260 won't go past 3K RPM

[Todd]

Runinng twin 260's. Good compression and good fire. Boat will get on plane but one of the engines will not go past 3K - 3.5K. Fuel pump pushing 38 lbs so I don't think that is the problem. Plugs all seem normal after shutdown.

Engine starts easy and idles smooth.

Thoughts?

[T-REX]

MMMMMMM, Stator

[Todd]

T Rex, I think you may be right. I lost a switch box 2 weeks ago. usually a 1st sign. Funny thing, I was running 8500 RPM last weekend.

[Jay Smith]

High speed windings on the stator would be my 1 st guess.......

[us1]

Or high speed circuit on a switch box. Use timing light with the motor on the hose and check for spark at 3000 plus.

[apache21]

Stator, Just had the same problem on my 24 Skater. Fixed the problem

[Todd]

Changed the stator and went to run. Still no better. Could it be the rectifier? I orderded one anyway and will change on Thursday. US1, I did check the spark above 3K and it is there.

When I was in the boat by myself, it would top at 4K instead of 3K. Just dies off in power.

[us1]

Are you sure the fuel pressure is 38 lbs at 4000 RPM?

[Todd]

I have fuel pressure guages for each motor on the dash. It never fluctuates. I also tried running the trim during the 3 - 4K issue to see of added electrical drain would make it worse. No change.

The recitifier does need replacing but I can't see how this would impact.

When the 1st switch box went, I but a used extra one on and it worked "gave spark". Since these are not my specialty, is there a possibility that one or both are still bad at high speeds? It starts easy and idles perfect.

Just put a volt meter to check the wires between switch box and coil. All seem ok.

Also checked Water seperator and filter which were fine. The other engine is running fine so I can't say bad gas or water.

[Todd]

Kurt,

I will give this a go after a few more changes, but I believe it is electrical. Too strange to run good at low R's, no problem getting on plane, even with a load, and then cap out. It seems that if it were fuel delivery it would bog down when getting on plane with a load. I had 2 adults and 4 kids in the boat and it got on plane. I even tried to run it under 3K and water plow to see if it would get starved for fuel but it didn't. Never even sputtered.

Todd

[Markus]

A bad rectifier will do some weird stuff to an engine, but it will hit idle performance, not top-end in my experience. However, to find out if the rectifier really is the problem, swap the tach leads to the other side of the rectifier and see if your tach reading goes away. If it does, one side of the rectifier is bad.

[Todd]

Rectifier was the culprit. Never heard of it effecting high end speed, but it sure did.