1996 suburban fuel pump

flintgen · #1 01-31-2006, 02:28 PM

hello

i have a 96 suburban with 230000 miles on it. recently the fuel pump went out on it and i have changed that out. i can now hear the fuel pump engage however the truck will not start. will not even act like it is going to start. any suggestions? the fuel filter was changed about 2 months ago. any help appreciated. thanks

Old Dave · #2 01-31-2006, 03:34 PM

Have you checked the fuel pump pressure with a know good gauge at the fuel rail? I would do this first and make sure you're getting the correct pressure, which according to the Mitchell book should be 55-61 Lbs. When you turn the key to the on position (not start) the pump should run for 2-3 seconds and build a minimum of 55 Lbs. If you're not getting it up to there work your way back towards the tank.

777stickman · #3 01-31-2006, 08:16 PM

Did this just happen or did it run with the new fuel pump? What engine and model??........Steve

flintgen · #4 01-31-2006, 09:53 PM

in response to steve's question the fuel pump went out on this vehicle. i could not hear the fuel pump engage when i turned the key and it would not start. that is when i changed the fuel pump and since changing it can not get it to start put i can her the pump operating. it has a 350 in it.

thanks

MT-2500 · #5 01-31-2006, 10:01 PM

You need to get a fuel pressure gauge on it and check fuel pressure.
Fuel pressure specs are 60/66 on that one.
here is guide lines on checking fuel pressure.
I know you can not check the running pressure untill it starts but do the other checks
Also check for good hot blue spark to all plugs.
Hard to start cold.
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.
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.
Post back fuel pressure readings.

SM401 · #6 04-18-2006, 05:06 PM

My 98 (125K) just started doing the same thing. The fuel pump is working - but it won't start. Didn't start one day a couple weeks back. Shot some quick-start and it fired right up. Then the other day - I drove it a couple miles - no problem. Came home, shut it off. 15 minutes later...cranked - but wouldn't kick. Quick start made it fire - but it wasn't pretty. I'll pick up a fuel pressure gauge and go from there. I've already picked up a new fuel filter. Can't hurt.

MT-2500 · #7 04-18-2006, 06:42 PM

Quote:

Originally Posted by SM401

My 98 (125K) just started doing the same thing. The fuel pump is working - but it won't start. Didn't start one day a couple weeks back. Shot some quick-start and it fired right up. Then the other day - I drove it a couple miles - no problem. Came home, shut it off. 15 minutes later...cranked - but wouldn't kick. Quick start made it fire - but it wasn't pretty. I'll pick up a fuel pressure gauge and go from there. I've already picked up a new fuel filter. Can't hurt.

GO EASY ON THAT QUICK START.

Safer to use carb cleaner.
Post back fuel pressures and check it when it gives trouble starting.
Might be better to start a new post on it.
MT

SM401 · #8 04-20-2006, 09:40 AM

Got the fuel filter changed last night. Was kinda surprised when the gas just kept flowing out. Was expecting some from the lines - but when I drained a gallon and it was still coming....I figured it wasn't going to stop. THe tank was full. Must have been siphoning. Anyway, I was able to keep my thumb over the line long enough to 'get er done'. A gear-head friend came by - and we determined that the fuel pump was working, there was pressure - tho we didn't have a gauge to check it....and it is getting spark. He thinks it's a sensor gone bad. I plan to pick up a code reader and a pressure gauge - hopefully tonight.

MT-2500 · #9 04-20-2006, 09:55 AM

Quote:

Originally Posted by SM401

Got the fuel filter changed last night. Was kinda surprised when the gas just kept flowing out. Was expecting some from the lines - but when I drained a gallon and it was still coming....I figured it wasn't going to stop. THe tank was full. Must have been siphoning. Anyway, I was able to keep my thumb over the line long enough to 'get er done'. A gear-head friend came by - and we determined that the fuel pump was working, there was pressure - tho we didn't have a gauge to check it....and it is getting spark. He thinks it's a sensor gone bad. I plan to pick up a code reader and a pressure gauge - hopefully tonight.

Check that fuel pressure. Even 2-3 lbs low can give a no start cold.
MT

MT-2500 · #10 04-20-2006, 10:25 AM

Quote:

Originally Posted by SM401

Got the fuel filter changed last night. Was kinda surprised when the gas just kept flowing out. Was expecting some from the lines - but when I drained a gallon and it was still coming....I figured it wasn't going to stop. THe tank was full. Must have been siphoning. Anyway, I was able to keep my thumb over the line long enough to 'get er done'. A gear-head friend came by - and we determined that the fuel pump was working, there was pressure - tho we didn't have a gauge to check it....and it is getting spark. He thinks it's a sensor gone bad. I plan to pick up a code reader and a pressure gauge - hopefully tonight.

