1995 blazer fuel pump?

A couple of years ago, Blazer LT helped me to install a new CPI and nut kit. I am hoping he or someone can help me with a new problem. Last night the blazer stalled on my wife on the Interstate. She said it just cut out. When it came to a stop she was able to get it started, though it barely ran, and was able to get to the shoulder. When I got there it would not start and I could not hear the fuel pump kick in/whine. So I am guessing it is the fuel pump. I towed it home and picked up a new fuel pump. I have been unsuccessful in siphoning out the gas, so I thought that I would take the fuel filter out in hopes that it would just drain out there. A little came out but not much. So, I decided to turn the key on thinking that it might open up a valve on the fuel line/pump. To my surprise, the fuel pump kicked on and sprayed some gas. I tried it a few times (with the fuel filter removed), it kicks on sometimes and some times it does not.

Do you think the fuel pump is my problem? If not, what should I test? If so, how the heck do I get the gas out of the tank? It is 3/4 fuel. My siphoning effort fail because I can't seem to get the hose in far enough into the tank - the hose is not even getting wet - must be too many bends.

I appreciate any help!

First thing you need to check the fuel pressure and for good hot blue spark with everything hooked back up and on.
Did the check engine light come on before it quit.
If so check codes and post back code no.
And Before you hook up fuel filter see if you can blow threw it.
Could be clogged.

Post back fuel pressure with key on engine prime up and with engine cranking and if you have good spark to more than one spark plug.

check the fuel pressure and for good hot blue spark with everything hooked back up and on.
Did the check engine light come on before it quit.

Post back fuel pressure with key on engine prime up and with engine cranking and if you have good spark to more than one spark plug.[/QUOTE]


HI Mt - Thanks for the reply.

I thought about checking for the pressure but my gauge does not go high enough for this vehicle. Any way around this or do I need to break down and buy another gauge? I can tell you this, I went to releave the pressure at the shrader valve - there was some there but very little. This was with the key off and the blazer had sat over night.

I will try compressed air from the forward fuel filter line toward the engine to see if it is clear. I will also check for spark. And, I will put the new fuel filter in.

The ckeck engine light did come on about two weeks before this happened. It was on for 3 days and never came back on again. All this time it was running good. I do not have a scan tool. I had broght it in to the auto zone to get the code read but they were unable to get their scan tool to work with it. They said it was something to do with a cross over year? My Blazer is a W vin code if this means anything.

The old scrader valve squirt is not a very good test and after sittiong all night the fuel pressure will leak off anyway.
To keep from just throwing parts at it you need to do some testing.
Check for good hot blue spark to more than one spark plug.
If you have good spark then borrow or rent or buy a good fuel pressure gauge.

Some parts places loan or rent fuel pressure gauges.

You need to check for full fuel pressure with engine cranking.
When key is first turned on you should hear a 2 second fuel pump prime up.
But sometimes it takes engine cranking or a couple of key off and on to get full pressure and also watch for a fast leak down after pump quits running.

The 4.3 W engine needs 60 lbs of fuel pressure to start on a cold start.

A quick test for fuel problem is to see if the engine will start on a squirt of carb cleaner.

Also check all fuses.

Let us know what you find.
MT

Hi MT

I installed the new fuel filter.

I checked for spark. One plug on each side. Had very good blue spark, although the plugs should be changed - pretty worn. Boy are they hard to get to! - I remember now why I had the dealer chang them last. I think this set has 80K miles on them.

While checking for spark, it did fire a couple of times but it never started. I also noticed that the fuel pump never energized during any of this like it was doing every once in a while this afternoon.

I also checked all fusses by the drivers door. All were good.

I will go purchase a high pressure fuel pressure gauge tomorrow morning. I will post back my readings.

If you think of anything else, please let me know. I sure appreciate your help!

Check this Thread (http://www.automotiveforums.com/vbulletin/showthread.php?t=633098) to trouble shoot the fuel pump and replacement if necessary. (Includes how-to on draining fuel tank with photos on pump replacement)

Let us know what you find.

Hello Del Coch and MT,

Great pictures on the other thred - in my search I did not come accross this - so thank you!

Here is my update. Went and purchased a fuel injector pressure gauge and hooked it up to the shrader valve. The gauge is showing zero pressure even while cranking. This is a little odd to me because when I hit the pressure relief valve on the pressure tester fuel spews out at a pretty good rate - so I am not sure while it isnt registering some pressure.

