Alright guys so I am having a problem that has been driving me mad.

I have a 87 runner that I drove to a spot and parked it. I would start it every few weeks and let it run for about 8 months. Then, all of a sudden a few weeks ago RIGHT BEFORE I went to move it and get her ready for some fun, it wouldn't start. The fuel pump isn't kicking on.

So, I went ahead and swapped the fuel pump and then confirmed by running power to the fuel pump that it is working fine, hooked it up and sat a little bottle around the output line so I could see if it was moving gas and nothing.

I tried the Circuit Opening Relay jumper, nothing. The circuit opening relay clicks on and off with a turn of the key.

EFI Fuse is good.

Also, the Main relay under the EFI fuse I think is good. That's my question I guess. I had another Main relay and hooked it up and the car wouldn't turn over, but the COR would click on and off. I hooked the old one back and the car turned over, and the COR clicked. I don't know how to jump the main relay so that's the only thing I have not actually tried.

I also took apart the computer to make sure no corrosion and it is in spectacular condition. I cleaned all the contacts through the fuel wiring, nothing.


Suggestions? I assume that main relay is good if it's turning over/COR clicking and the other one I put in was just clicking/ no turn over.

 

Just because the COR clicks doesn't mean it's working. Can you open it up and confirm it's running correctly? No corrosion/burnt contacts?

 

Are you getting power to the pump? You need a multimeter for this; there is no excuse to not have one.

The COR should ONLY click when the key is turned all the way to STA (Start). Not in the RUN position.

If you're not getting power to the pump, check at the output of the COR.

Electricity is not magic; just follow its path until you find out where it went.

 

I jumped the COR by following this step

Wouldn't it have activated the fuel pump if I did the jump?

 

I did not check the COR yet. I need to do so in the next hour.

For those that are reading this with the same problem someday.

 

Unreal.

So my brand new fuel pump that was confirmed working with a 9v before I put it in is now dead. How can this be? I read many places online of people testing with a 9v, did that kill it?

How much power is supposed to be going to the fuel pump? multimeter was OL when I tested and 32 was the highest I had seen.

 

The pump runs on 12v; 9v will not hurt it (where did you get 9v? A tiny 6LR61 battery?)

What does "OL" and "32" mean wrt your multimeter? Volts? Ohms? Something else?

Last how do you know (now) that the fuel pump is "dead"?

 

I just turned the Multimeter to DCV, and had somebody hold to power and ground going to the fuel pump and when I was on start, it was reading all the way to 32.xx and then said OL?

I am not the greatest with a multimeter but I believe it was confirming it worked fine.

I pulled the fuel pump out and ran wires directly to the ground and power of the fuel pump and then to the 6LR61 9V. No spin. Before I installed it, it would spin up. I only did it for a second but it was spooling up and running.

 

a) Before you conclude that your pump is dead, put that 9v battery away (actually, throw it out. You've discharged it.) a 9v battery only has about 400 mAh; the load of the pump probably just ran it down. You've got a giant (~110Ah) truck battery; if you want to test your fuel pump (and you don't have, for instance, a battery charger) you could use that.

b) What would make you think that "32.xx" on a DCV scale confirms anything is working fine? The largest voltage (other than the secondary side of the ignition) on your truck is battery voltage, and that isn't higher than about 12.7v (maybe as high as 15v when the alternator is running). What would 32.xx mean?

I'm going to guess you had it set to the millivolt scale, 32mv is just static electricity when nothing is on, and when you turned the key to run you got OL which means -- overlimit. Take at look at http://www.autoshop101.com/forms/h4.pdf Before you use your multimeter, just touch it to the battery and see if the reading makes any sense. 32.xx doesn't make sense.

 

ktreece - If you did have the meter on DCV (dc volts) and it is auto-ranging, I would suspect 32.XX means 32 milliVolts...sounds to me like you aren't getting power to the fuel pump. Measure the voltage across the battery with the meter, make sure it reads somewhere in the 12 to 13.8 volt range, just to make sure your meter is measuring what you think it is measuring.

Assuming your meter is working, I would then measure B+ at the diagnostic connector under the hood after the Main Relay (with IGN on by the way).


That should tell you if your Main Relay is working. If B+ measures out ok, you can bypass the COR by putting a jumper wire in from B+ to Fp. And then you can move back to the fuel pump connector and measure your voltage there.

 

Hah scope you beat me to it. You are always posting in people's troubleshooting threads, and your posts are always spot on. I'd take Scope's advice if I were the OP. I wouldn't rule out the fuel pump just yet.

 

So I hooked the old fuel pump up to everything I could find. Nothing.

I went to a local NAPA down the road and snagged one of their cheapos for 50 bucks. Hooked it up and whala. She runs fine.

HOWEVER. Right when I hooked it up, I turned the key to start and could hear it priming but as soon as I went to turn it over everything died. I checked all the fuses (good) and unhooked the battery. Hooked it back up and it fired up and I drove it a couple miles and came back.

Seems to be running fine.

 

Yeah, I gotcha. I think that's what it was. It was on a millivolt scale and getting up to 3.2 and over limiting. It was correct.

I'm such a rook when it comes to the electrical. I'm learning though. :o

 

Son's 91 Runner suddenly died after repairing fuel line leak. Sounds similar to your problem. No fuel pump pressure however pump works with 12 volts applied directly and no spark. Any assistance would be great.

 

Amen to that.

 

Ok so found EFI 30 amp fuse blown replaced and now it starts but blows the 15 amp EFI fuse. Runs very rough and will not idle -suspect fuel pump grounding out causing fuse to blow. Any ideas?????

 

Capt B, it would help if you mentioned what year-model you have. A problem well-stated is a problem half-solved.

 

It is a 91 4Runner SR5 with a 3.0 L V6 5 Spd manual trans

 

i have a 87 pickup and my pump lost power and i was told that i could bypass all fuses and run a hot wire from the battery to a inline fuse then to a switch and run a wire from the switch to the pump. It is an in tank pump also.

Would this be ok to do?

If not where would i locate all the fuses for the pump?

 

Only if you aspire to be the human torch.

Your truck has a switch in the VAF which shuts off the fuel pump when the engine stops sucking air. If you get into an accident that breaks a fuel line, you want that pump to shut off immediately. If you bypass the VAF/COR circuit, you'll be a lump of charcoal long before you can reach your DIY switch.

The fuel pump circuit can be found here: http://personal.utulsa.edu/~nathan-b...87fuelpump.pdf (This is for a '93, but the basics are the same). You can help locate the problem by jumping the fuel pump test connector; yours can be found here: http://www.4crawler.com/4x4/CheapTri...CheckConnector

If the truck runs with the fuel pump test connector jumped, you've isolated the problem to the VAF/COR circuit. DON'T drive around with the jumper in; that's just as bad as your bypass switch.