Genset Puzzle

[buster53]

Someone above mentioned the tank pickup. The anti-siphon valve on the tank my not be opening fully at high rpm. If the genset and engine are using the same tank pickup on the port tank, a sticking valve may open enough for the engine to run but not open enough for both to run. Even if the genset has it's own fuel line the anti-siphon valve be something to check. I had a similar problem and after new fuel filter, carb rebuild, etc. it turned out to that $25 valve.

I had a lot of problems with my Kohler last summer. Replaced my anti siphon valve and all is good.

[denpooch]

Buster can you tell me where the valve located? Would you happen to have a part number or ink to purchase.
Thanks.

[denpooch]

UPDATE:
Let me start by saying that the people on this site are both knowledgable and terrific. I know that I can always come aboard with questions and there will be plenty of suggestions and feedback. I very much appreciate all of you.
Attached are a couple of images of the fuel feed. The little device which I thought was a fuel pump is actually a solenoid. This is the 'anti-siphon' component fo the system. I am told that eventually they can 'wear out' constricting fuel flow, but I am told that is unlikely.
I spoke with Brian at Carver Yachts, who actually was on the crew building this model and he believes it is raw water feed issue, much like many of you have stated. As it is a unidirectional strainer, when at rest the water pressure helps to feed the system, yet when running, the impeller and system must work harder to supply enough water. Brian suggested that it may be a clogged strainer or bad impeller, even though I just replaced with new a couple of weeks ago.
I called a Genset service facility to schedule a service call and was fortunate to get to speak with the owner. He said 'no' to the solenoid. He does believe that it is an issue with water feed/overheating.
His suggestion is that someone should stand aft and observe the water flow output from the generator when idling and at cruise speed. He implies that if the water slows or diminishes out the exhaust at cruise it is a WATER PUMP issue. The gentleman mentioned that it can also be an 'O' ring that is leaking, although I don't have water in the bilge. Brian at Carver suggests that if this is the fact it's possible that a bad belt driving the pump can be the issue.
This is all starting to make sense.
Thanks again for your input.

Fuel Feed.1.jpg

fuel feed.2.jpg

[Viper]

Ya could be a few things. Good point about the impeller, just because it was recently replaced doesn't mean it or the pump is working as it should now. Every little thing will contribute to the overall fault. A little leak here, drawing air there, going at high speed, worn impeller, bad belt, dirty strainer, it all adds up and the speed may be what's pushing it over the edge.

Keep us posted.

[buster53]

Buster can you tell me where the valve located? Would you happen to have a part number or ink to purchase.
Thanks.

I believe my mechanic said it was right at the top of the fuel tank. I don't recall if it was on the outside of the tank or just inside.
Not sure if that is your problem, but I've read enough posts on the subject of genset problems to say it is worth looking into

[Viper]

An anti-siphon valve will be right where the fuel hose hooks up to the tank. It'll look just like a connection fitting which it is but will have a built-in check valve.

I don't recall if the fuel solenoid valves are utilized for most generators, I don't think they are. In any case, make sure the connections on the solenoid are clean and tight.

[KeithS]

Electric fuel solenoids are Canadian requirements. Some manufacturers like Sea Ray put them on all their boats so they don't have to have a special Canadian model. To eliminate the boat fuel system, run the generator off a small outboard tank.
I agree with the sea water issue as the most likely cause. Even impellers with low hours can spin the hub and slip. Try a new one and be sure the o-ring is replaced and properly installed. Watching the exhaust water flow is not very helpful. The lift muffler design will always flow the same amount, it just will take longer to fill with a weak impeller. Unless you have timed the "pulses" with a good impeller, it it hard to know what is normal. I had one that did just what you said, and despite my best efforts confounded me. I finally put a new sea water pump and all was well. My guess is the housing was just worn and just wasn't providing enough surface.

[denpooch]

Update:
I had a generator mechanic pay a visit and he believes, like many of you, that there may be some restriction at the intake. He changed the impeller which showed some wear at the age of about 3 weeks, so we know it was running dry. He mentioned 'cavitation' several times.
The mechanic did 'back blow' as was mentioned on a previous post. I know that I poked each of the holes in the strainer before spray painting with a zinc compound, so perhaps there is something living on the boat side of the strainer.
Has anyone ever snaked that sum-o-bitch? Unfortunately, it has a 90 degree joint with little room to maneuver. Best I can think is use a short length of wire with a loop on the end, close the valve, take off the hose (should be easy because the guy had it removed to back blow), open the valve and work as fast as possible to squiggle around in there whilst she takes on water. All tricks and insights are welcomed.
Thanks.