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1985F20 SuperCab "REDRUM"

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ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

You might want to check that your pump is delivering a quart every 15 seconds to the carb (like the TSB says)
Even if it is rated at 60 gph I have my doubts that it can pull that through the in tank pumps.

Electric pumps are not so good at pulling liquid to get a prime.
That's why any factory system has them in the bottom of the tank, where they are always full, and cooled by the liquid they are submerged in.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

I dropped the front tank and replaced the fill neck. I verified the in tank pump is working because I used it to pump the remaining gas out of the tank.

I have to calibrate the sending unit though, it would rarely read above half. Sometimes if I hit a bump it would swing to full, but not drop to E. I assumed it was getting hung up on something, but I pulled it out and the range of motion is clear and unobstructed. I am going to put 5 gallons in and bend the rod until the float reads E and go from there. Out of the tank, full droop reads ~75 ohms, full raise reads ~9 ohms, but this puts the float above the locking ring so not a feasible full scale point.

I did remove the float and checked for leaks. It's fine, no bubbles when submerged in a glass of water.

For the rear tank, I ordered a new 87 tank and fill neck. I'm going to try to make my early pump assembly work since the difference is only the notches to align the assembly. That sender has the same trouble, rarely reads above half and acts like it's hanging up on something. I still have to drop the rear, but it's full so I'll have to spend some time draining it first.

Chris
1985 Ford F250 XLT SuperCab
ZF5-42 swapped 460 hot fuel, factory AC.
Part way through 4WD swap.

1988 Suzuki Samurai -- Daily Driver
1968 Dodge Dart -- Project car
1957 Chevy 4400 Flat Bed -- Collector Project

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

I think you will need the smooth grey plastic inner 'fill' hose as well.
Not sure if the corrugated vent hose from an '80-'86 truck will flow or even fit an '87^ filler neck.

Please let us know how it goes.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

I bought the later fill neck that has the inner hose for filling. My old inner hose was dishwasher drain hose that I am fully expecting to have melted by now.

Once I get to the rear tank I'll know for sure.

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

I didn't realize the fill tube came with the neck. (not that way from Ford)

Parts from LMC? Or filler necks dot com?

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

I ordered it from Amazon. I believe this is the same part that Gary ordered for his truck. I grabbed the number off a screen shot earlier in this thread.

Fill neck

and the separate outer vent hose:

outer vent hose

CRittaler

Re: 1985F20 SuperCab "REDRUM"

alright, I dropped the front tank and used a bench power supply to run the in tank pump to drain the gas that was in it. I replaced the fill neck and the roll over vent and I adjusted the float to read just over E with 5 gallons in it.

Put it all back in place and it seemed to fill reasonably well from the gas cans. I still have to deal with the rear tank and replumbing the fuel lines to go around the aftermarket pump. I also have to fix the wiring to connect the in tank pumps back up.

I was able to drain ~14 gallons out of the rear tank using the in tank pump and bench supply and with any luck I should be able to drop the tank today.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

ok, I just dropped the rear tank and was pleasantly surprised by the fact that my dishwasher drain hose has survived acting as a vent. It hadn't swelled or gotten spongy at all.

I also opened the box for the new tank. This tank is a later model, '87 I believe. It has nothing in the fill neck opening to support the inner hose for the replacement fill neck. I'm tempted to try to 3D print something out of nylon to slip over the inner hose and hold it near the top of the filler opening. Not sure yet if there is supposed to be some kind of support there or not.

I also have to see how far off the tabs make the pump assembly sit. I might cut new notches to fit the old assembly.

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

Right. The '87> tanks don't constrain the lower end of the fill tube.

If you have the MPC illustration or the new filler neck you should see how they clamp at the top.

When you're looking at the sender/pump assembly take note of where the supply and return are pointing.
IIRC it's just one of the tabs that's different.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

I will have a look! I have another 87+ tank that has a pump assembly so I will compare it with my current one.

good to know the lower end of the hose isn't constrained. I probably didn't need to replace the tank then, oh well may as well now since I have it.

The filler neck I have has the inner hose already attached at the top, I'll take a closer look.

If I can get away with just removing a tab on the assembly, even better.

CRittaler

Re: 1985F20 SuperCab "REDRUM"

Should be able to test drive the truck tonight.

