I have an '89 F150 4x4 with dual fuel tanks. It died while it was at the body shop, and I'm nearly sure that the problem is the switching valve. Additionally, my fuel gauge only works for tank 1.

I've noticed a lot of people have had a ton of issues with this particular dual tank setup. I've had an idea about how to deal with it, but I'm not sure if it will work, so I thought I'd run it by others here for feedback.

What I'm thinking is to eliminate one in-tank low pressure pump (by disconnecting the electronics?) and also tossing the switching valve. Then connect the two tanks via a passive fuel line, letting gravity do its thing by keeping the two tanks at the same level. I'd rely on the fuel gauge in tank 1 to give me a level for both tanks.

Here's a diagram:



Do you guys think this will work? My guess is no, because it seems too simple.

 

I think that if driving for a long distance you could run the front tank dry before the rear could catch up. Plus you'd probably have to switch to a vented gas cap so the pressure wouldn't be an issue.

 

Interesting idea, I had to think about it for a little bit - A couple of additional thoughts -

I'll add that if you were to park on a steep hill, all of the fuel will eventually transfer to the lower tank, that is unless you have more than half full tanks. If that happens and the low pressure pump is on the high tank, you may not be able to start your truck due to no fuel at the low pressure pump.

The other thought is that to function properly the fuel transfer hose has to be at the lowest point, and just like on a over the road semi with a connect / transfer hose between the fuel tanks for just the purpose you propose, it is subject to snagging and road damage due to its low position.

Just food for thought -

David

 

Are you calling the front tank "tank 1"? I guess you could install a one-way valve so that fuel only could flow into the active tank. That should eliminate the parking on a hill problem. Fill "tank 1 first", then fill "tank 2".

If you park facing down hill, excess fuel will run into "tank 1", if you park facing up-hill, nothing will happen. If the hill was steep enough, I wonder if you would have fuel come out the filler neck on "tank 1".

You might as well do the bronco fuel tank mod and just eliminate the front tank if you dont want to switch back and forth. It would be a lot simpler.

 

Thanks for the input guys. Didn't think of the hill issue.

Do you have a link or any info on this?

I love this truck, but I absolutely hate the fuel tank set up and all of the easily broken parts.



BTW is that blue '50 yours? If so, VERY nice.

 

Here is some information on rebuilding the Duel Function Reservoirs (DFR).

1983 Ford Bronco '84-89 Fuel Reservoirs pictures, videos, and sounds | SuperMotors.net

I picked up a spare DFR at the junkyard for $15 and will try this rebuild on it first. If it works, it will be alot better then paying $150-$200 for a new one if you can find one.

 

https://www.ford-trucks.com/forums/7...ml#post6620139


Thanks,that's my baby. If you wanna see more pics, check out: https://www.ford-trucks.com/forums/6...rucks-261.html

 

why not fix it right. here's something I posted in md, to explain how it works:

Quote:
<TABLE border=0 cellSpacing=0 cellPadding=6 width="100%"><TBODY><TR><TD style="BORDER-BOTTOM: 1px inset; BORDER-LEFT: 1px inset; BORDER-TOP: 1px inset; BORDER-RIGHT: 1px inset" class=alt2>Originally Posted by BPofMD
Morning world !

Howdy Junior......hope this is a paying job!

Charlie.... how do you know that BOTH pumps went south??? Seems weird to me to have BOTH go out at same time! Sounds more like you lost elect to both at same time. I know you are usually pretty through in diagnosing problems, but......
</TD></TR></TBODY></TABLE>
this truck has 2 lift pumps, and a main high pressure pump.In the middle is a transfer switch, that closes off when the other tank has pressure against it. Back tank flap up, front tank flap down. No pressure, flap stays where ever it was last time it had pressure. Now for the fun part. when a pump won't run, the high pressure pump acts like a siphon pump, until the tank equilizes pressure, or fuel becomes level with the pump, then it quits. SOOOOOO, back to your question, yes, both pumps are bad, because,
1. key cycled, and listening in fill cap, both tanks, no pump noise heard
2.back tank ran out at 1/4 tank, which would be level with pump
3. switch was on front tank,guage was reading full, back tank ran out, so flap was in the up position, high pressure pump was drawing off back tank.



on a good note, I pumped the front tank out into 5 gal buckets, dropped it, put in the new fuel pump, put it back up, filled it, and it is pumping off the front tank. I have to drop the spare, and the class 3 hitch to get the back tank out, so that will be later in the week.
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If it helps - I have owned four of these trucks in the past, and none of them have ever experienced a fuel tank issue, except for a single non functional gauge, and the gauge issue was unrelated to the pumps, and did not affect return fuel. (1-1985, 3-1986's, all EFI's)

On my more recent 1990's (different system, only two pumps - which is why I decided to go to the 1990 model year, well that and the availability of a EFI big block), and while they also can have the fuel return issue, I have had zero problem with either of them, although I have only owned two, a recently traded in 1990 and still have one. The 1990 Bronco that I have doesn't count since it only has one tank )

Perhaps I am luckier than most, I certainly see the potential for problems, and even Ford has covered this issue, but it is not one that I am concerned with, given my personal history with the trucks.

I have given the Bronco tank a serious thought, if only there was something to do with the spare tire, but to me havving that in the way out front or in the box taking up valuable cargo space just did not give me the benifits that i was looking for. Perhaps, now with fuel prices going up, I could add the Bronco tank in addition to my front tank, and I might save some money in the run due to the almost daily price jumps!

Lots of good ideas on work arounds none the less!

David

 

Dusty, going with the Bronco setup is quite easy and basically an OEM option for the F-150, since they're almost the same. The Bronco system is extremely reliable, i have to say in the 18 years we have had this truck only once we were left stranded because of fuel issues. And it was just a loose pigtail connector.

 

I had thought about the bronco tank on my 94, and leave the front tank too. That is my road truck, I could leave here in Md, and not fuel up until Fla. My wife was the tie breaker there though, she said, "you still have to stop for bathroom breaks". So I bought a stock rear tank for it.

 

Having both tanks would be good to have a longer range, but the idea behind the swap is actually leaving the Bronco tank only, making for an easier setup that's more reliable. That tank has 33 gallons capacity and is more than enough for you to have to take those bathroom breaks without having the need to fill up the tank.

 

Lots of excellent input on this thread that's helped a great deal toward me deciding what to do about my gas system issues. Glad I joined here.

Looks like I have some decisions to make.

 

Hi. The second image showing one tank draining into the first tank is how old Harley Davidson fuel flows as they have 2 tank and the system works fine but the method in image one should also work.