fuel pump or relay?

[blue92]

My 92 5L decided not to start today. It gave me no warning as she was running just fine earlier. I hopped in after lunch and cranked it over, but no go. I checked under the dist. to see if it was moist butit looked fine. About a year ago I had to replace the ignition modlule under the dist. I thought that may have went out again. I had a guy turn it over for me while I checked the injectors for fuel; there was none. I couldn't hear the fuel pump when I turned the key to accessory, but I was under a speaker playing music at the lot I was in. Both the injector fuses; one on fire wall and one by steering column looked good. There is the fuel pump relay on the firewall that I couldn't check cause I didn't have the voltmeter with me. Does this sound familiar to anyone? Any tips with testing the relay would be helpful. I don't want to change the fuel pump for no reason. Please help.

Ryan

[ChevLoRay]

There are posts and threads on here that deal with fuel pump issues. Try doing a search and see what you find.

Also, I'm sure that someone with the right words will let you know what you need to know.

[scotts62]

Yes there is a fuel pump relay on the left side of engine bay looking at the engine, check the ground on the top of the frame just under the fuel door. If all that checks out and is good sometimes you can have someone turn the key as you hit the bottom of the tank and if the pump comes on then i would replace it before it leaves you stranded again.

[bwood]

No fuel during cranking and you can hear the pump would point to the ignition module again. The module has a cranking and a running mode. The cranking mode is just what it sounds like, it is looking for engine rpms under 400. If it doen't see any, the ECM will not trigger the injectors. Once the module sees above 400 rpm, the ECM will go into running mode and start using all the other sensor inputs. Try using a little fuel or some starting fluid and see if it starts. BE CAREFUL, IT SHOULD ONLY TAKE A SMALL AMOUNT OF FUEL AND READ THE INSTRUCTIONS ON THE STARTING FLUID, IT ALSO ONLY TAKES A LITTLE. If it starts with the fuel/starting fluid, the module is still working in the running mode. The modules can be tested at many parts stores for free. Make sure to test it at least 6 times as they do heat up and only one test may give false results. When reinstalling the old or installing a new module, make sure the alum mounting surface of the distributor and the bottom of the module both have some heat sinc compound on them (not dielectric grease) or it will fail from overheating.

[BigBlocksRule]

Whack the tank a few times, then see if you can hear the pump. If it's close to out but still working, you may be able to start it with a good shake, kinda like a starter.

[bwood]

I just reread and you say you couldn't hear the pump, sorry. Find the relay and have someone turn the key on, it should click on and off for the prime before starting.

[blue92]

After the tow company dropped it off I went out to turn it over just in case. I did the process slow, so I could listen for fuel pump or the relay clicking on then off. Turned the key to accessory and I could hear the relay "click", turned the engine over and it started right up! What's up with that? Should I trust the results or should I look into at least picking up parts for when she fails again? Thanks all

[blue92]

Don't think it's the fuel pump any more. After the truck started, I drove it to work without any issues. After I parked and shut it off I tried to start it again to see what would happen; it just cranked and cranked and wouldn't turn again. I can hear the relay click and prime the system, so I'm not sure if I have a fuel issue know. Gonna let it cool completely and see if she starts. It seems that after it sat and cooled last night that helped it start. I bought an ign. cntrl. module just in case. I'll install it after I try to start it this evening. Guess it's good to have a spare anyway. What does this sound like in your experiences?

[blue92]

Just installed the new ignition control module and that did not fix it. I had a friend tell me that I probably still need to replace the fuel pump. That it starting this morning is kinda normal when they are going bad. What do you guys think? I've been trying to not have to do the fuel pump, but I guess that's the next step.

[bwood]

The pumps can give false hope when going out, making you think they might be good. It might be worth the money to install a pressure test tee into the system and put a gauge to it. IF you can hear the pump and it still doesn't start, you might concider inspecting the rubber hose between the pump and the sender unit in the tank. They have been known to split and spray the fuel in the tank and not build pressure in the system. Unfortunately to inspect the hose mentioned, you will have to pull the pump. When it doesn't start, have you tried some starting fluid or something?

[blue92]

Bwood,
I have tried starting fluid and it runs for a second or two and dies. It's probably just burning the starting fluid and still not getting fuel, right? Thanks for the tips. I'll be replacing the pump as soon as the weather clears. I got a nice piece of advice; since it's a pickup I've heard it's easier to unbolt the bed and move it back for access to the tank, rather than pull the tank and juggle it around.

[sfran]

I have done three pumps in my 96. The last one I did was the same as you described. Parked it and it wouldn't start 2 hours later. If the pump does not make a noise with the key turned on, it is most likely the pump. They act really funny when they are on the way out. I put a fuel pressure guage on the fuel line and cranked it and it only had like 18 PSI. Not enough pressure to start it. If you have a pressure guage, put it on, if not pick one up. They are a cheap way to tell if you have pressure. I have unbolted and lifted the bed off the three times I did mine, the easiest way in my opinion, although I kind of have it down to a science now. I can't recall the exact pressure it should have, I think like 60 -70 PSI. I will check when I get home and post it as I left the guage on my truck.

[scotts62]

92 should have around 13psi, use the T inline where the fuel filter goes.

[Damien]

If you take the fuel filter off to check the pressure, Make sure you are prepared to change a fuel pump. I have had a handful of trucks that drove in for a tune up, I change the fuel filter and It won't start. Once a weak pump looses its prime, it will not restart.

[blue92]

Fixed it today. After testing the relay and old pump we deemed it to need a new pump. Just wanted to check all possibilities before I got to the pump. I took the bed off cause the tank was full. It was fairly easy. Way easier I've heard versus dropping tank, but I've never done either. Replaced the fuel pump and she fired right up. Put bed back on and re-connected the taillights. I learned a lot about diagnosing and repaired something on my truck that I never have before. Thanks sfran and erveryone else for their replies. This forum rules!

[scotts62]

Originally Posted by blue92

This forum rules!

Good glad to hear it, and we think so too

[umwtnt]

One item to remember on these trucks is do not run the tanks below a quarter of a tank of fuel. These pumps are cooled by the fuel in the tank and without the fuel as a coolant they run hot and will gradually die out.

[ChevLoRay]

Ruh-Roh....my truck spends most of it's time with the gas guage needle on the lower end of the guage. I try to keep it above a 1/4, but I only live 3 miles from my job and that's just the facts of life.

[scotts62]

Guess mine runs hot all the time then because it lives around a 1/4 tank

[sfran]

Your welcome. I know these pumps can be a REAL pain in the butt. You'll get used to replacing them lol I did just check my pressure and it is 58 PSI. I used an Accell pressure gauge that mounts to the fuel rails and leave it mounted all the time. This way if my truck acts up I can check the pressure real easy and fast.

Steve