cAT
10-25-2008, 11:32 AM
Thanks for the response.
I believe the second pump is an Airtek. I understand this is not the best.

\

Steve

steve it appears you well on your way to repairing this problem ... Airtek pumps are not good...pressures low...

simply replace pump with the recommended types and obviously make sure the feed and return electrical connections are solid...


this should take care of this ,for you , for many years..

Schrade
10-25-2008, 12:05 PM
Clean the injector baskets, and do an ohm test of the injectors.

Pics here...
http://forums.corvetteforum.com/showthread.php?t=2033363

777stickman
10-25-2008, 07:05 PM
One more note. Make sure the pump you buy (hopefully AC Delco) is matched to your VIN.

monskr
10-28-2008, 11:38 AM
Mmm- the site wouldn't let me log in yesterday...seems fine now.

I've got some debugging to do. I need to mount the test gauge so I can drive and record pressures under the various condition for debugging. The hose on my gauge isn't very long but I think I can make it to the windsheild.

I'll post the pressures when I get them.

Steve

j cAT
10-28-2008, 11:51 AM
Mmm- the site wouldn't let me log in yesterday...seems fine now.

I've got some debugging to do. I need to mount the test gauge so I can drive and record pressures under the various condition for debugging. The hose on my gauge isn't very long but I think I can make it to the windsheild.

I'll post the pressures when I get them.

Steve

steve why do more testing??? as MT-2500 said you need 65psi on a cold start ...you got 52 psi....this will not result in a good starting condition as when the temps drop your engine will not have sufficeint fuel to run...

this is well known.....here at these forums ..

monskr
10-28-2008, 04:48 PM
Just because I had not run any on road tests or let the engine warm up completly to verify there was not a quick pressure drop after shutdown. I suspect the pump as well, I just want to be sure. Here's the results:

Outside temp 75 degress F.
Took (5) attemps to start

1st crank 48psi
2nd crank 52psi
3rd crank 58psi
4th crank 59 psi
5th crank 59psi (started)
pressure then dropped to 52psi
45mph - 56psi
55mph - 59psi
70mph - 59psi
Hard acceleration - 62psi
After engine shutdown pressure went from 52psi to 60psi and remained stable.
After 1.5 hours dropped to 42psi
Turned on ignition and it went back to 60psi

Sure looks like a bad fuel pump.

I'll pick up a AC Delco and post the results after replacement.

Thanks all.

MT-2500
10-28-2008, 05:49 PM
Just because I had not run any on road tests or let the engine warm up completly to verify there was not a quick pressure drop after shutdown. I suspect the pump as well, I just want to be sure. Here's the results:

Outside temp 75 degress F.
Took (5) attemps to start

1st crank 48psi
2nd crank 52psi
3rd crank 58psi
4th crank 59 psi
5th crank 59psi (started)
pressure then dropped to 52psi
45mph - 56psi
55mph - 59psi
70mph - 59psi
Hard acceleration - 62psi
After engine shutdown pressure went from 52psi to 60psi and remained stable.
After 1.5 hours dropped to 42psi
Turned on ignition and it went back to 60psi

Sure looks like a bad fuel pump.

I'll pick up a AC Delco and post the results after replacement.

Thanks all.

Go threw the fuel pump test as outlined.

monskr
10-28-2008, 09:55 PM
MT-2500 - OK I'll go through the entire test as listed. How would you suggest blocking off the return line? Do I need to buy a blockoff tool with fittings or is there another workaround I could use?

MT-2500
10-29-2008, 10:17 AM
If a rubber hose on it any place you can pinch it shut.
But may be best to plug it or hook direct on to fuel filter gas in line.
And do not let pump run at full pressure very long.
A few seconds or long enought to get the pressure reading.
Good Luck

monskr
10-29-2008, 01:32 PM
The only part of the pump test I did not complete was blocking the return line. I pinched the return line where it connects between the back of the engine and the hard lines on the frame rail with no pressure increase at all. Just to be clear this was the line without the fuel filter. I tried this a couple of times from start and then with the engine running pinched and released the return line a couple of times with no change in pressure reading.

The pressures posted earlier were from a 35 minute drive around town and on the freeway. I did not notice any pump fade or quick bleed down after engine shutdown on this test.

Looks like the pump.

Even if there's something else going on I want that Airtex out of there. I understand Delphi and AC Delco are vertually the same. Will both offer the same quality?
I can buy Delphi in town but the AC Delco will have to be ordered, even from the dealer. I will wait if there's any question on Delphi quality at all.

Steve

MT-2500
10-29-2008, 01:53 PM
Delphi or AC Delco is the same.

