On our 1991 Catalina 30, the Universal M25XP engine has been stopping shortly after it reaches operating temperature, circa 160 degrees. When this started last year, we assumed fuel contamination and this summer installed a new fuel tank from Cat. Direct, replaced all fuel hoses, added new Racor 500 filter, new Facet pump, added fresh clean fuel. We bleed the engine with the knurled knob and it starts fine, with plenty of cooling water discharging. But the problem is still there. After 30 to 40 minutes running in the slip under load at about 1500 rpm, temp 160, the rpm begins to rise and fall every 5 seconds or so, gradually falling closer and closer to dying. After about 10 minutes of this it dies. We've double and triple checked for any air leaks or fuel leaks in the new work. At the yard's suggestion, we replaced the bleed valve, but no change. The yard is stumped and is now suggesting replacing the injector pump (pricey). We'd be grateful for any suggestions.
Universal M25XP dies after 30 to 40 minutes
- Thread starter V&J
- Start date
The vent hose might be clogged, causing a vacuum in the tank that the pump can’t overcome. To check for that try running it with the fill cap open.
A couple things to try. For a diesel its either fuel, air or timing.
1) Try adding a temporary piece of clear tubing to the fuel system as close to high pressure pump as possible. Leaks will be visible
2) Harbor freight has an inexpensive compression tester for diesels. You can check compression by removing a glow plug. I assume that your oil is not milky and you are not losing closed loop antifreeze water.
3) remove the valve cover and see if all the valves are working. You can stop the engine after it heats up and rotate the engine by hand.
4) Do you have a Racor filter? there may be a ball check in the top of the filter. I forget which screw on the top of the filter hides the ball..
You don't say if the engine dies at 160 deg at idle or it's under load.
Could be fuel starved - defective high pressure pump under load.
Or insufficient air under load
insufficient fuel under load
Could be faulty injectors under load not operating correctly
So with the heat added to the equation could be leaky head gasket m(do compression check) , could be stuck valve ( do visual inspection and compression test)
1) Try adding a temporary piece of clear tubing to the fuel system as close to high pressure pump as possible. Leaks will be visible
2) Harbor freight has an inexpensive compression tester for diesels. You can check compression by removing a glow plug. I assume that your oil is not milky and you are not losing closed loop antifreeze water.
3) remove the valve cover and see if all the valves are working. You can stop the engine after it heats up and rotate the engine by hand.
4) Do you have a Racor filter? there may be a ball check in the top of the filter. I forget which screw on the top of the filter hides the ball..
You don't say if the engine dies at 160 deg at idle or it's under load.
Could be fuel starved - defective high pressure pump under load.
Or insufficient air under load
insufficient fuel under load
Could be faulty injectors under load not operating correctly
So with the heat added to the equation could be leaky head gasket m(do compression check) , could be stuck valve ( do visual inspection and compression test)
The symptoms certainly fit with air in the fuel line. But it seems to be heat related, which might make sense if there is a tiny crack in the fuel filter housing. Bear in mind that in "checking for air leaks" you cannot observe the leaks on the suction side, only the pressure side. So that can be a bit tricky.
Question: After you let the engine cool down, does it start right up and run well for another 30 to 40 minutes without rebleeding it?
One other thing you might try is bypassing your main fuel tank by getting a jerry jug or other portable fuel tank, e.g., like for an outboard motor, and run the engine temporarily with that and see if it makes a difference. Just temporarily reroute both the input hose and the injector return line into this temporary tank and run it again in the slip as you have done, and then see if the problem remains.
Do not, under any circumstances, listen to this mental black hole ! ! ! ! If the engine runs fine for 30 - 40 minutes (as you say) THERE IS NOTHING WRONG WITH THE INJECTOR PUMP.
I got a nickel bet on the fuel tank vent line being plugged. Follow posts #2 and #3 very closely as I think you'll find the answer in there, all for free.
I'm with you, Ralph. Replacing the injector pump is one of the last things I'd try, and not without some really good reason to think that's it.
Trying my suggestion with a temporary day tank would be a really simple way to eliminate all tank-related issues from the equation. Of course, a quick inspection of the vent surely makes sense, especially if there is something obvious.
when you replaced the tank was there a screen on the end of the fuel pick-up tube. if so I would suggest removing. good luck
If you have not already remove the pickup tube from the tank and remove the screen.. Also check the filter in the fuel-pump..
https://pbase.com/mainecruising/facet_fuel_pump_filter
https://pbase.com/mainecruising/facet_fuel_pump_filter
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,076
For possible suspects, I like:
Of note it happens 30-40 minutes while running at the dock. That is really a decent length of time to get out of a marina and put the sails up.
- the Fuel Vent Line
- Fuel pick up tube screen
Of note it happens 30-40 minutes while running at the dock. That is really a decent length of time to get out of a marina and put the sails up.
We had previously run the engine out of a jerry can when the problem first appeared and it ran fine. That’s why we put in a new fuel tank and all new fuel hoses including the vent, thinking they were the problem. Also brand new is the Racor 500 and the Facet pump, which comes after the Racor. The pickup tube on the new fuel tank had no screen and was airtight. We took off the fuel fill cap after running for a while but didn’t notice any sucking noise. We will try running with the vent hose off to make sure there’s no vacuum building. If that isn’t it, we may try running out of a can again. Thanks for all the helpful suggestions. When we get to the bottom of this we’ll post again.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,076
V&J sounds like your attacking the issue logically.
The rpm issue I believe is fuel associated. Sounds like fuel starvation. I have experienced the same behavior on my diesel. When the fuel mixture gets lean the engine surges. At some point the fuel volume fails and the engine stops.
I know you have redone the fuel system. You will need to go through it again. Checking all of the connections to be sure they are clear of any debris, all connections are air tight, check the engine fuel pump for any check valves sticking, make sure all filters are clean. Check the lines at the High Pressure pump and the Injectors to be sure there is no contaminates. Be sure to replace all copper washers or compression sleeve ferrels you disturb.
Our auxiliary engines are simple systems. It was mentioned earlier that the run because of
I do not think the issue is connected to the engine temp. Your description suggests the engine is running at a normal temp (based on the data you are getting on the temp gauge). I would verify that by using an IR temp sensor aimed at different areas of the engine. The area of the engine temp sensor should match the temp showing on the gauge. The exhaust manifold should be hotter.
The rpm issue I believe is fuel associated. Sounds like fuel starvation. I have experienced the same behavior on my diesel. When the fuel mixture gets lean the engine surges. At some point the fuel volume fails and the engine stops.
I know you have redone the fuel system. You will need to go through it again. Checking all of the connections to be sure they are clear of any debris, all connections are air tight, check the engine fuel pump for any check valves sticking, make sure all filters are clean. Check the lines at the High Pressure pump and the Injectors to be sure there is no contaminates. Be sure to replace all copper washers or compression sleeve ferrels you disturb.
Our auxiliary engines are simple systems. It was mentioned earlier that the run because of
- Clean and ample volumes of fuel
- Air
- Compression.
@V&J , did you try @RitSim 's suggestion to prove/disprove air in the fuel leading to the injector pump ? You could, at the very least, forget the possibility of air bubbles in this conundrum.
You're both logical and methodical in your approach. This problem doesn't stand a hope in hell against that form of attack. I won't wish you luck as I don't think you need it.
Carry on
.