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Hi..

NEWBIE ALERT

'86 F150 4x4, 300 I-6.

I bought it a few weeks ago.. 99k miles.

REAR tank works FINE.... Guage works, fuel is consumed, etc..

Flip the switch to FRONT..

Guage flips to FULL.... But it still DRAINS from the REAR..

Somebody PLEASE tell me this is an EASY fix??

...still waiting for the Chilton Manual to arrive.

I'm assuming there's a "cutoff" that's stuck down or something. The sending unit, and selector switch appear to work..

...THE system DID work when I bought the truck.. I decided to run the FRONT tank yesterday, and thought I was getting INCREDIBLE gas mileage.. Then REALIZED.. No.. THIS ISN'T RIGHT... Flipped the switch, and blamo.. The REAR tank, (which WAS full) was reading at 3/4.. Flipped back to front.. DRIVE.. REAR tank 1/2.. You get the idea.. Drained the "rear" tank to near empty with the switch on "front.." Hoping it'd get "over" it..

Oh, I used a fuel additive (system cleaner) "Chemtool" last week, and apparently knocked enough yick out of the BACK tank to clog a fuel filter.. I was going to start running a tank out of the FRONT, in order to do the same..

Sigh.. This is my first "dual tank" vehicle.. Unless you count my first Motorcycle, that had "reserve.." Sputter, flip stop****, GO GET GAS!!


I thought I'd read something SOMEWHERE last week about the dual tank system "stealing" from each other, or the overflow pressure FILLING the other tank, but, now, of course, I can't seem to find it! If that article would help, directions are all that is needed.. I don't want to clog the board..

Thanks, in advance..

AJRN

 

Knocking.. Knocking..

Anyone in there??



Guess I'll fix the backing lights..





AJRN

 

Sorry man...I've never had or heard of that. My front tank guage almost never works on any of the trucks I've had, but never ran into that problem. Like you though I'd have to assume that its a switch or valve some where. could it be that your tank switch is bad? I don't know, just brain storming....
let us know how it turns out.

 

Desi..

You're going to LOVE this.. (okay, maybe just I will)

The REAR tank strap on the FRONT tank had broken, but in a way that I couldn't see the "remaining strap" I didn't realize it, till I was under the truck..

SOOO.. For now, a racheting "web strap" (like you use to tie down a motorcycle) is doing the work.. I've ordered FRONT (side mount) tank straps from AutoZone.. ($34)..

The tank KINKED the fuel lines in it's "drooped" position, precenting fuel from getting sucked out of it.. Not sure HOW I was getting fuel from the back tank..

I'm glad I found this, before it became a disaster..

AJ RN

 

ajrn, my problem is just like yours, only different. My 88 F-250 (300 CID -6) has dual tanks, but will only take gas from the front tank. Doesn't matter what position switch is in, only the front tank provides fuel. To complicate matters, gas gauge is always pegged high. To attempt to troubleshoot, I pulled connector on switch to see what would happen, nothing happened--vehicle continued to run. My next step will be to look real hard for wiring modifications or other changes. If you have any ideas please let me know, if you don't check back here in a week or two I will probably make this a new post. Thanks, Rick

 

I'm not sure my troubles are over, either.. I'm more hoping that's all it is, than really sure..

I'm holding the tank up with a "rachet strap" so I'm not driving it more than I have to.. It SEEMS to be using the front tank again, however..

The new tank straps should arrive before the end of the week..

I'll keep you updated..


AJ RN

 

ajrn,
Hope it turns out to be a simple fix. the other thing I would do is to replace all fuel filters and the line that was kinked, just for fun.

Desi

 

Desi..

You're going to love this..

I see that my "functional" rear tank LEAKS!!

...when it rains!

Are their "tank" filters?? I'm going to siphon and DROP the front tank out, when the new straps arrive, I was going to blow out or replace the lines, if I could, but are their filters or screens I should be looking for?

I have a BMW Motorcycle.. They put the fuel filter in the TANK, along with the fuel PUMP....

I don't think there's more than ONE filter, or fuel pump (mechanical) on the PRE-Fuel Injected 300 I-6..


If there is, somebody tell me..

I'm currently contemplating...

1) use a tank sealant, and keep my old tank...
2) junk yard tank... maybe find a "bronco" tank for the additional fuel capacity...
3) new tank ($99... for another 19 gallon...)

The truck is a rustbucket.... I'm not sure how much "meaningful" life she has in her.. So this is some serious consideration..

The cab BOX itself is starting to rust thru, at the back corner (Below the "B" pillar...) If you step on the door edge, you can see it FLEX... (ewwwwwww...)

It's not really ever going to be "primary" transportation.. More a "home depot" hauler, rain and snow ride, for a guy who loves his Motorcycle (a wee bit too much!)..


