1998 Silverado-problem with fuel pump?

[mcconaughy]

My truck turns over but would not start. I noticed that the coolant line was broken off so spent the weekend getting the old threads clean and getting new line in, but that isn't even the problem.
I then took out the fuel filter late last night and noticed I could not blow air from one end to the other, this morning I walked over to Napa got a new filter and noticed I could blow air(from my mouth)through either side so thought that was the problem. Whopee, I thought problem solved so went home at lunch, put in fileter and expected it to start, NOT.
Before all this happened I had a "whiny"fuel pump and has always been that way. I did notice now when I turn ignition on I don't hear fuel pump "click on" like a freind said it would.
I don't have any electrical equip for checking things and am not really very good at working on cars but am broke and need to fix it myself.
Any ideas on a logical sequence of steps I might try.
Thanks in advance for any help.

[777stickman]

In the "underhood fuse block" there are the "ECM B" Fuse (20a) and the "Fuel Pump Relay". Check or replace those 1st. Make sure you disconnect the NEG batt cable 1st as the fuse has power to it at all times. If those don't help, check wiring, otherwise you'll probably have to replace the pump.

[mcconaughy]

That makes sense, I have a couple of other questions.
1) Is the "fuel pump relay" something that NAPA could check for me if I brought it in to them?
2) Since the fuel filter was totally plugged, could that cause the relay switch to overload and fail?

I was also browsing yesterday and noticed that other people have "whining fuel pumps" mine has always done that, people always say it is getting ready to fail but it seems that it is common and is more annoying than harmful.
I really appreciate your help,thanks again.
Rick

[mcconaughy]

Well I pulled the relay and took next door to NAPA, they couldn't test it but had one in for $18. I went to another auto parts store down the street and they couldn't check it but their price was only $10 so I bought it and went home and replaced it and checked the fuse but still no start.

I guess the next step is to pull the fuel filter and see if I can get fuel on the side before the filter, if not then I would assume it's the pump, if I do get fuel, then guess it is still on the other side of the filter.

Does that make sense?

[Riche]

Rick,
try getting a test light and test the wires at the fuel pump. One of them should light up when the key is turned on. (if you can remeber before your truck broke, hearing the pump run to prime the system when you first turn the key) if it not lighting up for a sec. then going off your pump has to be bad.

[777stickman]

Originally Posted by mcconaughy

That makes sense, I have a couple of other questions.
1) Is the "fuel pump relay" something that NAPA could check for me if I brought it in to them?
2) Since the fuel filter was totally plugged, could that cause the relay switch to overload and fail?

I was also browsing yesterday and noticed that other people have "whining fuel pumps" mine has always done that, people always say it is getting ready to fail but it seems that it is common and is more annoying than harmful.
I really appreciate your help,thanks again.
Rick

?1) I doubt it!!
?2) It could happen, but I doubt that too. More like the pump overloading and failing, or the fuse blowing, due the filter restriction

My '98 Sub fuel pump has whined since I've had it. 80K miles later and it's still whining and still working. You've reminded me that I need to change my fuel filter!!

You say you don't have any electrical tools. One of the most inexpensive and usefull tools is a 12v test light. Spring for one.

C103 is a connector located "Part of the engine harness to fuel pump motor, in the left rear side of the engine compartment, under the brake master cylinder". It's a 4 wire connector but on gas engines it only has 2 wires in it. One is light green (backup lite feed) and the other is grey (fuel pump feed).

Disconnect it and put your "new" test light probe into the grey wire socket and clip the other wire to a good ground. Turn the key to the "run" position. The test light should come on for about 2 seconds and go off. This would mean the fuse and relay are good and the pump is probably bad.

[mcconaughy]

A friend told me there may be some type of screen or filter actually inside the fuel pump too, perhaps that is clogged up but I should still hear the "clicking" if it is trying to prime the pump I think.

Thanks you guys, I appreciate your replies.

[Bob B]

Originally Posted by mcconaughy

A friend told me there may be some type of screen or filter actually inside the fuel pump too, perhaps that is clogged up but I should still hear the "clicking" if it is trying to prime the pump I think.

Thanks you guys, I appreciate your replies.

