my 1992 LT1 keeps dying after 15 to 20 minutes of running
11-18-2015, 09:14 PM
#1
my 1992 LT1 keeps dying after 15 to 20 minutes of running
have been chasing this problem for around one week now. so far in parts I have brand new coil and ignition module,,, completely refurbished ECM,,, new fuel pump and fuel filter,,, and I have read the specification on a OHM meters for all 8 injectors..... all reading good at 12.9 to 13.4..... the distributor area looks so fresh, and the car runs so perfectly, when it runs that I don't think it is distributor cap rotor related.... my next move is to run the car again until it dies, then quickly ohm out all the injectors again when hot, and also spray into the intake a little gas to see if it starts up to prove if its losing gas or losing spark,,,, anybody familiar with this?. I had read in one of these forums that a bad injector can heat up under running conditions and short out after it heats up and it said the ECM will tell the fuel pump to shut down in this case,,, has anybody ever heard of that,,?,,, it seems if and when I Drive the car like a grandmother, I can drive all day,, but as soon as I put a high demand, winding up run it hard, it will die shortly after that,, kind of like a clogged fuel filter but this one has been changed. thank you
Last edited by Bentleyben; 11-18-2015 at 09:22 PM. Reason: error
11-18-2015, 09:48 PM
#2
sounds like your on the right track. also try smacking your ECM and see if it dies then try straping a cold pack on it and see what it does.
did you use the proper heat grease on the icm?
and put a fuel pressure gauge on it and tape it to the windshield and test
did you use the proper heat grease on the icm?
and put a fuel pressure gauge on it and tape it to the windshield and test
Last edited by antfarmer2; 11-18-2015 at 09:51 PM.
11-19-2015, 01:02 PM
#3
My L98 had two injectors that would fail when hot. Let it cool down it would start and run... up until the dash read about 208 or so, then it would just shut down and wouldn't re-start until it cooled off again. A new set of Bosch injectors and it was running again.
11-19-2015, 09:38 PM
#4
Staling???
Ahhh Grasshopper.
Your energy is admirble. But you'd be better off listening to the gurus on this forum. Their experience and benevolence is limitless. All you need to run is fuel, compresion, & ignition, right?
Suggestion - start here ... put a fuel pressure gauge on it, then drive until the stall occurs. Watch the gauge closely at the 15 minute mark as to be accurate with your findings. If the fuel pressure drops, you've found your problem. I did this - per the guru's suggestions - and simply replaced the fuel pump relay.
If not, it's ignition ...
Your energy is admirble. But you'd be better off listening to the gurus on this forum. Their experience and benevolence is limitless. All you need to run is fuel, compresion, & ignition, right?
Suggestion - start here ... put a fuel pressure gauge on it, then drive until the stall occurs. Watch the gauge closely at the 15 minute mark as to be accurate with your findings. If the fuel pressure drops, you've found your problem. I did this - per the guru's suggestions - and simply replaced the fuel pump relay.
If not, it's ignition ...
11-19-2015, 11:18 PM
#5
Ahhh Grasshopper.
Your energy is admirble. But you'd be better off listening to the gurus on this forum. Their experience and benevolence is limitless. All you need to run is fuel, compresion, & ignition, right?
Suggestion - start here ... put a fuel pressure gauge on it, then drive until the stall occurs. Watch the gauge closely at the 15 minute mark as to be accurate with your findings. If the fuel pressure drops, you've found your problem. I did this - per the guru's suggestions - and simply replaced the fuel pump relay.
If not, it's ignition ...
Your energy is admirble. But you'd be better off listening to the gurus on this forum. Their experience and benevolence is limitless. All you need to run is fuel, compresion, & ignition, right?
Suggestion - start here ... put a fuel pressure gauge on it, then drive until the stall occurs. Watch the gauge closely at the 15 minute mark as to be accurate with your findings. If the fuel pressure drops, you've found your problem. I did this - per the guru's suggestions - and simply replaced the fuel pump relay.
If not, it's ignition ...
11-20-2015, 08:39 AM
#6
always best to find the problem first and fix it. then if you ant to replace old parts thats up to you.
if you want new injectors talk to Jon at FIC
if you want new injectors talk to Jon at FIC
11-20-2015, 02:57 PM
#7
my l98 had two injectors that would fail when hot. Let it cool down it would start and run... Up until the dash read about 208 or so, then it would just shut down and wouldn't re-start until it cooled off again. A new set of bosch injectors and it was running again.
11-20-2015, 03:05 PM
#8
Fuel pump relay was going to get changed as a next choice,, then Injectors. I plan to travel to FLA. with it,, occasionally. Can't have any breakdowns, over 20-50 dollar parts. Been doing my own work on my cars for 43 years. This exact scenario, is the same symptom of a bad injector / bad ICM / bad ECM / bad fuel pump / clogged fuel filter / bad fuel pump relay / bad coil,,, ,,,,, Thank You for the input,,,, Happy Motoring !
