1981 Ford F100 Revival (Parked for 12 years)

[ArdWrknTrk]

You need to replace all the fuel hoses as they will all be soft and spongy. On Dad's truck I wadded one line up into a ball and it stayed there as the hose was that sticky. It allowed air in while running, and that killed the vacuum of the fuel pump, and it leaked fuel out when stopped.

There's a hose from the tank to the hard line, one from the hard line to the fuel pump. But if you have dual tanks there will be a hose from both of the hard lines to a switching valve on the frame below the driver, and then a hose from the valve back to the hard line going to the pump.

As for the tank, I wouldn't mess with getting a pump and cleaning out the tank. I tried that and never, ever got rid of the rust sediment. It continually plugged filters. Just buy a new tank. They are about $100 and will give you a lot of peace of mind.

Interesting you mention air in the lines. I couldn't get a solid stream of fuel in the clear hose of my vacuum pump. There was always air bubbles in the line. Can you tell by the picture if I have the 16.5 or 19 gallon tank? Mine looks more like the 19 gallon from what I can tell. It is very long and slender. I guess I probably will need a new pickup and sending unit too.

Only Shortbeds and Flareside get the 16 gal tank.

Any 133" WB truck is 19 gallon front and rear.

[Gary Lewis]

You need to replace all the fuel hoses as they will all be soft and spongy. On Dad's truck I wadded one line up into a ball and it stayed there as the hose was that sticky. It allowed air in while running, and that killed the vacuum of the fuel pump, and it leaked fuel out when stopped.

There's a hose from the tank to the hard line, one from the hard line to the fuel pump. But if you have dual tanks there will be a hose from both of the hard lines to a switching valve on the frame below the driver, and then a hose from the valve back to the hard line going to the pump.

As for the tank, I wouldn't mess with getting a pump and cleaning out the tank. I tried that and never, ever got rid of the rust sediment. It continually plugged filters. Just buy a new tank. They are about $100 and will give you a lot of peace of mind.

Interesting you mention air in the lines. I couldn't get a solid stream of fuel in the clear hose of my vacuum pump. There was always air bubbles in the line. Can you tell by the picture if I have the 16.5 or 19 gallon tank? Mine looks more like the 19 gallon from what I can tell. It is very long and slender. I guess I probably will need a new pickup and sending unit too.

Yes, a porous fuel line admits air and causes all sorts of problems.

As for the fuel tank, I don't know if you've said what your wheelbase is. But according to this from our page at Documentation/Fuel Systems/Fuel System Part Numbers/Fuel Tanks a 1981 F100 shortbed got a 16 1/2 and the long bed got the 19 gallon tank.

[Gary Lewis]

Only Shortbeds and Flareside get the 16 gal tank.

Any 133" WB truck is 19 gallon front and rear.

Beat me to it. And with far fewer words.

[Jonathan]

Only Shortbeds and Flareside get the 16 gal tank.

Any 133" WB truck is 19 gallon front and rear.

Thanks! Mine is a long bed. What does WB mean?

[Jonathan]

Yes, a porous fuel line admits air and causes all sorts of problems.

As for the fuel tank, I don't know if you've said what your wheelbase is. But according to this from our page at Documentation/Fuel Systems/Fuel System Part Numbers/Fuel Tanks a 1981 F100 shortbed got a 16 1/2 and the long bed got the 19 gallon tank.

http://forum.garysgaragemahal.com/file/n94532/8005830.jpg

Thanks, AutoZone has the 19 gallon in stock.

 

[Gary Lewis]

Yes, a porous fuel line admits air and causes all sorts of problems.

As for the fuel tank, I don't know if you've said what your wheelbase is. But according to this from our page at Documentation/Fuel Systems/Fuel System Part Numbers/Fuel Tanks a 1981 F100 shortbed got a 16 1/2 and the long bed got the 19 gallon tank.

http://forum.garysgaragemahal.com/file/n94532/8005830.jpg

Thanks, AutoZone has the 19 gallon in stock.

