A little background. I have a 1983 E350 Class C motorhome with a 460. It's been sitting in a garage for 4 years and never started. The guy was going to junk it so I said it I get it running can I have it? The answer was yes. Here's what I did:
1) new fuel
2) new carb (rebuilt from Ford)
3) new fuel filter
4) new electric fuel pump (from Ford, the one up by the motor)
5) changed all the fluids.
It started up and runs just fine. Used it this past fall and winter for various short duration trips. But, I have two problems.
1) The front fuel tank I can only put 9 gallons of gas in and the back tank I can only put 11 gallons in.
2) When I run on the front tank it works just fine unless I have a lot of weight in the camper, and from the back tank I can't get over 45mph even if the camper is empty. In both cases it acts like it's starving for fuel and on the back tank I'll actually eventually kill the engine if I don't let it get back down below 40mph. On the front tank if I just ease up on the throttle sometimes it'll go again, otherwise I need to get below 40mph. Under 40 mph I could run that thing all day long.
I'm thinking there's some kind of connection between the inability to fill the tanks and the fuel starvation, but fuel systems just aren't my thing.
Any suggestions? What should I be looking for or what do I need to replace?
From my experiences with a 1981 F100 that had set for about 5 years.
Gas had turned to varnish in tank and fuel lines. Filter sack on fuel pick up in tank was completely plugged. I had to remove the tank to clean it and the filter. Hope your problem is simpler.
From my experiences with a 1981 F100 that had set for about 5 years.
Gas had turned to varnish in tank and fuel lines. Filter sack on fuel pick up in tank was completely plugged. I had to remove the tank to clean it and the filter. Hope your problem is simpler.
Thats your performance problem.............The inability to fill the tanks is because the rubber filler necks have partially collapsed and the tank vapor vents may be blocked by wasp nests or other debris............You would not believe how much insect life moves in on a vehicle that has sat for long periods. I went thru the same things with my Chevy class C..............At least you have a better platform to work with than I did.
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I haven't work on the filler tubes or vapor vents, do you have to drop the tank to do that stuff or can it be done with the tanks on? Sounds like I need to go over every rubber line from the tanks to the engine and maybe juts replace them. Might be easier than trying to find a plug somewhere. Assuming I don't find any issues at the tanks themselves.
I haven't work on the filler tubes or vapor vents, do you have to drop the tank to do that stuff or can it be done with the tanks on? Sounds like I need to go over every rubber line from the tanks to the engine and maybe juts replace them.
First off do you also have a fuel pump on the side of the engine?
If yes did someone add the electric fuel pump up by the motor?
Does not sound stock. If so let me know and I will try to help you through this 40 MPH problem as my 83 class "C" did the same thing and was a very common problem back then.
I can write a book about working with this problem.
If you do not have a pump on the side of the engine you should have a electric fuel pump in each tank and no electric fuel pump up by the motor. In this case it also sounds like the rubber hose inside the tank between the pump and the tube is gone. That is why you can put very little fuel in the tanks and yes the tanks will have to come down to replace the hose or maybe the fuel pumps also.
At any rate the 40 MPH thing is also called vapor lock and you may as I did have to replace the radiator with a four row to help get around it.
Quote:
Originally Posted by KevinE350
Might be easier than trying to find a plug somewhere. Assuming I don't find any issues at the tanks themselves.
There is not a pump on the engine. Where a mechanical pump normally goes on the block there is a plate. Not sure that a mechanical pump would even fit as the oil filter is in the way. The way the engine is shoe horned in there they put a 90 degree elbow extentsion onto the oil filter to get around the frame, that gets in the way of where a fuel pump would go.
What I meant by "plug", is that it's probably easier to just replace any and all vent tubes instead of trying to find where it might be plugged up and just fix that.
Sounds like I need to drop these tanks and find out what I have exactly for vents and pumps. I was hoping to avoid all that. If I could just get the front one working I'd be happy with that!
How does a 4 row radiator help with vapor lock? Just keeps it cooler which helps avoid the heat that causes a vapor lock?
There is not a pump on the engine. Where a mechanical pump normally goes on the block there is a plate. Not sure that a mechanical pump would even fit as the oil filter is in the way. The way the engine is shoe horned in there they put a 90 degree elbow extentsion onto the oil filter to get around the frame, that gets in the way of where a fuel pump would go.
I have a 93 home on a 92 E350XL with a 460 with a mechanical fuel pump mounted on the engine and the 90 degree elbow extension that the oil filter to mounts on to.
Quote:
Originally Posted by KevinE350
How does a 4 row radiator help with vapor lock? Just keeps it cooler which helps avoid the heat that causes a vapor lock?
Yes that is correct.
I will guess then that you have the hot fuel bypass with fuel pumps in each fuel tank that are not being used.
Sounds like someone gave up on the fuel system and put a electric fuel pump out side the tanks and wired it in somehow.
As I do not think that Ford ever made a fuel system like you have now.
Do you still have the oil pressure fuel cut off switch, fuel pump relay, fuel tank selector relay and the motorized fuel tank selector valve and gauge?
A lot of owners never understood this system and changed it to something they thought would work and that would cause the 40 MPG problem.
I have worked with others to understand this system and other then the selector valve it is not that complicated.
I will give some links below to click on for information on this system.
Thanks for the great pictures. All of those parts are still in place and appear to be hooked up. What's different is that in your schematic I have an electric fuel pump and filter in the line from the Electric Selector Valve to the Fuel Vapor Separator & Fuel Shutoff.
I wonder if someone along the line had a problem with the in tank pumps and added this other pump as a booster. The previous owner, prior to letting it sit for so long, did take this camper all the way from MN to KY with no problems.
Next step is to drop the front tank (looks easier than the back tank) and check out all the lines and since I'm in there I'll replace everything inside the tank.
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