| Onan runs like hell [message #276416] |
Tue, 21 April 2015 18:08  |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma:
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Well I've installed my Pertronix module (home made bracket - not the fancy kit) and replaced the carburetor, plugs, coil, and wires but the old troll runs awful. Sometimes if I twist the main jet on the carb she smooths right out and then back to running poorly again - the wiggle shuffle. I'm beginning to hope it's just carbon build up - here's why:
When I initially installed the Pertronix I set the timing rather advanced. It ran well, but still stammered and was rough. I moved the sensor down to about 26 degrees. Still ran poorly.
I bought a carb rebuild kit (I don't know why) and once I put it back together she wouldn't start. (I'm certain I gave up too soon on the rebuild...) I bought the rebuilt carb from Nick at Advanced GMC and put it on, but the screw for the main jet was toward the block and not accessible. Still it started and ran okay. I twisted in the idle screw and it ran a little better, not great.
After installing the new Air Conditioner I let the Onan run for about an hour until I heard it clank and rattle and cough. In a panic I ran to the coach and shut off the old beast.
Today I took the carb off, loosened the bowl and positioned the main jet outward, put it all back together and started it up. Running poorly I adjusted the screws to what the manual recommends. No help. Twisted the main jet in all the way - she ran beautifully for 20 seconds and then stammer and shake.
I have never, ever, ever, met a carburetor that liked me, but I don't think it's the issue. It runs, so I have fuel and I have spark. All the twisting and fiddling with the carb makes no substantial improvement.
I'm at a loss. Valve adjustment? Burnt valve from too-lean carb? Decarbonize the cylinder heads?
I had thought to do a compression check but could not find my gauge set. Any suggestions would be appreciated.
Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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