Mace 2.6 generator stalls when engine started

[captstu]

Our 2010 R-25 developed a strange problem.

Both the engine and generator run perfectly when only one of the two is started.

If I start the engine first, the generator will not start - cranks fine, voltage measures 12.8, but it won't start;.

If I start the generator first, it runs perfectly but when I turn on the engine key (even if I don't start it), the generator dies in about 10 seconds. The generator cranks fine, runs for a second or so, and stalls.

If I turn off the engine (it doesn't matter if the engine is running, just the key on), the generator immediately starts and purrs.

I think, after tracing every wire, cleaning corrosion of a few, and lots of thinking, that I found the problem.

Fluid Motion draws fuel for both the generator and engine from the same fuel line, splitting the line before the two separate filters. I thought it was improper to run more than one engine from one fuel line - now I understand why.

Both the Yanmar 4BY2 engine and the Mace 2.6 use self priming fuel systems - this means that some fuel is always being pumped into each engine and pushed back into the tank - so if air were to get into the system, the self priming mechanism would clear the air automatically.

Self priming is really, really nice.

But, when I turn on the engine key, even without starting the Yanmar, the engine is drawing fuel that might otherwise get to the generator. During the discovery process, I took the fuel line off the generator after the fuel pump. Fine, fuel flowed freely into the collection tank whenever I turn on the generator to pre-start.

Eventually, I stumbled into the idea of testing fuel flow with the Yanmar key turned on but the engine not started. The generator fuel line now sucked air - turns out the two check valves built into the generator fuel pump were both leaking sufficiently that when the engine is running, no fuel is pumped into the generator.

I ordered a new diesel rated fuel pump and will install it tomorrow. I was unable to remove the Mace pump so I must put the new pump in a different location.

Has anyone had their generator fuel pump fail?

 

[captstu]

I put a new fuel pump in the generator this morning. The engine started right up her nicely the air conditioning went on and call down the boat.

I turn the key to start the engine and 10 seconds later the generator shutdown.

I ran the engine a while to make sure as well Brian, shut it down, started the generator and repeat it again.

I'm stumped, why do I do now?

 

[Andrew Custis]

I would suspect that the fuel filter may be contributing to this. I would suggest adding a separate fuel filter for the generator if it doesn't have one already.

 

[captstu]

Andrew,

My ranger has a large and small Racor feeding the engine and generator respectively. I, also, suspected the filters so I removed the cartridges for a test. No different. I also tested with the generator filter out of the circuit completely. No change. Finally, I put in a new generator fuel pump, still no change.


Is there a screen at the bottom of the dip tube that draws fuel from the tank?

Maybe I need to remove the fuel screen?..



Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[knotflying]

I was going to suggest that you check to see if there is a filter at the end of the pickup tube. You may be getting enough fuel for one or the other, but not for both.

 

[captstu]

Knot. (May I call you knot?): I think you are correct. If I can get at the point where the tube comes out of the tank at the top, I will remove the dip tube and take off the foot check valve that is shown on the print of the tank. I'll replace it with a piece of fuel grade hose that goes over the dip tube and down to about a half an inch above the bottom of the tank.

I'm not sure why the main engine runs without fuel starvation and the generator starves rather than the other way around.

This is been going on so long I am not thinking clearly! A couple of days ago I took a vice grips and crimped the hose to the main engine. The generator continue to run when I turned the key to the main engine on. Clearly the main engine was starving the generator for fuel.

Thanks for the suggestion, It was beginning to dawn on me that I had to take the fuel line out of the tank.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[NorthernFocus]

Ouch. That's not an easy task. Take pics for us who will no doubt follow someday 🙂

 

[ixlr8]

Thanks for the suggestion, It was beginning to dawn on me that I had to take the fuel line out of the tank.
Stuart Bell

Is there any way you could try blowing air back into the tank thru the fuel line before you went thru the effort of removing the fuel line? I know you said there is a check valve there, but maybe it has some dirt on it that will prevent it from sealing properly and you can blow something off the screen that might be there.

