1993 Stumbling and No Start
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Safety Car
Joined: Sep 2006
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From: Greer, SC
1993 Stumbling and No Start
Hi fellow C4 owners.
I purchased a 1993 Anniversary Edition with 60,000 miles on it about 3 years ago. I purchased it for my son. I drove in a few times and my son finally got his license and has been using it frequently. We have had multiple issues with the car that we have addressed.
The only major issue left is when the car gets up to temp and you shut it off, it will restart but idles between 300-600 RPM then shuts off. It then will not restart for about 30 minutes. Then is restarts and drives mostly OK until we shut it off again. So far we have replaced the following items:
OPTI
Coil
ICM
Wires
Plugs
Not related to above issue but replaced for another reason:
Water Pump
Radiator
Fans
Transmission
Switched to Bosch III Injectors
Any ideas where to look next? We have been unable to make any progress. I'm thinking it might be something C4 owners can help with.
I'm not sure if related to the above but when above 4500 RPM the check engine light will come on then go right out once eh RPM comes down. We have been chasing issues with this car for a while. I know we put way more into it than it is worth. That said, my son loves this car and really wants to keep it.
Thanks for any assistance.
I purchased a 1993 Anniversary Edition with 60,000 miles on it about 3 years ago. I purchased it for my son. I drove in a few times and my son finally got his license and has been using it frequently. We have had multiple issues with the car that we have addressed.
The only major issue left is when the car gets up to temp and you shut it off, it will restart but idles between 300-600 RPM then shuts off. It then will not restart for about 30 minutes. Then is restarts and drives mostly OK until we shut it off again. So far we have replaced the following items:
OPTI
Coil
ICM
Wires
Plugs
Not related to above issue but replaced for another reason:
Water Pump
Radiator
Fans
Transmission
Switched to Bosch III Injectors
Any ideas where to look next? We have been unable to make any progress. I'm thinking it might be something C4 owners can help with.
I'm not sure if related to the above but when above 4500 RPM the check engine light will come on then go right out once eh RPM comes down. We have been chasing issues with this car for a while. I know we put way more into it than it is worth. That said, my son loves this car and really wants to keep it.
Thanks for any assistance.
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Any codes? Did you use the proper thermal grease on the ICM? Did you get all the air out of the coolant system? My 94 has two bleeders the temp sensor on the water pump can do strange things. I would change o2 sensors too if original.
Last edited by antfarmer2; Feb 27, 2016 at 11:58 AM.
Thread Starter
Safety Car
Joined: Sep 2006
Posts: 4,364
Likes: 408
From: Greer, SC
Thanks for your input.
No CEL but need to verify if any other codes. Yes, used thermal grease on the ICM. It was evenly coated. Cooling system was bled to avoid air bubbles. I have heard it could possibly be the O2's but others have said to check the alternator and fuel pump. The gas guage no longer works so thinking of replacing the whole assembly, if needed. I'm not sure how the fuel pump could do this but I'm at a loss right now.
No CEL but need to verify if any other codes. Yes, used thermal grease on the ICM. It was evenly coated. Cooling system was bled to avoid air bubbles. I have heard it could possibly be the O2's but others have said to check the alternator and fuel pump. The gas guage no longer works so thinking of replacing the whole assembly, if needed. I'm not sure how the fuel pump could do this but I'm at a loss right now.
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I would have the coil and icm tested they can be bad new. Make sure all connections are good and clean from the opti on up.don't think it is the o2 but just good maintenance. Check your temp plug on your pump. If your opti was working save it!!!!!!!!!!!!! Also pull the vacumme line off your FPR and smell for fuel. And check your fuel pressure.
Last edited by antfarmer2; Feb 28, 2016 at 08:01 PM.
Thread Starter
Safety Car
Joined: Sep 2006
Posts: 4,364
Likes: 408
From: Greer, SC
We replaced the new ICM with another new one and the no start condition is gone. It still will stall out after it's warm. The idle will drop to 300-600 RPM then stall.
I put a FP gauge on it today and FP reads 35 lbs with the engine running. What would be my next step?
I put a FP gauge on it today and FP reads 35 lbs with the engine running. What would be my next step?
Last edited by Mike02z; Mar 1, 2016 at 07:25 PM.
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did you sniff your fpr?Read again might as well pull the pump and fix the gas gauge I would go ahead and change the pump sock and fuel filter. Easyest pump ever done. Filter is a pita better to break at the back and pull from the top.
Last edited by antfarmer2; Mar 1, 2016 at 07:59 PM.
Thread Starter
Safety Car
Joined: Sep 2006
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From: Greer, SC
To low how old is your fuel filter? Might have a leaky pulsater. did you sniff your fpr?
Read again might as well pull the pump and fix the gas gauge I would go ahead and change the pump sock and fuel filter. Easyest pump ever done. Filter is a pita better to break at the back and pull from the top.
did you sniff your fpr?Read again might as well pull the pump and fix the gas gauge I would go ahead and change the pump sock and fuel filter. Easyest pump ever done. Filter is a pita better to break at the back and pull from the top.
I did not sniff the fpr. It was recently replaced when we did the injectors. I will take a wiff.
When we put the fpr and the injectors in I wanted to replace the filter. I had it up on a lift and it looked like a real PITA. It looked new so I left it. I'll replace it. The gas gauge is dead so I think we'll pull the pump.
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Went up after 30 minutes never saw that one it should hit 40 right away I would change the fuel filter. Best to break it at the back release the lines under the hood and take it out the top. If the tank is full might get a bath clamp off the fuel line by the pump or remove.
