Howdy Everyone!
It is Saturday, which means time to work on the RV!
My generator has stopped working, but was recently working fine. I did some research and diagnostics, and have concluded the most likely cause of the problem is my fuel pump has failed. I came to this conclusion by reading and learning about the procedure to purge air from your diesel fuel lines. I removed the fuel line at the top of each injector and cranked the engine. I got only a little bit of fuel out of the two left injectors, and none out of the two right injectors. My fuel filters have less than 10 hours on them and were professionally replaced by Foretravel. While I know there are many possible reasons for this, a bad fuel pump was top of my list. Since I already have a replacement fuel pump, I decided I would try to replace it today.
I have fuel pinch clamps, so I should be able to seal off the fuel feed line from the diesel tank with no problem. I have some questions though that relate to the photos and diagrams.
1) I think I have properly identified my fuel pump (see diagram). But, it looks NOTHING like the replacement fuel pump I have, which Powertech says is the approved replacement.
2) I see only one wire going to the pump. I'm guessing that is because the pump used a ground connection as the other wire.
3) My replacement pump (also photo) has a red wire that is bare and an black wire that is black with a lug. I'm pretty sure the black wire is ground, and I need to attach that to the engine block.
4) In a Beamalarm diagram for these generators in general, it shows a much smaller pump in a very different location. Is that common?
5) Obviously, I'm going to have to figure out how to mount the new pump. Can I use standard automotive fuel line to help me get the pump mounted and the connections made to it, or do I need some special kind of fuel line, or, do I need metal fuel line like what is shown in the pictures?
Any commentary from someone with experience would be greatly appreciated!
Thanks
Mark
Your replacement pump looks like the pump on my generator.
Mine is mounted on the base plate about where the spot of fuel is in your picture.
Yes, red is 12 volt, black is ground. You should be able to ground through the mounting bolt.
I have the Isuzu engine, yours is Kubota I think.
I had one just like your new one. Agree with Steve. You can mount to base right behind pull handle, underneath the old pump.
jk
Just for trouble shooting I would first check the fuel line to make sure it's not pulling in air.. second I would change the filters again ( they are cheap)
Thirdly I'd take the new pump put some fuel line on it and bypass the old one from a separated fuel sours ie fuel can and test it that way.. but first two I would try first then the last.
Wouldn't trust anyone who said they changed filters and secondly.. bad fuel and other causes could clog or whatever.
Just a suggestion
Maybe professionally, maybe not.
When working on diesel fuel systems. Clean, air tight, connections are required. Normally you do not loosen fuel lines at injectors until after you conduct all possible tests.
WHY! Because there may be o rings, metal to metal connections. These may not reseat upon your tightening process. There by inducing a problem where there was not one.
Just because you hired what you assume (ass-u-me) was professional mechanics. Doesn't mean that you received professional service.
Answers
1. Yes it's your oem fuel pump. Fuel in, out, power. Ground is provided by engine.
2. New pump.
The small part with fuel inlet and then threads is a fuel filter. It is a consumable part. Use, replace.
2. Mount new if needed pump where its able to be mounted. Pick a spot to secure ground wire. Check that ground is good.
3. You are dealing with diesel and bio diesel. You will need to install proper quality fuel line for repair. Yes you can use gas fuel line to run tests.
You will most likely end up using rubber diesel approved fuel line if you replace current pump. Metal line can crack. Over time from vibrations. It would be obvious via sight, smell.
Do you smell raw fuel at your passenger spare tire, can you see wetness on tank fuel lines by shining flashlight on lines.
Have your fuel lines been replaced. The pictures appear oem.
Test items needed
Clear fuel line
Regular fuel line
Clamps as needed
Rags
Proper wrenches
Clean dry Glass container for test fuel.
Clean diesel fuel.
Small Jumper wires to allow connection to 12 volt source and + _ of both fuel pumps.
To test existing pump.
Remove outlet metal fuel line from its connection. Not the pump connection.
Disconnect inlet fuel line. Install your test fueline that will be new suction line for fuel from glass container.
So you now have glass container with fuel - new suction line - old pump - existing fuel line - with a catch container to catch pumped fuel.