99burbGW
12-13-2008, 06:38 PM
I had a similar problem last year, with my fuel pump stopping. Bought a new fuel pump, problem re-appeared 3 months later. Took the new pump back out and looked inside the top connector - contacts for pump power were discolored (common sign of over-heated pins), and no longer made a good connection. I took the top housing apart, took off the 2 power wires, drilled the top of the plastic housing and added 2 16 gauge red and black wires - soldered them directly to the wires from the pump (be sure to observe the polarity), covered them with heat shrink tubing, epoxy over the hole drilled, and connected them directly to the power wires in the harness. Problem solved, and it's been over a year now.

New problem yesterday - fuel pump pressure was fine, wouldn't start. Re-charged the battery, started fine an hour later - now the fuel gauge jumps. I suspect alternator noise, and will check with my scope tomorrow. I will keep you updated...

j cAT
12-13-2008, 08:24 PM
I had a similar problem last year, with my fuel pump stopping. Bought a new fuel pump, problem re-appeared 3 months later. Took the new pump back out and looked inside the top connector - contacts for pump power were discolored (common sign of over-heated pins), and no longer made a good connection. I took the top housing apart, took off the 2 power wires, drilled the top of the plastic housing and added 2 16 gauge red and black wires - soldered them directly to the wires from the pump (be sure to observe the polarity), covered them with heat shrink tubing, epoxy over the hole drilled, and connected them directly to the power wires in the harness. Problem solved, and it's been over a year now.

New problem yesterday - fuel pump pressure was fine, wouldn't start. Re-charged the battery, started fine an hour later - now the fuel gauge jumps. I suspect alternator noise, and will check with my scope tomorrow. I will keep you updated...

start a new post about this fuel gauge jumping...I would be very interested as this always comes up with no answer...since you have a scope and with your fuel pump repair have the ability to track down exactly whats up with this needle movement...thanks....j cat

gferris1000
06-06-2014, 02:09 AM
Just a heads up. I had replaced my fuel pump about 7 years ago and it just starting acting up again. It felt like a random loss of ground, but after 7-years I figured it was time for a new pump.

Since I replaced the bad factory connector last time, I figured I would just use the same connector this time. Bad move, a week after putting the new pump in the same random pump failure came back.

I dropped the tank again and this time I cut off the wiring pigtail and replaced it with a new one. Upon inspection of the old one, as I was removing the tape covering the butt splice for pump ground the wire came right out of the butt splice and I could see signs of overheating. That was my random loss of ground.

I agree, if you know what your doing these connections should be soldered and heat wrapped. Toss the butt splices, they are a dissimilar metal and will corrode over time and loosen up (the end that slide out of the old splice was now silver instead of copper in color.

All soldered up and it runs great now.

j cAT
06-06-2014, 07:33 AM
Just a heads up. I had replaced my fuel pump about 7 years ago and it just starting acting up again. It felt like a random loss of ground, but after 7-years I figured it was time for a new pump.

Since I replaced the bad factory connector last time, I figured I would just use the same connector this time. Bad move, a week after putting the new pump in the same random pump failure came back.

I dropped the tank again and this time I cut off the wiring pigtail and replaced it with a new one. Upon inspection of the old one, as I was removing the tape covering the butt splice for pump ground the wire came right out of the butt splice and I could see signs of overheating. That was my random loss of ground.

I agree, if you know what your doing these connections should be soldered and heat wrapped. Toss the butt splices, they are a dissimilar metal and will corrode over time and loosen up (the end that slide out of the old splice was now silver instead of copper in color.

All soldered up and it runs great now.

now where I live in the rust belt you might get ONE year out of that butt splice tape job.

warren33
10-07-2014, 03:03 PM
The dancing needle is the dash gauge itself. It occurs when your original fuel pump fails and you replace it with the newer style Delco that requires the harness end to be changed. It happened to me as well as my brother's truck. I have a 99 Suburban that ate three fuel pumps in a row, five all together. The first I replaced with a genuine A/C Delco pump and it lasted two years. I tried Carter / Airtex, Bosch, back to A/C. I did the same thing, changing the rear ground location, added grounds engine to frame, cab to frame, etc. The last A/C pump drove we crazy, it would pass a fuel pressure test each time I checked it, but would cause a higher rpm stumble I couldn't narrow down When I finally decided to replace that pump I finally found a good one. The last fuel pump I installed was a Delphi fuel pump. It has been in for over three years now and still running strong. I replace my fuel filters three times a year, and try to buy gas at the same gas station. I'm glad you lucked out with a ground issue.

j cAT
10-07-2014, 09:02 PM
I find you fuel pump issues along with the fuel filters interesting.

