Low RPMs at WOT

[tia34698]

Re: Low RPMs at WOT

***UPDATE***

Took out today...2900 - 3000 rpms, 34 mph at WOT...

ran better than it ever has, but still not getting enough rpm and speed at WOT.

Thinking about testing fuel pressure next? Has MPI is testting same as for carb?

Thanks,
CC

 

[Fun Times]

Re: Low RPMs at WOT

***UPDATE***

Took out today...2900 - 3000 rpms, 34 mph at WOT...

ran better than it ever has, but still not getting enough rpm and speed at WOT.

Thinking about testing fuel pressure next? Has MPI is testting same as for carb?

Thanks,
CC

Is your engine [TBI] or [MPI] if it is MPI then it is easy to do, You will have valve on the fuel rail that looks like a tire air valve and you just screw the fuel pressure gauge on and key it up and start the engine, Then unhook the vacumm hose going to the fuel regulator with the engine on and see if the fuel pressure goes up to specks. You will need a tool like in this link either way of what style engine you have.http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92699 Now if you have a [TBI] style engine then you will also need from mercruiser part number # 91-806901. This part number is a adapter that will go right in between the main fuel line going into the throttle body it self, And then all you would need to do is hook the pressure gauge up to this adapter to get your reading.

 

[45Auto]

Re: Low RPMs at WOT

Sounds like may be time for a compression check. I recently had a motor doing exactly what yours is. It had 150 PSI compression in 6 of the cylinders, 110 PSI in the other 2. Cranked, idled, and ran perfectly, it just couldn't make it past about 3800 RPM. Turned out it had a cracked piston in one cylinder and a leaking exhaust valve in the other.

 

[tia34698]

Re: Low RPMs at WOT

Thanks,

I will do fuel pressure test this week, and if that doesnt work have a compression check done.

WIll update after testing.

Chris

 

[leeschaumberg]

Re: Low RPMs at WOT


Hello
Of the hundreds of boats that I sold new or used each was lake run to ensure proper operation. First weight makes a big differance. My body weight is less than 160 lbs. Is this boat a NEW bought boat or second hand from a private party. May be this boat is not propped like it should be. Do not chase a problem that doesn't exist. Good Luck