[Flfishindude]

We have an Oday 31 with an Universal M18.

The engine starts easily, runs great, no smoke, no oil use but does not turn up much past what I would consider half the normal RPM's (Do not have tach) in gear. I have tried filters, fuel pump, mixing elbow and had a diesel mechanic look over engine and he can't find anything and suggested it may be the transmission.

Any ideas???

 

[MarkSF]

The most common reason for this problem is marine growth on the propeller. Has this been checked / eliminated as a possible cause?

 

[Flfishindude]

Bottom, shaft and prop have no growth, rope - anything and shaft turns easily what uncoupled from transmission.

 

[MarkSF]

Has it ever run at acceptable rpm - when did this problem start?

My 5424 won't exceed 2300 rpm because it's a bit over-propped. It will do 2800 rpm in neutral. Hence the question, has this always been the case?

 

[Flfishindude]

I so seldom run engine up that I don't really know when it started, It used to turn up probably twice as many RPM's. We only have to go a couple of hundred yard to put up sails, so no need to run engine hard. I found out it wouldn't run up about 6 - 8 months ago when the wind caught me and I had to get away from the dock. I started doing things like checking bottom, shaft, prop, filters, fuel pump, mixer in an attempt to resolve issue. I had a diesel mechanic check a couple of days ago and he doesn't see anything not working properly. Plenty of fuel, no restricted air flow, shaft turns easily. He thinks maybe transmission.

 

[MarkSF]

Has anyone checked the most obvious thing? That the throttle is opening fully? Open the throttle lever fully at the pedestal (with the engine off), and observe the mechanism at the engine. Is it opening completely?

 

[Faster]

No limitation of the throttle linkage anywhere? Loose clamp on outer cable sleeve? Kinks?

 

[MarkSF]

Like he said ^^^^^

 

[Faster]

Like he said ^^^^^

Like WE said pretty much simultaneously!

 

[Flfishindude]

There is no binding. The throttle lever moves all the way to the stop. With the engine out of gear, engine will run up but in gear will not. As the throttle lever moves forward with the engine in gear, RPM's will not increase once lever gets about half way but lever will move past there.

 

[Stu Jackson]

Have you changed the transmission fluid?

 

[Flfishindude]

No, but checked it and it was full. Mechanic also checked it and said that if transmission was binding, engine should smoke, if it were slipping engine would run up but no power.

Im certainly open to any suggestion at this point.

 

[deniseO30]

But you don't know what the rpms actually are. suggest at least checking that with a hand held tach

 

[Flfishindude]

I had the injector pump serviced and they told me that it looked fine. Put it back on and ran as before.

Mechanic used a screwdriver to open throttle up and engine ran as it should -- Full RPMs. Everything looks as it should in throttle linkage inside and out.

Any ideas??

 

[Faster]

.....

Mechanic used a screwdriver to open throttle up and engine ran as it should -- Full RPMs. Everything looks as it should in throttle linkage inside and out.

Any ideas??

How, exactly, did the mechanic manage to run the revs up 'with a screwdriver'?

Starting to sound, to me, like the throttle lever may be traveling full throw, but slipping on its shaft at some point?

 

[Flfishindude]

He removed the screw on the back side of pump housing that holds spring in place and put a screw driver in that hole and pushed throttle up.

 

[Faster]

He removed the screw on the back side of pump housing that holds spring in place and put a screw driver in that hole and pushed throttle up.

So then... it would seem that the actual/normal throttle mechanism is failing to do that?

 

[Flfishindude]

Yes, thats what it appears. Linkage is moving but inside it must not be.

 

[Flfishindude]

GOT IT!!! Almost so simple it seems too simple.

This morning we checked all the linkage and then made sure all the springs inside the governor were on, everything else appeared to be as it should. Started the engine and backed off the governor adjustment screw and engine RPM's came up as it was. Problem solved!