Next I tried to locate the fuel circiut test wire. The only unused lead I could find is a blue wire. The other thread seemed to indicate that it was a red wire? Have I located the right wire? In any event, I hooked up a fused 12 volt lead to this blue wire and nothing happened. I then tried cranking it over while this test wire was hooked up - still no pressure on the gauge or no sound from the fuel pump.

What do you think my next step should be? I read about a fuel pump solinoid in the glove box and that it should click. I am not hearing any clicking sound. I have two solinoids in the glove box - which one operates the fuel pump? Should I replace this and see what happens.

I am anxiously awaiting a response and I really appreciate all the help. Thanks.

The gray wire feeds power to the fuel pump.
Hook a fused jumper to it and see if fuel pump runs.
And also check fuel pump ground.

If fuel squirts out the scrader valve your gauge should show pressure.
Check your gauge connector.

Can you hear the fuel pump run at any time?
Key on 2 second prime or engine cranking or with gray feed wire jumpered with 12 volts?

The gray wire feeds power to the fuel pump.
Hook a fused jumper to it and see if fuel pump runs.
And also check fuel pump ground.

I cannot find any grey wire in this area and I have looked many times over. In another post it said this wire is a red one. There is a blue wire in mine - but when I put power to it it does not seem to do anything. Where is the fuel pump ground? I can check that.


If fuel squirts out the scrader valve your gauge should show pressure.
Check your gauge connector.

I checked the gauge connections - seem good. I removed the gauge and hooked it up to my air compresser and it worked. Hooked it back up to the blazer and still showing zero even while cranking. Some fuel does purge out of the shrader valve so there has to be some pressure.

Can you hear the fuel pump run at any time?
Key on 2 second prime or engine cranking or with gray feed wire jumpered with 12 volts?[/QUOTE]

I have not heard the fuel pump whine at all today. It did intermitently yesterday.

I am not sure how to proceed.

The gray wire should be on back side of fuel pump relay.
CAN YOU HEAR OR FEEL THE FUEL PUMP RELAY KICK ON.
On the key on 2 second prime up.

If you can not get to it there.
Go back to the fuel pump plug in at fuel tank.
Tap and check the gray wire there.
You can also check for the ground grounding there.
Reverse a bulb type test light to the positive side of battery power to check for ground.

Check and test it at the 4 wire fuel pump plug in.
If it does not run with the gray power feed wire jumpered and it has a good ground then your fuel pump mhas went over the hill.
MT

I do not understand. I thought the grey test lead wire was on the driver's side near the brake master cylinder. You are stating that it is behind the fuel pump relay which is in the glove box. I do not see access to get behind the relay to get to any wire. And, on the engine bay side access is blocked by the heater fan motor.

What I did do - and I am not sure if this tells us anything - is I hooked my voltage tester to the positive terminal of the battery and onto the grey wire at the fuel pump/tank. With the key on, it registered 11.68 volts.

Does this tell you anything? What do you suggest I try next? Sorry if I am not following you on the grey wire thing - I am just confused. Thanks.

using a second 12 volt battery source back at the fuel pump, I put the positive into the grey connector and the negative into the black connector. Nothing happened. No clicking no noise, no nothing. Can I assume the fuel pump is dead or isn't this how it is powered up?

What I did do - and I am not sure if this tells us anything - is I hooked my voltage tester to the positive terminal of the battery and onto the grey wire at the fuel pump/tank. With the key on, it registered 11.68 volts.

Does this tell you anything?

This tells me that you're lucky you didn't blow your meter.

Connect the black lead of the meter to the chassis (ground), turn key on, and with red lead of the meter, probe the gray wire at the fuel pump. If any voltage around 12V shows up, you have power to the pump. I'm not sure which wire is the power feed on the connector, because you also have the level sensor in there, but check them all for power.

Next, set meter to "ohms" setting, and probe the black wire (to see if black is actually the ground). Low reading (<0.5 ohms) will indicate good ground.

BTW, My '97 has a RED test lead wire inside the engine compartment, near the firewall, driver's side, with a spade terminal on the end. This is "supposed" to be the fuel pump hot wire, but I tried it once when I had EEM problems, and I got nothing to the pump. You might want to swap the relays in the glove box, just to eliminate the relay as a cause of the problems. One is fuel pump, the other is A/C - I think.

using a second 12 volt battery source back at the fuel pump, I put the positive into the grey connector and the negative into the black connector. Nothing happened. No clicking no noise, no nothing. Can I assume the fuel pump is dead or isn't this how it is powered up?
Yes that is the 12 volt power to fuel pump.
But also check for good ground on black wire.
You have to have good power and good ground to run the fuel pump.
A old bulb type test hooked to a 12 volt positibve sourse and touch the ground with other end and if you ghave a ground the bulb should light up strong and bright.

