I think I know the answer to this but don't like it so thought I would reach out to you guys to see if I missed anything. This motor had an electric automotive fuel pump with no primer bulb when I got it and would surge at high rpm (4500 down to about 3800 then back up). I figured it wasn't getting enough fuel at high rpm and switched to a regular rebuilt fuel pump and a brand new primer bulb/filter.
The first time we took it out when we got up in the rpm range the primer bulb started going flat and we had the same surge issue. The tank had a quick connect fitting for the fuel line so I thought that might be the issue. After we got in I reran the line straight from the tank connector to the filter then to the bulb and then pump.
We took it out today and for the first 10 minutes or so it was running steady at 4500 rpm (full bulb) and I thought we were good (we were already at my fishing spot so I just shut it down). After tooling around for the day we went for a little cruise before heading back to the dock and I noticed the bulb going flat again. Although the motor didn't surge with the flat bulb I didn't want to risk hurting anything so I brought it back down to about 2500 and got back to the dock.
I think there is something in the fuel tank or the pickup. I hope this is not the case as its a built in tank and would be a pain to service. I did take the bowls off the carbs and checked everything and they look fine but am I right to assume this issue is on the inlet side of the fuel pump? Im going to take a 5 gallon portable tank out next time and run the line directly to it but is there anything else I am missing? More details below, sorry if this is long or too much detail but I thought too much would be better then not enough.
previous work:
new head gasket, good compression on all cylinders
good spark on all cylinders
new plugs
adjusted idle and air/fuel
replaced diaphragm, gaskets, seals on fuel pump
new primer bulb, fuel filter
new ignition switch
The first time we took it out when we got up in the rpm range the primer bulb started going flat and we had the same surge issue. The tank had a quick connect fitting for the fuel line so I thought that might be the issue. After we got in I reran the line straight from the tank connector to the filter then to the bulb and then pump.
We took it out today and for the first 10 minutes or so it was running steady at 4500 rpm (full bulb) and I thought we were good (we were already at my fishing spot so I just shut it down). After tooling around for the day we went for a little cruise before heading back to the dock and I noticed the bulb going flat again. Although the motor didn't surge with the flat bulb I didn't want to risk hurting anything so I brought it back down to about 2500 and got back to the dock.
I think there is something in the fuel tank or the pickup. I hope this is not the case as its a built in tank and would be a pain to service. I did take the bowls off the carbs and checked everything and they look fine but am I right to assume this issue is on the inlet side of the fuel pump? Im going to take a 5 gallon portable tank out next time and run the line directly to it but is there anything else I am missing? More details below, sorry if this is long or too much detail but I thought too much would be better then not enough.
previous work:
new head gasket, good compression on all cylinders
good spark on all cylinders
new plugs
adjusted idle and air/fuel
replaced diaphragm, gaskets, seals on fuel pump
new primer bulb, fuel filter
new ignition switch
