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Spent 6 hours chasing a ghost in a Cummins ISX at my shop in Phoenix
Last week I had a 2014 Peterbilt come in with this weird intermittent power loss. It would run fine for like 20 miles then just fall flat on its face. I checked fuel pressure, changed filters, even pulled the turbo actuator to test it. After six hours of poking around I finally found a tiny chunk of rubber clogging the fuel return line back near the tank. It was a piece of old hose that must have broken off years ago. Has anyone else had a small trash piece like that drive them crazy?
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miles_robinson204mo ago
Man, you're right. I used to think clogged return lines were rare. I always chased high-pressure stuff first - injectors, pumps, that kind of thing. But after finding a similar piece of rubber in a return line on a Cummins last year I changed my mind completely. It's wild how a tiny bit of junk can cause such a big headache. Now I check return lines early, saves me hours of head scratching.
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the_emma4mo ago
Bet it was a fuel hose liner delaminating, those old hoses shed bits inside like a snake.
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the_emma4mo ago
Oh give me a break with the return line theory. I have been turning wrenches on these trucks for fifteen years and I have NEVER seen a piece of hose cause a problem like that. Fuel systems are way too robust for a tiny rubber chunk to be the culprit. You probably just had a bad sensor or a ground issue that fixed itself when you were moving lines around. These newer trucks have electronic gremlins that come and go for no reason. Everyone jumps to blame the mechanical stuff first when half the time it is just a wire rubbed bare somewhere you cannot see. Your six hours were wasted on a wild goose chase that could have been solved with a scan tool and a half hour of idle time watching data.
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