1977 Johnson 35hp- Fuel pump??

[rscrooks]

Hi guys,<br />I was wondering what you think about this. My motor starts to bog down then back up when I open her up. She runs pretty good at half throttle and also at idle. Ihave rebuilt the carb and the fuel pump. However it seems as though the gas pressure to the carb might not be 100%. I have all new hoses.<br /><br />What do you think the problem is?<br />Should I replace the fuel pump?<br /><br />Thanks, Shawn

 

[JB]

Re: 1977 Johnson 35hp- Fuel pump??

Howdy, RSC.<br /><br />What happens if you pump your primer bulb when the engine is misbehaving? If that does cause it to pick back up you may have a restriction somewhere in your fuel supply system, or you may have a failing fuel pump.<br /><br />Good luck.

 

[rscrooks]

Re: 1977 Johnson 35hp- Fuel pump??

When I pump the bulb, the it picks back up to normal. I'll check the lines again. Then I might put in a new fuel pump if thats not the problem.<br /><br />Thanks

 

[oldboat1]

Re: 1977 Johnson 35hp- Fuel pump??

You can test the pump operation by disconnecting the fuel hose at the carburetor, and cranking the engine. Look for a fairly steady flow. If fuel is flowing you can be reasonably sure your pump is working and the lines between the carb and the tank are open. If the motor passes that little test, check to be sure there are not small cracks/leaks somewhere in the line(s) -- typically at or around the clamps. It may be that the lines are airtight until there is a heavy draw, then air enters the system. If in doubt about any of the fuel lines, it's better to just replace them. 15 yr. old lines are due to be replaced.

 

[Scale Performance]

Re: 1977 Johnson 35hp- Fuel pump??

rscrooks, you might want to check the fuel tank and fittings for air leaks! that will cause your problem. Areated fuel is not a good thing. jsut make sure that all of the fittings are tight..<br /><br />good luck<br />SP