Carb Problem...

[Brandon241]

I have a 78 35hp Evinrude.. Finally got the boat all done and now am working on getting the motor runnin.. I can get it to turn over and run for maybe 3-5 seconds and then dies... I can get my buddy to prime the bulb while running and it will stay running... I am guessing it is just burning the gas thats in the bowl and then not getting anymore gas... I pulled the carb off and cleaned all the jets out.. Tried it again and stil no luck.. Anyone have any advice or something I have yet to do??? Thanks

Brandon

 

[ddennis]

Re: Carb Problem...

have you checked all the fuel lines for leaks or cracks?
How about the fuel tank vent?

 

[svenr]

Re: Carb Problem...

This sounds like fuel delivery problem. One possible cause is a bad fuel pump (they do go bad, although you can get a rebuilt kit pretty cheap). The fuel pump works off of vaccum pressure, and a lack of it would also cause the fuel pump not to work. Could be bad reed valves or worn piston skirts in that case.

I would check the simple things first though like fuel hoses, tank vent, o-rings on the fuel hose quick connects. These can go bad from time to time.

Also, you may also have some sort of fuel line blockage that is causing only limited fuel to get through unless under pressure from the fuel bulb.

Good luck!

 

[ezeke]

Re: Carb Problem...

Try a different tank and fuel line and try elevating the tank so that gravity does the work of a fuel pump.

Any air in the lines before the fuel pump will cause that problem.

Best to start eliminating possibilities working from the tank. If all that turns out OK, check the screen and membrane on the fuel pump for debris or damage.

Between the engine and the fuel pump is a pump mounting gasket. It has to be air tight for the fuel pump to function.

 

[fireman57]

Re: Carb Problem...

Pumping the primer bulb to keep it running is usually the test for a fuel pump. Like they said above, it could have crud in the screen but more likely is a hole in the diaphragm. I would replace the whole thing. Takes five minutes.