[bobthebuilder52]

My 1991 Evinrude 9.9 would die unless pumping the bulb almost constantly. I put in a NAPA fuel pump rebuild kit (hopefully correctly) and it helped some, but I still have to pump the ball occasionally. I'll have to admit I didn't take adequate notes when I dissassembled the fuel pump for the first time. Also, recently switched to a synthetic blend 2-cycle oil. Motor starts and runs strong otherwise. Thoughts?

[MAW31]

how do you define 'occasionally'. before you start the motor for the day?

do you have an in-line filter thats clogged possibly?

[Rick.]

http://www.sschapterpsa.com/rambling...OMC%20info.htm
Good step by step on the pump here. Make certain your tank screen is clear and your pump screen too. Best of luck. Rick.

[bobthebuilder52]

Thanks Rick. Occasionally as in every 20 seconds instead of every 3 seconds. Checked the pump screen and pickup screen already. Rebuilt the pump according to the linked website you sent.

[Rick.]

So did the rebuild fix the problem? Rick.

[bobthebuilder52]

No, all recent problems after rebuild. Took it out today. Hard to start now, have to pump ball every couple of minutes at no-wake speed. Runs fine at high speed.
Could my switch to a partially synthetic two cycle oil be causing problems. Sometimes the ball pumps up hard, and sometimes it doesn't. It pumped up hard when I went to start it, but had to pull a lot to get it started.

[Rick.]

Partial synthetic is good and should be no problem as long as your mix is 50:1.

Have you adjusted your slow speed needle and done a link and sinc.? What do your plugs look like? fouled , dry, wet? Rick.