Marine Beta 38 cut-out after some minutes

[chlini]

I have a betamarine engine 38 (about 1500 hours) ran fine for the last season. Before winterizing we changed all the filters.
Now if i run it on 2000 rpm I get some rpm loss and today it even died. I then checked every replaced filter, and replaced it again. No Leaks as I saw.
Then replaced manual hand pump, cleared the fuel hose, checked fuel tank. Still the same problem!
Sometimes it works perfectly fine, on other days it dies on 2000-3000 rpm's.
What could cause this kind of problem?

Thanks for your help.

 

[Laysula]

Is your fuel tank breather clear? Try it out with the filler cap removed.

 

[footsoldier]

I then checked every replaced filter, and replaced it again. No Leaks as I saw.

Stating the obvious - if it was running perfectly up until you changed the filters and now it is not, there you have the most likely culprit. Something has not sealed correctly. Re-check all the seals.

 

[jdc]

...manual hand pump...

Apart from the tautology, what is this?

If it's one of those outboard motor rubber squeezy thingies for priming the fuel, does it compress when the problem manifests? If so, it would indicate a vacuum at that point, so a blockage in the fuel or breather upstream of it (or just maybe, fitted it backwards?).

In any case the problem is most likely fuel - most diesel problems are! So looking if you can at the pressures in the pipework will help.

Alternatively, disconnect the pipe-work between the tank and the primary fuel filter, and feed the primary filter by a short (1m or so) pipe leading from a 20 litre drum of clean fuel. If this runs perfectly, then the problem is the tank side, if the problem still exists then it's the engine side (of the primary filter), although I have seen an engine stop when the return line to the tank was choked.

 

[Bobc]

Have you closed the bleed valve on the engine?

 

[Boater Sam]

Is the tank fuel tap fully open after you replaced the filter? Its easy to forget!

 

[chlini]

Thanks for all the respondings.

Well we already replaced the filters again, checked the seals looking good no twists, checked again for leakings after replacement. Runs the engine (died), checked for leaks again to be sure we didnt messed up after second replacement.

We checked the diesel system again and blow through it to check that there was no blockage between the diesel-water-separator (first filter) and the tank. No blockage.

The manual handpump that we use to priming the engine with fuel was fitted correctly, we checked that aswell also we check that it doesnt allow diesel to go back to the tank. No blockage there and no vacuum occured.

Fuel tank breater is clear, we have also opened the tank to make sure the hose is not blocked and no dirt is in the tank. Everything looks good and clean.
Fuel tap was always fully open, we also started the engine with the tank closed to be able to bleed the system empty again to get any air out. Bleeded System fully through but failure still occurs.

 

[jdc]

We checked the diesel system again and blow through it to check that there was no blockage between the diesel-water-separator (first filter) and the tank. No blockage.

This is not how it's used when you are running the engine; it's sucking not blowing. It's possible to have crud in the pipework or tank which acts as a one-way valve impeding the flow from tank to engine, so this test was very unlikely to give a useful diagnostic result.

The manual handpump that we use to priming the engine with fuel was fitted correctly, we checked that aswell also we check that it doesnt allow diesel to go back to the tank.

But what is the pump? Was it designed for diesel engines, and fitted by the boat manufacturer? Or was it an after-thought fitted by someone else?

No blockage there and no vacuum occured.

At what moment did you observe the pressure? It shouldn't be zero - it's under negative pressure at this point - so what is it at the moment the failure occurs.

...but failure still occurs.

Did you try feeding the primary filter from a clean can of fuel? And do try blowing down the return line to the tank.

 

[bluerm166]

I had a recent engine failure despite clean filters and eventually discovered that the inline shut off valve - a wade fitting - was not a full bore fitting but reduced from the 8mm dip tube to 3 or 4mm giving a substantial step at which the debris from sailing on my ear in rough seas and churning a low level of diesel had totally shut off the supply.Have changed it for a full bore fitting.

 

[david_bagshaw]

Run the engine directly from a fuel can to eliminate holes in the plumbing of the fuel feed system, look extremely at the filter housings for a small crack, including where the fittings enter. when it stops, doyou have to bleed again to to get it going, or does it restart immediately? How old is the lift fump, as I have had one fail over winter, does it have a gauze filter which need s cleaning?

 

[SvenH]

If I recall correctly, the ball squeezepumps for outboards are not really suitable for diesel long term. Maybe air enters there in a crack?

 

[Daydream believer]

If I recall correctly, the ball squeezepumps for outboards are not really suitable for diesel long term. Maybe air enters there in a crack?

Buy a diesel rated one. Mine has lasted 15 years so far

 

[Daydream believer]

Is there a very small gauze filter in the fuel lift pump itself? There is on some & I expect that fuel pumps are interchangeable between engine manufacturers.