While you have a jumper on gray fuel pump wire tap bottom of fuel tank with a rubber hammer.

MT - I will try what you just wrote, next.

Mike, with the key on, I registered .025 volts on the grey wire, 8.3 volts to the purpleish wire, and zero volts to the back wire. Does this mean I am not getting sufficent power to the pump? The battery is new and measure just under 12 volts. I am sure it was over 12 volts but I have had the hood light on for some time now.

MT - I ran a wire from the positive side of the batter to the test light. I plugged the other end of the test light into the black wire terminal on the fuel pump harness. It light up nice and bright.

I also ran a positive line from the battery to the grey wire on the pump. Nothing happened until I tapped on the tank with a rubber mallet. The pump came to life.

Now what??? Is the pump good bu the connection somewhere is bad???

now that the fuel pump is working after tapping on the tank, I have 59 lbs of pressure when I turn the key on. It starts right up and runs at about 55 lbs. When I shut it off it stays at 55 lbs.

So the pump seems to be strong, but what do I need to do to make sure that it stays working? My wife will not carry a mallet with her in case it doesn't work one day. She would probably hit me with it, though!

now that the fuel pump is working after tapping on the tank, I have 59 lbs of pressure when I turn the key on. It starts right up and runs at about 55 lbs. When I shut it off it stays at 55 lbs.

So the pump seems to be strong, but what do I need to do to make sure that it stays working? My wife will not carry a mallet with her in case it doesn't work one day. She would probably hit me with it, though!

Oh yes if you do not replace it now she may take the mallet to you.
Because it may quite all together the next time.
But At least you done the proper testing and found the problem.

If you have to tap on it to get it to run the fuel pump is on it's last leg.
May start the next time and may not.

Replace it and be done with it.

I would suggest the GM delphi fuel pump for it.

Check your blazer listing .
I think on that one you can replace the just the fuelp pump.
But sure you have not fried you fuel gauge unit.
Jumping the blue or purple wire is not good.
After market brands such as airtex do not have a good track record.
Good luck and let us know how it goes.
MT

Thanks MT - I guess I will start the tear down process. The fittings on the tank are really rusty. I have had them soaking for 24 hours now. I hope I can get them free. I will post progress.

Thanks MT - I guess I will start the tear down process. The fittings on the tank are really rusty. I have had them soaking for 24 hours now. I hope I can get them free. I will post progress.

Go easy on the lines.
The fuel pump hanger with tubing out of the tank is about 300 bucks at cost.
Get some good line wrenches and do your best to save it.
Good Luck
MT

Mt - Are you still around by chance? I got the threads loose on the fitting I can get to. However, I am assuming that the metal line should have a swivel nut and that the rubber line would have the fixed nut. The problem is that it will not swivel. Obviously I can not heat it! I am not sure what to do to get them free. I have been non stop soaking them with PB blaster and have been trying to work them back and forth but no success. I can't believe they don't make this out of a better material especially if it is so expensive. I certainly welcome any suggestions!

Mt - Are you still around by chance? I got the threads loose on the fitting I can get to. However, I am assuming that the metal line should have a swivel nut and that the rubber line would have the fixed nut. The problem is that it will not swivel. Obviously I can not heat it! I am not sure what to do to get them free. I have been non stop soaking them with PB blaster and have been trying to work them back and forth but no success. I can't believe they don't make this out of a better material especially if it is so expensive. I certainly welcome any suggestions!

Yes it should swivel but may be froze up.
Keep working at it . Tighten up and lossen up.
OR
Is there ant way you can get the other end of line lose and of of frame and take it down that way?

If not you may have to cut the line.
But cut it where you can reflare it or get another line.

Hi Mt - I thought about that too. But, It looks like the other end of the rubber hoses are fixed (no removable fittings) right to the steel fuel lines that run up along the frame rails. I'll take a closer look at it but that is what it felt like.

. . . the other end of the rubber hoses are fixed (no removable fittings) right to the steel fuel lines that run up along the frame rails.
You're right - the rubber hose is a permanent connection to the metal line.

The smaller metal line is the return line and you can cut it and splice it back together with a rubber gas hose. The larger metal line is the high pressure line and it carries too much pressure to be spliced with a rubber line.

Just be patient and soak the line and nut a lot. Be careful not to twist the metal line and eventually it will break loose. You may have to soak it for a couple days or so, but keep it wet with your PB Blaster. The gas line running up the frame is a bear to replace; the high pressure line runs all the way from the tank to the fuel filter without a connection in it and there’s no room to work in there.

