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landonshaw · 08-02-2012, 04:06

I have been having problem with my 40HP Volvo Penta engine. MD2040. I am suppose to run at around 3000 RPM, I have found that if I do, the engine will cut out after a little while. Maybe an hour or so. I can run all day at 2300. This past weekend I realized it was shutting down and quickly reduced the throttle to 2300 and the engine remained running. In the past, it would shut down but I could restart and leave at a lower RPM. I had changed the fuel filter at 1060 hours, I'm now at 1283 and will be doing that in the next week or so. Any ideas? I have thought that possible it is an air leak that at the higher rpm it is able to suck in enough air to stop the engines.
Any thoughts of what it might be and how to find, fix it? Thanks

**captain58sailin** · 08-02-2012, 04:28

On your fuel filter housing seal.

atoll · 08-02-2012, 04:36

i've also had this issue on volvo's from the bosch fuel filter housing,where the bleed bolt on top has been over tightened and partially stripped the aluminium threads.

landonshaw · 08-02-2012, 05:45

I always carry spare fuel filters and maybe this is old. Maybe the seal is not properly sealing. I will change sooner rather than later and see. Thanks

**SkiprJohn** · 09-02-2012, 10:47

Please let us know what the results are.
kind regards,

Podjo · 09-02-2012, 11:59

It sounds like the engine is not getting enough fuel pressure to run at the higher RPNs. There a many things that can cause low fuel pressure. I found a bad electrical wire crimp to my electric fuel pump (that I caused when I changed out the fuel pump a year earlier). I borrowed a real crimping tool from a retired professional, and plan to deep six my old stamped metal crimping tool. I hate it when I cause my own issues....argh.

Celestialsailor · 09-02-2012, 14:43

Could also be a fuel constriction issue

**Therapy** · 09-02-2012, 16:52

Atoll and capt58,

As I understand it there might be just a little bit if air getting in at higher rpms and if caught quickly (by reducing throttle) the motor won't stall?

The air that gets in is then just passed through the injectors/engine?

Or does it enter the return line?

atoll · 09-02-2012, 17:29

Quote:

Originally Posted by Therapy

Atoll and capt58,

As I understand it there might be just a little bit if air getting in at higher rpms and if caught quickly (by reducing throttle) the motor won't stall?

The air that gets in is then just passed through the injectors/engine?

Or does it enter the return line?

once enough air has entered the filter chamber then the engine will lose revs and die,needing rebleeding to fill the filter chamber again.

tiny amounts of air entering will cause the engine to run rough and not attain higher revs, the air passing through the pump and injectors.

to the op have you changed both filters?

there should be one on the engine and another one near the fuel tank,your problem definetly sounds like fuel starvation.

i normally change filters at 200 hours,and have a large racor but if your fuel is contaminated getting fuel starvation after 20-50 hrs is not uncommon.

sailorchic34 · 09-02-2012, 20:51

Check your discharge elbow for blockage too..... Cut out at high rpm can be caused by blocked discharged elbow.

Celestialsailor · 09-02-2012, 21:16

I had an issue one time with a copper draw tube in the tank and diesel additive that attacked diesel. Slowly built up a black crystalline substance chocking the ability to draw. It would starve. Of course it only happened at the harbor mouth going out on a blustery day...

landonshaw · 10-02-2012, 04:49

discharge elbow? I am thinking the exhaust leaving the boat. THis is tied to the cooling system though.

sailorchic34 · 10-02-2012, 09:14

Correct. The heat as the water mixes with the hot exhaust, drops out minerials in the water, that build up on the wall of the elbow causing restrictions / blockages. This increases the back pressure and is generally first noticed at higher rpm.

Oh its probably fuel related, just offering one other option.

landonshaw · 01-04-2012, 04:22

Finally got around to changing the fuel filter. It seemed tight enough before taking it off to not cause a problem. In addition changed the pre fuel filter. It had stuff all over it. I am guessing that it was the problem. When I got up high RPM it might have reduced the flow of fuel. Over Easter headed to Tobago Cays for 4 days and will be able to see then. I will report the results of my efforts after the trip.

landonshaw · 09-04-2012, 17:40

sailed to Tobago Cays and all went well. Changed the filter and pre-fuel filter. The pre=fuel filter had stuff all over it. Ran the engine at 3000 RPM and it never hesitated once. I will change the pre-filter this week and see how it looks. So my problem was in one of the filters and I suspect the pre-filter.