Community Forums

expedition1 · 06-06-2011, 04:07 PM

I have a 2005 coach with a 7.5 diesel genset. I just returned from a trip today. Yesterday while the coach was underway I had the genset running and occasionally the unit would shut down. However, the genset would start right back up. Today while I was home I started the genset and put at least a half load on it and let it run for at least 1.5 hours with no promblem. During the trip I once let the fuel tank go down to a quarter of a tank but once I filled up I did run the genset for a total of 5 hrs during the course of 3 days. The genst has 380 hrs on it and I have never changed the fuel filter. The air filter has been changed recently. Anybody have any ideas? Thanks.

RJay · 06-06-2011, 04:12 PM

My guess would be that while driving with the gas sloshing around got below the pickup tube in the fuel tank. It may be a good idea to change the fuel filter.

docj · 06-06-2011, 04:15 PM

I does sound like you should change the fuel filter. Onan recommends changing the filter ever 500 hours, but it is possible it picked up some "crud" maybe when you let the tank get low. While you are changing the filter you may want to consider also changing the coolant since that is recommended at least every two years.

Mr_D · 06-06-2011, 10:35 PM

Quote:

Originally Posted by RJay

My guess would be that while driving with the gas sloshing around got below the pickup tube in the fuel tank. It may be a good idea to change the fuel filter.

OP has a diesel gen set. Hope he NEVER runs gas in it!!

Gary RVRoamer · 06-07-2011, 12:19 PM

Check the oil too. If low, it may have sloshed around enough to cause a low oil shutdown.

The Onan 7.5 always has a error code when it shuts down. The light on the switch blinks one, two or three times. If it blinks three times, press Stop and it will blink out another number in a two digit code, There will be 1-4 blinks, a pause and 1-9 blinks to give the two-digit code.

The codes can be looked up online via Google, or in the Onan owner manual for your model of generator. FInd them online if you don't have the manual
Cummins Onan

steved44 · 06-07-2011, 12:24 PM

Also if you suspect air in the system you can hold down the off button on the generator for a minute and it will purge any air from the system.

expedition1 · 06-07-2011, 03:53 PM

I have purchased a fuel filter and I will give it a go. Does anyone have any advise on changing the filter or is it straight forward? I did check the oil level and it is good.

RJay · 06-07-2011, 04:03 PM

Quote:

Originally Posted by RJay

My guess would be that while driving with the gas sloshing around got below the pickup tube in the fuel tank. It may be a good idea to change the fuel filter.

Quote:

Originally Posted by Mr_D

OP has a diesel gen set. Hope he NEVER runs gas in it!!

You might not get the point but I bet the OP does.

Martind4 · 06-07-2011, 07:09 PM

Quote:

Originally Posted by expedition1

I have purchased a fuel filter and I will give it a go. Does anyone have any advise on changing the filter or is it straight forward? I did check the oil level and it is good.

Changing the fuel filter is easy, the inlet and outlet hose sizes are different so it's hard to mess up. Just be sure to hand tighten the fittings as much as you can to insure no cross-threading before you use a wrench.

Gary RVRoamer · 06-08-2011, 07:22 AM

I don't think the fuel filter on a Onan 7.5 is easy to change at all. You have to crawl underneath, open a trap door and loosen two connections with very little working room. And diesel runs out of mine as soon as I open either connection - the genny filter must be lower than the fuel tank on mine. What a PITA!

Olpapa · 06-09-2011, 07:36 AM

I do agree, the cover plate must be removed...however, I use a dolly to lie down on. I use the jacks and raise my coach almost lifting the front tires off the ground. I then get safety-jacks under the front end (I just don't trust anything without the safety jacks in place), I then have lots of room to work freely under the Onan to do what I need to do. Just be safe

steved44 · 06-09-2011, 02:43 PM

I used to be a mechanic, and I thought diesel running down into your armpit was supposed to happen. ha ha

BABrede · 06-10-2011, 07:51 AM

Had a similar problem with same generator. Was hard to start, and only would run when parked. Once I moved it would shut off. I had approx. 350hrs on that fuel filter, I did not change it at last oil change. I suspected water in the filter, I was correct. Had it changed at a Speedco location and had them dump contents into a clear container, sure nuff, had water in filter. I won't be skipping that filter again. I change the oil every 200-250hrs and that fuel filter will get replaced every time from now on. In fact I carry a spare on board, can't travel with out the genny running, gotta have roof air!

Kerry

buck62 · 06-10-2011, 08:26 AM

When I do my 15000 mile/yearly oil change at Speedco I always include the generator oil change, oil filter and fuel filter. For me it is just easier to do them all at once.