WB is wheel base.

On the tank, make SURE that it is the one with the smaller opening for the sender. In '85 the opening went to 4" from 2 1/2". And yes, while you are at it you may need to add a new sender.

[Jonathan]

WB is wheel base.

On the tank, make SURE that it is the one with the smaller opening for the sender. In '85 the opening went to 4" from 2 1/2". And yes, while you are at it you may need to add a new sender.

Thank you again. I added a sending unit to the cart. Hopefully it matches it. Is all the fuel line I need going to be 5/16th? What about the filler neck or vent valve? Any other parts I should get?

[Gary Lewis]

WB is wheel base.

On the tank, make SURE that it is the one with the smaller opening for the sender. In '85 the opening went to 4" from 2 1/2". And yes, while you are at it you may need to add a new sender.

Thank you again. I added a sending unit to the cart. Hopefully it matches it. Is all the fuel line I need going to be 5/16th? What about the filler neck or vent valve? Any other parts I should get?

I think all of the fuel line is the same size. I bought several feet of new hose that's rated for ethanol and used it everywhere.

The fuel filler hose is probably fine, but the vent valve's hose should be inspected. Some I've seen are gooey and some are fine.

[FuzzFace2]

I ran the '82 Explorer for years w/o that part - because I damaged it in towing. And the guy that bought the truck is still running it w/o that part. So I'd say it isn't necessary. But I'd start looking for one anyway 'cause it is nice to have it.

Thanks, I will pull it off for now. It is bugging me looking at what I did.

OUCH!

As long as the front bumper is left in place it acts as a cross member you can run with out the one you bent up.

Now if you have access to a press or maybe the weight of the truck? you can bend it back into shape.

If using the truck with the member off place wood blocks on the ends on the bottom and use a bottle jack placed where you bent it up and start jacking and see what happens.

In a press you would do the same thing just that you would be standing when jacking and I would think if the truck is not heavy enough it will start to lift before the bend is out, not so with a press.

On the fuel system:

As for tank size that looks to be a side tank or mid ship tank and a easy way to know the size it how long the bed is.

Short bed trucks / flare side have a 16 gallon tank.

Long bed trucks have a 19 gallon tank.

And yes the sending units are different for the 2 different tank sizes so check before odering sender you have the right one. I think some places list the same part number for the senders and this is wrong.

I am with Gary on get a new tank & sender as you will never get any rust that may be in it out.

Besides that filter you see between the pump & carb you may also have a filter that screws into the carb.

I had to open my carb up and found rust in the bowl. This was a little over a year after getting the truck on the road.

Tanks looked good before I installed them back in the truck with new senders as part of the 4 year rebuild so was a little shocked on the rust.

Anyway my truck had 2 filters, one like you pictured and a screw in one. When the carb was apart I backed flushed both and the first (like yours) was pretty bad with crud.

I had to take the carb apart a 2nd time and the rust was not too bad but I replaced the first metal filter (like yours) with a plastic see through and ran 2 rear tanks through it and I dont see any rust.

I just started to run on the front tank and will run 2 tanks to see what one if either gives me rust and go from there on a fix.

If you want to run the motor and move the truck under its own power while you get the fuel system fixed get some 5/ 16 hose, you need some to replace it on the system anyway, to go from the pump inlet to a small gas can you can place on the inner fender and run the motor from it.

I did this for years as I did not know how long it would be before my truck was on the road and did not want gas in the tank(s) going bad from sitting.

You can see the gas can on the inner fender.

Dave ----

[Jonathan]

I think all of the fuel line is the same size. I bought several feet of new hose that's rated for ethanol and used it everywhere.

The fuel filler hose is probably fine, but the vent valve's hose should be inspected. Some I've seen are gooey and some are fine.

Do you know what size the vent valve hose is?