11-20-2015, 03:13 PM
#9
,,,,, A typical part of diagnosing problems, is sometimes replacing parts that still worked. If you have a way to go straight to it,,, the first time,, I will like to hear about it. This car has high mileage,, with all major things rebuilt, but I have no clue about relays replaced ?? all the little components that surround the motor and make it run correctly. If I want to travel with this car,,,, ALL this stuff needs to be done anyways.
11-20-2015, 03:19 PM
#10
Race Director
OptispArk.
Also dont put a cheapo unit in there. If you cant get luck and find an oem nos optispark then id go with the petris unit.
It Adds a vented setup to prevent future problems
Also dont put a cheapo unit in there. If you cant get luck and find an oem nos optispark then id go with the petris unit.
It Adds a vented setup to prevent future problems
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Bentleyben (11-20-2015)
11-20-2015, 03:32 PM
#11
11-20-2015, 04:06 PM
#12
what did the tests show? no way to go straight to it but with testing it can be found. any codes? a look at youtube and a paper clip can be very helpful.
Last edited by antfarmer2; 11-20-2015 at 04:16 PM.
11-20-2015, 04:38 PM
#13
so it is there for good,,,, that was a plan before I had this problem. ... been doing the paperclip trick for 20 years. ,,,, Code 43,, Knock sensors,,,,, would have nothing to do with sudden shut down. somebody may have put 87 octane in it, and lugged the gears a little,,, and there you get the code,,, and that may have happened 5 years ago. ,,,, Nothing to do with the problem ,,,, Just purchased 8 new injectors,, and doing fuel pump relays. This car could not run better,, when it runs.
Last edited by Bentleyben; 11-20-2015 at 04:43 PM.
11-20-2015, 04:59 PM
#14
true but very hard to read the gauge when driveing under the hood when driveing to test. my 94 ran bad when I hit the gas hard no codes. new 02s took care of this. if you give us the results of the tests. we can help.
and never answered about the thermal grease.
and never answered about the thermal grease.
Last edited by antfarmer2; 11-20-2015 at 05:03 PM.
11-20-2015, 07:33 PM
#16
,,, if you have a gauge under the hood,,,, (stay with me now),,, If you have a gauge under the hood,, if the car dies because of a loss of fuel pressure,,, (you simply pop the hood and read the gauge),,, if you did not loose fuel pressure,, it would show 40-45 lbs. on the gauge,, just as if you were still running. If you DID loose fuel pressure,, the gauge will show 0, fuel pressure or not much more. If you read past posts of this thread,,, it says (I did) read the codes,, it has a 43 code (knock sensor),,, has nothing to do with the problem. ,,,, And yes,,, Of course I used the thermal grease, provided by the manufacturer of my new ICM. ,,,, The first ICM I ever installed,, using the grease, was over 20 years ago. ,,, I know the drill. ,,,,, This forum is a little frustrating because,, almost everyone wants to treat a person who asks for some ideas over a problem,, like their trying to fix their car, for the very first time in their life. I knew how to tune up my fathers 1969 Chevrolet Impala,,, 327 2bbl,,, points and condenser with timing light, when I was 14. ,,,, I am gaining on my Corvette issues and doing all fuel pump related relays and new injectors. I can't be breaking down in hooterville Alabama over a few hundred in parts.
Last edited by Bentleyben; 11-20-2015 at 07:35 PM.
11-20-2015, 07:47 PM
#17
still waiting for answers on any tests that have been done. we can not see it from here. happy to try to help you.
when it dies what is your fuel pressure? will it start right back up? what do your injectors ohm out when hot? do you have a noid light to test with if it does not start?
might be your opti.
I believe yours is batch fire so one injector can kill it.
when it dies what is your fuel pressure? will it start right back up? what do your injectors ohm out when hot? do you have a noid light to test with if it does not start?
might be your opti.
I believe yours is batch fire so one injector can kill it.
Last edited by antfarmer2; 11-20-2015 at 11:27 PM.
11-20-2015, 11:19 PM
#19
Multimeter on the ohmmeter setting. Unplug the lead and measure each injector. Good injectors should read around 16 Ohms. The two bad ones were reading around 7 or 8 Ohms. Unplug them and the engine would start and run, obviously very roughly since it was only on 6 cylinders at that point... but with them hooked up it would crank forever without firing until it cooled down.
11-20-2015, 11:52 PM
#20
Multimeter on the ohmmeter setting. Unplug the lead and measure each injector. Good injectors should read around 16 Ohms. The two bad ones were reading around 7 or 8 Ohms. Unplug them and the engine would start and run, obviously very roughly since it was only on 6 cylinders at that point... but with them hooked up it would crank forever without firing until it cooled down.