Here is a link with some good oinfo on checking fuel pressure.
It might take a while to go threw it but you will know how to check fuel pressure when you do.
http://www.automotiveforums.com/vbul...d.php?t=540525

SM401 · #11 04-27-2006, 02:45 PM

Quote:

Originally Posted by MT-2500

Check that fuel pressure. Even 2-3 lbs low can give a no start cold.
MT

Okay, I went to buy a code reader - and the store had used readers available. You "buy" it, use it - then return it for a full refund when you're done. Works for me!

Anyway, I had a couple P0108's - but after reading the translation - it didn't seem to fit the symptom. I erased the codes. Then I checked the throttle-body - and found it to be filthy. I sprayed carb-cleaner in. Turned the key - and it fired right up. Then it quit as soon as it burned up the carb-cleaner. Tried this several times with the same result. No further codes - but it won't start.

So...

The fuel pump is pumping
The fuel filter is new
There is fuel pressure (tho I don't know how much)
There is spark
The engine seems to run fine, but no gas is getting through.

I know I should check the fuel pressure - but I hesitated at spending $40-50 for a gauge until I know for sure that I'll need it. If the fuel pressure is not right, WHAT would be causing incorrect pressure?.....and how would I go about fixing it?

Which sensors - if any - would shut down the injectors? Would the MAP sensor cut off the gas completely?

MT-2500 · #12 04-27-2006, 03:19 PM

Is it a 5.7 350 engine multi port fuel injection?
If you have spark and no anti theft the only other thing that could shut down injector pulse is no 12 volt power to them or the computer.
Check emc 1 fuse. It feeds 12 volt power to injectors.
If power there check the injector 12 volt power to them and for pulse with a niod light.
If you have pulse you need to check that fuel pressure.
Some parts places will rent or loan a fuel pressure tester.

Hard to start cold.
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.
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.
Post back fuel pressure readings.

MT

SM401 · #13 04-28-2006, 04:07 PM

[quote=MT-2500]Is it a 5.7 350 engine multi port fuel injection?
If you have spark and no anti theft the only other thing that could shut down injector pulse is no 12 volt power to them or the computer.
Check emc 1 fuse. It feeds 12 volt power to injectors.
If power there check the injector 12 volt power to them and for pulse with a niod light.
If you have pulse you need to check that fuel pressure.
Some parts places will rent or loan a fuel pressure tester.
----------------

Thanks! I'll check the fuses and power. That seems to fit the symptom - as it was running fine - and then when I tried to start it 10 minutes later, there was nothing as far as fuel to the cylinders. No anti-theft (that I know of!) - and it is a 350.

Next on the agenda is my Dodge Van that had a mouse nesting on the block - and chewing on some wires! At least that one is running. Only #6 is down. After that, it's on to my daughter's Buick. That one runs - but I think her boyfriend dumped trans fluid in the oil - or something. It's parked until I can changed the oil and then get the trans flushed. Then I'll take it from there.

Have a great weekend.

flht · #14 05-01-2006, 02:36 AM

I will add this, my problem is with cold start only, I will crank for 6 to 10 seconds and then it will start, at warm temps (above 50 degrees) it will start with just a touch of the starter. The following was done in steps without a change in the results. I have changed the fuel pump, filter, fuel pressure regulator, complete tune up (plugs, wires, cap, rotor, new duel batteries, had timing checked and distributor gear checked) the fuel pressure is 58 PSI (seems low by my book). will raise to 79 psi with return line shut off. Code reader does not get a code. some times I get a O2 code but it points to the exhaust (it has a 2 1/2" MAGAFLOW system) Sorry for the long list everyone.

SM401 · #15 06-08-2006, 04:09 PM

Follow up on my fuel issue. Turns out it was the fuel pump. The mechanic had seen this issue many times in the past. THe dealer I bought it from had put an after-market cheapo fuel pump on it. Mechanic said they last about a year on average. Mine lasted about 15 months. It was still pumping - but not enough pressure for the injectors to open up. They replaced the bad fuel pump with a REAL one. Back in business....AND my fuel gauge is working again!

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