dave1088

Hi there, first time poster. I'm having fuel issues with my 1994 Toyota pickup 4 cyl. I'm a bit lost with how to fix this issue and not in the least bit mechanically skilled so I'll start from the beginning.

My truck sat for about 10 days while I was out of the country. When I came back it fired right up, idled for about 20 seconds and died, wouldn't start up again after that. I first checked all the fuses and found the EFI fuse was blown, somehow a 20Amp was being used where it should have been a 15Amp. Unfortunately I didn't notice that it should have been a 15Amp and jammed a new 20Amp right back in, oops! Tried starting and this time I got it to run for maybe 2 seconds, then died again. From this point I thought maybe the fuel pump was the issue so I used a jumper (paper clip) from Fp to B+ in the Diagnostic Box. Cranked and still no fuel getting to the engine. From here I was fairly convinced I needed a new fuel pump. So I unbolted the truck bed and replaced the pump. In order to connect the wires I had to crimp the new wires on to the old. I tried running the new pump and nothing... Then I discovered I accidentally crimped the negative wire to the positive... Crap. Another run to the auto parts store for more butt connectors. I reconnected the wires correctly and this is where I discovered that my EFI Fuse was supposed to be a 15Amp. So, now I have the wires hooked up correctly with proper fuses, also I checked my EFI relay which works fine. Still, no dice. Last thing I tried checking was the wiring to see for any obvious signs of grounding and couldn't find anything. The only odd thing I saw was in this picture. The negative wire connector seemed to have burned a little on the fuel pump harness.

No clue if this could be an issue. Sorry for the long post guys, just trying to include any info that some of you could use to help steer me in the right direction. Thanks

scope103

If you replaced a fuel pump, you may be selling yourself short. Still, there is no shame in taking it to someone who does this work for a living.

But I think you would be well served by getting and using a multimeter. Don't have one? No excuse for that! http://www.harborfreight.com/7-funct...ter-90899.html

Right now you don't know if the pump is running, and if not, why not. Check for 12v to ground on B+ with key-on. If you don't have 12v there, there is a problem in the EFI circuit (and the pump will NEVER run). If you have 12v on B+, jumper it to FP and you should be able to hear the pump run. If not, lift the bed back off and check for 12v on the pump connections. It's really that simple.

Note that you could have done these tests (if you had a multimeter) back when you first used the Fp-B+ jumper. It would not surprise me that your problem is in the EFI end of the circuit, that your old fuel pump was fine, and you replaced it (and hacked up the wiring) for nothing.

PS: If those are your crimps in the photo, you need to start over. They will short out the moment you hit a puddle.

dave1088

On my way to get a multimeter now! I'll let you know what I find out. Also, yes that's my first attempt at "crimping" wires haha. I guess I need to be sure that those wires are not exposed right? Thanks for the help.

dave1088

Ok so I tested the B+ to ground and got 11.5v. So then I tested my wires that connect to the fuel pump and got nothing. The key was in run and I had Fp to B+ jumper'd. So does that mean the wiring somewhere is most likely bad?

dave1088

Update...
So after checking the wiring and all fuses and relays once again, I'm beginning to think I have a bad ECU. Apparently the EFI fuse is tied into the ECU. When my truck first wouldn't start, I had a blown EFI fuse that was the incorrect amperage. A 20amp instead of the correct 15amp. My thought is that 20 amps were allowed to go through the ECU, frying it. Can anyone shed some light on this?

scope103

No, you CAN'T "get nothing" with a multimeter. You can get infinite ohms or zero volts or 565ma, but none of these are "nothing." 11.5v on the B+ connector sounds like a (very) under-charged battery. Check your technique by testing the battery + post to ground, and again to the negative post. Get 11.5v there? You need to charge that battery, or you'll be chasing you're tail.

The FP connector goes straight to the fuel pump. When the pump is running (like when the engine is running) you should get about 12v. Since yours is not running, with key-on (or -off) and no jumper, you should get 0v (because the COR is open). Your resistance measurement to ground should be single-digit ohms (your measuring through the pump windings, which have very few ohms, and even a good multimeter has 0.5-1.5ohms in the leads, so that sets the minimum resistance you can reliably measure). If you get more than 20ohms or so you have an open in your wiring or pump.

Probably not. A fuse "blows" if something tries to pull too much amperage through it. The ECM won't pull more than single-digit amps, UNLESS it fries internally and shorts out. Then, like anything else, it tries to pull "infinite" amps and the fuse blows to protect the wiring (and avoid a fire).

Also, the fuel pump will run even if the ECM is sitting under your mattress. You don't even know if the pump is running, so you've got a long way to go before you need to worry about something like the ECM. When you jumper FP to B+, can you hear the pump running? This has nothing to do with the ECM. If you can hear something, try replacing the fuel return line from the Fuel Pressure Regulator with a 1/4" (uh, 6mm) line to a bucket. You should get about 1/2 liter / min using the jumper. (DON'T "crack" a fuel line on the high pressure side, as you might see suggested by some on this forum. Not only is it dangerous and messy, it doesn't tell you what you need to know, and you MUST replace the crush washers on any fitting that has been loosened.)