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Generator quit running


tmw188
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Ok my diesel 7.5 gen has been running fine but recently quit. I thought maybe it was the fuel tank being too low, it was at about 3/8 of a tank when it died. After getting fuel a few days later it didn’t make a difference. It will however start and run when primed until the prime runs out. I’m going to change the fuel filter first but the fact that it runs until the prime is used up, does that still lend itself to the fuel filter? I’m assuming the fuel pump is working ok being it is priming, but that is  a manual call for fuel maybe when it’s running it’s not getting voltage. Anyone experience this before? Typical Code 36 

 

Edited by tmw188
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 I don't believe the air flow ( fan ) is powered by the belt.  IIRC the belt only turns the water pump.  Remove enough screws on the gen rear panel and you can probably     pull the panel out enough so you can see.

 If it is the belt I may be able to offer some tips if you decide to DIY

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I think that’s right, I was thinking that myself. I will let you know for sure. My gen is on a power slide and today is one of the days it doesn’t want to open. I’ll have to check into that too.🤪

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Check the fuel line to and from the genset to the fuel tank.  Pin hole leaks introduce air into the system. IMO, the fan belt can create a lot of problems.  

Like most all systems in a motor home, Preventive Maintaince  (PM) is a recommendation in all the manuals.  Yet, a lot of folks ignore it.  Nothing breaks until you start to use it.  I have always suggest that if your coach has set up for several months, the weekend before you leave on a trip take the coach out to a local campground and live in it for a couple days and nights.    Chuck B 2004 Windsor

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Yep on the maintenance. That’s all I seem to do with previous coach but it paid off when I sold it. This coach is only month old to me so I’m doing a lot of maintenance right now to start with a clean slate so to speak. I’ve put about  12 hrs on the gen over the last two weeks while doing things inside and it just quit. It had a complete service in 11/19 then sat almost 1.5 yrs but has ran good since I bought it. I’ll be checking more when the temps drop some. I’ll look at the belt before changing FF. Air filter is brand new and from the looks of the FF it may be too. As soon as the primed fuel is used up it dies.

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Todd, code 36 is a fuel fault. I would suspect the fuel filter to be the culprit first then proceed onto other possible causes as described in the troubleshooting manual section.

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I installed a small Racor marine 10 micron water fuel separator to the incoming fuel tine to my genset.  I mounted it to the outside of the genset on the drivers side.  That way I could replace the filter very easy.  I could also see if any bad diesel fuel is in the bottom of the separator.  Chuck B 2004 Windsor

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56 minutes ago, Chuck B said:

I installed a small Racor marine 10 micron water fuel separator to the incoming fuel tine to my genset.  I mounted it to the outside of the genset on the drivers side.  That way I could replace the filter very easy.  I could also see if any bad diesel fuel is in the bottom of the separator.  Chuck B 2004 Windsor

I might do that. Changing the filter inside the housing is a big messy PITA. And I’d sure like to have some visibility into the generator fuel supply 

Cheers

Walter

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Here is a photo of Chuck's Racor Fuel Filter he added to the side of the generator. The OEM fuel filter can be seen in the second photo near the bottom of the generator and it is silver in color. It is to the bottom left of the black oil filter. In order to remove it you have to maneuver it in a specific manner to get it out of the small space where it sits.

Onan QD7500 Fuel Filter.JPG

Onan QD 7500 Oil Filter.JPG

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26 minutes ago, Dr4Film said:

The OEM fuel filter can be seen in the second photo near the bottom of the generator and it is silver in color. It is to the bottom left of the black oil filter. In order to remove it you have to maneuver it in a specific manner to get it out of the small space where it sits

There is a trap door under the fuel/oil filters, unless your slide blocks that for some reason. That will let the fuel filter easily drop out the bottom. 

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I've changed my gen fuel filter many times.  It's a PITA.  I used to use the little door on the bottom but my coach has a cross bar about mid way of the door and the door will not open wide enough.  So I would always remove the 2 screws holding the door and just remove it.  Now that I'm 80 I really don't like laying under there so now I remove the gen side panel which allows easy access to the fuel and oil filters.  After seeing Chuck's filter mounted externally I may rig one up.

