I brought this issue up a while back but I'm still having the problem and can't find the old post so I will start over. 1988 110HP Johnson has 2.5 hours run time since total rebuild. My initial outing the boat ran great with the cowling on, approx 60 minutes. After that every time out the motor makes no power (won't get on plane) with the cowling on. Boobie suggested an exhaust leak so I tried looking for smoke around the powerhead but I can not see any, even when squirting oil in the carb throat.
The lower engine pan has a generous size thermostat access port cut out with a removeable panel. The first time I took the boat out the access hole was open as I had not yet fabricated the panel and I thought maybe that opening evacuated any exhaust fumes which would explain why it ran good with the cowling on initially. I took the boat out again today and motor would not make power with cowling so I removed the panel covering that access port but still no power. Take the cowling off and motor runs great.
I will attach a picture of the access port cutout.
Is it likely an exhaust leak would develop after running 60 minutes on the first outing? If there is an exhaust leak large enough to choke off the motor why can I not see any smoke around the back of the powerhead? Wouldn't it seem that large access port would evacuate any exhaust gasses if they were present?
I have considered spark plug wires grounding out on the cowling latch but that seems unlikely too. I hate running the boat without the cowling...it's noisy and ugly. I appreciate any inputs!!
The lower engine pan has a generous size thermostat access port cut out with a removeable panel. The first time I took the boat out the access hole was open as I had not yet fabricated the panel and I thought maybe that opening evacuated any exhaust fumes which would explain why it ran good with the cowling on initially. I took the boat out again today and motor would not make power with cowling so I removed the panel covering that access port but still no power. Take the cowling off and motor runs great.
I will attach a picture of the access port cutout.
Is it likely an exhaust leak would develop after running 60 minutes on the first outing? If there is an exhaust leak large enough to choke off the motor why can I not see any smoke around the back of the powerhead? Wouldn't it seem that large access port would evacuate any exhaust gasses if they were present?
I have considered spark plug wires grounding out on the cowling latch but that seems unlikely too. I hate running the boat without the cowling...it's noisy and ugly. I appreciate any inputs!!