Need help troubleshooting the fuel pump

[greg0145]

A few times over a period of six months, the engine has failed to start. (Cranks but doesn’t fire) The first time it started after a short delay. The second time after a few hours thinking the fuel gauge was bad I added some fuel and it started. The third time I knew the fuel tank was more than half-full and discovered there was not any fuel pressure at the rail. When I turned the key to the run position, I think I could hear the click of the relay but not the faint few seconds of the fuel pump running. Lacking other ideas, I dumped a quart of fuel into the tank and gave the truck a good shaking. I turned the key again and this time I did hear the fuel pump run and of course, the engine started.

I have a few questions. Before I assume that, I have a fuel pump problem and spend a considerable amount of money to replace the pump, may there be other things to replace or investigate first. If it is the fuel pump, does anyone have an opinion of a good replacement manufacturer? If it is the fuel pump and I remove the bed to replace it, are there some things anyone has learned that you could share to help me avoid some mistakes.

Thanks

 

[McCormack]

You didn't mention anything about it, so I'm going to assume that you've already done the obvious and replaced your fuel filter.

If it does turn out to be the pump, then be aware that the pump and fuel gauge sending unit are assembled into one unit inside the tank, and you can save some money by buying just the pump and not the whole pump/sending unit assembly. On the other hand if you're going to keep your truck for awhile then it might not hurt to replace the whole thing. I suppose the naysayers will be chiming in here, but I replaced just the pump in my truck and haven't had any trouble since - the choice is up to you.

From the reports I've read, pulling the pickup bed off to get at the pump is a whole bunch easier than pulling the tank off to get at it, so that's what I would recommend. One guy who doesn't do much work on vehicles claimed he replaced his fuel pump in just a couple of hours via pulling his bed off. You will need a couple of friends to help you lift the bed off, though.

 

[Earl43P]

Get the pump and sock from RockAuto. (I recommend replacing the entire sending unit, which comes with new FP and sock installed as well as a leak-proof float)

Get several T55 drivers and a long breaker bar for the bed bolts. Use steady, even pulls. Bribe a friend to help.

Soak the bedbolts w/ PB Blaster from underneath at least a few times, days before removal and while "breaker-barring" the bolts out. Wirewheel the corrosion off the threads before reinstallation, use anti-seize.

Clean the top ring / top of tank before opening it up (I used a pressure washer).

Don't forget the filler neck screws (3) and disconnect the tail lights harness (connection is at rear center of bed). Use two men to lift bed off or prop it / slide it aft and work precariously, alone.

Clean and apply dielectric grease to the big square connector under the DS cab. Water and corrosion in there causes problems.

Check the inertia switch.

Try turning the key to Run and Off several times before attempting starts. It could simply be losing its pressure (= bad FP checkvalve or leaking fuel filter). Replace fuel filter after the new FP is in and working.

 

[fleck]

Everyone is going in the right direction, you can diagnose a bad fuel pump in several ways. The fuel pump could have a bad wiring connection to it if it really wasn't making a sound, and you should definitely check the inertia switch seeing as how 'rocking' it helped and it doesn't seem to matter how much fuel is in the tank. Of course the fuel filter could be the problem but it wouldn't keep the fuel pump from running--but that all depends on whether what you think you heard is really what you heard.

 

[greg0145]

I did check the inertia switch both times. It had not popped up, or at least when I pushed on the red button it did not move. The fuel filter I am embarrassed to say I have not checked or changed for years and years and some say that may be a cause for pump failure. (along with ethanol) Because the fuel pump did not seem to run at all, I eliminated the fuel filter as a likely problem. I will investigate the large connector under the cab for corrosion. The RockAuto recommended by Earl43p does look like a good site and all the other suggestions will be helpful going forward.

 

[McCormack]

Because the fuel pump did not seem to run at all, I eliminated the fuel filter as a likely problem.

If the filter is completely - or close to completely - plugged, then the fuel pump isn't going to run. If it were me the first thing I would do in diagnosing the problem would be to slap a new filter in and see what it does for the situation.