It's the 4 cylinder engine model. Just driving down the freeway one day last week and the engine quit as though the truck ran out of gas. I towed it home. Sure enough, no gas was being pumped through the fuel filter, so I replaced the fuel filter thinking that it may be plugged. Still no gas flow? I checked the fuse and the relay, both okay. I dropped the gas tank and replaced the fuel pump. Still no fuel flow? While I had the tank out, I blew through the gas line to make sure that it wasn't plugged. It wasn't. Anybody got any ideas of what could be wrong and maybe how to fix it?

i would start by checking for power to the fuel pump when you turn the key on (use a test light or voltmeter). If you have power, then I would check the ground to the pump. You said you checked the relay, Does it click and is there power coming out of it?

Apparently the problem is in the harness connector located near the battery. Using a test light, there is power to the pump connector at the fuel tank. In disconnecting and reconnecting the connectors near the battery the fuel pump started working again! Looks like I spent money on a new fuel pump for nothing! Anyway, after tucking the connectors out of the way, the fuel pump quit working again. The fact that it worked at all, and that there is power to the conector at the fuel tank would lead me to believe that there is a return ground wire that feeds through the connector near the battery. I'll have to check the schematic again when I get back home this weekend. I assume that the other ground wire at the fuel tank if for the fuel sending unit. Damn...whatever happened to the good old days with the mechanical fuel pumps!!

Opps, I goofed! I thought this was a different web site and started a new thread on this same subject, except with more information. See the "cranks but won't start" a couple of threads above this one. Interestingly, I posted this exact same question on three different web sites, and two "ask the mechanic directly" type sites. Nobody has an answer to correct the problem??

Turned out to be a defective ECM. See the other thread for what I ended up paying!

Turned out to be a defective ECM. See the other thread for what I ended up paying!


What's an ECM? Forgive my ignorance....

- Matt

What's an ECM? Forgive my ignorance....

- Matt

E...Electronic C...Control M...Module

That's the fancy term for "computer," or electronic control unit. Makes that $40 box sell for $600 just by changing the name. At least that's what it seems like.

Ohh! Such a common problem on the pick ups! As a former tech I saw this problem many times. A transister in the ECM that controles ground on the fuel pump relay fails. I wish I caught your problem before now. It could have easily been fixed by instaling a simple $10 relay to controle the ground when the key is turned to the crank and run positions.
Sorry!

If you check the other thread on this same subject you'll see that the dealer mechanics seemed to just start changing parts until the engine ran. That's the feeling I have. But since you seem to know more about the subject, what type of relay and where do you install it? Oh, and yes, my original fuel pump still works great when connected to a battery. I now have that original and a new fuel pump as spares which the dealer said didn't work, when the problem was with the ECM.

Ohh! Such a common problem on the pick ups! As a former tech I saw this problem many times. A transister in the ECM that controles ground on the fuel pump relay fails. I wish I caught your problem before now. It could have easily been fixed by instaling a simple $10 relay to controle the ground when the key is turned to the crank and run positions.
Sorry!

First you need an electrical schematic to find the wire that controles fuel pump relay ground at the ECM. then a simple 4 terminal normaly open relay. using the terminals in a maner as (some relays may be differ in configuration) terminal #1 to a +terminal on the fuse bus that is on during both cranking and in the run position #2 to chassis ground, this allows the relay to energize. Now find the wire from the ECM harnes that controles fuel pump relay ground rerout this wire to go from fuel pump relay to terminal #3 of the relay and add a wire to terminal #4 and attach the other end to chassis ground. when the key is turned to the start or run positions the relay will energize and supply a ground to fuel pump relay. Problem solved!

Hummmm....sounds simple, but logical. Oh well, if the same problem happens again I'll know what to try.