Brian Smith
Well-known member
1993 LT1 Coupe Six speed 165,000 miles. It is my daily driver and I love this car. It now seem to have what seems like a hard long term (3-5 millisecond) miss or the like while accelerating. Here is a little recent history.
I replaced the fuel pump a week ago since it was of unknown age, a potential single point of failure and because the car had quit abruptly twice a couple of times. Never stopped running since I replaced the Rochester injectors with the retooled Bosch version a year ago. 10,000 miles on the new injectors.
A week or so ago it quit when I turned a tight hard climbing right turn and it stopped mid turn. Coasted to a stop and after opening the hood to look if something was amiss tried restarting and it lit right up.
The next morning when coming to a red light while going about 50MPH in fifth gear I stepped on the clutch and it died. When it quit it seemed to just run out of gas. The tach just fell to 0 rpms like you had shut the car off. Once stopped it would crank briskly but not restart. I couldn't smell any fuel smell (combusted or otherwise) coming from the tailpipes.After about ten minutes I remembered something that said to push the throttle to the floor three times to reset something and it restarted the next time I cranked it.
That morning I ordered and got the replacement fuel pump, harness and suction filter and replaced them. I also ordered the fuel pump relay as well thinking I would just shotgun the fuel system. All inline filters are relatively new and when I replaced the pump parts there was no visible debris in the tank. (As an aside, There was however a yellow rectangular pan affixed to the bottom of the tank and positionally it looked like where the pump and sending unit float might live. What is this thing? Is it meant to reduce fluctuations of the fuel gauge and pump aspirating air?)
To continue, I looked in the FSM for the location of the fuel pump relay and was deeply distressed to see that it might be inside the car under the middle of the dash (like behind the radio?). The FSM didn't point me to the location with anything other than the drawing of all the sensors and relay etc. page.
The week before it started quitting on me I had to replace the power brake booster assy because of a diaphragm failure so I have spent considerable time under the dash very recently and hope that I don't have to take all that stuff back out to replace this relay.
The car seems to run a good bit stronger now but occasionally will just hesitate under hard full throttle acceleration. Generally after turning but sometimes when going straight. The plugs were replaced at 144000 miles. There are no codes being set so this tends to point me toward the fuel pump relay since it doesn't feel like one or two plugs failing to fire but like a coil failure that cures itself within a millisecond or two. No power washing under the hood to explain some sort of insult to the OptiSpark.
You guys think I am barking up the wrong tree with the fuel pump relay? If so point me right. If it is the damn relay where is it and what is the easiest way to get to it?
It is an interesting coincidence that after replacing the power booster this starts. I did remove the negative cable to the battery when replacing the booster. I did find the fitting that takes vacuum through the firewall to the cruise control/brake switches broken and I replaced it.
I know this is a mess of info but know how hard it is to help others with spotty data.
I replaced the fuel pump a week ago since it was of unknown age, a potential single point of failure and because the car had quit abruptly twice a couple of times. Never stopped running since I replaced the Rochester injectors with the retooled Bosch version a year ago. 10,000 miles on the new injectors.
A week or so ago it quit when I turned a tight hard climbing right turn and it stopped mid turn. Coasted to a stop and after opening the hood to look if something was amiss tried restarting and it lit right up.
The next morning when coming to a red light while going about 50MPH in fifth gear I stepped on the clutch and it died. When it quit it seemed to just run out of gas. The tach just fell to 0 rpms like you had shut the car off. Once stopped it would crank briskly but not restart. I couldn't smell any fuel smell (combusted or otherwise) coming from the tailpipes.After about ten minutes I remembered something that said to push the throttle to the floor three times to reset something and it restarted the next time I cranked it.
That morning I ordered and got the replacement fuel pump, harness and suction filter and replaced them. I also ordered the fuel pump relay as well thinking I would just shotgun the fuel system. All inline filters are relatively new and when I replaced the pump parts there was no visible debris in the tank. (As an aside, There was however a yellow rectangular pan affixed to the bottom of the tank and positionally it looked like where the pump and sending unit float might live. What is this thing? Is it meant to reduce fluctuations of the fuel gauge and pump aspirating air?)
To continue, I looked in the FSM for the location of the fuel pump relay and was deeply distressed to see that it might be inside the car under the middle of the dash (like behind the radio?). The FSM didn't point me to the location with anything other than the drawing of all the sensors and relay etc. page.
The week before it started quitting on me I had to replace the power brake booster assy because of a diaphragm failure so I have spent considerable time under the dash very recently and hope that I don't have to take all that stuff back out to replace this relay.
The car seems to run a good bit stronger now but occasionally will just hesitate under hard full throttle acceleration. Generally after turning but sometimes when going straight. The plugs were replaced at 144000 miles. There are no codes being set so this tends to point me toward the fuel pump relay since it doesn't feel like one or two plugs failing to fire but like a coil failure that cures itself within a millisecond or two. No power washing under the hood to explain some sort of insult to the OptiSpark.
You guys think I am barking up the wrong tree with the fuel pump relay? If so point me right. If it is the damn relay where is it and what is the easiest way to get to it?
It is an interesting coincidence that after replacing the power booster this starts. I did remove the negative cable to the battery when replacing the booster. I did find the fitting that takes vacuum through the firewall to the cruise control/brake switches broken and I replaced it.
I know this is a mess of info but know how hard it is to help others with spotty data.
