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2018/04/08 21:53:00

jeckel7234

B&S 42A777-E1 Diaphragm Fuel Pump Issues

Hi all,

I have a B&S 42A777-E1 18.5hp motor on my riding tractor. This motor has a diaphragm style fuel pump that is integrated into the body of the carb, Ive had massive issues with the ability of this pump to pull a vacuum on the fuel tank.

Every 2-3 mows, (during the season 2-3 weeks) i have to rebuild the fuel pump, most of the time i really can just pull the springs and diaphragm out and reinstall to get the motor to work. As i go to crank over the mower I notice that fuel is not flowing through the fuel filter as well as ive verified little to no suction where the fuel line connects to the fuel pump.

I took the springs out of the fuel pump and bought a low pressure/low flow fuel pump off ebay with the hopes that i could bypass the diaphragm pump. I could the motor to start but not stay running for longer that a few seconds.

Does anyone have any suggestions or ideas for a more permanent fix?

Thanks,

2 comments Leave a comment

AVB

If are pulling a massive vacuum on the fuel tank then the fuel tank is not venting properly. To verify if this is the case leave the fuel cap loose for testing purposes. If this resolves the issue then replacing the tank's fuel fill cap should resolve that issue. Return the carburetor mounted fuel pump to working order. To bypass simply cap off the vacuum line and use your electric pump inline with the pump as if it was an added filter.

I have seen the Briggs vacuum operated fuel (Hockey Puck) used with these carburetor mounted fuel pumps though not needed. Actually removed the external pump on the last Opposed engine.

As for only running a few seconds you still have carburetor problems as it should run until the carburetor fuel bowl is empty. Verify that the fuel bowl is filling, if not then it is likely you have a blockage. A cleaning and rebuild of the carburetor is also in order.

2018/04/09 02:41:00

jeckel7234

Thanks for reply,

I've attempted to start the engine with the fuel cap removed to no avail. I tried the electric fuel pump at the end of last year, I installed it in line with the fuel line as if it were a fuel filter, but I don't think I caped off the vacuum line, I'll attempt it again hopefully tonight.

I don't remember much more than it just shutting off quickly with the electric pump, but I do remember verifying positive fuel flow to the carburetor.

I reinstalled the diagragm and springs after removing the electric pump and it was able to start up the last few cuts of last year.

2018/04/09 05:16:08

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B&S 42A777-E1 Diaphragm Fuel Pump Issues

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