Aux tank overflowing!
Thread Starter
|
Junior User
Joined: Feb 2015
Posts: 58
Likes: 0
Aux tank overflowing!
1978 f-250 supercab 400 motor 4bbl carb
Hey guys so I almost never use my aux tank because the sending unit is bad and it should be close to empty (i keep about 3 gallons in it for emergencies). I drove my truck 2 weeks ago and filled up the main tank, then drive it again 2 days ago. It was 3/4 full when I got home. Yesterday morning I got a call from a neighbor that the aux tanks cap is leaking. When I got home there was no leak but some gas on the ground. I opened the cap and the tank was full to the top! I suspected the neighbor kids may have put the water hose in there until this morning when I went out there and it was dripping again. I removed the cap and it just keeps pushing gas out. So I put the cap back on to slow the leak. How could the tank be all of the sudden full and how could it be pushing fuel out of the cap? I wondered if gas was somehow making its way there from the main tank but it's still showing 3/4 full. Also It did rain yesterday but not today. Anybody have any ideas? I'm lost on this one
Hey guys so I almost never use my aux tank because the sending unit is bad and it should be close to empty (i keep about 3 gallons in it for emergencies). I drove my truck 2 weeks ago and filled up the main tank, then drive it again 2 days ago. It was 3/4 full when I got home. Yesterday morning I got a call from a neighbor that the aux tanks cap is leaking. When I got home there was no leak but some gas on the ground. I opened the cap and the tank was full to the top! I suspected the neighbor kids may have put the water hose in there until this morning when I went out there and it was dripping again. I removed the cap and it just keeps pushing gas out. So I put the cap back on to slow the leak. How could the tank be all of the sudden full and how could it be pushing fuel out of the cap? I wondered if gas was somehow making its way there from the main tank but it's still showing 3/4 full. Also It did rain yesterday but not today. Anybody have any ideas? I'm lost on this one
Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
I would also suspect that your tank selector valve is stuck half way between the two tanks allowing fuel to move from the aft tank to the saddle tank. I've had this happen on my supercab. It is strange however that you still show 3/4 tank on the rear. Maybe the saddle tank has been filling for a while and just now overflowed.
Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
Is it warm outside? Gas will expand quite a bit. Could be that during the day it warms up enough to push it past the cap.
I don't know how you would check for water, maybe someone else on here will have a bright idea.
I don't know how you would check for water, maybe someone else on here will have a bright idea.
Thread Starter
|
Junior User
Joined: Feb 2015
Posts: 58
Likes: 0
It's hot outside as far as us Washington people are concerned (51°). I was thinking I'd try siphoning some gas and seeing how it settles (wouldn't gas and water separate)? I had to leave for the day so I parked it on a slight incline with that tank at the top, who knows maybe that'll help a little
Laughing Gas
Joined: Jun 2016
Posts: 855
Likes: 56
From: Des Moines, Washington
Water any gas don't mix. I'm old enough to remember glass bowls in the fuel line to catch water before it hits the carb. It settles to the bottom, that way you could open the petcock n the bowl and drain it out. Small aircraft had then in the wing tanks and were checked preflight.
Unfortunately, you won't be able to check for water from the top side (except maybe with a test strip) so you'll have to draw some from the pickup or the drain plug. I also think it could be the tank selector and that it's still leaking out of the aux because the both the main tank and aux tank contents are expanding. Try opening both caps. If it's the selector, I'd think the level in the aux would go down.
I'm stuck in a windowless building in Kent just south of IKEA. I'll have to take your would that it's nice outside ��
Michael
Unfortunately, you won't be able to check for water from the top side (except maybe with a test strip) so you'll have to draw some from the pickup or the drain plug. I also think it could be the tank selector and that it's still leaking out of the aux because the both the main tank and aux tank contents are expanding. Try opening both caps. If it's the selector, I'd think the level in the aux would go down.
I'm stuck in a windowless building in Kent just south of IKEA. I'll have to take your would that it's nice outside ��
Michael
Trending Topics
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
The OP's truck probably has a mid-ship tank and an aft axle tank...both located on the left side of the bed.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Laughing Gas
Joined: Jun 2016
Posts: 855
Likes: 56
From: Des Moines, Washington
Confusingly, I tend to use saddle to mean any tank outside of the cab. I do have an actual saddle tank on mine but it's clearly not from Ford. And it's got 3 or 4 gallons of 7 year old 2 stroke fuel in it. Very unlikely to burn, even with a match!
Michael
Michael
Laughing Gas
Joined: May 2006
Posts: 1,140
Likes: 13
From: Port Orchard Wa
Just to make sure, are you reading the level on the correct tank? I'm going to try to attach a file for you. Ford changed which tank is considered "main" and which is "aux" over the years. This is from page 9 of the owners manual for 1978 trucks. "Main" is your midship tank.
I'll have to be more precise in my terminology so ND doesn't have to correct me.
I'll have to be more precise in my terminology so ND doesn't have to correct me.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,189
Likes: 5,793
From: S/W Missouri, Polk county
1. Beat/tazer the neighbor kids for touching you truck...now I know that really can't happen, I just typed what I was thinking. But WTH a neighbor kid might of put a water hose in there!!!
X2 on sounds like you could have a stuck valve and some how fuel went from one tank to the other.
I'd drain the one that you do not use, and is full of who knows what, then disconnect it from the valve. I'd drain the other if there is a chance it got a water hoes in it.
Get a locking vented or none vented what ever applies gas cap. Then I'd go talk to the neighbor kids dad.
78/79 duel fuel tanks frame switch-Duralast/Universal 3 port fuel selector valve used with SW48 toggle switch Part Number: FSV4
X2 on sounds like you could have a stuck valve and some how fuel went from one tank to the other.
I'd drain the one that you do not use, and is full of who knows what, then disconnect it from the valve. I'd drain the other if there is a chance it got a water hoes in it.
Get a locking vented or none vented what ever applies gas cap. Then I'd go talk to the neighbor kids dad.
78/79 duel fuel tanks frame switch-Duralast/Universal 3 port fuel selector valve used with SW48 toggle switch Part Number: FSV4
Thread Starter
|
Junior User
Joined: Feb 2015
Posts: 58
Likes: 0
Wow thanks for all the replies, it seems unanimous that I need a new valve (and a tazer). For the record my truck has a front (main) tank that is long and skinny on the side of the bed, and a aux (rear) tank that is square and at the back of the bad. It did seem to stop the leak when I backed the truck up on an incline but I'll hold off on driving it until I do the valve.
Thread
Thread Starter
Forum
Replies
Last Post
D-rat
1973 - 1979 F-100 & Larger F-Series Trucks
6
Sep 21, 2017 12:31 PM
Brokewhiteguy
1987 - 1996 F150 & Larger F-Series Trucks
6
Sep 4, 2014 08:04 PM
MarksA-C
1987 - 1996 F150 & Larger F-Series Trucks
13
Nov 27, 2011 06:38 AM