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Topic: Powertech Isuzu fuel pump not getting power (Read 799 times) previous topic - next topic

Powertech Isuzu fuel pump not getting power

My 1998 U320 has a Powertech Isuzu generator. I had an issue where the fuel filter came loose, then came off, and the generator stopped from fuel starvation. I filled a new filter with diesel and installed it at the recommendation of the Powertech guy and It cranks but doesn't start. I loosened the bleeder on top of the fuel filter cap and cranked it again and no fuel was being pumped. I put an ammeter on the fuel pump (which I think is the rectangular thing on the bottom front of the tray) and it was not getting any power thus not pumping fuel.  I don't know if there is a fuse or breaker that controls this pump. I followed the fuel pump wires as far as I could, and they just went way back deep into a harness that was hard to follow. Does anyone know where the power source, fuse or breaker is for this fuel pump? I ran out of daylight looking for it. Frustrating as heck. Everything worked before the filter came off.
Thanks
Chris

Re: Powertech Isuzu fuel pump not getting power

Reply #1 –
I'm chasing down a similar problem with my 10kw Powertech Isuzu generator.  Short version is it looks like the run relay socket inside the control box on top of generator is worn out and not passing proper voltage to fuel/run solenoid and lift pump.
If you open the top of the control box on the right side there are 3 relays, on mine the middle relay is the fuel/run relay (has 3 grey wires on the bottom socket + red wire).  Check that the relay has a tight connection to the socket.  It is possible the relay is bad and they are available at auto parts stores.
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

Re: Powertech Isuzu fuel pump not getting power

Reply #2 –
That wire harness flexes when the generator is running, and especially when the generator is run in and out on its slide.  My fuel pump feed wire failed inside that harness.  Open up the wire bundle and inspect all the wires.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Powertech Isuzu fuel pump not getting power

Reply #3 –
That relay is feed from a low oil pressure switch on the back side of the engine. If that switch is bad no power to the fuel pump . I had my fuel pump go bad a few years ago. Then last year then switch failed in the pressurized position allowing the fuel pump to keep running.
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Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Powertech Isuzu fuel pump not getting power

Reply #4 –
How do you access the back side of the generator?  Is there a panel you remove to get access?
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

Re: Powertech Isuzu fuel pump not getting power

Reply #5 –
Thanks for the input.  I'm going to try it out tomorrow afternoon.  Also, is there a fuel priming switch or pump to get the fuel going once repaired?  I couldn't find anything like that. Or is it just keep cranking it to get the fuel flowing?

Re: Powertech Isuzu fuel pump not getting power

Reply #6 –
Put a jumper across the oil pressure switch and see it that passes power to the fuel pump.

Had same issue on my previous 1994 Bluebird BMC37 generator (same engine).  My pressure switch failed where it would not pass power.  On that coach oil pressure switch was at front on left side facing the generator engine.  Power Technology South East sells the switch if the jumper works.

Here's the switch from a 1994: Oil Pressure Switch (2 Pole)  Original  one looks very slightly different.

Other pressure switches if yours is different: pressure switch

2 pole oil pressure switch - Bing

Ebay: nason oil pressure | eBay 
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Powertech Isuzu fuel pump not getting power

Reply #7 –
Reply #4, look under the generator bay their is a cover that can be removed. Mine has 2 3/8 bolts 9/16 wrench in the front and 2 rolock bolts 1/2 wrench in the back. Once removed you can slide the generator out then have access to the back of the generator. It's tight though.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Powertech Isuzu fuel pump not getting power

Reply #8 –
My genset is on a slide out. You have to remove two bolts that lock the slide then you can extend the generator out of the compartment. On my coach there is a cover in the compartment to the rear of the generator compartment that has a air intake for the radiator. I had to remove that cover to access the oil pressure sensing switch. My 10 kw generator has a cylindrical electric fuel pump located on the outside of the generator just below and to the rear of the control box.
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Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: Powertech Isuzu fuel pump not getting power

Reply #9 –
Quote from: bbeane –
Reply #4, look under the generator bay their is a cover that can be removed. Mine has 2 3/8 bolts 9/16 wrench in the front and 2 rolock bolts 1/2 wrench in the back. Once removed you can slide the generator out then have access to the back of the generator. It's tight though.
I just have 2 bolts that lock the slides.  Generator can be pulled out with the bolts removed.  I have to remove the air cleaner and rubber air intake tube to gain access to the back.  It is tight.  This engine also has a drain plug under the exhaust manifold for draining coolant.  I think it is a metric pipe thread.  I wanted to install a drain cock, but could not find anything that would fit.  Not your problem, but thought I would mention it.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt
 

Re: Powertech Isuzu fuel pump not getting power

Reply #10 –
Thank you all for your help. Fuel pump was the issue.