Engine shuts down abruptly
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Engine shuts down abruptly
Aight, I got a -91 Camaro RS with 350 tpi (aparently from an older Corvette).
It has started to shut the engine of, while driving.
Driving normaly, it simply shuts of the engine and the speedometer drops to 0 (while the car is still moving) all other gauges works... Like oil pressure, heat, tachometer, still works.
It will be impossible to start (by popping the clutch or by turning the key).
If I see the speedometer start working, I can pop the clutch and the car will start again.
Fairly sure this is an eletrical problem, but dont know where to search?
Thinking possibly someting with the ignition lock?
Edit: Realized I left something out... The engine cranks when I turn the key. It just won't start.
It will start, if I wait a bit.
Its also quite erratic in how long it will run, when its running. This weekend I moved the car from its "winter garage" home. About 30 miles or so.
It stopped 4 times... I waited mybe 5 min, started the car and speed of.
One time I got a mile at best, (the engine ran for maybe 30sec, at best... Just so I got up to 80ish mph), Last time it ran for 20 min or more (untill I came home and freely turned it off).
It has started to shut the engine of, while driving.
Driving normaly, it simply shuts of the engine and the speedometer drops to 0 (while the car is still moving) all other gauges works... Like oil pressure, heat, tachometer, still works.
It will be impossible to start (by popping the clutch or by turning the key).
If I see the speedometer start working, I can pop the clutch and the car will start again.
Fairly sure this is an eletrical problem, but dont know where to search?
Thinking possibly someting with the ignition lock?
Edit: Realized I left something out... The engine cranks when I turn the key. It just won't start.
It will start, if I wait a bit.
Its also quite erratic in how long it will run, when its running. This weekend I moved the car from its "winter garage" home. About 30 miles or so.
It stopped 4 times... I waited mybe 5 min, started the car and speed of.
One time I got a mile at best, (the engine ran for maybe 30sec, at best... Just so I got up to 80ish mph), Last time it ran for 20 min or more (untill I came home and freely turned it off).
Last edited by Perkalov; Apr 28, 2025 at 06:18 AM.
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Car: 1986 IROC Z
Engine: 5.0 TPI
Transmission: 700R4
Axle/Gears: 3.23 Posi
Re: Engine shuts down abruptly
The basics:
When it cranks but won't start:
*check fuel pressure
*check for spark at the plugs
*check for injector pulse with a noid light
The results of these basic steps will provide you with some direction with which to proceed.
When it cranks but won't start:
*check fuel pressure
*check for spark at the plugs
*check for injector pulse with a noid light
The results of these basic steps will provide you with some direction with which to proceed.
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From: Armstrong B.C.
Car: 1991 camaro Z28
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Re: Engine shuts down abruptly
I had the same issues with the stock ECM crap. Yea you can fix it for a while but it'll just come back, rinse and repeat. My solution was to throw it all in the garbage where it belongs and went Holley HP now Dominator. Pissing around with the factory stuff just isn't worth the headache IMO.
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Car: 84 TA orig. 305 LG4 "H" E4ME
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Re: Engine shuts down abruptly
This weekend I moved the car from its "winter garage" home.
Any mice or critters?
Any mice or critters?
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Re: Engine shuts down abruptly
Okay, thanks. I'll check that out, just to make sure.
Thinking that this should also shut down the tachometer (layman thinking, RPM is calculated there?), but the ECM isn't hard to get to, just to make sure.
Does the speedometer share ground with anything in the ignition switch/lock?
Not much of a mechanic, so I will just have to this one thing at the time.
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Re: Engine shuts down abruptly
Fuelpressure and fuelpump ok.
Ignition and/or injectors will be "off" when it happens. However, not easily checked at 80 mph.
But I'll check the ignition next time.
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Car: Yes
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Re: Engine shuts down abruptly
Thinking that this should also shut down the tachometer
OTOH the speedo IS driven by the ECM. Which explains readily why it will quit working when the ECM loses power.
Does the speedometer share ground with anything in the ignition switch/lock?
the ECM isn't hard to get to
See my signature for a logic shortcut that often saves a great deal of useless tail-chasing "maybe it's this maybe it's that" stuuuupidity. LOOK AT what is happening CAREFULLY, and make a mental list of all of the things that if ONE THING goes wrong, all the observed symptoms occur. I'm talking, SINGLE POINT OF FAILURE stuff; we're not looking for evidence of alien abduction, trying to figure out why 3 different failures occur ALWAYS exactly at the same time and ALWAYS together which is beyond improbable, or anything else that requires a set of circumstances SO UNUSUAL as to be impossibly unlikely.
The ECM's ground could be the SINGLE point of failure, since that's simply the opposite side of its power feed. Pretty sure it gets grounded at the rear of the pass side head in most if not all variations of these cars.
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Car: 1984 Camaro Berlinetta
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Re: Engine shuts down abruptly
Fuel Pump problem maybe ?? I had TPI with a similar fault, it turned out to be a bad valve ( backflow ?) on the fuel pump. It would ruin, but then just kinda' "studder" and then stall out. Maybe test the fuel pressure after priming the pump and then waiting/watching how long it takes that fuel pressure to 'bleed' off...........?
