Universal M25 cuts out after 6 minutes.

[John Kissack]

Hi, I have a Universal M25 fitted in a 1964 Kings Amethyst. The engine was installed second hand five years ago and has functioned normally until last Saturday. Previous to last Saturday it was used the previous Sunday when it ran for five hours.
On Saturday it started and ran under normal power manoeuvring out of her winter marina berth and got me out into the Clyde to hoist sails when the engine coughed and died. It started again immediately but only ran for 2 or 3 minutes. I tried it about thirty minutes later and it ran normally for six minutes before a cough and the engine stopped. I tried the engine four or five times during the weekend but always the same result.
As the electric fuel pump is connected via the oil pressure switch my original thought was a lack of oil. Oil level is normal, no sign of oil in bilges and no blue smoke from the exhaust (which is clean). The dip stick shows no sign of contamination of the oil.
The tank is full of diesel and I use reinforced transparent fuel lines so can see no air in the system.
Unfortunately my engineer friend is sailing back to the Clyde from Croatia!
Has anyone any ideas? Filters are changed annually when hauled out in May or June, but the suddenness of the cut out makes me think it is not a fuel blockage or obstruction as it will go to 2800 rpm when started.
Thanks in anticipation.

[a64pilot]

Still sounds like fuel starvation, I'd look for a blockage in the fuel pick up tube, remove it and inspect if possible, or at least blow back through the lines.
I've had an almost identical issue with my Yanmar, that was a blocked fuel pick up tube

[Sailmonkey]

I'll second the fuel.

Sounds like the filter is clogged enough to allow running for a bit before the vacuum overcomes the pumps ability to pull fuel.


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[Sailuke]

you might have had some sludge or debris at the bottom of the tank that were finally kicked up enough to be picked up and clog a filter. if you have the electric fuel pump, there should be a nut that you loosen on the bottom that unscrews the bottom access cover. Once removed, you'll see a red mesh pre-filter that may be clogged up.
check out this resource on the Catalina direct website. It may be a different style pump but as i believe they all have a pre-filter of some kind.
Catalina Direct: The Unknown Filter

Also try replacing the universal fuel filter on the engine this may be clogged as well

It may also be this: have you changed the micrometer size of the Universal fuel filter? I think the stock fuel filters for my M-18 are 10 micrometer, and if i were to screw on, say, a racor 3 micrometer filter, the pump might not have enough pressure to pump the fuel through this tiny filter media. I dont know much about the filter system, but I only buy the 10 mic filters from toad marines universal section, the filters that are made for the engine.

[svHannabel]

I'd start with the fuel filters. Depending on which model M25 you have, there are likely either 2 or 3 fuel filters. Check/change the Racor (or other brand) filter and separator between the fuel tank and the engine. Check/change the spin on filter on the M25 itself. If you have a newer M25-XPB, there's also a small in-line fuel filter (see In-Line Filter Westerbeke 48076 Sailboat Supplies, Engine Parts and Boat Parts).


You might also check the air filter to make sure the engine is breathing properly.

[MSN-Travelers]

+1 on fuel system restriction/blockage. Start at either the engine and work back to the tank or in the tank & work towards the engine.

We had a similar experience and found a blockage at the inlet fitting to the primary filter housing. In our case, we learned that a "clean" looking filter doesn't mean there isn't a blockage in a line or at a fitting.

[Xthewater]

Fuel filters are the obvious first thoughts of course.
I was curious re the fuel pump wired via oil pressure switch. Is this a n/o permissive switch that closes when pressure is up at start and then starts fuel pump? Is there a separate lop alarm switch?
If so then I'd suspect the permissive switch has developed a small leak losing the internal differential pressure over time and opening. Failing the more obvious filter changing to cure I'd change the switch.

[Infatuation]

I had the same problem with my Universal 5411...What I found out eventually was the fuel lines had a varnish build up in them that restricted fuel after about 5 minutes. I changed the filters, mechanical fuel pump and still had the problem. Then replaced the fuel lines and finally the problem went away...I would guess the electric fuel pump does not have push a mechanical one does....not sure...Even though you have clear plastic fuel lines you may not see varnish build up in these lies as the varnish is nearly transparent....I could not believe the varnish amount built up in the lines.

[bailsout]

I don't like the pressure switch.

[John Kissack]

Thanks for the suggestions. I did not realise there is a filter at the pump. As soon as the weather permits I will get out to the boat and start at the injectors and work back. I will do a complete fuel line strip down when out of the water as a block could be an issue, though the tank was cleaned last year.
The forecast is not good for the rest of the week, but maybe Sunday the winds will be quieter.

[Xthewater]

Here's a quick one.
Jumper/bypass the pressure switch and see if the problem goes away. Then you'll know if it's the switch.

[hamburking]

I had the identical problem...but it was the fuel tank vent. Spiders had totally sealed the vent, so that when the engine ran, the tank went into vacuum, and stopped the engine.

Easy enough to test...just take the filler cap off...if it runs normal, you know where to look.

You might want to try this simple fix before starting your complete fuel line teardown.

[Celestialsailor]

I wouldn't start at the injectors. I'd start with fuel pick up and delivery. That is to say, try disconnecting the feed hose to the filters and blow back into the tank to ensure there is no restrictions. Then replace the filters. I used Valvtec additive that corroded my pickup tube one time. It quit right out in front of a jetty with a cross current and breeze. Could have lost the boat. I will add my pick up tube was copper, so replaced it with brake-line tubing.

[Xthewater]

Originally Posted by hamburking

I had the identical problem...but it was the fuel tank vent. Spiders had totally sealed the vent, so that when the engine ran, the tank went into vacuum, and stopped the engine.

Easy enough to test...just take the filler cap off...if it runs normal, you know where to look.

You might want to try this simple fix before starting your complete fuel line teardown.

Bingo! Best sense yet.

[Cadence]

I would go with those saying change the filters. If that is not it, it is a cheap elimination. Annually may not be enough or you picked up an unusual amount of crud. Second I would consider an electric fuel pump heating up and locking up. JMHO