 

[knotflying]

I would bite the bullet and pull the tube. It is doable. An R-27 had a bad problem with the engine starving for fuel and he pulled his. It is not one of the worst projects. It seems to me that your engine is more forgiving with the lack of fuel flow than the Genset. Perhaps the engine pump is stronger and overtakes what the genset is drawing and hence the weakest is failing.
Quite frankly I would remove the filter and leave it off. I would rather have a clogged primary and deal with that rather than the filter in the tank. Then again, there may be a good reason to have the pickup filter, but I can't think of one, to me clogged is clogged and I would rather replace the easier access filter. I wouldn't mind drawing gunk out of the tank either and having it drawn up into the primary is a way of removing it from the tank.

 

[Andrew Custis]

It's been a while since I have looked at the 25 classic fuel system layout but believe Mike is right. ON this model, one fuel pickup is shared with the Engine and Generator. If the pickup is restricted, one might be drawing everything it can handle. I agree that removing the fuel pickup out of the tank is the most likely source of your issue.

 

[captstu]

We all agree the next step is to remove the dip tube and clean or remove the filter on the bottom of the dip tube.

How do I access the top of the fuel tank on the R25?

 

[Just Dreamin']

Stuart, on our R25 classic there is an inspection plate inside the cabin at the step. Fuel tank connections are accessed under this plate.

 

[captstu]

Thank you. I'll be at the boat tomorrow and will remove the screen at the bottom of the tank.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[captstu]

I took the filter out of the end of the tube that took the fuel out of the tank. I was able to easily reach it from the access port just inside the "door". The fuel screen was partially clogged, but the situation did not improve when I removed the filter. I replaced the filter with a short length of 3/8" refrigeration water line that I was able to push inside the original "down tube" without expanding the diameter much.

I disconnected the fuel line from the output of the generator fuel pump to the generator fuel injection pump.

Placed a clear line on the pump and led it to a clear collection bottle.

When I turned on the generator (but did not start it), a steady clear stream of fuel came out of the temporary hose.

When I turned on the engine key, the fuel turned to mostly air - some fuel, but maybe 90% air.

Clearly I had an air leak.

I took apart everything, one connection at a time, and eventually found that the generator fuel filter was admitting air. The generator and engine run perfectly (better than ever actually) without the generator fuel filter. I know the fuel filter is required, but I figured that 10 minutes of testing wouldn't hurt.

Since this is a new leak, I'll slowly put stuff back into the circuit until I isolate the air leak.

Thanks for your help!! /Stu

 

[knotflying]

Keep going Stu! It is all about patients. I guess when one or the other is running it is fine, but when the engine is on the pump on the engine overpowers the generator draw and then the increased negative pressure causes the generator to suck air from the leaking connection. Let us know your final fix.

 

[captstu]

Hi, a few weeks ago, my Mace 2.6 was stalling when the main engine started.

I inserted a piece of clear tubing in the fuel line and found air was being admitted when the additional suction of the main engine was present. No problem, I thought - just replaced the hose clamps, tightened the connections, and the air leak went away.

But, in the process it seems the fuel pump failed - so I replaced it.

After that, the engine ran for about 3 minutes each time it was started - with our without the main engine.

Now it won't start at all.

I disconnected the high pressure fuel line where it goes into the injector - and little or no fuel was coming out of the high pressure fuel line.

I'm stumped - I've ordered another fuel pump, but can't figure out what happened.

It appears the high pressure injection pump has lost prime - the book says it is self priming.

Two questions:

1. What engine is used on the Mace 2.6 generator?
2. Any idea where I get the engine manual for this engine.

It is a single cylinder air cooled engine - kind of a strange mix since there is a radiator cooled with sea water that cools the air that cools the engine - but these are all working fine.

I did check the solenoid that shuts off the fuel flow to turn off the engine - it clicks when turned off and on.

Prior to failure the panel was showing code 85 and 80 - meaningless codes since the engine was stalling from an apparent lack of power.

Thanks!