1995 blazer fuel pump?

[JasonSpaeth]

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!

[MT-2500]

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.

[JasonSpaeth]

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.

[MT-2500]

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

[JasonSpaeth]

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!

[DelCoch]

Check this Thread 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.

[JasonSpaeth]

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.

[MT-2500]

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?

[JasonSpaeth]

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.

[MT-2500]

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.

[MT-2500]

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

[JasonSpaeth]

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.

[JasonSpaeth]

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?

[mike2004tct]

Originally Posted by JasonSpaeth

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.

[MT-2500]

Originally Posted by JasonSpaeth

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.