generator still only runs for 4 hours!,,

Havana Shamrock

Havana Shamrock

Well-Known Member
SILVER Sponsor
Sep 9, 2008
5,422
Sarasota Fla.
Boat Info
2019. 250 SDX OB
Engines
300 Verado V8
I’m still having trouble with my generator it started last season and I cannot find the cause after 4 hours I have to fill the racor filter with fuel. So far I have replaced the entire racor and fuel line from racor to the mixing valve.
It doesn’t matter which tank I pull from it’s the same results so it’s highly unlikely it’s both pick up tubes.
I have installed a clear hose going into the racor and see no bubbles or bubbles in the racor. It’s absolutely driving me nuts does anyone have any ideas maybe I missed something?
 
I like your thought process with air getting in somewhere... The only other thing that came to mind was your fuel pump, but why it would crap out after 4 hours is a mystery. I will be following for greater minds to share their wisdom.
 
What about the return line? That could cause back pressure...maybe builds slowly?
 
Havana Shamrock said:
I’m still having trouble with my generator it started last season and I cannot find the cause after 4 hours I have to fill the racor filter with fuel. So far I have replaced the entire racor and fuel line from racor to the mixing valve.
It doesn’t matter which tank I pull from it’s the same results so it’s highly unlikely it’s both pick up tubes.
I have installed a clear hose going into the racor and see no bubbles or bubbles in the racor. It’s absolutely driving me nuts does anyone have any ideas maybe I missed something?
Click to expand...
Maybe install a new hose from the Racor directly to the fuel tank on the supply side and run the generator to eliminate the crossover valve system being a problem. The issue must be somewhere between that filter and the fuel tank....
Also install a vacuum gauge on the Racor so you can monitor to see if the fuel system is restricted and a high vacuum is being created.
 
Maybe filter orientation or a casting flaw (metal burr) in Racor housing.
 
I did blow the lines back into the tanks and heard a lot of bubbles so no restriction, racor was changed so no burr, I disconnected the crossover and went straight to each tank same thing happened 4-5 hours later she ran out of fuel. ttmott when I opened the lid this morning it is def Under a vacuum
Air rushed into the racor I plan
On installing a gauge but I know air is getting in.
 
Blowing air into the lines with compressed air and hearing bubbles isn’t a definitive way to prove that the lines aren’t somehow restricted. The air pressure is much stronger than the pull of the fuel pump.

You may have a blockage where only a small amount of fuel can pass through, but you will still hear bubbles when forcing compressed air into the line.

I had this same issue on a fuel line on a old car that sat for a few years. I could blow compressed air into the supply line near the engine mounted fuel pump and hear bubbles in the tank. However the pickup tube in the tank was almost completely blocked with crud. Air bubbles could be forced in, but fuel couldn’t be drawn out.
 
Do you know that it starves for fuel when it shuts down?
Will it restart immediately after shut down?
It sounds like by elimination you should have reduced the chances of it being a fuel problem. I'd start looking at sensors that may be providing a shut down signal.
 
It’s definitely a fuel starvation problem the racor fuel level is low when it shuts down and then I’ll fill it and it starts immediately. As I stated it happens on both supply lines from 2 different t tanks so the chances that both got blocked at the exact same time is unlikely the code shows only “shut down without the switch” or something like that a general code.
I put a clear length of hose to view the fuel supply it ran for 5 hours yesterday without any trace of bubbles in the line and this morning I will try to restart it without touching anything.
 
Havana Shamrock said:
I did blow the lines back into the tanks and heard a lot of bubbles so no restriction, racor was changed so no burr, I disconnected the crossover and went straight to each tank same thing happened 4-5 hours later she ran out of fuel. ttmott when I opened the lid this morning it is def Under a vacuum
Air rushed into the racor I plan
On installing a gauge but I know air is getting in.
Click to expand...
If air rushed in there is definitely a problem in the suction side of things (inlet to the Racor).
How about simply taking the hose connected on the Racor inlet and dropping it into a 5 gallon fuel container full of fuel and with the vacuum gauge installed on the Racor run the generator and monitor what happens. At this point I suspect the transfer valves; possibly the handle is not oriented correctly. If you changed all of the hoses then it's not a hose inner liner collapsing. As a note a high vacuum in the Racor will "boil" off the fuel (fuel vapor pressure). Reaching......
 
Joe, I agree with Tom. The supply side of your Racor is not keeping up with the demand of the fuel pump, which is why you have a vacuum on the Racor and the generator trips. As Tom indicated, it is possible, but very unlikely your return selector valve is somehow mis-oriented. Not sure if that could lead to excess return or if that would lead to over demand by the pump causing it to suck like mad. Doubtful but this is quite a mystery you have been dealing with for a while. Have you tried moving the return line to "off" and see if that has any effect? We use pretty sophisticated testing devices to detect leaks using helium, small leaks are really tough to pinpoint but I'd still be inclined to think it's on the inlet side of your Racor. Have you thought of bypassing the Racor altogether for a test run? You still have the on engine fuel filter to protect you.
 
Brian I did think about bypassing the racor as my next step.
So from yesterday and today the generator has run w/load a total of 9.3 hours Can’t figure this out it hasn’t run this long is over a season.
I’ll keep testing I guess
 
Reading every post on this thread - to learn everything I can.

Not so much boating - but back to my days on the farm growing up with tractors and trucks - fuel issues can get very challenging sometimes.
 
Possible to heat up enough to vapor lock? I think it would shut down for overheat by then though.
 
Havana Shamrock said:
Brian I did think about bypassing the racor as my next step.
So from yesterday and today the generator has run w/load a total of 9.3 hours Can’t figure this out it hasn’t run this long is over a season.
I’ll keep testing I guess
Click to expand...
Joe - whatever happened to this? Did you figure it out?
Tom
 
Tom funny you ask I was back at it today I need to get this figured out.
I bypassed the selector valves and ran straight from the port tank using port return also it shut down after a while
Switched to the starboard tank and return (straight no valves) then decided to bypass the racor went straight to the generator and it only ran 10 minutes at a time
I have a clear length of hose inline and saw no bubbles at all.
Now I’m thinking I’ve been chasing an air leak that doesn’t exist. Ore googling tonight and a guy described the same symptoms, he says he followed a guys advice and removed some oil from the crankcase and his has been runnng over 40 hours now.
I’m almost at the point of trying anything.
So tomorrow I’ll check the oil level. Heehee
 
It looks like you have all but ruled out a fuel problem, I had something similar happening, turned out to be a loose wire in
the control box on top of the generator, it would run for hours then shut off, drove me crazy. I'd check all of the connections.
 
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