Splitting generator fuel line?

SMB_Beancounter · 08-08-2022, 01:40 PM

So I’m wanting to install a gas powered furnace, likely a planar. I have a Onan generator that was factory installed and is tapped into the vans fuel tank. Would it be possible to remove the fuel line at the generator, and split it so I can run one line to the furnace and the other to the generator? I don’t imagine I’d be using the generator and furnace at the same time. Where is the fuel pump for the generator? I couldn’t seem to locate it when I was under the van looking yesterday.. if this is possible, would I attach the fuel pump for the furnace after the split? So it would go split, one side to generator, other side to furnace fuel pump, and connected up to the fuel inlet for the furnace?

I live in a remote area of WY, so there isn’t any shops to help out with the install, so I’ll likely be doing it on my own. I don’t want to drop the tank to put in another tap. Any other suggestions?

Thanks!

86Scotty · 08-09-2022, 08:15 AM

So, the small diesel furnaces (Espar/Webasto/Planar/Chinazon) don't usually like anything but a dedicated fuel line. It's been tried with bad results but I do not remember who or if they eventually figured it out, nor do I know if it was even on this forum. There is tons of info on these small new fangled furnaces on about every camping/van/DIY forum. The little in-line fuel pumps these use are not high pressure but they are finicky about stable pressure and folks have had bad luck Teeing off of other lines.

But, I have very rarely if ever seen a diesel Onan generator on a van. Is your van/generator diesel or gas? If it is gas you are talking about a much more expensive furnace. Espar makes a gasoline model at a lot higher cost than the diesel one, not sure if Planar or Webasto even do and if the Chinese have knocked off a gasoline furnace I wouldn't trust it in a million years.

SMB_Beancounter · 08-09-2022, 08:40 AM

Thanks for the response! It’s a gas van, with a gas generator. I have my eyes on the planar 4G which is a gas powered furnace, it’s not crazy expensive and would prefer the one fuel for convenience.

Does anyone know where the fuel pump is located for the onan generator? Is it inside the casing of the generator?

I would never use the generator and furnace at the same time, if I split the fuel line prior to the generator fuel pump, wouldn’t that basically be a dedicated fuel line?

86Scotty · 08-09-2022, 07:22 PM

I do not know. As I said above, everywhere I've read where people tried it it didn't work so well. Try and let us know!

I did not know of the Planar 4G. I was one of the first, at least here, to put a Planar furnace in a van, albeit a diesel one (in a gas van with a separate tank). They make a great product.

If you can link the one you are looking at it might help others. I tried Googling it and all I get links to is 4g phone stuff.

SMB_Beancounter · 08-09-2022, 07:55 PM

Here is the furnace I’m looking at..

https://pantherrvproducts.com/at-air-4g-12/

https://planarheaters.com/product/pe...toterm-air-4b/

On the panther Site it’s called the 4g, on the planar site it appears to be a 4B

jrobe · 08-09-2022, 09:38 PM

I have no idea if splitting the fuel line would work and I doubt anyone else here would know either. I don't think I would spend money on that heater and then experiment with the fuel line but let us know how it turns out if you try it.

We have a Sprinter SMB and our diesel Espar heater is one of the best features of our van. It works perfect and it sips very little fuel. I also am comforted knowing that it is a tried and true heater design confirmed by thousands of semi-truckers. Our local Freightliner dealer (where we bought our Sprinter) now just automatically installs the Espar heaters on all of their new trucks now before their sales.

I have thought about switching to a gasoline van for our next Class B in the future. I would be tempted though to install a small auxiliary diesel tank just to stick with the tried and true diesel furnace. It wouldn't have to be a very big tank to meet our heating needs. The 13 liter (3.5 gal) auxiliary tank on that Planar web site would work well. Depending on how cold it is, I could probably heat for week on that tank. Just a thought.

rnj · 08-09-2022, 10:28 PM

I have an Onan 2800. The fuel pump is inside the case. My generator is facing rear behind the rear axle so the fuel pump is on the drivers side. The line goes in near the end of the generator close to the electrical connection. I cut my rubber line inside the rear wheel well where I could reach it and added 2 Honda Lawnmower shutoff valves and a tee so I could shut off fuel to the generator and run it dry or put the other end in a gas can when I was trying to determine if my fuel pump was bad.

marret · 08-10-2022, 03:46 AM

I have a gas van and Planar diesel heater. Fuel tank is installed behind my box on the back.

I put an inline petcock in my generator fuel line as well to cut off fuel when needed. As RMC mentioned, the Oman fuel pump is in the case. I also installed a T right outside the gas tank for a heater, but did not go in that direction for the reasons Eric mentioned.

I really don’t know why it wouldn’t work, but I just decided not to try and go with a diesel heater. I have heard the gas heaters are more finicky.

One thing I will say, if I let my gas tank go below half, my generator often loses prime. This is not good for the heaters, as Eric mentioned the heaters don’t like it.

SMB_Beancounter · 08-10-2022, 08:51 PM

Thanks for the info on the fuel pump, knowing that, in the coming weeks I’ll likely order up the furnace and get it installed prior to ski season. I’ll keep everyone posted on how it goes. Thanks all for the info!