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1974 105 fuel system problem

T

Tom Woods

New member
Greetings sleuths; pleased to have found this forum as I have not been able to solve a fuel delivery problem on a 1974 105. After checking cleanliness of the 6 gallon fuel tank pickup, running carb cleaner through several times, replacing the fuel line (with new primer bulb), the fuel pump diaphragm, checking the screen filter at the fuel line input on the pump, replacing the float bowl gaskets, tightening all hose clamps, adding hose clamps on the aspiration line which actuates the pump, even setting the 6 gallon tank on the rear deck in order to raise it relative to the motor, it still does not run perfectly. Starts up immediately with choke, will run up to about half throttle but with slight missing, but will not run at high RPM. At high speed it quits and then a restart is necessary with choke. Difficult to idle but tapping the choke keeps it running. Any suggestions appreciated, thanks. Tom Woods (My mother Erika worked for Chrysler Marine late 60s, early 70s, producing the Crew's News).
 
Hi Racerone; appreciate the interest - I rebuilt that motor (block bored, new pistons, etc.) about 20 years ago but have only put about 100 hours operation on it since then - 99% of which has been at half throttle. Compression is good all around (it starts immediately and puts out full power with tremendous acceleration - that is when fuel is there). So it is something with fuel delivery. I have not rebuilt the carbs but have cleaned them and installed new gaskets to the intake manifold. Fuel is fresh of course, - all the regular things have been checked.....
Thanks, Tom
 
Sounds like it might be sucking air somewhere??
Do the starting fluid test: start the motor, at an idle, spray SF around the intake side of the motor.
That includes under the pack and coils and under and around the carbs and by the port covers.
If the motor backfires or even coughs and stutters that can blow a gasket thus letting the motor suck air.
If spraying the SF makes the motor run differently then you need a gasket, maybe 2 ???
 
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