1990 Johnson 70 hp VRO bogging at speed

[cj5jeep80]

Hello everyone.

I have been enjoying the summer so far running my boat all over( this engine has been running flawlessly). Last night I took it for spin to watch the fire works. At about 3/4 throttle running very smoothly the motor began lose power(bog down) and then return to normal, then a short bog then return to normal. I then lowered the throttle to 1/4 and it seemed to run fine. Brought it back up to maybe 1/2 throttle and it started the same pattern running fine then a short bog then back to running smoothly.

After work today I pulled the fuel filter out and found a bit of dirt inside so I blew it out nice and clean but have not yet tested it on the water to see if it has solved the problem.

I wonder if I might get someones thought that may have experienced this themselves in the past. Fuel pump?

Thanking you in advance...Rick

 

[ob]

Hard to determine from your description whether the engine bogs down gradually or all of a sudden and then regains it previous speed. In other words it's hard to tell if you're chasing a fuel delivery issue or an ignition glitch. Let us know how the next water test goes since you say you've cleaned the fuel filter and take from there I suppose.

 

[racerone]

Test run with another tank and hose.

 

[cj5jeep80]

Thanks ...Yes the engine would bog down all of a sudden not gradually. The RPM's would drop suddenly and then back to normal just as fast. I also tried swapping out to my other gas tank but the problem was still there.

I still have not yet water tested it due to fowl weather, but I should know more by the week-end.

Thank you for your help