I just got an 85 F150 base model with a 302 in it, dual-tank fuel system and a Holley 4180C carburetor. It sat for over three years and has a few fuel system problems as a result, plus the usual age- and design-related ones as well . The original mileage is only 89000, and the engine sounds surprisingly good when it runs, so I'm hopeful that I can get it running reliably and soon have a serviceable truck.

So, it has the dual-tank system. At some point the selector valve/reservoir died and was replaced with a Pollak 3-port valve/reservoir. I do not know if that is functional. The rear tank has not been used for quite some time, judging from the stink of varnished gas, and the front tank is not working anymore either. I dropped it and discovered that the sending unit (stock) was pretty much disintegrated, and the rubber grommet for the "pressure-relief valve" (?) is rotted as well. (I need to find part numbers for that to replace the valve and the grommet.) I am going to get a new 19-gallon side-mount tank and sending unit for starters and just run the system off that for now. I noticed that the tank had some kind of "padding" on each end where it rests against the frame, that was completely hardened and full of mud. it pretty much crumbled when I pulled it out. What can be used to replace that when installing the new one?

I would like to replace the filler neck extension hose (the rubber one), and I saw someone indicating that you can use a 87+ one which swaps the way the vent and fill sections work so that it fills faster. https://www.ford-trucks.com/forums/1...l#post11988763 Recommendations on this either way? I would still need to find the rubber extension hose, but I figure I'll see what I can find on eBay.

As for the carb, here's a curious thing. the truck has a Holley 4180C ("Motorcraft") carburetor, but it has no mechanical fuel pump that I can find. It had a frame-mounted high-pressure electric pump with is missing now, so I've come to the conclusion that this truck was originally FI and has been swapped to a carb setup, for reliability maybe...don't know. Is there a way to tell for certain if it was originally FI? there's random connectors in the engine compartment that aren't hooked up to anything, but nothing like a full harness connector that looks like it would have been for an FI setup. I have not looked for an engine computer yet. not sure where that would be located but I assume under the seats somewhere? Also, something I'm trying to figure out now is whether a frame-mounted electric pump will be enough for the carb to work correctly since there's no mechanical pump and all the indications I can find are that the electric pumps were for FI systems only.

I assume it originally had a 6-valve reservoir that failed and was replaced with the Pollak, and from then on they only ran the front tank. (one of the lines from the 3-valve does run back to the rear tank though.) I've been doing a lot of reading here and elsewhere trying to get a handle on how this system was set up originally and what's the best way to change to a single-tank setup with the seemingly odd assortment of parts I have. One guy told me that you can use a (Datsun/Nissan) 280Z electric pump, which may be the case but I can't imagine it would be a significant improvement over a direct replacement for the Ford pump.

Another thing I need to know is how to wire the sending unit so that the fuel gauge works correctly with only one tank. A friend of mine has an 86 F150 that had the dual-tank setup as well, which has been modified to run only the front tank. He says his fuel gauge reads 1/2 full when the tank is full, so I would love any help on how to wire it to prevent that (and fix his, hopefully)...I think I may have figured this out. I guess as long as I leave the tank selector switch set to the front tank, it should read correctly if there's nothing wrong with the wiring.

I'm sure some of this stuff has been answered elsewhere on here, and I just haven't found it yet. It's a lot to get a handle on and a lot of searching and reading, so I would appreciate folks bearing with me and either pointing me in the direction of existing threads or providing concise answers on the best way to get from where I am now to a fixed and reliable fuel system for this truck.

thanks in advance for any useful info.

 

found this info on the vapor separator valve and grommet:

https://www.autokrafters.com/p-2836-...ick-comet.aspx

the part number listed for the separator valve is E7DZ-9B593A.

anyone know if this is the correct part for this application? it would appear to be but at $55, if I were to buy it I'd want to make sure it was the correct part. I guess the real question is whether they even go bad and need to be replaced.

 

Ford did not make a truck with a 302 and a 4 barrel carb. It's safe to say your truck and many things about it are not original. So you have a puzzle to figure out what the previous owner did and didn't do. If your truck was indeed fuel injected, then you are going to have electric pumps in the tanks also, it would have had 3 pumps. What type of fuel pump did they install with the carb, don't know. Are they trying to pull fuel through the old elec pumps in the tanks?

 

OK, that probably clarifies that it wasn't originally fuel injected. the center tank did not have an electric pump in it, and it was definitely the original tank and sending unit. I have not dropped the rear tank yet, but I would guess it also doesn't have an electric pump.

since the original carb that would have come on a 302 is a 2-barrel, what are the pros/cons of having a 4-barrel instead? and did they make carbureted models in 85/86 that had no mechanical pump? that may have been removed but I can't see any indication that there's even a space on the timing case for it, as best I can see around the PS pump.

 

Most 302's had fuel injection that year, but it may have been a mid-year change, I believe some of the parts houses do show a 2bbl 302 as a option.

Your truck could have come with a 351w, which did have a carb, and some did have a 4bbl carb from the factory. If the 351w blew up, the could have dropped the 302 in place and plopped the 4bbl carb on the 302 if they rounded up a intake for the 302.

The 300 six was also carbed that year and would have been a fairly simple swap to a 302, but it would have been a little bit more involved.

The 460 was also carbed but they only came in the f250/350 trucks.

