Engine stalls, when gear engaged

[Smiling Ben]

Hi folks,

My Thornycroft90 is now running happily and starts first time, so progress at last.

Unfortunately, it stalls everytime I engage the transmission. Either forward or reverse.

I have a new and clean fuel system, with temporary clear hose to monitor air ingress and fuel quality.

It will run at all revs, taken it to 2000, but not for long.

I can turn the prop shaft by hand and the prop is clean.

I have tried starting it in gear, but no response.

Struggling for ideas......!!!!!

 

[Amlov]

I don’t suppose you have a cut off switch on the throttle/gear shift to preventing starting in gear, if so, it could be faulty.

 

[Thistle]

Engine runs, shaft turns: what about gearbox?

 

[neilf39]

If the engine won't turn over when in gear then sounds like the gearbox is jammed from the rest of what you say.

 

[Boater Sam]

What is the gearbox? Will the starter engage when you try to start in gear?

 

[colind3782]

Or, from experience, something as simple as a rope around the prop?

 

[Tranona]

Running without load is not an indication that all is well with the engine. It should run up to full revs which is much higher than 2000. If it stalls when under load then either the gearbox is jammed or the engine is not producing power.

 

[Smiling Ben]

Thanks Folks for your thoughts. Got an engineer sticking his head in tomorrow morning. I'll let you know how it goes

 

[PCUK]

Almost certainly, It's rubbish round the 'prop.

 

[Bilgediver]

I don’t suppose you have a cut off switch on the throttle/gear shift to preventing starting in gear, if so, it could be faulty.

It could be working as designed if preventing starting in gear. This is normal on some throttle controls.

 

[Tranona]

Almost certainly, It's rubbish round the 'prop.

But the OP says he can turn the shaft by hand and the prop is clean!

 

[QBhoy]

So are we saying that it won’t even turn over when in gear ? If there is an interlock for that…nothing will happen at all…but If it’s allowed to and you are just hearing a jam or click…that’s totally different. Got the be the drivetrain somewhere. Gearbox or otherwise.
What happens if you put it in gear exactly ? Does it stall with a hard stop ? Or stall gradually to a halt ? That would tell a story too. If it’s the former…again back to drivetrain

 

[savageseadog]

Fuel starvation

 

[gordmac]

Tickover too low?