Engine Won't Idle Under Load

[Stillraining]

Originally Posted by meyermm

Sorry but prop problem would not cause out of gear cut out due to load from alternator.

Bingo..either way there is a fuel demand issue Ill bet...I still say govoner.

[Tiki 38']

Yeah, that makes sense. There was water in the fuel when I bought it, so mabee that has bunged up something in the govenor/pump thing.

[nhschneider]

If it were my engine, I'd be looking for air being sucked into the fuel lines. Perhaps a filter not seated properly or maybe a crack in a fuel line that (for some strange reason) doesn't leak fuel but allows air to enter when it's in a vacuum.

Fair winds and calm seas.

[Sailmonkey]

If your batteries were always flat, they may be bad......if they'll never hold a charge you could be trying to charge a dead horse with a large alternator. At idle a 27 hp engine is only producing around 8 hp. It is concievable that an alternator producing 80 amps can and will stall an engine if it's attempting to charge batteries that won't take a full charge.

[neilpride]

Question?? How many Amps is your new alternator??

[Sailmonkey]

I suppose I should have asked that........

[Tiki 38']

Thanks guys, your too much. 55 amp alternator, not big, just enuf to charge a starting battery. I had an auto electrician install the alt and check the system over. All good when he did that. Battery is new as well. Air being sucked into the system is something I have not considered.... Steaming along at say half throttle, after a while the revs drop away slightly. More throttle brings the revs back up and the engine continues to run fine.... for a while. When I bought this boat, there was fuel leaking from every possible connection in both engines. I have sorted 99% of the leaks, however, still a bit of weeping at the primer pump to filter on the engine going on. Air leaking in?.... Could be. Never thought of that! I googled "diesel governors", this sounds very likely. So much to learn. I have learn't, yanmar is short for "steal my money!" Cheers, Charlie.

[Charlie]

Hi Charlie Like your name. I had a problem like that and it turned out to be an air leak in the fuel line. If you have Caulder's book he has some tests to track down leaks. If you need those pages I can get you the info but can't do it right now. Send me a PM. Feel around all of the hose clamps for holes in the hoses. This is especially common with the hose clamps that have holes that run all the way thru the band.

[meyermm]

Yanmar has nothing to do with it, lack of maintenance by previous owner is the culprit. Buyer beware!

[Tiki 38']

Thats true... but, $170.00 for two small foam air filter elements? Probably worth about $10.00 each. Might be ok in Brisbane, not here in N.Z. Cheers anyway. Cheers for the tip on Caulder's book , Charlie and the hose clamp thing.

[Sailmonkey]

In light of new information I'd also bet you're sucking air........any air at all will kill the engine at idle

[Morganministry]

You might also be dealing with an injector problem. If you had water in the system that can cause rust and corrosion wich will partially block the injector. That inturn will hinder the atomization of the fuel and cause a rough idle.

I am curious how the test with out the alternator went.

Scott

[Chief Engineer]

Heck...they are just foam....and they don't rally filter air....they are more loke silencers that cut down the popping sound

Originally Posted by Tiki 38'

Thats true... but, $170.00 for two small foam air filter elements? Probably worth about $10.00 each. Might be ok in Brisbane, not here in N.Z. Cheers anyway. Cheers for the tip on Caulder's book , Charlie and the hose clamp thing.

[Chief Engineer]

Does your return line go to the tank or back to the filter on the engine?

When it goes back to the filter, that is the accumulating point for air.

Weeping fuel has to be corrected. Period

[Tiki 38']

The return fuel line goes back to the fuel tank. I think? Thanks for that. Something else to take note of. I will get new copper washers and correct the weeping fuel. I ordered the foam elements without checking on the price first. I will not make that mistake again. While I'm on this subject, here is a little story about the other engine in my boat. First time out in my "new" boat, I run the engines hard for about an hour. When I got back to port, I noticed one of the foam air filters had, almost completely dissintergrated and been sucked thru the engine in small disintergrated bits! I replaced with new, and after another hour of running this engine died. From what, I don't know. But I am thinking the engine is possibly damaged seriously. Anybody with a comment on that? Morgan, going back to the boat tomorrow, with a head swimming with new ideas and information. I will definately be reporting back! Thanks everyone.