I replace my fuel filters every 30K miles cut them open and they are with some debris but not bad. on the fuel pumps . my fuel pump is 14 years old 150K plus miles. the fuel gauge has been jumping around for over 10 years now but the fuel pressure is still correct as I do check it at the fuel filter 30K replacing interval.

now your filter replacing 3X a year . what do you find in these dirty filters coal ?
you operate with little fuel in the tank ? buy gas at some cut rate joes gas station ?

never found anyone having to replace filter that often some never replace them...

warren33
10-08-2014, 10:57 AM
Same company yes, but you need to take a look at an A/C Delco, then look at the Delphi. The Delphi was more $ as well.

warren33
10-08-2014, 11:25 AM
j cAT, Thank you for judging me as some sort of moron. Notice the lack of replies on my profile. It's is because of these types of reply's I usually don't reply. I simply use this site look up previous issues for pointers on things I am having issues with. While looking, I saw this persons problem and felt his pain and wanted to let him know what helped my fuel problem. I gave the short version and didn't mention I have also replaced the tank and all the fuel lines too. I live in the rust belt and replace my filter more frequently by choice, in part due to the new road salt / liquid calcium mix Penndot is putting down the rusts everything quite quick, and the fuel quality we have in the area. I only drain the fuel filter into a clean container, and tap the inlet end on a paper towel to determine if any thing I see come out would prompt me to cutting into the filter for further investigation. I use almost exclusively Citgo gas due to the complete closing of all the BP gas stations in our area. I'm not going to say my wife keeps the fuel level above half at all times, but I do, because of the percentage of ethanol per gallon of gas, but I have a much better understanding of diesel fuel, due to my trade in a dealership in heavy construction equipment, as well as my part time gig in the fuel transportation business.

j cAT
10-08-2014, 04:03 PM
I did not judge you. just was wondering why you needed to replace your fuel filter 3X in a year. this is a gasoline engine that this posting was about , not diesel fuel.

you may also have a bad / broken / disconnected venting of the fuel system. this would certainly cause dirty fuel ..

no big deal on why you must do all this filter changing because I don't do as you do. then again I live in the rust belt but not in the coal belt and the air in that area is very dirty so the coal dust may be as I guessed the reason.

these forums are to help people solve problems not create problems ..

Joe Bltsphlk
12-10-2014, 05:11 PM
Does anyone know how much current should be flowing to the fuel pump? Assuming the pump is good, as well as the power and ground wires. I measured 5.7 amps on mine, while trying to determine the cause of 52 psi fuel pressure. I saw a video where scannerdanner measured about 7.7 after replacing the fuel pump. Yes, I crimped on the new plug when I replaced the original pump with a Delphi pump almost exactly one year ago. Here's what it looked like before shrinking the heat shrink.

j cAT
12-11-2014, 09:09 AM
Does anyone know how much current should be flowing to the fuel pump? Assuming the pump is good, as well as the power and ground wires. I measured 5.7 amps on mine, while trying to determine the cause of 52 psi fuel pressure. I saw a video where scannerdanner measured about 7.7 after replacing the fuel pump. Yes, I crimped on the new plug when I replaced the original pump with a Delphi pump almost exactly one year ago. Here's what it looked like before shrinking the heat shrink.

these connector wires should be soldered. then the heat shrink will keep them from the corrosion of our rust belt winter atmosphere.

with the key on eng off the pressure should be 60-65PSI..with any pump change this old replace the fuel pump relay. measure the voltage at this fuel pump connector for 11.5 volts plus..pump running,, if lower than there is a wiring problem also make sure the frame rail tank ground is removed cleaned and secured.

the ECT will also cause hard starts. this when old fails to report the correct temp...

Joe Bltsphlk
12-14-2014, 12:02 AM
I wire brushed the ground connection to the frame, but it had no impact on current flow or fuel pressure. Today I lowered the fuel tank to the point that I could disconnect the power/ground line and take a look at the crimped connection. My crimps from a year ago looked pristine, but I measured voltage across them, just in case. There was no voltage drop. I will replace them with soldered connections anyway. I also looked for a voltage drop from the ground wire all the way back to battery negative, and there was none. Total voltage across the pump was about 11.6 volts. Seems like it ought to be close to 12, so I can investigate that, but I don't think it would explain the 52 psi fuel pressure. I can't start the engine with this pressure, so I don't know if a bad ECT sensor is involved yet.

