Aux. fuel pump causing front tank to overfill.

[polarman]

 I don't know why I never find what I'm looking for when I use the search, but I failed again.
I purchased my 73 Brave from an old gent that purchased it from the original owner. He only had it for a few months, and fixed some things up on it to make a few hundred dollars turning it over. One of the things that he worked on was getting the generator running. He put in a new inline electric fuel pump.
Here's the problem:
When I flip the switch to the aux fuel tank, the fuel pump automatically turns on. With the generator running or off, it seems that it is pumping fuel out of the rear tank and into the front tank thus overfilling it and causing fuel to spill out of the fill. I'm already unhappy with fuel prices, and dumping 89 octane fuel with lead addative onto the ground is distressing to say the least.
I know that things are wired screwy in my Winnebago. The original electric pump is in the right front mounted to the frame, so I can run those wires to the new pump to have it on a seperate switch to operate the pump. I'm not sure what to do with the plumbing for the fuel system though. Even if I wire the pump to a seperate switch, when I run the generator it will pump fuel from the rear tank and into the front tank, overfilling it and making a big, smelly, costly mess.
I could use a little advise if anyone has experienced a similar problem, or is more enlightened on how the dual tank/generator fuel system should be plumbed properly than me.

[Oz]

Not to despair!  You didn't find anything with the search because this is definitely a new problem we haven't encountered before... and, it sure is a unique one.  I'm sure the answer is pretty simple and the electric gurus will get you taken care of soonly.

[DaveVA78Chieftain]

I bet you are having a fit. 

1.  Originally, there never was an electric fuel pump only the mechanical pump on the engine.  That is a total add on by a PO. 

2.  Rather than setting it up correctly (http://cdn.wildhorses4x4.com/downloads/9720%2011-8-07.pdf), the PO set it up to transfer fuel from the Aux tank to the Primary tank.  Was the Aux tank added by the PO also?

Your choice is either leave it as it is and just use the aux pump as a transfer pump or set up like the PDF and use a transfer switch.

The generator should have it's own seperate electric fuel pump attached to the generator itself.  Your aux pump should have nothing to do with your generator.  What generator do you have?

Dave

[polarman]

It's the Onan 4K, I believe.

[DaveVA78Chieftain]

BGE or CCK?

[polarman]

BGE or CCK?

i?? please explain.

[DaveVA78Chieftain]

Do you have a:
4.0CCK-3CR

4.0BGE-1R

or some other model of generator?  You need to know all this to work on it or get parts.

Dave

[polarman]

I was wrong. That's what I get for posting at work. It's the 2.5LK.

[DaveVA78Chieftain]

There is very little information available for a 2.5LK unit.  Only manual listed is the UN Service manual http://www.cumminsonan.com/www/pdf/manuals/900-0196.pdf .  The wiring diafgram does indicate an electric fuel pump.

Dave

[polarman]

 I have not been able to reply because both of the computers at home are down.I'm going to borrow one, so I should be able to get some pics of what's happening with the fuel system. I think that the problem can be solved with a check valve, but I do not see any kind of valve or soleniod to switch from the main tank to the auxiliary tank.(so the engine should pull fuel from both tanks?) I'm not able to make much sense of how the system worked originally. I think the original pump is actually an air pump which must have pressurised the aux. tank to send fuel. It's a wierd set up. It will be alot easier to explain with pics, so I'll try to get some downloaded in the next few days. It's going to rain all week, so I probobly won't be working on it just yet anyway.

[jkilbert]

the engine should only draw from 1 tank. you should have a selector switch on your dash  to pick either the main or aux. tank. this switch also selects which tank your gas guage monitors. so, if your running on the main then the gauge reads the fuel level in the main. somewhere along your frame you should have a tank selector valve. most have 2 wires and 3 hoses. one line runs to the fuel pump, one to the main tank and one to the aux. tank. one wire is the ground and one goes to the switch. some are just one wire hook up that ground through the chassis. universal valves run about $50. just never saw anyone use a pump to fill one tank from another

[polarman]

 I suspect that the fella that I bought it from put a fuel pump in place of the selector valve. That would explain why it turns on as soon as I flip the swith to the aux tank. I think I'm going to have to start from scratch and redo the entire fuel plumbing system to make it work correctly. If it ever stops raining......

[polarman]

 Well, I got it sort of straightened out for now. I removed the fuel pump and put in inline going to the generator.I also ran a wire from the fuel pump switch to the pump, so it no longer runs off of the aux tank switch. For the time being, the fuel lines are T'd together so that the engine pulls from both tanks.I drove it to a snowmobile watercross race this weekend and everything seems to work fine. I'll have to see if I can find a selector valve that will work in it before next year. I'm just happy that it works!

[polarman]

http://broncograveyard.com/bronco/i-10261-electric-tank-switching-valve-66-85.html
That should do, right?

[DaveVA78Chieftain]

Yes, that is what you want.  You can also get them at Autozone, NAPA, O'Riley's, Pep Boys, etc.

Dave

[ramit]

my itasca has the same thing happen i was told by PO the the macnical pumps return line only goes to the main so if main is full it will over fill when running aux tank so to run off main tank frist then switch to aux  i??