Nissan sd22 diesel won't increase rpm when in gear

[Sandydog]

Again, help much appreciated.
The engine starts perfectly. When in neutral, it revs up to full throttle, no stumbles or misses. If I put in gear forward, the boat moves forward nicely in idle, no problems. If I advance the throttle, there is no increase at all in rpm. If I put in reverse at idle, the engine just stalls ( suspect there is more load in reverse).

I can see the throttle cable, and the throttle lever on the side of the engine, which moves forward both when in idle, and when in gear.

[BoatandBeach]

Sounds like something is wrong with the transmission. If the engine will idle forward with no problem but it stalls in reverse there is something wrong between the engine and the prop. Can you disconnect the prop shaft from the transmission and see if it shows the same symptoms?

Also just to cover all the bases, have you put a photo tach on the engine to verify idle speed and what speed it will rev to in neutral?

[skipperpete]

Originally Posted by Sandydog

Again, help much appreciated.
The engine starts perfectly. When in neutral, it revs up to full throttle, no stumbles or misses. If I put in gear forward, the boat moves forward nicely in idle, no problems. If I advance the throttle, there is no increase at all in rpm. If I put in reverse at idle, the engine just stalls ( suspect there is more load in reverse).

I can see the throttle cable, and the throttle lever on the side of the engine, which moves forward both when in idle, and when in gear.

Hi Sandydog
Do you have a fixed or feathering propeller?
Do you get heavy exhaust smoke at full throttle in gear?
There are 2 or 3 different types of injector pump fitted to the SD 22 Nissan, an inline Diesel kiki pump on some engines : a CAV type DPA pump and very rarely a Bosch rotary pump. The diesel kiki is very reliable and easy to troubleshoot. The DPA pumps have a few quirks that can cause the situation you describe but are tricky to repair ( actually , easy to repair but multiple pitfalls for the un initiated). If it's a DPA mechanical governor type try operating the stop lever at the pump, this can sometimes free up the fuel valve that the governor controls.
The Diesel Kiki inline pump governor to Rack linkage can be operated manually by removing the cover plate on the side of the pump body and with very clean hands move the fuel rack back and forth, it should move very easily.
If you don't feel confident about getting "up close and personal" with the injector pump, best to get a fuel injection technician to diagnose the problem.
Finally, did you explore the possibility of a choked exhaust system?

[Sandydog]

Some good ideas here. The prop shaft turns easily by hand. In forward gear the idle rpm is enough to move the boat. However there is zero increase in rpm when throttle is increased.

I will try to see what happens if I open it up and move the fuel rack. There is no smoke at all when running in neutral and the cooling water and exhaust sound normal.

[skipperpete]

Originally Posted by Sandydog

Some good ideas here. The prop shaft turns easily by hand. In forward gear the idle rpm is enough to move the boat. However there is zero increase in rpm when throttle is increased.



I will try to see what happens if I open it up and move the fuel rack. There is no smoke at all when running in neutral and the cooling water and exhaust sound normal.

Which injector pump is on your engine? It's worth having a backup plan, if the engine does have a sticky fuel rack or metering valve there is a possibility that it might overspeed so you need to be ready to either block the air intake or open the injector pipes.
I'm interested to know if the exhaust is smoky when the engine is in gear at full power lever position.

[Sandydog]

No smoke at full throttle. On iss he turn of since it has an electric fuel cutoff solonoid.

[Sandydog]

Still need help please. Tank pickup ok, changed all filters and lift pump. Prop shaft free, linkage ok, no air in system. Starts and idles fine. No smoke. Goes to full rpm in neutral. In forward, boat moves fine at idle. When in gear, zero rpm increase when throttle increases. Fuel stop lever wide open. Throttle on side of engine moves freely. Any ideas?

[Carver Power]

Will it get rpm in reverse? If no and transmission is fine, then governor, injection pump,and I believe you said shaft and cutless bearing and prop ok?

[Sandydog]

Yep, shaft bearing all good. I suspect the governor.

[helmanta]

I had the same problem in manzanillo... after changing filters, i stalling an electric fuel pump.... found my kill cable not pushed in all the way.. I’d disconnect the kill cable and manually move the linkage, then try it

Troy

[Sandydog]

Kill lever and all cables good. Engine runs to full rpm in neutral. In gear, boat will go forward of reverse, but only at idle speed. No increase in rpm.

[sdowney717]

Sounds like the engine cant develop any power.
Stalling in reverse shows that as well as not being able to rev in gear.
Either a low compression mechanical problem, how well does it start COLD?

OR something with injection system. Not injecting enough fuel.
Does it smoke at all?

[Sandydog]

375 hours on the engine. No smoke at all. This happened all at once.

[helmanta]

Did ya figure it out?

[Sandydog]

No, have not! Engine only has 375 hours, but it is a 1982. I replaced all filters, both lift pump and mechanical pump, checked all cables, checked fuel tank pickup, bleed carefully. Starts and develops full rpm in neutral. Zero increase in rpm when in gear. Boat will move forward and reverse in idle rpm. No smoke. Good exhaust and water flor.