Leaking fuel tank selector valve?

[IDIBRONCO]

So.... why did these trucks have two tanks, not one larger one?

My guess is that it was the evolution of fuel tanks. Fuel tanks used to be inside the cab, behind the seat. Then, from what I've seen, they started putting one under the bed as an option. Next, they went to two under the bed. Chevy used a right and left tank. Ford used a front and rear tank. They carried that until the later 90's. From the '99 model year and up, there is only one big tank.
To get a more detailed and precise answer, you'd have to ask Ford designers who were in on the designs if any of them are still around.

 

[XOLATEM]

you'd have to ask Ford designers who were in on the designs if any of them are still around.

More than likely they were all given a good bonus and retired...

It is my fantasy to take all of those engineers that fixed it for us that you have to 'lift the cab' to do any work to the engine and have them all....****

!!!???!!!

Well...at least make them 'run the gauntlet' with a whole major league football team all itching to get a piece of them...

That goes for the upper-level exec's that gave them the go-ahead on that abomination...

That includes at least a good backhand and fronthand slap....from both left and right...

They 'fixed' it so I would not even consider buying a newer Ford truck...

....and I just don't imagine myself driving anything else....but Ford.

 

[Cubey]

So.... why did these trucks have two tanks, not one larger one?

Better ground clearance, extra room being used that would serve no other purpose.

 

[Cubey]

My guess is that it was the evolution of fuel tanks. Fuel tanks used to be inside the cab, behind the seat. Then, from what I've seen, they started putting one under the bed as an option. Next, they went to two under the bed. Chevy used a right and left tank. Ford used a front and rear tank. They carried that until the later 90's. From the '99 model year and up, there is only one big tank.
To get a more detailed and precise answer, you'd have to ask Ford designers who were in on the designs if any of them are still around.

Dodge was using single tanks, at the very least in 1978. The 1 ton Class B i had, had a 36 gallon plastic tank. It was a barely used option, though. I had to rebuild the fuel sending unit as best I could (only showed 3/4 full at most) and hand make a new cork gasket because both are impossible to get, even used. And that was 12 years ago.

 

[tbowker]

Dodge was using single tanks, at the very least in 1978. The 1 ton Class B i had, had a 36 gallon plastic tank. It was a barely used option, though. I had to rebuild the fuel sending unit as best I could (only showed 3/4 full at most) and hand make a new cork gasket because both are impossible to get, even used. And that was 12 years ago.

I had a mid 70's dodge tradesman van in the early 80's that was extended and used to have a wheelchair lift. It had a 36 gallon plastic tank. Even though gas was cheaper then, I was young and poor and it hurt to fill that tank.

 

[XOLATEM]

mid 70's dodge tradesman van

I had one of those, too...can't remember how I got it...think it was abandoned because of a bad transmission....I fixed it and kept it next to the shop for a number of months...until someone came along that 'just had to have it'...

One of the guys that worked with me used it as a 'my wife/girlfriend is mad at me' doghouse...he called it 'The Hotel Tradesman'....

It was a one-ton...I should have kept it...

Even though gas was cheaper then, I was young and poor and it hurt to fill that tank.

As far as the Dollar Buying Power and gas prices now...I don't think much has changed...when you think about it...it still bites us all in the a$$...

 

[IDIBRONCO]

More than likely they were all given a good bonus and retired...

I was thinking that they're all probably dead.

It is my fantasy to take all of those engineers that fixed it for us that you have to 'lift the cab' to do any work to the engine and have them all....****

I completely agree.

 

[Rupert8]

Hi all,

I've been following the tank discussion. Love it!

But...... a new issue.

So I changed out the fuel selector valve (as above) and the truck has been running just fine, daily, for a week. On the front tank.

Early this morning I switched to the rear tank and drove, including on the freeway up to 60ish, for about forty-five minutes. I was experiencing a strange surging, most noticeable at speeds over 45. Almost like the cruise control was in charge (it wasn't on). This was after driving for fifteen minutes or so.

Later this morning I had some work to do locally and noticed an occasional surge while driving to the site. Still on the rear tank. Parked the truck for half an hour while I did what I needed to do and started the truck. Idled a little bit rough but not bad. But when I put it in reverse it was not happy at all, idling very poorly.

