1989, 85hp Force, When warmed up, motor dies above 1800 rpm.

[JoeKop1]

I have a 1989, 85hp Force. When cold, it works perfectly, When warmed up, it works good up to 1800 rpm but starts to sputter above that and dies before hitting 2000 rpm. I changed the stator because the resistance reading were marginal. Checked out the fuel system for clogs. tore apart one carburetor, it was very clean. bought a used CDI, but one side was dead. swapped it with the CDI that only used the one side. same problem. swapped my original CDI with my other original CDI, still doesn't work. I don't think its a fuel problem because it happens at the same rpm consistently I could be wrong. Anyone else experience something like this and found a correction.
Thanks
Joe

 

[pnwboat]

Need to figure out if it's possibly a fuel delivery or ignition problem. An in-line spark checker might be helpful when it's acting up to determine whether or not it's an ignition problem.

 

[JoeKop1]

That's the problem. It works fine at idle to 1800 rpm. I don't have a way of checking while running it above that. I can't get it to fail on a hose cup in my yard and I am 1.5 hours from the nearest lake.

 

[Jiggz]

First , I recommend verifying the timing with a timing light. Make sure it is set to 28 BTDC. If you haven't done this there is a video on youtube made by Frank A. that will walk you through. Thereafter, install a clear fuel filter (Fram G2 will work for less than $5 from walmart and even comes with hose clamps) between the fuel pump outlet and the carb inlet.

Next use a tub or trash can to provide cooling water instead of the hose muffs. Start the engine without the top cowling and see if the clear fuel filter stays at least 1/2 full. You can manually rev up the engine (NON-CONTINUOUS but like 2~3 secs at a time) with the control tower but do not exceed 2500 rpm to ensure you do not overheat the engine. Watch fuel filter and see if the engine will go above 2000 rpm. If it does, then you are now ready to go to the lake and do further testings.

 

[Frank Acampora]

Fuel pump probably can not supply the additional required gasoline at settings above low speed/ idle circuit. Try changing the diaphragm and gasket. Not that in the driveway on muffs there is no load and very little fuel is required to speed the engine well above 2000 RPM. Thus "gunning" the engine in the driveway tells you almost nothing.

 

[JoeKop1]

Thanks to everyone who responded. I ordered fuel pump diaphragm, gaskets and valves. I will replace them when they arrive. We'll see what happens then.

 

[JoeKop1]

I rebuilt the fuel pump, rebuilt the carburetors, Changed all the fuel and vacuum lines. Seems to be running fine now. Thanks to all who responded.