Hello All,

I'm sure this has been discussed somewhere but I'm having a hard time finding the exact answer I'm looking for in my search. I have a 1985 regular cab short box, looking to convert to EFI using the Holley Terminator X system. Truck came with a 351W, carbureted, with dual fuel tanks. Tanks, straps, and senders have seen better days so I'm looking to replace at the same time. I know not to get a tank for a 1980-1984 due to the small sender opening. I know that I should be going with a 1985+ tank for a 5.0L to ensure it has the proper sender opening.

1. What are the differences between the fuel tanks between 1985 and 1996?
Using Spectra Premium fuel tanks as an example, specifically the saddle tank for a SB. Part number for 1985 is F14B and part number for a 1987 is F14D. Dimensions of both tanks look to be the same, both are listed as 16 gallon tanks, and based on the pictures both look to be the same shape. What has changed that the tank required a different part number? Similar when comparing a tank for a 1992 - it is part number F14C but dimensions, capacity, and shape all look to be similar, what's different? I assume it might have to do with the filler pipe/hose but couldn't find a confirmation on that.

2. I assume the additional two wires in the EFI sender are a pos/neg for the fuel pump?
Current sender for the carb'd 351W is the plastic two pin. Sender for a 1986 5.0L looks to be the plastic 4 pin style. I assume the additional two wires would be for my in tank pump and I'd just need to tie it in to my Terminator X wiring harness? Outside of LMC and the junkyard, anyone know where else sells the plastic 4 pin wiring I would need to plug into the new 4 pin sender?

3. Anyone know for certain if these Spectra tanks for OEM EFI applications are baffled or have trays to prevent fuel slosh?
I've read forums stating no but I've also emailed Spectra and been told yes they are for the F14C and F14D tanks but no for the F14B tank. Anyone have any actual experience with this and can confirm?

Thanks!

 

I can tell you that the tank dimensions are the same between Bullnose and the 1992-1996 trucks. Did a frame swap a few years ago, and put a complete 1995 swb chassis under a 1980 F150 Flareside. I ordered a 1980-1984 fuel tank and installed it in the 1995 frame without issue.

I can't answer anything about the 1985-1996 EFI years, but one difference between the tanks is that the filler necks changed in the later model trucks...they vent differently.

If you look in the fuel filler opening of a 1980-1986 tank, you'll see a steel tube inside the filler neck that holds the plastic vent tube that runs inside the filler neck. I'm not 100% sure how the 1992-1996 trucks vented the filler necks, but they were different.

Bullnose tank below...see the tube in the filler neck? The later tanks do not have this.

 

What I would do is order the later tank and the later fuel pump assembly to go with it. They have a plastic surround around the fuel pump assembly that acts like a baffle. If you need a later filler assembly, I would get that that too. All these are improvements over the older EFI trucks, which had a low pressure fuel pump in the tank, and then a high pressure pump with a reservoir mounted on the frame. This two pump system eliminated the need for a baffle. The later EFI trucks only had one high pressure pump in the tank, and I would think this would be more compatible with your aftermarket EFI system. Of course you will need to run more wires to power the pump. Maybe you can buy a pigtail to fit the later model 4 pin connector on the sending unit.

 

FWIW, here's my tank on my 86' 302EFI.


Picture from driveshaft side

You can see filler hose on the back side of that picture

That's the vent hose in the old bottom filler hose

 

Thanks for the info! I agree that likely the part number difference between 86 and 87 would be due to the filler opening. Still not too sure why the 92-96 would get a different part number too.

If I were to go with an 87 tank that didn't have the filler tube neck in the tank like pictured, I assume I'd also need to get an 87 style filler tube to go between the bed and tank?

I think the later fuel pump assembly with the plastic surround on the 92-96 has a different resistance from the 85/86 years. Same with the 87-91. So I don't think my fuel gauge would read correctly without getting a MeterMatch or possibly a set of Dakota Digitals.

 

[QUOTE=Ruby22;20839263 I think the later fuel pump assembly with the plastic surround on the 92-96 has a different resistance from the 85/86 years. Same with the 87-91. So I don't think my fuel gauge would read correctly without getting a MeterMatch or possibly a set of Dakota Digitals.[/QUOTE]

You are correct, I forgot about that. That aftermarket system, does it come with a external high pressure pump? Any factory assembly with the fuel pump and the correct resistance for the fuel gauge is going to come with a low pressure pump, more of a "lift" pump.

 

For the Spectra senders at least, looks like it can come with or without pump, depending on what assembly you go with. I was likely going to go with an assembly without a pump and source one that I want. Was just trying to figure out the wiring before I click the purchase button since my carbed system currently has a two pin connector vs. it looks like the EFI senders have a 4 pin sender. I'm guessing the extra two pins are to power the in tank fuel pump so I think that should be easy enough to wire into the Terminator system.

FWIW, I did manage to find a local parts store that did stock the 4 pin pigtail for the EFI sender so it should be pretty simple to swap that over. Saved on shipping at least. I'm in Canada so I was looking at $30 of shipping for a $8 part out of the US which isn't great.

 

If you are going to get the old sending unit setup, and then retro fit a high pressure pump on it, you had better look into one of those Holley "mats" that fit on there and keep the pump supplied with fuel. That tank has no baffles in it, and you are not going to use the "cartridge" that is on the newer sending units.

 

Here it is. It's called a Hydramat. https://www.holley.com/products/fuel_systems/hydramat/

 

Yeah I've come across the Hydramat. Seems a bit pricey but could be a solution with a unbaffled tank.

Would fuel starvation really be that frequent of an issue? Plan is for the truck to eventually be something I can daily during the summer. Not going to be autocrossing or drag racing with it. Granted, I'm sure a hard launch or two will happen and a trip through the mountains could happen as well so there will be situations where the tank won't be level. I figure as long as I keep fuel level above 1/4, should be ok, no?

 

Look at the fuel level at a 1/4 tank.
I dont think that leaves a lot of fuel to be picked up by the pump.and then it has all that area to move around in, mostly front & rear.
So what would happen in stop & go traffic? There is a lot of empty tank for that gas to move in.

I think a good test would be take a water bottle and have just a little water that would cover the bottom when on its side.
Then mount it on its side front to rear on the top of the dash and go for a normal drive and see how much it moves front to back.
Dave ----

 

Gently accelerate, never go around turns and do not hit the brakes. You should be ok then. When in Rome, do as the Romans do. Copy what the factory did. Or call the fuel injection company you are going to get your stuff from and see what they have to say about it. If you wanted to go junk yarding, don't see why you couldn't get a later model assembly and see if you can combine the early sending unit ohms part with the later plastic cartridge. Or some combination there of.

If the aftermarket fuel injection system you are going to get offers a external pump, you could use it with the Ford reservoir system. It has a filter in it also.

 

There was someone on Gary's site https://www.garysgaragemahal.com/ that did just that.
Think his users name is Tarheal blue, might be all 1 word, and did a vary nice write up on this.
Dave ----

 

Thanks for the info. It's Tarheel Blue and thread is called " '95 FDM for your 85 gauge " in case anyone comes across this thread and wants to read it.

This could be an option. My only concern is the gph those pumps/modules put out. From just a quick search on rock auto, seems they put out anywhere from 35-45 gph. That should be good for 350-450 HP. I was hoping to target 500 HP so I think that would need about a 50 gph pump.

Unfortunately between work and a newborn at home, trips to the junkyard are few and far between these days. Does anyone know if these pumps/baskets/modules as they seem to be called on a 95 F150 for example can be opened up? Could you hypothetically open it up and swap in an aftermarket pump?