Turned it off and started again and all was well. I switched back to the front tank at this point.

Driving for 15 minutes I still got surging. It's mild, but noticeable. Got to an intersection (a big one....) and it was bucking for a while, thought it was going to die on me and block traffic, until it evened out. This happened as I slowed down to the red light, not so much when standing still.

I filled up the front tank and haven't had the problem since. (I've stayed on the front tank.) But, then again, I didn't have this issue with the front tank until I switched to the rear tank this morning....

So - a leak on the rear fuel tank part of the FSV, which had a lasting effect even when I switched to the front tank?

I recently replaced all the o-rings around injectors and put in new olives. Also put in a new fuel lift pump. The truck starts right up each time so I don't think air is getting in past the fuel pump.

All this happened after I used the rear tank (full) for a period of time for the first time. Worth noting that I don't often use the rear tank.

Any thoughts? I've looked elsewhere on this site but can't see anything relating specifically to the fuel selector valve (replacement).

Thanks as always.

 

[IDIBRONCO]

Surging. To me, there two kinds. The kind caused by air intrusion. This results in a short burst of power caused when the air gets to the IP. It's also accompanied by a loud, higher pitched rattling noise like when the engine is started when it's cold out. This surging doesn't necessarily cause starting issues.
The second type is what you're describing. To me, it sounds like you're experiencing lack of fuel flow. The fact that it started at higher speeds, which also means higher engine speeds. Also when you filled the front tank, the problem went away. I think that you may have separate issues with each tank. I would recommend using only one tank until you get that straightened out.

 

[Rupert8]

To me, it sounds like you're experiencing lack of fuel flow

Thanks. So I can understand, how would this lead to surges of higher power? Or is it more that I'm actually normally running underpowered and there's just the occasional full dose of fuel?

Come to that, how would air in the IP lead to momentary higher power?

Hoping that if I stick to the front tank I won't have a repeat of this issue, not that doing so actually fixes anything.

I didn't have this problem when only running on the front tank before....

 

[IDIBRONCO]

So I can understand, how would this lead to surges of higher power?

These are two separate types of surging. You're experiencing a fuel flow restriction, not air intrusion. I'm saying this due to the symptoms that you mentioned which are similar to the ones that I'm experiencing. I know that I'm experiencing a restriction which is most likely a broken off shower head in my front tank. I had that already figured out and a few people told me that anyway. You may be having the same thing happen since your symptoms went away after filling the tank. The fact that it wasn't doing it before doesn't mean anything. If your shower head broke off, then it will be fine one time and have problems the next. No you didn't do anything to cause it. It just happens from age.

Come to that, how would air in the IP lead to momentary higher power?

I can't get more detained that this, I can just repeat what I've seen. The air in the IP causes the timing advance to go full advanced. Then, when air goes through, and there's just fuel in the IP, you still have fully advanced timing, which then gives a short burst of power. I don't know enough about the inner workings of an IP to go farther than that. I can say that it does happen because I had that happen to me one time.
Again, you are not having any power bursts or hearing any loud clattering from the air in your IP so this is not your problem. You're having power losses and rough idle (occasionally) so you're just not getting enough fuel to your IP at times. That is why I recommended only running on the front tank until you can get that sorted out. As the fuel level in your front tank drops, you'll probably start having the same symptoms again, probably around 1/4 tank. That will tell you that you still have the issue which is, most likely, a broken shower head. Then, when you decide what to do about that, none of which are fun, you can concentrate on the rear tank issue. The rear tank and the front tank probably have different issues since you said that you filled the rear tank and still had problems. I will even go far enough to guess that it's related to the new FSV somehow, since you didn't have those issues before.

I didn't have this problem when only running on the front tank before....

Once again, I'm guessing that your shower head broke off. It just happened to break close to the time that you started working on the FSV. It's nothing that you did, it's just coincidence.

 

[Cubey]

That's why they say to put filters between the FSV and tanks. Cheaper to replace a filter than replace the valve.

And it seems Ford did update the FSV on 3rd gen (75-91) vans. I happened to look under from the passenger side and saw this over on the driver side.

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