Filter maybe?
LT1 Engine stalls, no start except w/ starting fluid
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
LT1 Engine stalls, no start except w/ starting fluid
I got a 1993 LT1 with 65,000 miles. After a short drive (5-10 miles) I would shut off the car, come back 2 hours later to have the car not start. It would turn over but not start. After setting for a couple of hours I would get back in the car and she would fire right up and drive like nothing ever happened. The last couple of times this happened I would spray starting fluid into the air cleaner and it would start and run fine. Today on the way home the car dies in traffic. I push the car to the side of the street, try the starting fluid. This time it would fire but only when the starting fluid was being sprayed into the air cleaner. I waited 10 minutes and tried again, this time she fired up and ran fine. I made it home with no problems but now I hate to drive again till I find the problem. This is defiantly a fuel problem. I am thinking fuel pump or the IAC. If it’s the IAC how difficult is it to change/clean? Would a fuel pump work intermittently when it goes bad?
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
No codes
No codes were set when this happens
I have replaced the fuel filter and also the sock on the fuel pickup about 5,000 miles ago. Not sure way a dirty fuel filter would cause the engine not to start only to start 10 minutes later and run with full power.
I just remove the IAC, it had a fair amount of carbon on it. Cleaned it with carb cleaner. Installed it back in and fired it up. Runs great but not sure if that could solve the problem. Not sure what the IAC does but read somewhere that a dirty IAC will cause these kinds of problems.
I have replaced the fuel filter and also the sock on the fuel pickup about 5,000 miles ago. Not sure way a dirty fuel filter would cause the engine not to start only to start 10 minutes later and run with full power.
I just remove the IAC, it had a fair amount of carbon on it. Cleaned it with carb cleaner. Installed it back in and fired it up. Runs great but not sure if that could solve the problem. Not sure what the IAC does but read somewhere that a dirty IAC will cause these kinds of problems.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
IAC wouldn't cause your problem--sounds like fuel pump--but I'd suggest checking fuel pressure to confirm.
Fuel pumps are not usually intermitent--but i have seen it a few times--your best bet is going to be a pressure check when it won't start. If you have no pressure when the problem occurs--check the grey wire at the fuel sending unit w/VOM hooked to that wire and ground (have someone else turn on ignition) If you have battery voltage--the pump is bad JMO
Fuel pumps are not usually intermitent--but i have seen it a few times--your best bet is going to be a pressure check when it won't start. If you have no pressure when the problem occurs--check the grey wire at the fuel sending unit w/VOM hooked to that wire and ground (have someone else turn on ignition) If you have battery voltage--the pump is bad JMO
Last edited by TWISTERUP; May 6, 2009 at 06:25 PM.
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Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
Starting fluid
Picked up a fuel pump ($90) and relay ($10) from autozone today
Will try to install this weekend. The box with the relay only had one relay. I see on the diagram above that the car has two relays. Are they both the same and I need to purchase a second one? The car has been running great yeasterday. I hate to throw money at the fuel pump if that is not the problem but I got to start somewhere.
Thanks for the help.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
When the problem occurs, have you ever listened for the pump running for the 2 seconds when you first turn the key to on. You can try that several times and listen for it. The fuel pump is controlled by the fuel pump relay in this case (for 2 seconds). Once the engine starts the relay is pulled in again and held by the ECM as long as it senses the engine is running.
Once the engine starts a pressure switch activated by oil pressure which closes and puts a constant voltage to the fuel pump. Even if the relay was bad, the engine will continue to run normal.
Under normal operations the fuel pump gets voltage from both the relay and pressure switch as a redundant power system.
Its doubtful the relay is causing this problem but easily recognized by just listening. A fuel pressure check would definitely be in order. Fuel pump could definitely be defective.
But when I hear some of these weird symptoms on a 93 I think of the ECM doing strange things. If possible at home I would connect a noid light across the injectors to see if the injectors are being driven. You might even permanently connect one to an injector so if it dies on the road you can quickly see if you lost the drive. Then you would know if the problem was there or not.
Once the engine starts a pressure switch activated by oil pressure which closes and puts a constant voltage to the fuel pump. Even if the relay was bad, the engine will continue to run normal.
Under normal operations the fuel pump gets voltage from both the relay and pressure switch as a redundant power system.
Its doubtful the relay is causing this problem but easily recognized by just listening. A fuel pressure check would definitely be in order. Fuel pump could definitely be defective.
But when I hear some of these weird symptoms on a 93 I think of the ECM doing strange things. If possible at home I would connect a noid light across the injectors to see if the injectors are being driven. You might even permanently connect one to an injector so if it dies on the road you can quickly see if you lost the drive. Then you would know if the problem was there or not.
Last edited by pcolt94; May 10, 2009 at 08:58 PM.
Drifting
Joined: Nov 2005
Posts: 1,361
Likes: 0
From: Downriver Mi.