Check the 8th digit of your VIN and post it back. I believe that will tell you what engine it originally had.

Here's a link that might have the info you need in it.
http://www.lmctruck.com/icatalog/fd/full.aspx?Page=11

 

Actually, I ran the VIN through Ford's parts site and it came up as a stock 302. Forgot to mention that. I'm pretty sure this engine is the original one, but the carb has been replaced. The model number on it is one of the ones that came on 351's. It's pretty new, and I'm certain was a replacement of some kind. I suspect the fuel tank(s) got fouled and the original 2bbl carb did too, or just age did it.

So the main question I have is whether I will be okay with just an electric inline pump and the low-pressure sending unit in the tank, with this carb? I am going to take subford's advice from one of the "Fuel selector valve" threads and put in a single-tank reservoir from a 86-89 Bronco rather than using the Pollak (assuming it works), until I get fired up to replace the rear tank/sending unit. As long as I'm clear on what fuel pump I need, I think I am good to get this part of it all fixed up.

Thanks for your input so far!

 

You can install a inline electric pump to supply the fuel. Have you looked on the front driver's side of the engine? If it had a carb, there should be a mechanical fuel pump there. If it's there, I would run it rather than the electric one.

 

this is what's in that spot:



not sure what it is, but it doesn't look like a fuel pump. I don't see any cover plate in the spot where the fuel pump should be either, so I'm stumped. I guess I'll just go with the inline (there was one there before...there's a bracket for it).

 

That's your oil pressure sending unit. And from what I can make out if you had a mechanical fuel pump, it would mount on the timing cover immediately ahead of that sending unit. My guess is that it will appear to be there, but is not machined at the factory to actually accept a pump there. That is just how the timing cover was on my '85 with the 5.0 EFI. You will have to get a new timing cover and an eccentric to drive it to go with a mechanical pump. But electric fuel pumps are very reliable, as that's what's standard on everything today-but you have to get a GOOD one, which will start at around $100.00. Do not get the cheapies for $30.00 that are on the sales floor at most auto parts stores.

 

right, that makes perfect sense. that's what it looks like, now that I think about it. I'm coming from Acura-land, where everything is newer, smaller, and fuel injected, but way back I used to have V8 Chevys, so my recollection of what those components look like is slowly coming back.

yeah, that's what I was thinking too, it's just really odd that there's no spot for it if this was a carbureted engine from the factory, unless someone changed the timing cover at some point. in any case, it's had an electric pump for a while, so that's what I'm going to do. thanks for pointing out about getting a good one. I was definitely eyeing the cheaper ones, but I guess I will just expect to buy the better one from the outset rather than regretting it later. I'll either get one of the better ones from Rock Auto or the one listed for 5.0 EFI engines on LMC's site ($170).

 

If the 8th digit of the VIN is an "F" it came with a 2bbl 302. If it's an "N" then it was EFI. EFI to carb swaps were common as people didn't know how to fix the EFI.

The EFI setup had an intake pump in each engine and a high pressure booster pump on the frame. They also had a reservoir selector valve that acted as an accumulator and kept about a pint of fuel in it so if the in tank pumps sucked air it wouldn't get to the engine.



The mechanical pump is mounted to the timing cover just in front of the oil pressure sender. If it's not there and there is no provision for it then you're best bet is an electric pump. Otherwise you have to swap the whole front cover over. You can use one of the Mr Gasket 'rattle' pumps as I call them. They're about $40, deliver 6-7psi and ~35-40gph. Hook it up to an ignition on 12v source with a relay.

Watch ordering pumps for the 5.0EFI engine. The in tank pumps are 6-7psi with ~70gph. If you have all the return lines and use a return style fuel pressure regulator that should be fine. IIRC that's too much flow not to have a return line hooked up, but I could be wrong.

Maybe someone else will chime in.

 

You can get an electric pump kit to replace the original mechanical pump. The PO might have done that. If so the pump will NOT be the high pressure version.
Some models / engines had electric pumps from the factory.

Don't put a high pressure EFI pump on a carb engine unless you add some kind of regulator.

The 3 port valves are correct for the 2 tank carb engine

The 6 port Pollak valves are for EFI or diesel engines to accomidate the fuel return lines from the engine EFI system back to the tanks.

On my '86 302 EFI, I replaced the the troublesome Ford non electric switching valve (Dual Function Reservoir) with a 6 port Pollak valve. Details link in my signature.

The computer is under the dash just above the gas pedal with sort of a metal box around it.

 

Klricks, have you had any issues sucking air with low fuel in the tanks not having the reservoir?

 

No I have not noticed but it's not a DD. I usually keep 1 tank full. I did add an inline fuel filter to each tank line that probably have about 1/3 the capacity of the DFR. Maybe next time I have a low tank I will try going uphill WOT and see if it starts a buck'n.

 

8th digit of VIN is an 'H'...10th is an 'F'. No 'N' anywhere in it.

Thanks for the info about the different fuel pumps. I will make sure to get one with the lower GPH rating. everything is set up for it already, so it should be pretty easy to hook up once I get that, the new gas tank & the sending unit. I am planning to use the reservoir from a 86-89 Bronco per subford's recommendation here (and a few other places in that thread). I will keep the Pollak three-port valve that came with the truck so if I eventually fix the rear tank, I will have that to use.

Now I just have to wait until I get paid at the end of the month.