Acceleration and starting issue - fuel pump?
08-31-2023, 11:17 PM
#1
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Acceleration and starting issue - fuel pump?
Hey guys,
So I got a used C5 with just under 80k miles on it recently and have been daily driving it while continuing to get some work done on it, general tune up, breaks, tires, fluids and belts etc. My most recent and concerning issue I've noticed is a two parter that I think might be linked by the fuel pump.
Starting the car: when I cold start the car in the morning, or after it hasn't been driven for probably six hours or greater, I notice it takes a bit more cranking to get going. Usually 3-6 seconds instead of the typical 1-3 I get, particularly after its already been turned on once recently. It has not failed to start (yet) and I rather need it to stay that way, not very familiar with C5s so not sure if this is just the norm for them or indicative of a bigger issue in conjunction with the following problem.
Low speed rolling acceleration: If I attempt to aggressively accelerate the car from low speed, say 20-40mph, up to a higher speed around say 60-70mph, it bogs down and almost jerks or staggers (forcefully enough that I'm getting shoved a bit) sporadically and does not speed up nearly as fast as would be expected. This issue has only happened 2 or 3 times, but I'm also babying it a bit. Pressure gauge has it staying in the 20-50 range, temperature around 210-230, and the interesting part to me to the RPM never exceeds probably 3.5/4k even with significant depression of the accelerator peddle.
Looking at both issues together I'm thinking its the fuel pump just based off some superficial research, but hoping someone more experience with the vehicle could either verify my hunch or point me down the right road. Maybe this is all just normal for the model too, I honestly wouldn't know. Incidentally, if anyone happens to have experience with weather stripping for the C5, feel free to reach out too. I'm starting to feel like I bought a lemon of a car with all the money I'm putting into it, even though the mechanic said it was rock solid during the PSI. Thanks!
So I got a used C5 with just under 80k miles on it recently and have been daily driving it while continuing to get some work done on it, general tune up, breaks, tires, fluids and belts etc. My most recent and concerning issue I've noticed is a two parter that I think might be linked by the fuel pump.
Starting the car: when I cold start the car in the morning, or after it hasn't been driven for probably six hours or greater, I notice it takes a bit more cranking to get going. Usually 3-6 seconds instead of the typical 1-3 I get, particularly after its already been turned on once recently. It has not failed to start (yet) and I rather need it to stay that way, not very familiar with C5s so not sure if this is just the norm for them or indicative of a bigger issue in conjunction with the following problem.
Low speed rolling acceleration: If I attempt to aggressively accelerate the car from low speed, say 20-40mph, up to a higher speed around say 60-70mph, it bogs down and almost jerks or staggers (forcefully enough that I'm getting shoved a bit) sporadically and does not speed up nearly as fast as would be expected. This issue has only happened 2 or 3 times, but I'm also babying it a bit. Pressure gauge has it staying in the 20-50 range, temperature around 210-230, and the interesting part to me to the RPM never exceeds probably 3.5/4k even with significant depression of the accelerator peddle.
Looking at both issues together I'm thinking its the fuel pump just based off some superficial research, but hoping someone more experience with the vehicle could either verify my hunch or point me down the right road. Maybe this is all just normal for the model too, I honestly wouldn't know. Incidentally, if anyone happens to have experience with weather stripping for the C5, feel free to reach out too. I'm starting to feel like I bought a lemon of a car with all the money I'm putting into it, even though the mechanic said it was rock solid during the PSI. Thanks!
09-01-2023, 10:19 AM
#2
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Could be a fuel pressure issue or dirty MAF sensor...you'll need a need a fuel pressure gauge and a scan tool to look at MAF, O2 sensors, and fuel trims to narrow it down.
09-06-2023, 08:48 AM
#4
Fuel filter/regulator?