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88 OMC 5L gm 305 wonbt go over 2500 rpms

J

Joe Presti

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" Have ?8 OMC w/GM 305 ?Carter

" Have ?8 OMC w/GM 305 ?Carter 4b Carb. The engine runs well at idle and up to 2500 rpms with out a load or under load. The problem starts when accelerating, (with or with a load) the engine bogs, spits and will stall.

I have installed new points, plugs, condenser, rotor, coil, water/fuel separator filter & Carb fuel filter. The dwell & timing are correctly set and oiled the distributor advance weights.

I have check the following for blockage -fuel tank vent, the fuel tank gas line, siphon valve, gas line from the gas tank to the separator and from separator to fuel pump! No blockage!!! After all of this ?it still runs the same!?

I have also checked the fuel pressure at the entrance to the Carb, it reads 3.5 psi. Should I replace the fuel pump? Have I over looked something? If anyone could help id my problem, it would be appreciated

Thanks, Joe "
 
" Don't know for sure what

" Don't know for sure what your actual problem is, but your fuel pump should put out close to 7 psi. If it's a mechanical pump the diaphram may be going out causing a loss of presure. "
 
" Unless you have the wrong pi

" Unless you have the wrong pitched prop, which you probably already have verified, I would recommend trying a rebuild on the carburator. The accelerator pump could be shot or one of internal gaskets is bad. The carburator has different sections that relate to load, acceleration, and RPM -- which would explain why your engine could run great at 1 speed and not another. "
 
" I had this problem also ...

" I had this problem also ... the short answer is that after rebuilding the carburator,replacing the fuel pump, gaslines, adding an inline filter,replacing the ignition parts, rewiring,replacing the alternator & starter..it was the metal gas tank !! The inside coating of the tank was disintegrating and the fine particles were getting thru the filters & up into the carburator causing a gas demand restriction under a load at higher speeds/RPM's. I went from 2500 rpm max to now 4100 rpm & that fixed it. Buy a Plastic replacement tank ... that was the fix ... I have a 1972 OMC 307 Cubic Inch Chevy in a Penn Yan Inboard Tunnel Ram ... good luck .. it took me an entire season to figure it out .. and alot of patience .. "
 
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