Hi, New member and first post. I have a 96 Yukon 5.7 liter. Drove it home from work two weeks ago and everything was fine. The next day i go out to start it and all it would do is turn over, and when releasing the key you could hear a sputter from just one cylinder. I then try and start it the next day and fires up with some hesitation, very rough at a low rpm and clears up and runs fine after revving it a few times. I drive it for the next week with no problems. I go to start it the other day and same thing, wouldn't fire except a random cylinder with built up fuel when key is released.
Now to bring you up to date on parts replacement and tests. Fuel pressure is 62 psi when key is first turned on and pump runs for 2 seconds. The fuel pressure then drops to 54 psi when pump stops running for the first 2 seconds. Not sure what the fuel pressure is when the engine is running since it wont start. I have spark at the coil wire and spark plugs, but maybe a little week. Could the coil be going out but still have a week spark? Replaced spark plugs after checking and they were fouled out with gas. Replaced fuel spider (CSFI) with a new unit. Did a compression test on all cylinders with the highest cylinder at 180 and the lowest at 159.
Now to bring you up to date on parts replacement and tests. Fuel pressure is 62 psi when key is first turned on and pump runs for 2 seconds. The fuel pressure then drops to 54 psi when pump stops running for the first 2 seconds. Not sure what the fuel pressure is when the engine is running since it wont start. I have spark at the coil wire and spark plugs, but maybe a little week. Could the coil be going out but still have a week spark? Replaced spark plugs after checking and they were fouled out with gas. Replaced fuel spider (CSFI) with a new unit. Did a compression test on all cylinders with the highest cylinder at 180 and the lowest at 159.