I'm concluding the fuel pump circuit is OK, so maybe it's the fuel pump. (The fuel filter is new one year ago.) By the way, could the fuel pressure regulator fail in such a way that would prevent the pressure from achieving 60 psi? I'd like to briefly close off the fuel return line to see if the pump can get above 66 psi. The procedure says to install a special tool at the union in the return line, near the fuel filter. It's just a valve that you slowly close. Any idea on how to accomplish this same test without the special tool? I'm afraid of pinching off the flexible return line that connects to the pump and damaging it, because I don't know what it's made of.

One other observation: I have two pinhole leaks in the fuel tank. They are up high, and are located at the back end, just above the rubber pad that is squished up against the frame when the tank is secured. I'm sure the holes were produced when I scraped off the dirt that accumulated above the edge of that pad last year when I had the fuel tank completely removed. 1) Do you think this might cause the pump suction to get clogged with corrosion? 2) Do you think these pinholes can be sealed off, for example with some sheet metal screws and maybe epoxy?

j cAT
12-14-2014, 08:41 AM
to be sure the pump is good and all the other factors concerning the pump ,, pinching the return line is done and should not cause a problem. the pressure should rapidly rise to 75 psi with the eng ON...now this must be done quickly like just long enough to see this is reading.

then the low pressure should be caused by the regulator. too much return fuel causing low pressure.

with a metal tank that is rusted / well if rusted then I would replace it. the rust will damage the injectors.. since alcohol is in the fuel this is not good with metal tanks.

sure you can use a product to repair the fuel tank .. marine tex and some fiberglass cloth over the hole will fix it.

see if you can get a scrap yard tank .

Joe Bltsphlk
12-15-2014, 07:41 PM
I squeezed the return line and it had utterly no effect on the fuel pressure, still about 52 psi. I then took off the fuel filter (only a year old) to see if it was clogged, but it was not. I let the gas drain out of each end onto a paper towel, but no debris came out. Then I blew out the rest, and still no debris.

In the struggle to remove the fuel filter, one of the rusty fittings rounded out. The extreme rust on the fuel lines has convinced me to replace them before they fail. The fitting at the front union on the return line refused to let go of the line and twisted it until it failed. So: do I need to install steel lines, or will nylon do? I'm just going to replace the six foot sections that run along the frame. The rest of the lines look OK.

Back to the fuel pressure...what's next, pull the pump and see if the strainer is partially restricted?

j cAT
12-15-2014, 09:15 PM
since the return line being squeexed did not show any pressure increase I would say you did not squeeze it enough becausw it should have moved somewhat. therefore place guage on the fuel filter . key on eng will be off see what the pressure goes to should be over 75 psi and hold for a few min at the high pressure. using steel repair lines or the nylon and steel to complete the line repair is up to you the steel lines are cheaper. using compression fittings and the steel with a bender not too hard about 30 USD or so... surprised 1 yr old filter and it was rusted solid.. perhaps you need better wrenches.. the real bitch will be the quick disconnects at the front/top of the fuel tank/canister .. these with rust and grit are tough to remove.. I did do my return line and supply line in this area recently. then I used a rust preventive on all these metal lines ..

Joe Bltsphlk
12-19-2014, 10:17 AM
I removed the pump from the tank. There was a lot of debris inside the "cup" that the pump sits in. Check out the photo. It was a mixture of fine particles and some bigger rusty ones. The "internal" sock looked like it was clogged up. The fuel tank itself did not have any of the debris. My theory is that the return line is starting to rust on the inside, and the debris is getting carried back into the fuel pump where it gets trapped in the cup. The pinhole leaks in the tank are much smaller than some of the debris, so I don't think they are the source. I cleaned out all the debris, and my plan is to see if the pump can still be used.

I was going to replace the fuel lines with Goodyear fuel injection hose SAE 30R9, but tech support at summitracing said you're not supposed to run flexible line for the entire length of the vehicle, because it will result in too much pressure drop. So I'm looking at NiCopp rather than steel, because there are so many bends. My question is how exactly do I get it to mate up with everything else. For example, it seems like all Dorman connectors are for nylon tubing, like part 800-080. At the fuel filter connection, do I use a compression fitting to Dorman 800-153?

j cAT
12-19-2014, 04:48 PM
I would replace the return line most of it with the nylon. one long piece. use loom to protect where needed. then on the ends use the nylon to steel adapters. use plastic tystraps/raps to secure this line to the old bending is not a problem and this is a faster way .. you still have a tank with rust holes this is not good.

steel tanks/steel fuel lines are not good with this ethanol fuel. nylon can take the supply pressure easy. I would not use rubber hoses not good with alcohol and other gasoline additives and injectors ... rubber is bad idea..back in the non alcohol era it was ok..

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