Why the fuel selector valve?
Thread Starter
|
Posting Guru
Joined: Oct 2011
Posts: 1,647
Likes: 1
From: Exton, PA
Why the fuel selector valve?
ok - somewhat of a philosophical question here, but some talk about pick-up tube vacuum levels and such in a different thread got me thinking about this:
Why the heck did ford bother with the fuel selector valves and dual pickup tubes on our trucks - and even worse - the fuel selector valve and dual fuel pumps on the 97 F250 gasser I have - one of which doesn't work, so i'm down to just one working fuel tank...
why not just let the rear tank gravity feed into the front tank? i'm pretty sure the bottom of the front tank sits significantly lower than the bottom of the rear tank.
so, why not just connect the two, get rid of the selector valve and switch and be done with it?
maybe there's a good answer out there, but I can't think of one.
on a related note, I like to empty my front tank first, then my rear, to keep the weight over the rear axle better, so i'd prefer the gravity flow to go the other way between the two tanks, but I doubt this would be ford's reason for the selector valve...
Why the heck did ford bother with the fuel selector valves and dual pickup tubes on our trucks - and even worse - the fuel selector valve and dual fuel pumps on the 97 F250 gasser I have - one of which doesn't work, so i'm down to just one working fuel tank...
why not just let the rear tank gravity feed into the front tank? i'm pretty sure the bottom of the front tank sits significantly lower than the bottom of the rear tank.
so, why not just connect the two, get rid of the selector valve and switch and be done with it?
maybe there's a good answer out there, but I can't think of one.
on a related note, I like to empty my front tank first, then my rear, to keep the weight over the rear axle better, so i'd prefer the gravity flow to go the other way between the two tanks, but I doubt this would be ford's reason for the selector valve...
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
IIRC, any kind of gravity fuel feed is illegal on road vehicles, for some safety reason. But the big advantage to multiple isolated tanks is fault tolerance. If that one pump that failed on your gasser had failed in a single-tank system, you would have ZERO working tanks/pumps. Same goes for a leak. You have a leak in your front tank, in a gravity feed system, the fuel would dutifully gravity feed from the rear tank to the front, and out through the leak, and you'd have no reserve.
It also allows you to do "in-service" repairs. When the rear tank failed (rust hole on the bottom, thanks to the stoopid design of the tank sitting right on the skid plate) on our '95 RCLB, we were still able to daily drive it while scoring replacement parts and setting up a time/place to replace it.
I'd much rather have the risk of one half of my fuel supply system shutting down, and still being able to get home on the other supply.
It also allows you to do "in-service" repairs. When the rear tank failed (rust hole on the bottom, thanks to the stoopid design of the tank sitting right on the skid plate) on our '95 RCLB, we were still able to daily drive it while scoring replacement parts and setting up a time/place to replace it.
I'd much rather have the risk of one half of my fuel supply system shutting down, and still being able to get home on the other supply.
Thread Starter
|
Posting Guru
Joined: Oct 2011
Posts: 1,647
Likes: 1
From: Exton, PA
very true points. but, with how cost-driven all automakers are - and have been for years - I was thinking there had to be some bigger reason than convenience to the owner.
I hadn't thought of the regulations/laws side of the reasoning. you're probably right there.
I hadn't thought of the regulations/laws side of the reasoning. you're probably right there.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
That's probably why they eventually went to a single tank. They probably didn't have the means back then to mold tanks of unusual shape in order to make them larger, but still fit under the truck. Once they nailed those things down, they went single tank to save on the extra sender, extra pump, switching, etc.
Thread
Thread Starter
Forum
Replies
Last Post
Iraa
1987 - 1996 F150 & Larger F-Series Trucks
11
Mar 1, 2019 03:17 PM
palletcutter
1987 - 1996 F150 & Larger F-Series Trucks
35
Mar 2, 2012 05:51 AM
quisp
1987 - 1996 F150 & Larger F-Series Trucks
2
Oct 26, 2011 04:07 PM
fordsuperduty250
1987 - 1996 F150 & Larger F-Series Trucks
3
Sep 20, 2011 01:04 PM
calbaker
Fuel Injection, Carburetion & Fuel System
4
Mar 16, 2010 04:36 PM
