Help! Engine mystery, potentially dangerous

[Fascadale]

I have a 3 cylinder beta 20, about 15 years old

After it has been running continuously at medium to high revs for about 48 hours it cuts out when the revs are dropped to approach a berth. It has done this twice after long windless Biscay crossings. It has also done this after a 6 or 8 hour passage

Coming into a harbour is not when you want your engine to cut out

The filters are clean, the tank is clean, the idling speed has been adjusted to run smoothly. The engine runs perfectly at high speed then it just dies as you slow down

I thought I had cracked it today by slowing very gradually but it still died

All advice very welcome. We still have another 700 mms to get home

 

[Graham_Wright]

We still have another 700 mms to get home

About 2 feet? You can reach can't you?

 

[Ruffles]

Will it restart after cutting out? Or do you have to wait for it to cool down?

 

[sarabande]

after a long run, does the return pipe cause the fuel in the tank to become very hot ? I am thinking of a vapour lock of some sort especially with highish ambient temps.

VL sometimes caused by an obstruction to the supply; is the fuel pipe clean / not kinked / otherwise obstructed ?

 

[RAI]

Does it still cut out if neutral is engaged?

 

[lw395]

valve clearances?
air leak in fuel supply?
lift pump?

 

[RAI]

Fuel tank vent blocked?

 

[JumbleDuck]

valve clearances?

Seconded. Also might be worth having the injectors serviced.

 

[Fascadale]

Thanks for speedy replies.

I restarted the engine maybe 10 minutes after it stopped and it idled happily in neutral. It will still have been quite hot after the 48 hour Biscay run

The vapour lock is is an interesting thought I think the retur I g fuel just squirts back in near the top of the tank. It seems to breathe well enough at high revs

I have never touched the valves so the clearances should not have changed

How would the lift pump effect it and what might be the problem there?

 

[vyv_cox]

Vapour lock is only usually a problem if the fuel pipe crosses over the engine, which causes it to overheat.

 

[rogerthebodger]

I used to have a similar problem. I found the tick over speed was a bit low. I adjusted upwards a little and I no longer have the engine cutting out going from highish throttle to neutral.

 

[Biggles Wader]

Not sure if valve clearances are your problem here but they do change with wear over time so should be checked/adjusted every so often.

 

[PetiteFleur]

I would also check idling speed, I've had to do this with my Beta 25hp. Also speak directly with Beta Marine, they are very helpful.

 

[JumbleDuck]

I have never touched the valves so the clearances should not have changed

Seats recess, though, valves wear, gaskets compress and other things move around. I had a 2CV which would only start when cold and wouldn't tick over when hot ... turned out to be slightly too tight exhaust tappet clearances becoming zero or worse when the engine was hot.

 

[FinesseChris]

Hi,
Had just that problem with a 3cyl kubota, same as the Beta basically. It turned out to be too much oil in the sump. Extracted a pint, checked dipstick, and all was well.
It provided some hairy moments approaching pontoons before it was sorted, though!
Good luck.
C

 

[Bilgediver]

I have a 3 cylinder beta 20, about 15 years old

After it has been running continuously at medium to high revs for about 48 hours it cuts out when the revs are dropped to approach a berth. It has done this twice after long windless Biscay crossings. It has also done this after a 6 or 8 hour passage

You are setting the slow running by the quadrant screw on the engine and not by adjusting the teleflex ????

 

[Fascadale]

Idling speed adjusted at the quadrant. Tappers beginning to sound interesting but not something that I think can be done in Britanny.

Too much oil is very interesting. Certainly the engine is full to the top marks on the dipstick. Any suggestions to the the theoy here?

 

[Ripster]

Not sure if valve clearances are your problem here but they do change with wear over time so should be checked/adjusted every so often.

+1 - defo worth checking these and the slow idle speed setting.

 

[penfold]

Idling speed adjusted at the quadrant. Tappers beginning to sound interesting but not something that I think can be done in Britanny.

Depending on access it's a 30 minute job at most, although the rocker cover gasket may need replacing(or patching with goo) if it tears on removal.

 

[pmagowan]

I had the same problem, as did someone else on here IIRC (may be worth a search), with a beta20. I did two things and I am not sure which was the solution. I increased the idle speed (don't think this resolved it) and I checked the fuel line. I think it turned out to be a fuel line issue, air getting in or summat. In the end I replaced the whole fuel line and tank as the old filter was a dodgy thing with multiple o-rings that were a fiddle to get right. I think this is where the air came from. The racor replacement makes filter changes easy and the engine has been perfect ever since.