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1987 B2 2.9 V6 fuel injector...


Nick1983M

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I just got done building the 2.9 for my b2. Reground cam, milled heads, port matched. I'm having some issues with these cheap (partsgeek) fuel injectors.
What is the original fuel injector lb/hr? A part number would be great if anyone has it
 


Nick1983M

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Also, is there any places that still make wiring harness parts? I need a new fuel injector wiring harness...
 

Uncle Gump

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I believe they're 14 lb/hr.

There have been a bunch of issues with replacement injectors. I've heard good results with Accel replacements... but spendy.

The other thing you can do... if you still have your originals... test/clean/rebuild them. Or send them out to have done. Results are much better then the cheap replacements.
 

Nick1983M

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I'm on my 4th batch. I finally bought a fuel injector test machine.
Ended up ordering a set from summit racing. I believe they are Standard Motors... they were 400$. They should be here today. I can swap these injectors out in about 25 mins lol.
 

Nick1983M

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Update: One issue i noticed while testing so many of these different brand of injectors, is the fact that they all tend to fire decently with the absence of fuel pressure. Once installed and under fuel pressure (36lbs), they would not fire.
these new injectors all tested good. Installed in vehicle and now it runs and firing on all cylinders!

New problems...
Engine is running rich.
It will be running very smooth, then just drops ignition for a split second and right before it completely dies it regains the ignition. It's literally like someone's switches the key off and then back on real quick (like we use to do back in the day to make the old truck backfire 🤣🤣). Any input? This B2 sat for 15 years, could the computer possibly be bad?
 

Uncle Gump

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What makes you think it drops ignition?

How did you test that?

Are you sure it just isn't loading up and the IAC opens to prevent a stall?
 

Nick1983M

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It loses spark at all cylinders. Tachometer will drop to zero for a split second. Haven't really ran any tests as this just happened today.
I don't think it's the iac opening to prevent a stall, with the cold air intake, would hear it opening
 

Nick1983M

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I also noticed that the o2 sensor wires are just dangling down by the exhaust. Does anyone have a wiring schematic for that sensor so I can splice it all back together?
 

Uncle Gump

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I have the schematic for an 86 2.9L... it's probably the same as your 87. I will post that for you in a bit.

Sounds like you have a couple issues honestly.

I guess I have a question... does it actually quit running? If so... does it restart easily?
 

Nick1983M

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It doesn't actually quit, it's aa ifyou quickly turned the key off and back on before it completely dies,
 

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Wiring diagrams as promised...

20231206_120731.jpg


20231206_120724.jpg


20231206_120711.jpg
 

Nick1983M

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Thank you.

Update. I was able to go out and do some testing today. On the coil there are 2 main wires, 1 consists of a single green wire, the other is 2 red wires together. The red wire holds power constantly, no voltage drops. The green wire doesn't completely lose signal, but definitely drops voltage to near 2-3 volts instantly, before it picks it back up. On a test light it would flicker, but would make the engine stumble and nearly die.
 

Nick1983M

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Update 12.14.23

Installed new coil. No change

Removed computer and this is what I found... normal?
 

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Uncle Gump

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I sure wouldn't think so...

Being you know nothing about it... I'd be looking for a replacement.
 

Nick1983M

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Installed new ecm. No change.
Did some testing at the coil: while idling it has 58 volts on the green wire, and approx every 7 - 10 seconds it will instantly drop to 28 volts and some times 14 volts. (This is a new coil) and just before the engine dies it picks right back up to 58 volts and back to running smoothly (well as smooth as the choppy little cam will allow 😀)
Any ideas are much, much appreciated!
 

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Nick1983M

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Update: at an idle I'm also losing power to fuel injectors, I checked this where the injector harness plugs in to the main harness. Ignition switch or key tumbler?

While running I wiggle the key tumbler. But I cant really tell if it helps any thing
 

Nick1983M

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Update, installed new ignition switch, no change, problem still remains. While pulling the wiring harness out (the portion that runs the IAC, TF module o2 sensor etc, I found this bare wire that's insulated.. pics below... what is this?

As mentioned before I'm chasing a dropping full ignition signal (fuel and spark) while running. Any help at all with be appreciated.
 

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Nick1983M

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Should I ground the bare wire or is it like that for a reason?
 

Nick1983M

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Could some one please post the ecm "pin-outs" image?
 

tw205

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Should I ground the bare wire or is it like that for a reason?
I think it’s supposed to be that way. It’s grounded at the ECU. The shield should be kept secure around the wires.

On your loss of power issue, on one of my 85 while doing the duraspark thing. When I would turn the key for power it would be random. No changes to anything just wouldn’t have power then it would. I found the electrical connector for the ignition switch under the steering column plastic was not full engaged. It was locked together but loose enough that just turning the key or getting in the truck was enough to lose connection. A single zip tie fixed it. I’ve never had it happen again. I’ve read other threads on here describe the same thing. Worth a shot. Good luck.
I don’t have an ECU map but I’m sure one of these fellers on here will hook you up.
 

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