Posts: 3518
Location: north central wisconsin | I had an issue with my Yamaha 90HP 4 stroke last year while in Canada. I would lose power while on plane, eventually killing the motor if i didn't prime the bulb while driving. We suspected it to be a bad bulb, but it was typically tight in the morning. We then assumed it was the pickup in the fuel tank. I have a (10?) micron fuel water separator as well, but everything checked out clean and tight. When I got home i did some digging and soon realized the fuel filter associated with the VST(vapor separator tank) was extremely dirty. I replced this filter and also the primer bulb to correct the issue. You mentioned changing the fuel filter. Make sure there isn't another filter in the engine. If your motor runs just fine after it starts, you might check the primer bulb too.
I'm not sure if this information could/would help you as your motor may not even contain similar parts, but it would be worth a check.
On a side note, I have a 2007 Mercury jet outboard. It runs very well. My issue is cold starts. Luckily it has electric start or the number of pulls involved with starting would be ridiculous. I have to push/pull the choke several times until it turns over, and then continue to do so until it runs. There are days that I don't know if it is going to start. I've changed plugs, cleaned filter, changed fuel line/bulb. My old 1983 yamaha 40 starts right up, and never skips a beat. This merc runs great once it is started, but getting it there can be a bit of a chore at times, and nearly impossible for anyone but me or someone intimate with it. |