Joined: Sep 2005
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Car: Yes
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Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Engine shuts down abruptly
Won't kill the speedo. 
Always start by seeking out a SINGLE POINT OF FAILURE that accounts for ALL observed symptoms.
Not saying of course "his fuel pump is good", or ANYTHING of the kind. Only, that it CANNOT account for ALL observed symptoms including the speedo failure, therefore can be safely ruled out as a potential culprit.
Always start by seeking out a SINGLE POINT OF FAILURE that accounts for ALL observed symptoms.
Not saying of course "his fuel pump is good", or ANYTHING of the kind. Only, that it CANNOT account for ALL observed symptoms including the speedo failure, therefore can be safely ruled out as a potential culprit.
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Re: Engine shuts down abruptly
Don't "think" things like that. The tach gets ignition pulses directly from the distributor and thus is completely independent of the ECM, except that if the ECM isn't telling the dist to fire, then there won't be pulses for it to measure. Which is of course why the tach keeps right on working in these cars when people carb-swap them and remove the ECM entirely.
OTOH the speedo IS driven by the ECM. Which explains readily why it will quit working when the ECM loses power.
Not that I know of. Only thing in the ign sw wiring that involves "ground", is the water temp gauge, such that it pegs when the key is in Start.
Very true. However the problem probably isn't at the ECM itself, but more likely, is in the wire that feeds power to it. Although it could be in the short part of it that's inside the car.
See my signature for a logic shortcut that often saves a great deal of useless tail-chasing "maybe it's this maybe it's that" stuuuupidity. LOOK AT what is happening CAREFULLY, and make a mental list of all of the things that if ONE THING goes wrong, all the observed symptoms occur. I'm talking, SINGLE POINT OF FAILURE stuff; we're not looking for evidence of alien abduction, trying to figure out why 3 different failures occur ALWAYS exactly at the same time and ALWAYS together which is beyond improbable, or anything else that requires a set of circumstances SO UNUSUAL as to be impossibly unlikely.
The ECM's ground could be the SINGLE point of failure, since that's simply the opposite side of its power feed. Pretty sure it gets grounded at the rear of the pass side head in most if not all variations of these cars.
OTOH the speedo IS driven by the ECM. Which explains readily why it will quit working when the ECM loses power.
Not that I know of. Only thing in the ign sw wiring that involves "ground", is the water temp gauge, such that it pegs when the key is in Start.
Very true. However the problem probably isn't at the ECM itself, but more likely, is in the wire that feeds power to it. Although it could be in the short part of it that's inside the car.
See my signature for a logic shortcut that often saves a great deal of useless tail-chasing "maybe it's this maybe it's that" stuuuupidity. LOOK AT what is happening CAREFULLY, and make a mental list of all of the things that if ONE THING goes wrong, all the observed symptoms occur. I'm talking, SINGLE POINT OF FAILURE stuff; we're not looking for evidence of alien abduction, trying to figure out why 3 different failures occur ALWAYS exactly at the same time and ALWAYS together which is beyond improbable, or anything else that requires a set of circumstances SO UNUSUAL as to be impossibly unlikely.
The ECM's ground could be the SINGLE point of failure, since that's simply the opposite side of its power feed. Pretty sure it gets grounded at the rear of the pass side head in most if not all variations of these cars.
On a diffrent note... Given the question posed by Ironwill. If I read this correctly;
"the tach gets ignition pulses directly from the distributor and thus is completely independent of the ECM"
Since tachometer is working when the problem occures... I got spark?
Re: Engine shuts down abruptly
.....Driving normaly, it simply shuts of the engine and the speedometer drops to 0 (while the car is still moving) all other gauges works... Like oil pressure, heat, tachometer, still works.
It will be impossible to start (by popping the clutch or by turning the key).
If I see the speedometer start working, I can pop the clutch and the car will start again......
It will be impossible to start (by popping the clutch or by turning the key).
If I see the speedometer start working, I can pop the clutch and the car will start again......
Sounds like an intermittent wiring fault starving the ECM for power, or perhaps a bad ECM.
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Re: Engine shuts down abruptly
Sofa, I believe what Perkalov is saying is that when the car is moving and the problem happens, the engine being driven by the manual transmission is still showing an RPM reading on the tach, even though the failure is not allowing it to produce power.
Sounds like an intermittent wiring fault starving the ECM for power, or perhaps a bad ECM.
Sounds like an intermittent wiring fault starving the ECM for power, or perhaps a bad ECM.
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Re: Engine shuts down abruptly
Thanks all.
Seems fixed, will just have to wait and see.
The ECM was just hanging in the wiring, somehow slid out of the harness that is supposed to hold it in place.
Made sure the connectors (?) was tightly in place and attached the ECM properly to the harness and it seems to work.
Once again, tnx for the help.
Seems fixed, will just have to wait and see.
The ECM was just hanging in the wiring, somehow slid out of the harness that is supposed to hold it in place.
Made sure the connectors (?) was tightly in place and attached the ECM properly to the harness and it seems to work.
Once again, tnx for the help.
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