Ok here’s the story. I’ve read through countless threads on here and some touch somewhat on the subject and give me insight on things to try but I haven’t seen my problem or a resolution so I’m gonna ask myself!
so I bought the truck a couple months ago.84 m1009. My first diesel. Ran great drive great everything was good, starts up so easily, as soon as h turn the key. No smoke at idle at all. I did a lot of maintence on it. Oil change, trans filter and fluid, alternator ect ect, lifted it and put 35s on it. Like I said ran Good.
So I drove it 55 miles to a destination, then 40 miles back to another. Went on some unpacked roads and had a little fun but nothing crazy. On the way home she fell on her face. Burping farting put pedal to the floor and she wouldn’t rev up in gear. Got her home but barely. Drove it like this about 15 miles. Next day changed the fuel filter. She was alive again but now she has this , what I call, misfire sound.
At idle it sounds perfect. Start driving withlight acceleration it’s fine. Highway speed 60mph she purrs along. But the in between, the getting up to speed, the half throttle or anything more, it sounds like a gas 8 cyl running on 6, or an exhaust leak.
so I spoke with a friend who’s a diesel mechanic. He gave me a few things to try so I’m gonna tell you what I’ve already done.
Ran the truck off a 5 gallon container strapped to front of truck and eliminated tank. No change
Bypassed fuel filter box and put fuel direct out of lift pump to injector pump. No change
Tested lift pump pressure -Teed in after fuel filter on line the goes to injection pump. 6 1/2 psi at idle and dropped down to about 4 at half throttle while driving from a stop. (Normal?)
Broke glass and spring out of injection pump return fitting no change
Put a clear line from fuel filter to injection pump. Solid fuel no bubbles
Clear line out of injection pump to return line- has small bubbles flowing and idle and sometimes gets frothy bubbles when cracking the throttle open
Injection pump is still retarded from military spec, loosened the 3 bolts and advanced it as much as I could but still couldn’t even meet the line, so it’s still retarded.
I cracked each injector line while running and engine stumbled equally for each one.
please help! My diesel mechanic friend said all return lines will have some air and it’s normal,but I read here that it’s not. could that cause this? I have a video where the noise can be heard it sounds like it has a pulse, only under load tho, getting up to highway speed. Sounds like a miss, but could also sound like an exhaust leak. I’m baffled. I don’t wanna spend 500on an injector pump and do all the laborfor nothing. HELP!!’