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Topic: Generator Fuel Pump Won't Stop Running (Read 311 times) previous topic - next topic

Generator Fuel Pump Won't Stop Running

My Powertech/Kubota 10kw Generator will intermittently start pumping fuel and won't stop until it decides it's done.  I can't make it happen, and I can't make it stop when it does happen.  It just comes on by itself and turns off when it wants to.  Otherwise, the generator itself starts, runs and shuts down fine.  I can manually turn the pump and/or preheat on or off from the dash, unless it's in one of it's moods to keep running.  I have done the following troubleshooting:


This generator does not have an automatic preheat cycle as far as I know. I have removed wires from the fuel pump/preheat switches at the dash and the bedroom.  Pump keeps going.

I have removed all 4 relays from inside of the generator control box.  Pump keeps going.

I have removed both fuses from my Magnum Automatic Generator Start system.  Pump keeps going.


Anyone know where else can this pump can be getting power?

Re: Generator Fuel Pump Won't Stop Running

Reply #1 –
The pump getting power is one thing. I would think why it's running is another. Have you checked the fuel line for leaks? Maybe you are losing fuel pressure.
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: Generator Fuel Pump Won't Stop Running

Reply #2 –
bdale,

On your age coach with that power unit the fuel pump should get it's feed from a relay on the ES-52 module. Here is a link to 2 threads that explain in more detail but most likely a burnt contact in a relay.

.No generator

Generator intermitten self shut down

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Generator Fuel Pump Won't Stop Running

Reply #3 –
Quote from: Dakota Slim –
The pump getting power is one thing. I would think why it's running is another. Have you checked the fuel line for leaks? Maybe you are losing fuel pressure.


I'm not sure I'm understanding the question.  The pump should only have power when it's being asked to run.  I can hear the pump clicking constantly, so it's got power and, while not actually pumping anything, it's trying to pump.  It doesn't seem like there's any leakage issues.

Re: Generator Fuel Pump Won't Stop Running

Reply #4 –
Agreed.  An electrical issue. Has to be getting 12 VDC positive from somewhere. 

If you can get to it while it is running by itself, start tracing back where the power is coming from.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Generator Fuel Pump Won't Stop Running

Reply #5 –
Mike....I'm not seeing anything that looks like your ES-52 module.  What I do see is 4 relays inside the generator control box, on the right side in the attached pic.  Is it possible that my generator uses a different relay design?  I assumed that one of these 4 relays sends power to the pump so I unplugged all of them but it just kept pumping.  If I also have the ES-52 then I haven't found it yet.

I also see a Bosch relay at the back of the box.  I haven't checked that one because I didn't think it would have been part of the pump circuit.

Re: Generator Fuel Pump Won't Stop Running

Reply #6 –
Sorry, 2nd pic of the control box didn't post....

Re: Generator Fuel Pump Won't Stop Running

Reply #7 –
Quote from: wolfe10 –
Agreed.  An electrical issue. Has to be getting 12 VDC positive from somewhere. 

If you can get to it while it is running by itself, start tracing back where the power is coming from.


Understood.  I was hoping to rule out the easy stuff before I start cutting wires.  Unfortunately, there are several places where wires from different upstream power sources are combined in crimped connections.  I'd have to cut them to isolate for testing.  It might come to that.

Re: Generator Fuel Pump Won't Stop Running

Reply #8 –
See if you can get a wiring schematic. shouldn't be that many places that connect to the positive to the electric fuel pump.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Generator Fuel Pump Won't Stop Running

Reply #9 –
On some of those that age there is a second control box mounted over under/beside the windshield washer tank. Shoot a pic of that area and let me see what you have over there. You are looking for a set/row of indicator lights sticking through the side of the box. It will have a sticker that tells what the light means.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Generator Fuel Pump Won't Stop Running

Reply #10 –
I found the schematic in the Powertech user manual.  If I'm reading it correctly, there are 4 potential sources of 12v to the fuel pump.  I have at least another 3 that are not on the schematic:

-On the schematic
----3 relays (OP, S & G) that all converge on the Circuit Breaker (CB) and the the Oil Pressure Switch (OS) before landing at the Fuel Pump (FP).  I have removed all 3 of these relays and the pump keeps running.
----Generator mounted switch (SW).  This switch will start/stop the pump and/or the generator unless the pump is stuck in the on position.  Could possibly be an intermittent switch failure I guess.  I'll have to remove this switch to test that theory.

-Not on the schematic
----Dash mounted pump/preheat switch.  Has been disabled and pump keeps going.
----Bedroom mounted pump/preheat switch.  Has been disabled and pump keeps going.
----Magnum Automatic Generator Start module.  Has been disabled and pump keeps going.

So thats at least 7 possible sources, 6 of which have pretty well been ruled out.  I'll try to test the generator mounted switch when I get a chance.

Re: Generator Fuel Pump Won't Stop Running

Reply #11 –
Mike,

I don't see anything like that in the radiator fan bay.  I'm not sure what that ES-52 module does but if it's an electronic start module that automates the preheat/pump priming process, I don't think I have that.  My preheat is a manual-only process.  When I activate my generator start button, it's immediately cranking....no delay.
 

Re: Generator Fuel Pump Won't Stop Running

Reply #12 –
Bdale,

It looks like you have one of the 1st generation set ups that came before the es-52 system, basically a manual system. With all what you have pulled it seems like you have a wire that is chaffed back feeding the fuel pump.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."