Good luck and keep up posted.

Hi Guys, I am just going to keep it wet with PB Blaster for a couple of days. I plan to try it again on Saturday. The smaller line did bend/twist a little but I do not think I cracked it. Any way, if I did - it is good to know that this is the return line so I could hose clamp a rubber line in there if necessary.

I have not tried the larger line yet since the smaller one is in the way. I sure hope it works but it is really rusty. And, I mean really rusty.

This vehicle was only driven in Mn Winters (stored all summer)....and it has 230,000 miles on it! I have just put new ball joints, exhaust, brakes, and tires on it so I would like to keep her going. The body on this truck literally looks new, though. I have kept it washed all the time. BTW, this is the original fuel pump!

I will post back progress. Thanks for all the help!

Check with your local Auto Parts stores and see if any of them carry "Zep" Penetrating Oil. It's a lot better than PB Blaster - actually it's the best on the market. It comes in a couple different colored aerosol cans, some are blue others are yellow.

Thanks for the suggestion on the Zep. I went to the two auto parts places in the town I work in and neither has it. I have two more stores in my home town that I will check out this evening. Wonder if this is something that a walmart would carry? - probably not, though.

It's hard to say if WalMart would have it or not. It would be worth checking on. Most of the Auto Parts stores don't carry it in my neck of the woods either. I don't know why, as it's really great stuff.

It's hard to say if WalMart would have it or not. It would be worth checking on. Most of the Auto Parts stores don't carry it in my neck of the woods either. I don't know why, as it's really great stuff.

Very Gocd stuff.
Run a web search for there web site.
The only way I can get it is to order from Zep manf co.
Or the old Zep route salesman.
MT

Hi Guys,

I got both lines off after working them back and forth with 1.5 cans of PB blaster! The return line is a little twisted but I think it will be alright. I just hope that the ring on top will come out once the tank is out.

Now, as for taking the tank out - I have both straps very loose. I have the hose clamps off of the filler and breather tube rubber couplers and I have loosened the rubber couplers as best I can by prying between them and the pipes. I am not sure what is holding up the fuel tank right now - is it just the filler and breather lines that are supporting it. How do I get it down and get these filler and breather lines to disconnect? I don’t want to break anything or start any fires! BTW, the tank is 1/4 full - I am hoping to drain the rest once I am able to remove the filler coupler. I also have stands under the tank for when I am able to bring it down.

Also, there is a small breather spigot on the top of the tank with a rubber hose connected to it. When I went to remove the hose the spigot broke. There is another one of these in the front of the tank - I have not touched this one. How do you guys remove these without breaking them?

bump

Ok - I got the new pump in and it is running well! This was not a fun job! Anyway, I broke both of the plastic fuel vent/valves that are on top of the tank. My local supplier said they are a dealer only part and of course our GM dealer is not open on Saturdays. Are these necessary to keep it running or are these vents/valves a safety feature? I really do not want to drop it down again to put these in but I will if they are necessary. Thanks for all the help!

I should add that both of these vents/valves function and are installed in the tank - it is the plastic nipple that I broke off so they are not hooked up to the rubber lines

I should add that both of these vents/valves function and are installed in the tank - it is the plastic nipple that I broke off so they are not hooked up to the rubber lines

If just the vacuum line it may run but you are going to have some emission canister vent problems.
It would be better to get them and replace them.
Good job on getting the lines lose and pump replaced.
MT

Thanks MT -

I went and topped off the tank and when I got home it was leaking fuel pretty steady. It was coming down the front of the tank - my guess is it is from these vents/valves that I broke - but I don't know for sure. I will go get new ones next week and take the tank back down and install them. Hopefully ,this is where the leak is coming from. I don't think it is coming from any of the fuel line fittings.

I am not looking forward to taking it back down but I am sure it will be much easier this time around, especially not having to deal with stuck fittings!

I purchased the new fuel tank vents/valves from the Chevy dealer that I broke off. I lowered the tank and installed these. It is running good and does not leak now. The only problem is that the check engine light is back on again. I disconnected the battery and reconnected it - but the light is still on.

I do not have a scanner and the last itme I brought it to AutoZone they said their software would not work on my blazer due to it being a transition year. Is there any way I can ckeck this myself or do I need to buy a scanner? If I need a scanner - which one do I need and how much will it cost? Thanks for the help.

Yours is one that needs a high end scanner high dollar scanner with a special adapter to check it.
For a one time check.
Best to find a good repair shop that has one to check it for you.
If the check engine light came on because of vent valves and you have them fixed it will reset itself and turn off after a few drive cycles.
MT