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Slow speed stalls
I have a 1969 25HP Johnson Model 25R69B. My motor stalls and dies when I'm speeding up, or when I've slowed down and am motoring toward my pier. I have to squeeze the bulb on my gastank a few times and then it starts right up again. It may fail again if I don't keep squeezing the bulb. Once I've planed out it runs like a top. Thanks for any tips that are given.
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Slow speed stalls
I disassembled the fuel pump to see if I could find anything obviously wrong. I didn't, the gaskets all look intact, and the checkvalve seems to pass the blow/suck test. Vacuum must be what makes the fuel pump operate properly, right? Could low vacuum cause my problem at slow speeds? I'm guessing that vacuum is created somewhere in the pistons cycle. It's like $80 to replace that part, so I want to be sure it's a good fix. This may be totally unrelated, but on several occasions this summer, while planed out and going full speed, the engine starts revving up. I slow down and then speed up to plane out, and it seems to be OK. I've never experienced this before, but is this called cavitation?
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Yes the fuel pump is vacuum operated. When you had it opened did the diaphram look stretched? You could also be having a fuel restriction problem in the fuel lines. This would make it hard for the fuel pump to suck fuel at low RPM's. The revving up could be cavitation, cavitation would have no effect on the fuel pump of fuel system.Comment
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Slow speed stalls
The diaphram was stretched some. There is a spring that is attached to a plastic part that pushes against the diaphram, and there is an airspace on the other side of the diaphram where the spring makes contact. I have not checked the rubber fuel lines for clogging. Are there low/slow speed jets in the carburator? The local guy that gave my engine a spring checkup, not a marine dealer, said it could be them. And he'd have to remove the carb. to get at the jets to fix.
What could cause my very intermittent cavitation problem, if that's what it is?
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I tried the EDIT function but that didn't work for me. Anyway this is what I forgot to mention. On the plastic part that has the spring attached, it looks like there is another tab that could have another spring attached. I only had one spring, should there be two? Do you have a fuel pump blowup for my 25R69B?Comment
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they do but it doesan't show that area of the fuel pump. its just a complete assembly.Comment
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