GMC 6.5 Bad Running
#1
GMC 6.5 Bad Running
Having issues with an 1994 GMC 6.5, it has a moind of its own. Runs perfectly 99% of the time then for no apparent reason will start but not ifdle correctly, sounds as if missing cylinders and will rev but not clear. Turn it off and restart it amnd it runs perfectly. No indication of any problems. Had injectors done, fuel tank good and pump running ok. Scratching head about this one !
#2
I know nothing about the electronically controlled engines; hopefully someone knows more than me and can make some suggestions. But if it were mine, I would read up on how the fuel system works, and figure out what parts could possibly do that, then start swapping in new parts, starting with whatever seems most likely. Electronics are great until they start breaking, which is why I prefer the older mechanical-injection engines. If you don't have a factory service manual, this would be a good time to get one.
#3
I know nothing about the electronically controlled engines; hopefully someone knows more than me and can make some suggestions. But if it were mine, I would read up on how the fuel system works, and figure out what parts could possibly do that, then start swapping in new parts, starting with whatever seems most likely. Electronics are great until they start breaking, which is why I prefer the older mechanical-injection engines. If you don't have a factory service manual, this would be a good time to get one.
Most of the fuel system has been swapped out or tested. No electronics come into play on idling anfd itys that intermittent its hard work. I am beginning to think it could be a mechanical issue with either the IP or valve gear but unable to accertain why its not continous issue.
#4
Most of the fuel system has been swapped out or tested. No electronics come into play on idling anfd itys that intermittent its hard work. I am beginning to think it could be a mechanical issue with either the IP or valve gear but unable to accertain why its not continous issue.
#6
my first place to look on my 6.5 is the notorious PMD. I keep 2 mounted under the hood behind BTY.#2. If it acts up I switch the PMD
wire to the fresh PMD, and go for a ride. In almost all cases of acting up the PMD has been the problem. Some PMD's last years, some hours.
You will need to have a spare at some point, so get one mounted where the wires can be switched over in seconds,.
wire to the fresh PMD, and go for a ride. In almost all cases of acting up the PMD has been the problem. Some PMD's last years, some hours.
You will need to have a spare at some point, so get one mounted where the wires can be switched over in seconds,.
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