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Discussion Starter #1
Hello, I just bought a 91, has a JDM GEN2 in it, however was a turbo chassis stock FWIW

I bought this from a friend for dirt cheap as it died while he was driving home last year. He hit a bump, and it died.

I have replaced the AFM, and distributor, no change.

The car with do one of thefollowing:
1) start, idle poorly for several seconds, die
2) start then die
3) crank constantly.

The car is getting spark, can verify this with a plug in a wire to ground. Car is getting fuel (can smell when it runs)

There is some wiring that has been done in the harnesses. I can grab pics and info if needed, however none is loose or damaged.

I checked AM1 and 2, they aren't blow. 15a EFI isn't blown. - still no CEL

No visible boost leaks or vac leaks.

Car ran fine prior and was a daily.

Also I did try unpluging the TPS and AFM, both same time and separately, no change.

Ideally not looking to throw parts at it - but any suggestions?
 

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Discussion Starter #3

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Try bypassing the fuel pump interlock, and see if that will let the car run. When this is the problem, the fuel pump will shut off as soon as you stop cranking.
 

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Discussion Starter #5
Try bypassing the fuel pump interlock, and see if that will let the car run. When this is the problem, the fuel pump will shut off as soon as you stop cranking.
Is there a write up on doing this?
 

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I've got one somewhere. I should really write a how to on this as well as how the turbo fuel pump system works.

Pretty much find your diagnostic port and get a wire and jump FP to +B to power 12V directly to the pump when the key is in the ON position.

The blue with black wire from image 3 to image 1. Powered by +B which is black with yellow.


Screenshot_20200925-113013.png

Screenshot_20200925-113001.png

Screenshot_20200925-113008.png
 

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Discussion Starter #7
I've got one somewhere. I should really write a how to on this as well as how the turbo fuel pump system works.

Pretty much find your diagnostic port and get a wire and jump FP to +B to power 12V directly to the pump when the key is in the ON position.
I will definitely give this a shot after I pick up a battery charger. Killed my spare battery yesterday diagnosing everything be trying to start it a few times.
 

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Discussion Starter #8
I've got one somewhere. I should really write a how to on this as well as how the turbo fuel pump system works.

Pretty much find your diagnostic port and get a wire and jump FP to +B to power 12V directly to the pump when the key is in the ON
so I did this. Didn’t hear a pump and it didn’t make starting it easier but I did get it to run on starting fluid. I’m going to do a fuel pressure test, but aside from that - it’s a dead pump right?
 

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Discussion Starter #9
so I did this. Didn’t hear a pump and it didn’t make starting it easier but I did get it to run on starting fluid. I’m going to do a fuel pressure test, but aside from that - it’s a dead pump right?
Or could it be a bad ECU?
 

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so I did this. Didn’t hear a pump and it didn’t make starting it easier but I did get it to run on starting fluid. I’m going to do a fuel pressure test, but aside from that - it’s a dead pump right?
I'd test the pump at the plug in front of the gear shifter. If you are able to do a pressure test, then that will help figure things out too.
 

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Discussion Starter #12
I'd put a lot of money on the ECU being fine.
ok so update here then. I went outside and listened when jumping the fuel pump in the diag box. I can hear the pump running clear as day but still no start unless it’s on starting fluid.

Guessing it’s fuel pressure test time anything else I’m looking for?

edit: looking at pressure testing this thing... is there a way to do it that isn’t a total pain in the rear? I can’t find a single solid writeup on it.
 

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Discussion Starter #13
I'd test the pump at the plug in front of the gear shifter. If you are able to do a pressure test, then that will help figure things out too.
turns out it’s working and I didn’t hear it on the diag side of the bay due to the IC fan.
See my reply above this one.
 

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So if it runs on starter fluid and the fuel pump runs but it won't start normally then we know the ECU is not firing the injectors. We need to find the reason for that.

For an engine to run it needs 4 things
Fuel
Air
Spark
Compression

In your situation based on the information you have provided us you have
Air
Spark
Compression

So we now need to figure out why there is no fuel getting to the engine.

How are you spraying in starter fluid? Through the AFM?
 

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Discussion Starter #17
So if it runs on starter fluid and the fuel pump runs but it won't start normally then we know the ECU is not firing the injectors. We need to find the reason for that.

For an engine to run it needs 4 things
Fuel
Air
Spark
Compression

In your situation based on the information you have provided us you have
Air
Spark
Compression

So we now need to figure out why there is no fuel getting to the engine.

How are you spraying in starter fluid? Through the AFM?
Loosened the boot on the throttle body, stuck the straw in, tightened, sprayed, started. More spray keeps it running.
 

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Loosened the boot on the throttle body, stuck the straw in, tightened, sprayed, started. More spray keeps it running.
That's logical. So if he hit a bump and it stopped and now refuses to work even with the pump running full speed then there could be wiring that's come loose.
It is hard to figure out from posts alone and not being at the car.

I feel it's something to do with the injector circuit because you can get it to run with starter fluid. But then why is the ECU not wanting to fire the injectors, I can't tell.
 

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Discussion Starter #19
That's logical. So if he hit a bump and it stopped and now refuses to work even with the pump running full speed then there could be wiring that's come loose.
It is hard to figure out from posts alone and not being at the car.

I feel it's something to do with the injector circuit because you can get it to run with starter fluid. But then why is the ECU not wanting to fire the injectors, I can't tell.
Yeah I’m stumped wiring looks fine, however who knows the actual story and if it’s correct? Any thread I find seems to be solved by something that I’ve already done or nobody says what solved it.
 

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Discussion Starter #20
Went out and checked all major vacuum lines and all boost piping, nothing loose, no change. I can’t find anything wrong. EFI fuse is good, pump is getting power and making noise.
Will start then stall, then after stalling continue to crank for the next hour or so then start then stall once more.
Throttle does nothing.
I’m so lost on this thing.
 
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