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Well it was the filter, however I have some seepage now at the fitting going to the filter from the pump. I tightened it sufficiently for a flared fitting but I needed to continue to tighten a little more while checking for leaks. After looking at the inside of the other filter it doesn’t appear to be a flared fitting but maybe has an oring style seat instead. The other end (small end)of the filter leading out of the filter Does look like a flare style seat. So I’ll need to pull it off again because it shouldn’t need to be any tighter than it is. We will see. 

3 hours ago, Ray Davis said:

I've changed my gen fuel filter many times.  It's a PITA.  I used to use the little door on the bottom but my coach has a cross bar about mid way of the door and the door will not open wide enough.  So I would always remove the 2 screws holding the door and just remove it.  Now that I'm 80 I really don't like laying under there so now I remove the gen side panel which allows easy access to the fuel and oil filters.  After seeing Chuck's filter mounted externally I may rig one up.

That’s unfortunate and sounds like it is a PITA. My door drops down vertically totally out of the way. 

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Hello  tmy188.  I also added a  Racor 10 micron filter an the left side of my generator.  It makes monitoring the fuel quality and changing the filter is much easier then the ONAN filter.  As a side note, while I was adding the Racor 12T filter project, I extended electrical leads from the back of the generator to the left front side of the generator so if its ever necessary to jump start the generator, I don't have to crawl so far under the coach to attach the jumper cables.  Terry  H 2005 Camelot 

BatteryCableExtension.jpg

GeneratorFuelFilter.jpg

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20160823_105241.jpg

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Posted (edited)

Nice upgrade, but I doubt I’ll be doing that. I like the idea of the water separator filter. 

BTW you can’t get a line wrench on the rubber hose fitting leading to the engine. It’s a 7/16 and you can’t slip it over the hose to get it on the nut. I opted to use a slim crescent wrench to get a better tighter fit on it because the 7/16 wrench seemed like it wanting to start to slip. It was successful. 

5BFAFF89-8562-4F1A-8C1C-9273ED6A83F4.png

Edited by tmw188
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2 hours ago, tmw188 said:

Well it was the filter, however I have some seepage now at the fitting going to the filter from the pump. I tightened it sufficiently for a flared fitting but I needed to continue to tighten a little more while checking for leaks. After looking at the inside of the other filter it doesn’t appear to be a flared fitting but maybe has an oring style seat instead. The other end (small end)of the filter leading out of the filter Does look like a flare style seat. So I’ll need to pull it off again because it shouldn’t need to be any tighter than it is. We will see. 

 

It's been a while since I've replaced my filter but I'm pretty sure there was not an o ring in there.  I believe your leaking line is a rigid metal line ( mine is )  and if you  bolt the filter down before starting the fittings it is hard to get it straight,  as in easy to cross thread.

Flare nut wrenches are the tool for those nuts,  available anywhere.    They are made to slip over the tubing but still act as a box wrench See related image detail

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Posted (edited)

I used flare nut wrenches(line wrenches same thing diff name). Finger tightened   very easily many turns. Yeah I wouldn’t think there would be oring especially on fuel,  but the seat looks different compared to the other seat on the filter. I looked at the other filter to see what might be the reason. I know it’s not cross threaded but your suggestion on leaving the nut loose that holds the filter onto the bracket might be the answer anyway, allowing it to float a little. I know sometimes that letting the line float a little might help it square up when tightening. 
Top pic line going to the motor, looks like a typical flare seat, bottom pic line coming from fuel pumps looks different.

 

 

 

 

 

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FD21309C-C2C7-4F72-8084-4F83FE391093.png

Edited by tmw188
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It sure seems that you did everything right.   I have had to go back and crank down a little harder before.   Yeah you might loosen the flare nut and the mounting nut so  everything can relax and as you say things can align as you tighten the flare back up.

I usually call them line wrenches too but wasn't sure if that would be as clear to most people. 

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I guess we’re old school guys on that terminology. What was really messed up was you can’t use a line wrench on that one line because it won’t slip over the fuel line to get to the nut. Nothing is ever easy. 

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Here is what the Service Manual states for Fuel Filter replacement.

"Installing the Fuel Filter: Rotate the filter half a turn around its mounting stud if the fittings interfere with the bracket. It only fits properly one way. Connect the fuel fittings before tightening the filter mounting nut. Take care not to cross-thread the fuel fittings. Thread them in by hand and tighten one flat past seating. Close the access door and prime the fuel system by holding the control switch down in its Stop position for at least 1 minute. Priming is necessary to displace the air in the new filter with fuel."

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