I finished swapping the rear tank, I didn't have to do anything with my sending unit tabs, they lined up just fine, not sure what was going on there, but it was a nice surprise. I for sure ordered a sending unit for pre 87 from LMC so I don't know why it worked out.

If you're standing looking at the tank with the pump assembly closest to you, the fuel outlet was at ~5 O'clock and the return was at ~7:30 This was the same on both tanks.

I did have to bend the float rod a bit to get it to land on E with 5 gallons in the tank. After that I wrestled it back into place.

New fill neck fit nicely and it all bolted together fine.

I also reconnected power to the in tank pumps and bypassed the aftermarket pump on the frame rail.

I started the truck and it ran without shutting off. Tried both tanks, it didn't die. We'll see how it goes when I can putter around a bit though.

I think I was right in the the frame mounted pump was losing it's prime while sitting and sometimes wasn't able to reprime before the float bowls would run empty. This pump is mounted on the frame rail up by the transfer case so there is quite a bit of fuel line that it would have to pull through to reprime.

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

I'm glad it worked out for you Chris!
I had issue with my sender clocking, but I don't have the in-tank pump.
Maybe there's a difference?

For my side tank I just ordered the '80-'86 tank and cut out the vent tube loop.
The '80-'86 sender fit fine.(as it should)

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: 1985F20 SuperCab "REDRUM"

Administrator

Yes, glad it worked!

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

CRittaler

Re: 1985F20 SuperCab "REDRUM"

In reply to this post by CRittaler

I ended up just replacing the front tank as well, so now I have both tanks new and new fill necks.

It ended up working well, though I have to angle the nozzle a certain way when filling the front tank or it will spit back at me.

Truck did well on another road trip to Canada. I picked up some car parts that I had left at my moms.

3 boxes of parts from my 1968 BMW 2000CS that I had to scrap and 2 7.25 drum to drum rear ends for my dart.

During the trip we drove from Victoria to Parksville and the truck managed ~11mpg

Next up on stuff to fix, speedometer is ~10% slower than actual speed. I suspect it's a bad cable since the rear end ratios are the same, but there's a chance that the PO didn't change the gear on the cable and I don't know if the drive gear is the same between the ZF5 and the original C6(?)

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

Chris, there's been some discussion in another thread about auto to manual driven speedo gears. https://forum.garysgaragemahal.com/Speedo-cable-driven-gear-color-code-tp138631.html
Gary put up a chart but obviously it wouldn't include a Zf, and mine is 4x4 so my speedo drive remained in the TC.
It would definitely help if you could determine the colour of the drive gear.

Sounds like a successful trip with reasonable milage depending on your rear ratio.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: 1985F20 SuperCab "REDRUM"

Administrator

Right, it would be good to know what gear you currently have. You need that info to figure out what gear to put in to correct the problem.

Speaking of the problem, if the speedo is off 10% then the odo is probably off that much as well. So if you based your 11 MPG off of the odometer then you may have actually been at 12. And while 11 is pretty good for a 460, 12 is even better!

Gary, AKA "Gary fellow": Profile

CRittaler

Re: 1985F20 SuperCab "REDRUM"

unfortunately, I added 10% to the mileage before calculating lol.

I do notice the needle bouncing so I might also try lubricating it. What should I use? Graphite dry lubricant or Lithium grease?

Gary Lewis

Re: 1985F20 SuperCab "REDRUM"

Administrator

I tried graphite and Teflon, but neither took the bounce out. So I used Mobil 1 synthetic bearing grease and that did the trick. And it worked through the winter as well.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: 1985F20 SuperCab "REDRUM"

Administrator

I've had trouble with thick grease in winter.
But I didn't use mobil-1 synthetic like Gary did.

I'd be more inclined towards a thixotropic grease like '00' grease from Stens, Oregon or John Deere..
This is what most people use in snowblowers.

I have Cable Life and a pressure luber from way back when motorcycles had clutch and brake cables, so that's what I use.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: 1985F20 SuperCab "REDRUM"

Administrator

If you just have a little bounce I’d start out with something like Jim suggested and keep the synthetic wheel bearing grease as the sledgehammer if the other doesn’t work.

Gary, AKA "Gary fellow": Profile

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