Universal M25 cuts out after 6 minutes.

[boeing1]

yes fuel filters first step, if no help, and possible blockage in fuel line at a elbow or fitting. if OK, I would bypass press switch and wire fuel pump direct to 12vdc.

[cstutz]

Your problem sounds so familiar. Years ago I had a C&C 26 with an Atomic 4. I would start the engine and it would eventually stall out after a period of running. To say the least it drove me nuts taking things off and replacing etc. etc. I finally found the cause. It was in the exhaust hosing. The inside was lined with a rubber substance. A part of the inner rubber lining had cracked and was loose making a flap. When I took it off it appeared ok but when I checked the lining I discovered a mark inside the hose. When I pulled on it it came out sort of hinge like covering the inside of the exhaust hose and blocking the passageway. Replaced the hose and no more problems. Hope this helps.

[seabreez]

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.

Definitely fuel starvation. Last summer we had a piece of silicone in the fuel line. Eventually it blocked the line completely. Had to clean it out with a wire.

To test yours, crack open the fuel line past the filters at different spots and try to start up. Your pump will run on the start circuit. If fuel does not pour out... keep loosening the fuel line closer to the fuel pump, between filters or before filters until you have fuel pouring out... then check in between for troubles.

[mariner-dovb]

Hello John, this sounds very much like "Diesel Pest". While this gets much attention in a warmer climate like the Med, and even in the North Sea, hardly anybody mentions this phenomenon in the USA or Carribean.
It ist caused by bacteria which live on diesel using traces of water. These bacteria produce a jelly-like substance which will clog up completely Your piping and hoses, even before anything is reaching Your filters. So Your filter is looking normal, though no diesel is passing through.
To cure this problem You will have to clean not only Your tank, but also all tubing. Remove all water out of the system. Use "Grotamar" as additive to your fuel.
This should always be used in order to prevent future problems.
Greetings
nw