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Home » Public Forums » GMCnet » Stranded at Repair Shop (Carb backfiring, stalling, and loss of power)
Stranded at Repair Shop (Carb backfiring, stalling, and loss of power) [message #102193] Thu, 07 October 2010 22:50 Go to previous message
harborgal is currently offline  harborgal   United States
Messages: 19
Registered: October 2010
Location: Winthrop Harbor, IL (NE I...
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We have a 77 GMC Motorhome Palm Beach with an Oldsmobile Toronado 455 engine that was just mechanically restored after being in slumber for 13 years. As part of the mechanical restoraion they rebuilt carburetor, distributor, and fuel pump along with a long laundry list of items. On the way from bringing her back from restoration she stalled about 4 times. Once when accelerating on to the highway when warm, once when warm backing into a parking space (stalled and couldn't get her started for 15 mins), and a few times when idling or driving at slower speeds.

We took her to a local mechanic who did the following...

"roadtested vehicle, hesitates upon acceleration, and back fires out carb at times. Checked timing, checked distributor, checked for vacuum leak, cheched PCV, checked vacuum hose routing, checked idle. Advanced timing 4 degrees, roadtested, ran better, but still not completely correct. May have carburator problem, is lacking fuel. Reset timing, 2 degrees advanced. These changes were made from the ignition system specifications."

After we got her back she seemed better (didn't stall and the exhaust was not as loud), however after about 3 hours of driving without issue she started losing power on slight inclines. We were trying to go 55, but she was barely holding 30. You can hear the engine struggling. These got worse and worse over the course of another hour. She got slower to the point she was not almost making small hills, was stalling, and back firing out of the carburetor along with not holding a constent speed with cruise control.

Please help! We have been camping at the repair shop for 5 days now. They have set the timings back to GMC specs and switched out the fuel pump, and checked the fuel filter. None of these has helped. We have another rebuilt carburetor on the way, but are not sure if that will solve the issue. Your expertise is much appreciated.

[Updated on: Thu, 07 October 2010 22:52]

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