Losing Power - Any ideas?

[Doc_Vegas]

Hello Folks:

Our Maxum (7.4L MPI) came off plane Saturday unexpectedly. We limped it back to the slip, and I realized it was pretty low on fuel. So, I hoped that was the issue. I fired it up the next day, started fine, putted to the gas dock, no issues. I put 67 gallons in the tank, which holds 89 according to the manual.

Took her back on the water. Now I could get her to plane, but it was definitely lacking power. Top speed formerly was near 40 MPH, now I struggled to hit 30 MPH. Today we took some friends, and could not get on plane at all, something is wrong. Gauges look fine, engine idling sounds normal. I am thinking it is likely a fuel delivery issue or possibly electrical.

I messed around with the wires, all looked new and in a great shape. Any ideas? Someone on the Maxum forum mentioned fuel seperator, but there is no mention of this in my manual.

Please help, it is not great timing to pay for a large repair bill.

Thanks!

 

[rrhodes]

Re: Losing Power - Any ideas?

What were your max RPMs before and what are they now? Did you notice if the fuel bulb was flat when you were at max throttle? Water separator looks like an oil filter and if you have one just follow the fuel line from the tank to the engine.. You can't miss it. We really need more data to help. If the bulb was crushed then check your vent line from the tank, this could be clogged.

 

[hydrick]

Re: Losing Power - Any ideas?

yo rick,
also on lake murray,cheers!

to the problem,did you see my post on cleaning flame retarder.

i had a terrible erratic planing issue off and on for a couple years....cleaned my breather(flame arrestor)retarder)
and have had no problem since.
i soaked it in purple power in a bucket, then blew it out with hose,then let dry.

granted you may have different problem.....but it's a cheap place to start.
as is the fuel seperator.

 

[kg5388]

Re: Losing Power - Any ideas?

does it rev up but not go?
mine did that would go good slow but fell flat when i tried to get on plane

I marked the prop nut and prop hub and went out on the lake and found the marks misaligned when I stopped.
put on the spare prop and the problem went away

the rubber hub went bad in the prop and was slipping

 

[Doc_Vegas]

Re: Losing Power - Any ideas?

Thanks guys. I do not know what the fuel bulb is, so I am not sure where to begin. Same with the spark arrestor, I am not sure my boat is equipped with these items. Keep in mind it is a 2001 with a 7.4L fuel injected motor. I think I will start with the fuel/water separator and see what happens. Local shop wants $150 to change the filter, I guess I will give it a try myself at that cost.

The RPMs do not seem to climb like they used to. Could be the prop slipping, but it seems unlikely... The boat feels exactly like what happened when I had too many people on board. Just does not have the pep to pull out and is pushing water.

I am betting it is a fuel delivery issue since I ran the tank close to empty.

Thanks again - I will post results when available.

Also - any other advice would be considered and appreciated!