Yes there is a sock type filter on the fuel pump.
There also is a pigtail wire below the brake master cylinder behind the fuse/relay box that you can jumper to 12 volts and the pump should run as long as the jumper is on.
The back of the fuse box has two big wires that are 12 volts right within inches of the pigtail.
Another thing that has caused problems is the connector at the fuel pump wires on top of the fuel tank. Some have had the pins burn from poor contact. If the pump doesn't run then I would take a very close look into the contacts.
I had a friend who had his pump replaced twice and still got stuck in the desert. We tracked it down to the plug.
The local NAPA has a poster on the wall showing this. I also have a technical service bulletin showing it.
Bob B

[mcconaughy]

After 3 nights of trying I finally got the "quick connects that attach to fuel pump off. Everything in electrical at engine checked out.

How can I test to make sure the fuel pump is shot rather than the connectors at the pump above the tank?

Is this something a auto parts store could check and see if the pump itself is shot?

[roadrunner_70]

You have the Vortec engine, which also has a schrader valve on the fuel line. You could turn the key on for two seconds, then carefully press in the valve. Use a rag just in case, as fuel pressure is usually between 50-60psi. If nothing comes out, or just a dribble, you know the pump isn't working.

[Bob B]

Originally Posted by mcconaughy

After 3 nights of trying I finally got the "quick connects that attach to fuel pump off. Everything in electrical at engine checked out.

How can I test to make sure the fuel pump is shot rather than the connectors at the pump above the tank?

Is this something a auto parts store could check and see if the pump itself is shot?

--------------------------------------------------------------
Hi,
The problem with the connector being bad is the pins inside the housing burn. When they do it is real obvious. look at both male and female plugs.
The picture I saw at a NAPA store exactly matched a friends 97 Tahoe problem.
The square plug is the problem plug. The replacement plug is oval with the pins in a row. As seen in a TSB, (Technical service bulletin.)

Bob B

[mcconaughy]

Just wanted to thank you guys for the help.
It turns out it was the fuel pump. It was complicated and took much longer than it should have, mainly because I didn't know what I was doing. The biggest problem was trying to get the quick connect fuel lines undone at the pump.
If it happens again though, I should be able to do the job in a afternoon.

Also, the new fuel pump does not whine like the old one did, it's really nice not having that aggravating noise.

Thanks again and have a Merry Christmas.

[mbumgua]

The fuel pump relay exists only to run the fuel pump until you get oil pressure. If the relay goes out you will still be able to start the vehicle after oil pressure comes up to operating pressure. This usually is about 10-20 seconds. If you were to lose oil pressure going down the road the oil pressure switch will cut off the fuel pump and engine will stop hopefully before too much damage is done. Also 1- ton trucks have a different run time for the fuel pump. They will run for 20-25 seconds after key is turned on to help prevent vapor lock.

[skipr]

You got fixed, so I guess this post is kinda useless. I was going say for others attempting to check line pressure by releasing valve pin.That is not a very conclusive test. I had a running fuel pump and out put volume was good. But the pressure was only maxing out at 42 psi. No way can your engine start or run with a 10 lb. drop from the normal 60 psi. And Bob B is correct about the bypass lead (red pigtail) from the under hood relay/fuse box. this over rides the relay (so you test the port without having to turn key every two seconds (the line prime presssure when first keyed on ) bleed down will prevent a accurate test if testing with engine off. Too much bleed down means FPR is bad. So in conclusion your failure to change the filter caused a pump burn up, and believe me those filters do not last as long as you think. change every 10k. I learned all this from experience not theory. What milege on your truck? I bet I can guess your next major engine problem.Also I have the 3000 page GMC service manuals for your 1998 (asumming it's a 5.7 litre, w/CPFI) if you every need detailed troubleshoot charts.

[mcconaughy]

[10k. I learned all this from experience not theory. What milege on your truck? I bet I can guess your next major engine problem.Also I have the 3000 page GMC service manuals for your 1998 (asumming it's a 5.7 litre, w/CPFI) if you every need detailed troubleshoot charts.[/quote]

Skip , my mileage is about 128K. What do you think the next major engine problem would be so maybe I can get a jump on it? Thanks for the reply. Rick