primer pump and o-rings

My trusty dingy motor, a 1987 Evinrude E4RCUD, started to give me trouble in the spring. I traced the issue to worn o-rings in what I thought was the choke, but is actually a fuel primer pump and fuel petcock all in one! Apparently this was a short lived idea of squirting more fuel into the carb rather then starving it of air to enrich the mixture. These pumps, as one web author noted, work great until they don’t! At least now I understand why the “choke” lever was so strange – its not a lever, it functions like a syringe and pulling it squirts fuel into the carb.

I replaced the o-rings with ones I got from the nice service technician at Crappy Tire – assuming they were automotive. The shut off o-ring swelled and fell apart. I thought I got all the bits but apparently didn’t. As the primer pump is between the fuel pump and the carb, the fuel doesn’t get filtered. I thought the o-ring bits were just in the pump/shut-off valve and I replaced the o-rings again with OEM rings. The engine still wasn’t happy and I left it home for the bulk of the summer. It wasn’t that bad rowing once I got the oarlocks sorted out.

Determined to get this motor running, I pulled the carb for a 3rd time and found what was clogging up the main jet and float needle. As pictured there were large chunks under the float needle and under the main jet.

I also serviced the fuel pump as it had never been touched and I thought it might be a fuel starvation issue (it was but not from there…!).

Better late than never, I finally got the engine sorted on Labour Day weekend!

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