mornin guys. ill first give you a little background on the truck.

its an 05 chevy 5500 4x4 fire engine. it has about 25k miles on the odo and has had a really rough life. it was stationed at a remote guard station where it was beat to crap. 99% of the repairs were "farmarized" and not done professionally.

we recieved it on a trade and have been slowly trying to get her up to par. lately its been cutting power when its under load. climbing hills, highway driving etc. another symptom is it starts to knock really loud.

you have to shut the truck off and shut the master power off to get everything to reset and your good to go for a while again. which can be a few mins or a few hours.

GM said it was a fuel filter but it happened again a few hours after being in the shop. they pulled a fuel code? my guess was something to do with the ECM because when you shut the master off it resets the codes and then works fine again.

a few years back they lost the fuel cap and put a non venting one on. it crushed the fuel tank and they had to replace it.:eek: could that have something to do with it?

all help would be great!

Tell us what the codes were. Without the codes...it is just a guessing game.

ill have to look tomorrow

the gm dealer had it all day and could not get it to fail. so were going to pick it up tomorrow and rod the hell out of it.

Loosing power and knocking, could be the injector wire harness failure, that so many of us have experienced.

might as well just put the truck on jacks and start from the back to the front inspecting axels pads wires and tubings all the way until you get the hardest part and the one that will cost you the most which will be the engine.
that way you learn a thing or two about the truck and also eliminate future problems

Loosing power and knocking, could be the injector wire harness failure, that so many of us have experienced.

we ended up taking it to a different shop and that is what the owner suspected. he changed the harness and were going to pick it up tomorrow

guess we will see what happens

I had the same problem after a year. The dealer replaced the harness and fixed the problem. Keep us posted!!!

Ck main harness connection on motor under air filter and harness connection on ECM on firewall in engine compartment pass side .

Also ck harness where it goes over alternator bracket top . That is where it gets worn .

Keep us informed and good luck with this issue .

Johnny

we went and picked up the engine this morning and they replaced the harness on a few of the injectors. they drove it 150 miles and could not get it to fail.

well we took it and drove it 3 blocks and it failed!
we limped it back to the place and they scanned the codes. all injectors were causing a code to pop up. so once again he figured something in the main harness.

he called back ten mins later and found a short in a wire going into some computer that controls the fueling of the engine.

so hopefully when we pick it up this fixes it.

Glad they found something , lets hope for the best .

Good Luck with it , Johnny

yeah i hope this is the fix. it would suck balls if we were trying to get out of a fire and the thing shut down on us. i guess ill always have that in the back of my head until this truck proves itself again..

yeah i hope this is the fix. it would suck balls if we were trying to get out of a fire and the thing shut down on us. i guess ill always have that in the back of my head until this truck proves itself again..

Hear Ya there , that would not be good . Lets hope you get back that reliable feeling after a while . As soon as you find whatever electrical BS is going on you should be back in business with reliability .

John