Jad

Hi all,

First post here, been lurking for a while. I've got a 1988 short bed pickup, 2.4L non turbo 22REC, 4WD.

Last week, after sitting for a week, I went to start it and it did start but died right away. Tried again and same thing. Checked the battery, etc, but still the same problem. Had it towed to my mechanic who ruled out the fuel pump/relays (it's getting lots of fuel), but has narrowed it down to the injectors, says they aren't firing. He thinks that the cold start injectors are working which is why it starts, but then won't stay running. He thinks it might be the ECM, but I'm in Ontario and I haven't found any at the local wreckers. Where can I find a used one? (eBay's got two right now but they are for the California model...won't work with mine I don't think?)

Also, if you have any input on the problem itself, I'd appreciate hearing it. I guess there's some water near/on the ECM which is why he's suspecting it.

Thanks in advance for your help!
Jad

iamsuperbleeder

welcome to YotaTech!


first thing I would do is check the EFI fuse (a 15 amp IIRC) in the fuse box on the passenger side under the hood

I think the cold start injector is on a different circut and will still work even if that fuse blows


but that particular fuse runs to the ECU, and if it blows, then your injectors will not fire

Jad

Thanks for the welcome and the suggestion. Before I had it towed to my mechanic, I checked all of those fuses on the passenger side in the engine compartment..they all looked solid. For some reason, I don't know which is which since nothing is labeled.

Would a bad AFM cause this behaviour?

iamsuperbleeder

well if the AFM isn't plugged in at all, it will give very similar results to be honest...

abecedarian

The 88 EFI fuse is under the dash, above the kick panel on the driver's side.
Bottom, left 15 amp fuse.




Anyhow, for a few dollars you can get a 'noid' light that plugs in to a fuel injector's harness connector that will blink if the injector is receiving the pulse from the ECU while cranking.

You say it dies immediately, but do you mean it dies as soon as you release the key, or it runs for 2-3 seconds after you release the key then dies?

iamsuperbleeder

ah-ha! thanks Abe

I'm bias towards my 91, lol

Jad

abe, that's awesome! thanks for the detailed photos, that'll help me out in the future.

The truck starts after cranking once or twice, runs for 1 or 2 seconds maximum, then quietly dies. Kinda feels like I just turned the key off but I didn't. Oh, and I tried pumping the gas pedal while I'm starting it and after it starts, but the tach doesn't show the RPMs going up at all and I don't hear anything from the engine either. It's like I'm not even touching the gas pedal. It all happens pretty quick tho, since it shuts off so quickly.

abecedarian

In the diagnostic connector under the hood, next to the fuses there:

Using the diagram on the lid, make a jumper between the Fp and +B terminals and see if it will keep running. If it does, it's not the ECU or injectors but more likely the AFM or Circuit Opening Relay.

Jad

Abe, thanks again. I did try that before I had it towed, too. I used a metal paperclip so I hope it was making a good connection, but jumpering those and trying to start it didn't change anything.

Think it's the ECU then?

iamsuperbleeder

hmmmm, try a section of electrical wire; usually paperclips are coated in a thin layer of clear plastic and don't conduct very well

Jad

Well folks, thanks for all the help and suggestions/photos. It turned out to be the ECM. Water was getting in there and it was wet, so I found a used one from an 89 4Runner (same drivetrain, engine, etc) and she starts up and runs perfectly now! Kind of a crazy fix but I guess it was the water that did it. They are going to relocate the ECM away from the water area in case we can't fix the leak.

Thanks to Defiant4wd.com for the used ECM and great price!

iamsuperbleeder

good job!

unfotunately, it's not always something small like a fuse; every once in a while, you do have to replace some parts

any idea where the water came from, or is it just moisture buildup you think?

Jad

Yeah and at $80 for the ECM, it wasn't too painful! Thought it was going to be a pricy fix/diagnosis.

It looks like there is actually water leaking into that corner near the glovebox, not sure how it's getting in there...maybe the engine compartment?

iamsuperbleeder

probably the window

Jad

The windshield? That makes sense, it already leaks from the top seam, drips onto the passenger side floor, just in front of the seat.

iamsuperbleeder

yeah it's probably running down

I think that's common actually, although I've never had the issue personally

abecedarian

Yeah, sometimes it is a major component failure that causes the problem, but we usually try to troubleshoot the smaller, easier to get to things first. ECU's usually last quite a long time compared to the other components in the system.

I'd check the air intake below the windshield, heater box and windshield seal for signs of leakage. If it damaged the ECU, the source of the leak should be fairly easy to locate. Unfortunately, it's not an easy place to get to.

Jad

Would some silicone around the outside seam fix it you think? I don't care if this thing looks pretty.

iamsuperbleeder

it should, so long as you know where and put it generally where the leak is originating from

pull the trim up though, cause you need to seal against the body and the window, not just blob it on around the trim, lol

mind sound like common since, but after working at an auto parts store for over 2 years in the past, I've seen my fair share of short-cuts like that, that horribly fail, lol, kinda like the tar-roofed Honda that some moron drives around here, lmao. he's seriously got a black-top on the roof of his CRX... sadest thing I've ever seen, lol

Jad

Thanks Abe, I'll take a look at those things and try to seal it up.

I was kind of skeptical of the ECU diagnosis too because like you said, they usually last a long time, but this is the second time now I've replaced one on a vehicle that was misfiring/not running. Oh well.