-
Engine Surge & Uneven RPM’s
As
I load my gen up with amps the engine starts to surge and slightly
rocks on it’s airbags. The voltage and amps remain constant, but
almost seems like the throttle or governor is trying to find the
right rpm. It’s only slight, but I know something is not right, it
used to me smooth and constant. Everything checks out, no external
problems.If
I decrease the amp load, it smooths out, so it’s appears to be engine
power related as the load increases, like maybe not enough fuel
pressure as it calls for more fuel. -
14 Replies
-
Tom,
The electric fuel pumps are known to weaken over time. I think the pressure output should be around 7 to 9 psi. You may also want to check the fuel bleed valve. It’s supposed to be cracked open a quarter turn or so. I think the effect is to slightly change the head pressure that the electric fuel pump sees. You might try fulling closing the valve to see if the behavior changes.
-
I have kept my fuel valve closed. However I do know on certain Kohler engines the fuel pumps were a problem. I replaced mine on a previous coach. But I don’t know if it is a problem on other than that vintage of Kohler gensets.
When the fuel pump started acting up it would bog down as the load increased, such as an AC kicking on, and then shut down. That doesn’t sound like Tom’s problem but it could be.
-
Tom, its nothing money won’t fix! Good luck
-
Tom, the hell with it ! It’s time for a different bus anyway….with slides !
-
The pressure is building…………………………..
-
Sheesh, I knew I wouldn’t get ALL straight answers.
Where the “H” is Al when I need him.
-
Looking for a H (with slides) of course !
-
I think he is waiting for an H of a deal.
-
But the real question is will he have a bus before OKC???
-
Tom,
If your generator has a fuel filter change that first.
Surging is an indication of “starving for fuel” or maybe as David said a
weak fuel pump could be causing the lean condition.Ken
-
I’m betting a $100 that Big Al will have a H before the ralley. Do I have any takers??
-
The surge continues when the gen is loaded and now I have black smoke that is pretty bad. I changed out the fuel filter, removed every piece of induction, hoses, air filter housing and checked the turbo on the inlet side and can’t find anything wrong. No oil anywhere, all clean and dry and the turbo spins freely with little play. Every fuel line has been checked, clamps tightened and no leaks of any kind. The more I load it up, the more it smokes and surges, but the voltage with 4 Cruisairs, bulk charger and BBG grill going is right on the money.
It acts like it needs more air or the injection pump is putting way too much fuel out. When I run the prime, the fuel pump never slows down like you would expect and just keeps humming away. Gen starts immediately and runs smooth with light loads, but smokes.
I would take it somewhere between home in GA and OKC to get it checked, but finding someplace that doesn’t want to tie me up for 2 or 3 days is impossible. You know, take off the pump, send it off to be tested along with injectors, if in fact that is the problem.
Kohler 20 KW, Yanmar engine. Jon and I both are scratching our heads.
-
I wonder what the frequency is doing when it surges…? I know mine was very hard to get it to stay close to 60hz, and any variation of RPM would make it either too high or too low.
-
Tom, I have same one, 20K kohler with Yanmar, it did a very similar thing recently with all roof airs on and some other loads going, coach was low on fuel, but that wasnt it. Not sure what it was but it righted itself and has been fine for nearly 50 hours since.
Log in to reply.