Last edited by antfarmer2; Mar 2, 2016 at 05:38 PM.
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From: Indiana PA
I see NO reason to change the pump or filter or pulsator at this point. What test has shown that one is needed?
The pressure went up after you shut off the engine due to heat in the fuel rail. This is normal, happens all the time. Engines get hot, so does the fuel in the rail.
You can also check for bleed down. Key on, engine off, a couple times, wait about 5 seconds between cycling key from off to on. To build pressure in the system. Note how long it take to drop the pressure any amount.
That picture you took? How was the pump running with the engine off? Did you jump the relay? Or did you snap this with key on, engine off as someone else turned the key to ON? The pump only runs for 2 seconds then shuts off if the ECM does not see engine RPM.
***You replaced the ICM and the no start is gone but stalls after 30 mins. of running. Did the car immediately restart? If it did not, what are you missing.***
Before you throw anymore time/money at this thing. Lets stop and assess what is happening rather than guessing.
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Really he turns the pump on without starting it goes to 20 then turns the key off after a while it goes to 40. Sure sounds like a pluged filter to me!!!!!!!!! JMO But I have been wrong before.
Last edited by antfarmer2; Mar 2, 2016 at 07:54 PM.
Safety Car
Joined: Sep 2010
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From: Indiana PA
If you read my post I asked him how he took that pic. If the key was on, the pump only runs for 2 seconds. Unless he had someone cycle the key and he snapped the pic when the pump was actually running OR jumped the relay that pressure reading may not be valid.
His engine running vac. line on the fuel pressure regulator and the 35PSI is a much more valid test as the car is RUNNING.
At this point if the car runs and then dies after X amount of time. That completely changes my diagnostic thought process.
I'm no longer really worried about fuel pressure. I suppose its possible for the pump to shut off after running for a period of time but unlikely.
I don't understand the confusion, I thought my post was pretty clear.
Difference might be in philosophy, I'm not real quick to suggest parts when more extensive testing is in order. I don't make a call until I have a complete picture. I don't think we are anywhere close to that at this point. Given the car starts runs and then after a time stalls. I've asked the OP some more questions to get more info on that condition. Lets wait to get those answers.
His engine running vac. line on the fuel pressure regulator and the 35PSI is a much more valid test as the car is RUNNING.
At this point if the car runs and then dies after X amount of time. That completely changes my diagnostic thought process.
I'm no longer really worried about fuel pressure. I suppose its possible for the pump to shut off after running for a period of time but unlikely.
I don't understand the confusion, I thought my post was pretty clear.
Difference might be in philosophy, I'm not real quick to suggest parts when more extensive testing is in order. I don't make a call until I have a complete picture. I don't think we are anywhere close to that at this point. Given the car starts runs and then after a time stalls. I've asked the OP some more questions to get more info on that condition. Lets wait to get those answers.
Last edited by 93Rubie; Mar 2, 2016 at 09:11 PM.
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I agree with that but he shows where the pump was running with the key on not running and only 20 pounds. Then turned the key off and it slowly went to 40 pounds. I have never seen this but believe a very clogged fuel filter could do this.
No confusion or throwing parts at it. JMO and maintenance.
No confusion or throwing parts at it. JMO and maintenance.
Last edited by antfarmer2; Mar 2, 2016 at 09:47 PM.
Thread Starter
Safety Car
Joined: Sep 2006
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From: Greer, SC
When running, the gauge read 35 lbs. I snapped the picture while the key was on but he engine was not running.
My son turned the key to the "on" position and that is when I saw 20 lbs. We repeated turning the key on and off several times. Leaving the gauge connected, and the key off, the pressure went up to 40 lbs after 30 minutes.
Before we replaced all the electrical components the car was hard to start and once hot, the idle would drop and it would stall and would not restart for 30 minutes or so.
So once we replaced the electrical components, and replaced 2 ICM's, the car is no longer hard to start and now restarts fine even when warm.
Everything replaced so far was needed as it was all original and the car has 75,000 miles on it. It was also father son bonding. We were not just throwing parts it at. We are fixing problems so he can have a safe dependable car. There were at least 10 things wrong with this car and we have whittled it down to this last issue.
Thanks for all the help.
My son turned the key to the "on" position and that is when I saw 20 lbs. We repeated turning the key on and off several times. Leaving the gauge connected, and the key off, the pressure went up to 40 lbs after 30 minutes.
Before we replaced all the electrical components the car was hard to start and once hot, the idle would drop and it would stall and would not restart for 30 minutes or so.
So once we replaced the electrical components, and replaced 2 ICM's, the car is no longer hard to start and now restarts fine even when warm.
Everything replaced so far was needed as it was all original and the car has 75,000 miles on it. It was also father son bonding. We were not just throwing parts it at. We are fixing problems so he can have a safe dependable car. There were at least 10 things wrong with this car and we have whittled it down to this last issue.
Thanks for all the help.
Last edited by Mike02z; Mar 3, 2016 at 06:49 AM.
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You will really bond over the fuel filter and teach him a few new words. Lol but not bad if you have the cheap tool to release the lines and take it out the top.
Last edited by antfarmer2; Mar 3, 2016 at 07:15 AM.
Thread Starter
Safety Car
Joined: Sep 2006
Posts: 4,364
Likes: 408
From: Greer, SC
Thanks for the continued assistance.
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both lines on the bottom?
Last edited by antfarmer2; Mar 3, 2016 at 10:43 AM.