Ball-squeezing can't be the only answer.

Pub911 · #1 (**permalink**) 08-09-2011

I've got a Universal M4-30 diesel with an intermittent issue where after a few hours of running under load, it shuts down due to lack of fuel. All the obvious ideas (obvious to me anyway) I've tried: cleaning fuel tank, replacing all the diesel, clearing fuel vent in the tank, clearing all the fuel lines, changing all filters, changing all fuel supply hoses, cleaning the lift pump, changing the 'lift pump' - heck I've even installed a squeeze-ball style inline pump-ball (like for an outboard) in line ahead of the lift pump. And that actually alleviates the issue temporarily. But unless i send crew below to squeeze that ball, she'll stall in anywhere from a few minutes to as much as 30 minutes. I'm baffled - no pun intended.

Out of desperation, I've got a new lift pump coming in the mail that I intend to place in-line where the pump-ball is. I'm thinking this won't fix the real problem, but it may save my crew (and wife) from strangling me every time I scream: "SQUEEZE the BALL!!!.

Can you help me figure this out - or at least figure out what to try next?

Thanks.

PaulfromNWOnt · #2 (**permalink**) 08-09-2011

Check the lines themselves. It sounds like she's sucking air.

Gary M · #3 (**permalink**) 08-09-2011

Quote:

Originally Posted by PaulfromNWOnt

Check the lines themselves. It sounds like she's sucking air.

Yep I agree likely an air leak.

Good luck

pk5352 · #4 (**permalink**) 08-09-2011

Interesting. I have and M4-30A in my Catalina 30 and had a similar issue 2 weeks ago. After about 45-60 minutes of running under load, the engine just shut down just as I was entering the tightest part of the inlet to my marina. Tried to restart but got really slow turnover- as if the battery were dead/dying. Managed to unfurl the jib, turn the boat around and get back out to clear water. Let the engine sit for 30 minutes and then she restarted, but with quite a bit more throttle than has typically been necessary.

Interested in the responses here...

arf145 · #5 (**permalink**) 08-09-2011

When my Yanmar would run for a while and then quit, it had a small air leak between the tank and the lift pump. If those lines are old, I'd replace them. And I'd check any fuel filter on the suction side.

Pub911 · #6 (**permalink**) 08-09-2011

Thanks for the ideas! I think I'll just replace the filter (it's an old Racor 200 with a 2-micron cylindrical filter element. The filter element is replaced regularly with no affect on the problem, but the filter unit itself has been on the boat since at least '93. I've replaced the o-rings, but never felt great about the fit or my skills on that job.

mitiempo · #7 (**permalink**) 08-09-2011

The other possibility is that some manufacturers installed a screen in the tank on the end of the pickup tube. There should not be a screen there as the crud should be caught by the filter which is much easier to access. I know some Catalinas had this "feature" but not sure which other boats might have it.

As posted above air in the line is also a possibility.

celenoglu · #8 (**permalink**) 08-10-2011

If your tank is well below your engine, the suction f pumps might cause voids (vacuum) in the system. this is very similiar to air in the wystem. Instead of differnt gasesfrom the fuel might fill the gaps or it might be pure vacuum.

treilley · #9 (**permalink**) 08-10-2011

Your fuel pump may have an integrated fuel filter. If you have a small cylindrical pump about the size of a RedBull can, look to see if the bottom end has a cap that comes off. They can be very difficult to get apart but you should see where it has a slot with a post that retains the cap. There is a very small filter in this pump that can cause the exact problems you are experiencing.

It is very common for folks to overlook this filter as most do not know that it exists.

RobGallagher · #10 (**permalink**) 08-10-2011

Quote:

Originally Posted by pk5352

Interesting. I have and M4-30A in my Catalina 30 and had a similar issue 2 weeks ago. After about 45-60 minutes of running under load, the engine just shut down just as I was entering the tightest part of the inlet to my marina. Tried to restart but got really slow turnover- as if the battery were dead/dying. Managed to unfurl the jib, turn the boat around and get back out to clear water. Let the engine sit for 30 minutes and then she restarted, but with quite a bit more throttle than has typically been necessary.

Interested in the responses here...

Try cleaning the fuel tank vent first. Spiders love those things for some reason.

As to the OP, +1 for the leaky fuel line.