Trucks running werid

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squaredeal91

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Location
Cave junction Oregon
First Name
Greg bush
Truck Year
1991 SB
Truck Model
K30
Engine Size
5.9 Cummins 12 valve
M code was low compression 350 HD emissions,so very doubtfully it would have knocknsensor
Side story lol, Interesting you mentioned low compression 350.
I once worked on a 78 c50 and the engine cranking over sounded dead like no compression and would spin over with the starter like plugs were removed but it always started and ran good lol.
 

Jgonick

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Jan 12, 2017
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Location
West Texas
First Name
Joel
Truck Year
1985
Truck Model
K10
Engine Size
350
Removed-

Already mentioned above. -sorry
 
Last edited:

peats

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Location
Pennsylvania
First Name
john
Truck Year
72k5, 81c10 short step, 83k10 short fleet, 03 SSR. 25 chevy doodlebug
Truck Model
k5 c10 k10 SSR doodlebug
Engine Size
406 360 6.2 5.3 171
You might have a worn out camshaft. I lost a cam once. Didn't make noise, just was really down on power.
 

squaredeal91

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Cave junction Oregon
First Name
Greg bush
Truck Year
1991 SB
Truck Model
K30
Engine Size
5.9 Cummins 12 valve
You might have a worn out camshaft. I lost a cam once. Didn't make noise, just was really down on power.
On my first truck had 350 in it when i was 14. it would pop through intake I think. when you stabbed the throttle to make it (go now!) It would always cough. I messed with timing and carb but couldn't make it go away. My dad suggested bad cam? He was right. 3 or 4 barely had anything left to open valves.
 

haxored

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Oct 25, 2018
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77
Location
California
First Name
Joe
Truck Year
1974
Truck Model
C10
Engine Size
454
Went through something real similar recently with my son's 350/350 '74 elco..

Same type of issue, it only surfaced when the engine was warm and at a certain rpm range. He was convinced it was bad gas, even though it had been going on for a few tanks worth, but it would run fine cold, and 75-80% of the time.

Ended up being a plug wire with a pinhole (near the plug boot) we didn't even think to check them due to then being less than 6 mo's old and a better quality brand/set, just happened to see it arc while troubleshooting into the evening. New set of wires, swapped just one out, problem solved! (He did go back and swap them all out the next day when he had more time.)
 

boblee09

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Feb 25, 2024
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6
Location
NC
First Name
Eric
Truck Year
1984
Truck Model
C10
Engine Size
5.0
I have an 84 c10 305. Mine had the same issue. There was a vacuum line T fitting on the motor near the firewall. It had broke. Can’t remember if I plugged it or replaced it. Anyway it runs great now.
 

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