Anyway... That's not the issue tonight..

Thoughts on repair, salvage or replace and...

Location of other "filters" would be appreciated..

Autozone will have my tank straps in... 3 days..

Honestly, if I can get it to draw gas off the FRONT tank, I think I'll just IGNORE the rear tank issue, and pull the REAR one, in the spring.. I rarely drive more than 50-100 miles a day.. Enough for a few days between station visits..

<-- a fluid that only leaks AFTER I've used it!

AJRN

 

AJRN,
I can only tell you what I would, I'd just get a can of sealer and fix the leak. I'm not sure about filters on the pre EFI 300I's but the ones I've been around have been near the tank on the fuel line, I'd check the chilton's or hays manuels.....
As far as the life of the truck goes, if you can fight off the rust the engine will run forever and a day.
enjoy
happy turkey day
Desi

 

ajrn:

There are a couple of possible things that could be happening.

1. Whenever a fuel level gauge goes crazy, or you suspect it's not delivering fuel...replace the sending unit. You have to drop the tank and change it.

2. Fill the suspected leaking tank to the brim, (be prepared to drain it or to siphon the gas in case of problems). Inpsect underneath, and even drive around and change grade slopes.

If the fuel leaks from a point where you can't see it. It's the sending unit seal. There is no easy fix, except not filling to much your tank.

This problem is a headache on my 87...I actually added a plastic tank in the rear, got it from JC Whitney...I just learn to live with it.

Good Luck.

 

I'm going to take down the front tank.. See if I can find an OBVIOUS reason it's not drawing fuel..

...plugged prefilter (if one exists)..
...plugged fuel line, between the tank and selector valve..

If I can, I'm going to divert fuel from the front fuel tank, straight into the primary line, avoid dealing with the switch, and rear tank issues for now.. With the holidays, I really have neither the time or cash to care about it.. The front tank is 19 gallons, enough to keep me on the road..

Both fuel GUAGES read, accurately, I might add.. I just can't get it to take fuel from the front one..

I'm hoping the selector valve is okay.. JC Whitney sells replacements, for about $50..

I'm thinking in the spring, find a junkyard with a LARGER rear tank, and a selector valve, and install THOSE.... Maybe start looking for parts after the front tank is functional.. One thing at a time..

I looked at JC Whitney.. They don't appear to sell PLASTIC tanks anymore.. IS your PLASTIC tank the one that's leaking??

Hopefully next week sometime I can deal with that FRONT tank, I'll update the board when I do..

All tips have been appreciated..

AJ RN

 

Well..

I was pretty sure, that the front tank was drawing fuel, after I replaced the tank straps.. I'd used a quarter tank, and refilled it.. JUST BEFORE....

I got in an accident Monday, hit in the side, between the back door, and the rear axle.. The truck runs, but looks even rougher than before.. The front tank was DUMPING fuel.. I'm surprised they let me drive it from the scene...

So, I've gone from 1 leaking tank to two.. And now it's not drawing off the front again..

Today, in agony and frustration, I found, and patched, a hole in the rear tank. It was under the tank strap.. I used an epoxy "putty" made by permatex... Drained the tank.. Jacked the truck up, raising the side that needed repair (so drops of gas didn't leak out) The putty, when mixed, is somewhere between "silly putty" and modeling clay in consistency.. It pushes INTO the defect, then you putty around it.. (gas tank "bondo??")

It comes in about package that looks like a "string cheese." You pinch it off, and mix it (it's black stuff covering white) till it looks an even dull gray color.. A sample that I'd mixed was dry enough I couldn't bend it, at about 30 minutes.. The package directs not to use the repair for two hours..

So far, no leaks.... I put about 4 gallons into it, to get home from my girlfriends house, where I repaired it.. (uh, she kept me busy two hours, while it dryed!!)

I haven't filled the tank, yet.. I figure I'll let it dry overnight, unless I have to go somewhere this evening..

I didn't go with the tank repair sealant "paint" for two reasons..

1) the defect was in the only tank I could get it to take gas from, and the tank sealant process takes about 48 hours, to do.

2) this putty was $2.99 at Autozone..

Since I got hit Monday, I'm just waiting for something bad to break.. The cab was damaged, and the doors aren't closing well.. The accident "tore" the rear bottom corner of the cab.. I'm hoping to get that welded into SOME shape within the week.

The packaging says gas tank AND radiator repair.. SO maybe it will hold.. (Radiators are pressurized, which impressed me that they thought this would hold).

The manager at Autozone said he'd repaired his truck tank with it several years ago, and so far did not see any evidence of leaking..


Hopefully, I've got ONE working tank now..

..the saga continues!

AJ RN