QuestionQUESTION: 1990 Cadillac. I commute 100 miles every day. When driving down to work every thing is fine .Upon returning about 35 miles into the trip the car starts to jerk and cut out when pressing the gas pedal.As i continue on my trip i have to let up on the pedal more and more. I have replaced radiator, thermostat,temp sensor,ECM, grounds. No codes except for oxygen sensor and e98. Have had problem for 2 years -Help.
ANSWER: Does this problem occur when the fuel level in the fuel tank is close to empty ?.
Does this ever occur whenever the fuel is OVER 1/2 full ?.
Have you ever replaced the fuel pump in the gas tank ?.
I have heard and found that the fuel pump tends to get HOT when the gas level in the tank is low as the gas is what keeps the fuel pump cool.
How I find out is to put a fuel pressure gage on the fuel line and use a long enough fuel line so that I can tape the fuel gage to the outside of the windshield and still be able to close the hood and watch the fuel pressure gage as I drive the car for a few days to see if the fuel pump pressure starts to drop below 12 lbs while driving the vehicle. If it DOES, I replace the fuel pump.
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QUESTION: It does this if the gas is full or empty but only when I come back from work. I get to work just fine. I've also changed the ignition module but it didn't help. I am stumped. I have checked the fuel pump pressure numerous times but it always registers fine.
ANSWER: OK, But if the vehicle sits in the sun all day this can heat up the gas in the fuel tank and if you have an intermittent temperature sensitive fuel pump the pump gets hotter when you drive home as opposed to your driving in the morning when the gas in the tank is COLD from sitting over night.
I would put a fuel pressure gage on the fuel line and use a long enough fuel line so that I can tape the fuel gage to the outside of the windshield and still be able to close the hood and watch the fuel pressure gage as I drive the car home and if the pressure starts to drop, replace the fuel pump.
It is also possible that you may have a temperature sensitive oil pressure switch as this switch also controls the battery voltage to the fuel pump.
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QUESTION: I'm going to check and or replaced the fuel pump this weekend. It acts like it could be the fuel pump. However here is some added information that I should have mentioned before. When the car starts doing its thing, if i turn the key off for a little while then start it up again I get a few more miles of the car running normal before it starts jerking again. This is my routine everyday. thanks
AnswerWithout having personal contact with your vehicle to drive it, This is going to be a little difficult to obtain a diagnosis. Without doing the fuel pump test procedure with the gage taped to the outside of the windshield so as to monitor the fuel pressure, I would have to go with a new pump and fuel filter.
