Got an 85 F-250 with a pretty hot 460, aside from all the other issues I'd been having with the build I finally was able to take it out on the road the other day. Under easy load this thing will fly right up to 6K rpms, now that I got my tranny working correctly I was able to really stand on it in 2nd. The engine came up to about 4K rpms under full throttle spinning the tires and then kinda tapered down to 3200 rpms after a couple seconds and just flat lined there under heavy load. What I think is happening is the stock in tank electric fuel pump can't keep enough fuel to the 850DP, so once it drains the bowls it just runs on what it can get and that is enough of 3,000 rpms under heavy load, b/c if you ease out and get back in it you can repeat this pattern constantly, or if you ease/half throttle/light load it all the way up you'll hit 6K no problem. As for the near future I am going to put on another fuel rail I have that has a fuel psi guage port in it and run a remote guage to verify this. My real question is when using the stock tank if I wanna go ahead and get a Holley blue and regulator setup, etc how do I go about setting that up since it has a in tank pump? My other toys run fuel cells and I just gravity feed the pump and no problems. I was thinking of maybe running a "reservoir" sorta deal with a 1 or 2 quart tank on the frame rail, let the stock pump, pump into that, then run a filter, big fuel pump, regulator after the return on the system, T into that return and make it also return to the reservoir tank. I'd prefer not to have to screw around with this reservior idea, but what do you do in these odd years of electric in tank pumps with carbs?

 

I honestly didn't think that ford used in tank electrics with carbs.

however i ran into a similar problem in my capri (it came with CFI) i had been running a cheaper inline pump pulling through the intank low pressure pump, but it tended to starve the engine (and lean backfires ain't cool at 120mph) and even though it was able to feed it when it was still just a 2bbl, it was when i started bolting stuff on that it ran into problems. i bandaided it (although unlike a bandaid it probably would have lasted just fine) by running both low pressure pumps together with a dead-head regulator (and before somebody says something its new engine has a racepumps piston style mechanical).

so yes it is possible to draw fuel past an in-tank pump, but it will have restriction. perhaps just swap out to a regular pickup? i think it would be simpler than building a reservoir.

 

I didn't think so either, I was under the assumption it was a fuel pump on the frame rail since 87/88/89 used that, but maybe that was just added in the sytem to up the psi for F.I. later? My 86 F-150 used a mechanical pump, idk why this 85 has electric?

Well it does have 2 tanks and I could fool with the wiring to make both of the pumps come on at once, but then I have to add fuel to both tanks constantly and for what this truck is used for, it barely needs one. I thought of cuttin off the return to the system, but figured that would do no good as it would still use the fuel up weather it could return or not.

I was a little weary of that being to hard on the Holley/etc pump. I had thought of changing out the pickup as well after I had typed this, you wouldn't think a regular pickup would cost nothing? I'd prolly just do this in the front tank and remove the rear one to lighten up the truck.

So next question: I was weary about doing this b/c those Holley type of pumps I'm refferring to (I'll most likely be using a cheaper Summit model) are made to be pushers and I was sure how well they would stuck up and outta the tank? I'd mount the pump on the frame rail, but that would be around "even" with the tank, not lower then it.

 

the single tank idea doesn't sound to bad to me. I would just mount the electric back close to the tank. my capri's old electric was even with the top of the tank, but not far away. i think yours would be fine on the frame.

 

the electric pump in the tanks keep up with my 460 just fine, however last year it wound up acting just like yours. Turns out it was a piece of dirt holding the needle almost closed in the seat. it would run and idle, but as soon as I gave it more than 1/2 throttle, it would die. try taking the fuel bowl off, and see if that's what's going on before spending any money.