Using a 12 v source and jumper wire. Power old pump - observing suction - discharge.
Pass
If it pumps strong fuel. It is probably good.
Fail
Weak dribble, stream.
If it fails. Conduct same test on new pump.
Pass - install new pump. With proper fuel line. Clamps. Check over all connections.
Without being crazy tight. Check for tight fuel lines at injectors.
Because you didnt mess with filters. You may be able to run new pump with 12 v source. With out cranking engine. Goal is to purge fuel lines of air. You will need to loosen the return fuel line to see if you can run pump until no more air pumps thru line.
NOTE. You may not be able to purge air by this method because of design issues. If so. Try cranking engine. It may start. Observe cranking time to prevent overheat of starter. If no start.
You can attempt purging air one by one at injectors. Loosen, crank, fuel squirting, tighten, move on to next.
Mark,
You can get a pump like the one on there now at a NAPA store. They are available in several discharge pressures. Think some are around 4 psi. I got one around 8 psi.
Powertech told me to get the higher one.
It's a direct replacement. Old one off, new one on. Done
Something else to consider... loose filter
8 psi may allow fuel to go past the relief valve and back to the tank purging any air from the system at the same time.
Pierce
Yep Napa has them and even Walmart I found out afterwards. There is a fuel filter on the bottom of that ( original paint ) OEM filter. Cleaning it might buy you some hours. Spins 1/4 turn. And then the magnetic spring plunger and filter drops right out.
Everyone,
Thanks for all the information! I'm going to check NAPA and Walmart tomorrow - that would be the easiest route. Also, Texhub - thanks for the very detailed explanation. Even before I go shopping, I'm going to do your tests. Everything you said sounds very reasonable, but I never would have figured it out on my own.
I will keep everyone posted - I certainly have some investigation to do tomorrow!
Mark
Howdy Everyone,
Success!!!
This morning, I got up and followed the testing instructions from Texhub. Power to the old pump was fine, but it just wasn't pumping. I pulled the old pump, tested it with clean diesel and an external fuel source, and it was dead. Clearly, a bad pump.
So, I called around to a few NAPA stores and following John Duld's advice, found a (nearly) exact match. The pump NAPA had did 6.5 to 8 PSI (awesome). But, the fuel inlet and exit were a slightly different size (larger). I headed to the hardware store, found two brass connectors that allowed me to go from the smaller to the larger size on the pump, re-used the old connectors, wired it up with a butt connector and shrink tubing to the old 12v power line, and she cranked right up! One thing I noticed immediately was that you could both hear and feel the pump pumping fuel while you were pre-heating the engine. It was clearly working, and the old pump made no such sound or vibration.
I'm so happy - I actually *fixed* something (I usually break things instead).
Thank you SO MUCH to everyone here who provided such great advice - Texhub for the diagnostic procedure, John Duld for pointing out a local source for a one-to-one replacement for the fuel pump, and everyone else for their insight. I'm super happy, and I finally get to cross something off my list as "done". :-)
Enclosed is information on very specific pump I purchased at NAPA.
Thanks!
Mark
Cool!
Perfect that you were able to go with similar pump thus saving fuel lines.
Now remember if your existing fuel lines to entire coach are oem. They may show up as next issue (gen or main). I have to replace mine.
You will want to follow up on all connections loosened during troubleshooting phase. Especially injectors. No muscle cranking. Just checking fittings.
Well done.
Texhub - thanks! Funny you mention that, I was just thinking about how much I learned through this process, and I suspect I need to do some more preventative maintenance. I suspect the fuel lines are probably original, so in need of replacement. For the moment, I'm just glad to have the generator back. I have a few other higher priority tasks to do with the RV before I'm ready to take on the fuel lines, but I plan to do it before the summer is over. I've been reading about the task - it sounds like I really need to do some preparation for it. I'm sure I'll have questions soon enough!
Mark
Do your fuel line when your fuel level is low, unless you plan to do it with the tank in place.
It's all learning process. I always feels good when you learn something new and fix it.
Mark,
It's takes less than 30 minutes to replace the generator feed/supply line in a U280/U300. No removal of the tank or even sliding out the generator is necessary. See my old posts for exactly how to do it.
Pierce