LUVTruck.com

The pump is supposed to come on when the truck is cranking. If you bypassed the relay, by wiring the pump to a acc or keyed hot it would run whenever you have the key on. It was designed to shut off when the engine isn't running so if you get into an accident it's not pumping gas...

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Resident lurker

My only purpose in bypassing the relay was merely for diagnosis. I was just wondering if I may have goofed in doing so because for a few minutes while the key was on the pump just kept running and I was still unsuccessful in reviving the LUV! I was hoping someone could help guide me as to why I had fuel and spark and no run! It ran last Monday when the relay died! The only thing I did since then was check fuses and power in and out of the relay! Then bypassed the relay. I figured with a no fuel problem, giving the fuel supply back would give me a running truck back! I'm a bit confused by this! The inside of the throttle body is still bone-dry after I got the pump running again! I'm at a loss!

This is just off the top of my head, cuz the wiring diagrams have no internal wiring of the electrical parts. That being said......the fuel pump starts running when you turn the key to start. The pump keeps running when you release the key, so there might be a hold-in circuit across a set of the contacts of the relay that directs the power back to the coil holding it closed until you turn the key off.

These trucks are some of the most contrary wired S>O>B's I have ever come across. I have no clue what to tell ya.....sorry man and good luck...
.................Buzz

Maybe you rebuilt the carb the wrong way. and for bypassing the relay it sounded like you plan on using that as a permantant fix but that is not a good idea.

My only purpose for bypassing the relay was to check the relay. If I can find one, I would rather just replace the relay than butcher my truck again! I rebuilt the carb in August and it made a world of difference in the way it ran!! I'm a little skeptical that the carb is my problem, but it was my first rebuild! I may have screwed up, but I figured the symptoms would be more immediate! But I do know that I've got power into but not out of the relay. Sorry to sound like I'm arguing, I just want cover all my bases!

The same relay that powers the pump also directs juice to the coil. It might not be getting spark while you have the relay bypassed. Get the pump running, and hook a wire from the battery to the resistor on the coil. that way you KNOW you have power to both the fuel and ignition.

The way that whole relay system works is a lot more complicated than it seems like it should be. The voltage regulator connects to the engine speed sensor, which hooks to the relays. Add a few dozen feet of wire in between it all and you have it all together. I believe the way it is supposed to work when it is all wired right and working right is this:

Key to START: 12v through relay directly to the coil, fuel pump runs
Key to ON, motor off: Power to the relays, relays not energized, no volts at coil or pump.
Key to ON, motor on: 12v at coil resistor, 12v at fuel pump
Key to OFF or ACC: relays, coil, pump all no power

When the fuel pump relay went out on my blue 4x4 right after i got it (nearly two yrs ago) I bypassed it and installed a toggle switch in my dash.NEVER have i had any problems w it since then.

No more getting stranded while flying across Arkansas at 3am

The truck I'm driving now came with the fuel pump wired to the ACC fuse. I just replaced the original wire and it all worked fine. Probably just the prior owner misdiagnosing the pump. Because the stock setup is so confusing. I left the wire in place though and it has been very handy troubleshooting fuel delivery problems. Just a quick swap back at the pump and I can power up the pump whenever I want without having the truck running. I'm thinking about wiring a manual bypass switch in just as backup for those stupid relays. I was thinking I could make it a double throw switch. Manual on, Normal on, and disabled. Troubleshooting and anti-theft all in one.

Fuel pump and coil electrical probs have to be in the top 5 stock luv problems. Because the system has some many sources for failures, it can be one of the worst to troubleshoot and solve too.

I don't remember 100%, but the pump should run continuously when the key is on. Once the pressure in the fuel line builds up the pumping sound will slow down a bit, but it should still be heard. It might be possible thet the jumper you ran is on a switched circuit where it does not have power with the key in the start position. Like I said, I am not 100% sure, but my 73 Midget works like that.

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I've never been wrong! Once I thought I was, but I was mistaken.
Rick
Loranger, La
1980 Stepside LUV (Again)

Thanks for all your help guys! I'll get back on my resurrection efforts after I'm well again! Had a fever and a sore throat since Monday so I've been out of work and unable to get to looking deeper into my LUV's problem! I'll try to get him running this Saturday!

had that problem on mine for awhile.. then i opened up the choke manually and it fired right up. might not be getting enough air/ too much fuel.

Turns out I've been chasing a ghost! Relay is good and pump is running, but not pumping enough fuel to even try to fire up! Where might I find a stock pump for this truck or a suitable replacement? My truck's been dead too long!! I just want to go out and drive my LUV!!

Just go down to the autoparts store and get a universal replacement. I got one at napa for $30. The stock replacements are too much $$

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Resident lurker

I finally got a stock type pump to put in it and in runs great!! Now I've just got to wait for the shell so I can restore this bad boy!! I'll need help posting pics soon after this project begins in a few weeks!