You have two fuel pumps, one external, and one internal.
The external one is on the driver's side frame near the front of the truck.
First, listen for the pump when you switch on the ignition.
If you hear nothing, you probably have a bad relay. Replace it and try again.
If you hear a pump run for a few seconds, you know at least one of them is working. Crawl under the truck and disconnect the wire to the external pump. Then listen for pump noise again, when you switch on the ignition. If you hear a pump, your in-tank pump is working. If not, then it or the wiring to it is bad.
If you hear the in-tank pump, then reconnect the external pump and have someone else switch the ignition while you listen from under the truck, so you can tell if both are working.
If both are working, then you may have a clogged filter, or some other problem.
There is a pump in the gas tank and a larger pump mounted
on the inside of the driverside frame rail below the
driver side door.
When you turn the ignition to run you should hear the
frame rail pump buzz for about 2 seconds.
To check the pump inside the gas tank, disconnect the
hose going into the main pump. Turn the ignition to
run and if gas comes out of the hose the intank pump
is probably good. Use a bucket or pan to catch any
gas that comes out.
To check the main pump disconnect the hose at the main
pump outlet, attach a rubber hose to direct the gas
to the bucket and turn the ignition to run.
The hoses have a plastic clip that you pry up with
a small flat blade screwdriver. You pry the clip up
(Don't need to take it completely off). You then
pull the hose off. To reinstall the hose, push the clip
back down then push the hose back on. If you break
one of the clips, the dealer has them and I've
seen them at Pep Boys. There are two different ones
used on the fuel hoses. Black ones and White ones.
Also, could it possibly be a fuse. I was reading other posts and one mentioned the fuel pump fuse was located under the hood. If this is something to check as well, is that where it is located or is it inside the truck in the fuse box?
In the first reply to my original post, it was mentioned to replace the relay if I heard nothing. I heard nothing but what is the relay, is it a switch or a fuse or something similar. If someone can tell me what and where this relay is I can try that first. Thanks
the relay is under the hood, on the drivers side , behind the air filter box. I think there is about 3 relays, mounted in a bracket. They snap in., I think under a plastic cover. and there not very expensive. At least this is the way my '91 is. (5.0)
Wouldn't it be a good idea to check the fuel pressure too....
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I have a 88 F-150 with a 351w and had the same problem just a couple weeks ago. Got to looking at the main fuel pump along the left rail and when I would wiggle the red wire I would hear the pump come on. To make a long story short I took the pump off and flattened the red spade on the wire, put it back on and haven't had any trouble since.
Well, I had the truck sitting for a couple of days and tried it last night and it started right up. I took it for a little test drive and there was no change in the way it ran for about 20 minutes. I was stopped at a light and the truck died with no sputtering and wouldn't start again. Any ideas regarding the direction to look, fuel related or electrical?
My `88 150 I6 did the same thing , guess what it was .. a loose connection at the top of the gas tank , a plug to be exact , had come loose. I pressed the plug back on , and no probs. since.
If not , at least take it to a shop you trust and have them do a scope on it.
1988 F150 300 I6 4spd. Warner T 18 Tranny
It has to be the pump. or one of the pumps if you have 2. Esp.if it still has the factory pumps. My '91 would go dead only at idle when it first started getting weak. (at about 70k)Mine does NOT have a pump on the frame rail. Both are inside the tanks. I'm curious about which models had a high pressure pump on the frame rail. An engineer at Walbro Engine Management , who makes the pump/module, told me that if you've run out of gas recently and kept on trying to make it run on "fumes", this will ruin a pump because gas running thru the little motor is what keeps it from overheating. As a previous poster said, have the fuel pressure checked. Doesn't take very long and won't cost much. Fuel pressure MUST be within range.
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