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Discussion Starter · #1 ·
Sorry this post is long.

My engine starts right up. It idles at about 900 rpm. Then, it dies. Dead. I can immediately push the start button and it will start right back up - for 2 more seconds. I can do this all day...

I have an l67 engine in a rock-crawling buggy. It has a manual transmission and I have had my computer programmed to remove all transmission and emissions info - and vats disabled. The engine is stock other than the computer being modified and removing the egr, oil level sender, oil pressure sender, etc. I am using AutoMeter oil and water gauges. This is an off-road only vehicle.

I went through almost every wire and made sure that all the connections were good and I had 12v and 5v where I was supposed to. The connections are all soldered and shrink-tubed. The voltage drops when I hit the starter (to about 10 volts) and immediately jumps back up to 12-13 or so as soon as the load it taken off the battery. The battery is a fully charged Optima yellow-top. This temporary voltage drop is consistent for the constant power and the switched power leads Fuel pressure is about 40 while the engine is running. When the engine shuts down, it jumps to about 45.

The electrical grounds are all good, too. I checked continuity from one end to the other on them… all checked out fine. The computer, itself, is fully isolated from the chassis.

Unplugging the MAF didn’t help. Or hurt… I checked all the vacuum hoses (hard plastic) thinking there may be a problem with the MAP; all the vacuum lines are good. I replaced the one that was a little bit weathered but that didn’t impact anything.

Oil pressure is good; about 70 psi.

I checked all the relays for the fuel pump and the static fused power and switched 12v, too. All that checked out, fine.

The engine idles at about 900 rpm.

When I hit the start button, the engine starts right up. Then, after 2 seconds or so (sometimes, I get excited when it runs for almost 3 seconds), the engine dies. I can immediately hit the start button and it’ll run for 2 or 3 more seconds. I can do this repeatedly until my thumb hurts. <grin>

Does anyone have any ideas of what to check, next?

Thanks. I am stumped.
 

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Does it shudder at all as it shut's off or is it like when you turn the key off ( a clean and smooth shut-off)? Have you checked your fuel pressure with the condition. It sounds like the pump is priming and after the vehicle starts the pump is not being activated like it should to provide continuous flow to the engine. The pump is activated for continous run via a different electrical path (sometimes a different, sometimes the same relay but using different grounds or powers, etc. depending on your set-up). It sounds like your problem lies here.
 

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Discussion Starter · #3 ·
Does it shudder at all as it shut's off or is it like when you turn the key off ( a clean and smooth shut-off)? Have you checked your fuel pressure with the condition. It sounds like the pump is priming and after the vehicle starts the pump is not being activated like it should to provide continuous flow to the engine. The pump is activated for continous run via a different electrical path (sometimes a different, sometimes the same relay but using different grounds or powers, etc. depending on your set-up). It sounds like your problem lies here.
It just dies like it was shut off. Like the ignition is being cut or the injectors are shut off. There's no stumble, backfiring, or anything strange. So, I suppose it is a clean and smooth shut off.

The pump does prime and I think it continues to pump as the engine is running. There's 45 psi of fuel according to my gauge on the fuel rail.

Before I wired the pump to the computer, I had the pump hard-wired "ON" and the engine performed the same way. ( I wanted to check the voltage of the fuel pump relay wire) Currently, the fuel pump relay wire is connected to my relay. I am not using a resistor. Not sure why I would - but my issue sounds like what I have researched form others on this board.

I am not sure what you mean by different grounds and the fuel pump/relay. My engine is from a 1999 Park Avenue Ultra and the wire hooked up to the fuel pump relay is "Pin #3, Clear connector - Fuel Pump Relay Control"


Am I missing something in my relay wiring?

Thanks!
 

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It sounds like you've got that aspect of the fuel delivery system covered. Do you have a noid light set? That way you could verify if something is disabling the injectors after those few seconds. If not you can pick a set up at most auto parts stores for less than $20.
 

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Discussion Starter · #6 ·
DOLP! I didn't even think of using noids. That's next. Thanks for the tip!

I'll report back tomorrow or Wednesday.

Cheers
 

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Discussion Starter · #8 ·
Noids indicate the injectors are shutting down after about 2 seconds. The lack of fuel is apparently causing the engine to die. The computer is going back for an evaluation.

The moment of truth is coming... stay tuned. I hope not to get egg on my face. :icon_redf

Thanks for your help and suggestions.
 

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You must be using a 1999 or up PCM, which requires a class 2 serial data signal from the BCM(which I assume you don't have). If no signal present, the engine runs for exactly 2 seconds and shuts down. The quick fix is to switch to a 1998 GTP PCM, which does not use a BCM and problem solved. Just double check the pinouts of the two and move prongs on the PCM connectors as needed, otherwise it WILL burn out. :coolbeer:
 

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Discussion Starter · #10 ·
Yes. The computer, engine, and harness are from a 1999 Park Avenue Ultra. What is the "B" in the BCM? I am assuming Control Module for C and M. The computer is being reprogrammed and I have been told that the "automatic disabling of engine functions due to anti-theft programming" can and will be removed.

If I do need to replace the computer, I'd rather not purchase an entire Factory Service Manual just for 4 pages of pinouts. Can you suggest a source for just the pinouts if I need them?

Lastly, thank you for the information. There is so much to know about this stuff! This board has been invaluable. :)
 

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The "B" in BCM is Body Control Module. I wish I could help with the 1999 FSM's however I only have the FSM's for the 1998 Model Year, but that may be what you need the info from. Let me know if I can help.
 

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PM me an email that I can send the 1998 pinout to, cheap PCM's can be found on Car-Part.com--Used Auto Parts Market for around $35 or $45 shipped, just make sure it is the VIN "1" and not "K".
 
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Discussion Starter · #13 · (Edited)
Thank you, Miko,

I'm going to wait and see what happens with my reprogramming. If it doesn't solve the stalling/dying issue, I'll take your advice. In the meantime, you have a pm.

Much appreciated!
 

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For an engine swap application; was the VATS disabled in the program? You should also have removed all the DTC's that would trigger if any of the original expected inputs are not seen by the PCM
 

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You guys need to check dates on posts. The forum will suggest some ancient dead conversations to generate clicks. It's best to use the NEW post button to chat about things with people actively posting.
 
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