I tried 3 or 4 times to get the car started with the fluid. I only sprayed the fluid for about 5 seconds each time I tried starting. What kind of damage do you think could happen because of using starting fluid?
Picked up a fuel pump ($90) and relay ($10) from autozone today
Will try to install this weekend. The box with the relay only had one relay. I see on the diagram above that the car has two relays. Are they both the same and I need to purchase a second one? The car has been running great yeasterday. I hate to throw money at the fuel pump if that is not the problem but I got to start somewhere.
Thanks for the help.
Picked up a fuel pump ($90) and relay ($10) from autozone today
Will try to install this weekend. The box with the relay only had one relay. I see on the diagram above that the car has two relays. Are they both the same and I need to purchase a second one? The car has been running great yeasterday. I hate to throw money at the fuel pump if that is not the problem but I got to start somewhere.
Thanks for the help.
Drifting
Joined: Nov 2005
Posts: 1,324
Likes: 5
From: Charlotte NC
I had this exact problem years back on a Mercury Lynx. After months of replacing this and that, we found the fuel tank had leaves (yes, leaves) in it that would float over the pickup and stop the fuel flow intermittently.
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
Update: new fuel pump, not the problem
Yeasterday I installed a new fuel pump. The car started fine and ran fine. Today I took my son to his ball game in the vette. After the game I get in the car and it would not start. I did hear the fuel pump come on for a couple of seconds when I turned the key so I know the new pump is not the problem. I did spray starter fluided in the intake, it tried to start but would not stay running without the fluid.
I caught a ride home and returned 2 hours later, got into the car, hit the key and she fires right up like nothing ever happend, wtf. Must be some type of heat issue with something that controls the fuel injectors.
How do I release the shrader valve to check fuel pressure?
Where do I purchase a Noid light to check the injectors?
Could this be a problem with a computer?
I caught a ride home and returned 2 hours later, got into the car, hit the key and she fires right up like nothing ever happend, wtf. Must be some type of heat issue with something that controls the fuel injectors.
How do I release the shrader valve to check fuel pressure?
Where do I purchase a Noid light to check the injectors?
Could this be a problem with a computer?
Last edited by pacat; May 11, 2009 at 09:14 PM. Reason: added more info
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
No fuel at injectors, good psi
Today I got my car to give me a "no start" while in the garage (got lucky).
As I stated before the car will crank but not start unless starting fluid is sprayed into the intake, then will only run untill I stop spraying the fluid. Then after the car sat for a couple of hours it would start.
I had a fuel gauge hooked up to the schrader valve, got around
40psi.
I got a set of Noid lights hooked to three of the injector plug wires. None of the lights come on while I was cranking the engine. (I know the lights do work, they were flashing the last time the car would start)
Looks like my problem is the fuel injectors not firing. I'm thinking a bad ECM. Any other ideas way the injectors would stop working intermittantly?
As I stated before the car will crank but not start unless starting fluid is sprayed into the intake, then will only run untill I stop spraying the fluid. Then after the car sat for a couple of hours it would start.
I had a fuel gauge hooked up to the schrader valve, got around
40psi.
I got a set of Noid lights hooked to three of the injector plug wires. None of the lights come on while I was cranking the engine. (I know the lights do work, they were flashing the last time the car would start)
Looks like my problem is the fuel injectors not firing. I'm thinking a bad ECM. Any other ideas way the injectors would stop working intermittantly?
Thread Starter
Instructor
Joined: Jul 2006
Posts: 153
Likes: 0
From: Erie PA
Drifting
Joined: Nov 2005
Posts: 1,361
Likes: 0
From: Downriver Mi.
Today I got my car to give me a "no start" while in the garage (got lucky).
As I stated before the car will crank but not start unless starting fluid is sprayed into the intake, then will only run untill I stop spraying the fluid. Then after the car sat for a couple of hours it would start.
I had a fuel gauge hooked up to the schrader valve, got around
40psi.
I got a set of Noid lights hooked to three of the injector plug wires. None of the lights come on while I was cranking the engine. (I know the lights do work, they were flashing the last time the car would start)
Looks like my problem is the fuel injectors not firing. I'm thinking a bad ECM. Any other ideas way the injectors would stop working intermittantly?
As I stated before the car will crank but not start unless starting fluid is sprayed into the intake, then will only run untill I stop spraying the fluid. Then after the car sat for a couple of hours it would start.
I had a fuel gauge hooked up to the schrader valve, got around
40psi.
I got a set of Noid lights hooked to three of the injector plug wires. None of the lights come on while I was cranking the engine. (I know the lights do work, they were flashing the last time the car would start)
Looks like my problem is the fuel injectors not firing. I'm thinking a bad ECM. Any other ideas way the injectors would stop working intermittantly?
buy a FSM before you scrap your motor.