83 F150 EFI PUMP

[SK83f150]

hello. i am almost done with my install of a 94 efi motor into my 83 f150. only two main issues are left. First, the 94 had a e40d trans which needs some work before it can go in. So instead i bolted it up to my old c6 that was already in the truck. Not too worried about that one right now...
The second issue is that the computer does not want to turn the fuel pump on. When i jump the pump throught the test connection the engine runs fine. I am going to pick up a manual computer this weekend to help with the c6 issue.
My main question is whether the 94 computer not having its trans will cause it to not run the fuel pump. the engine was running before it was removed from the donor truck.
i installed the harness from the 94 into my truck after eliminating most of the in dash compnents(radio, airbags, heater controls..).
im gonna do more troubleshooting tomorrow just hunting for info i guess. pics will be posted soon.

[Lazy JW]

....
My main question is whether the 94 computer not having its trans will cause it to not run the fuel pump......

I don't have the answer to your question but were it mine I would just wire the fuel pump through an oil pressure switch like Chebbie did on the old Vega. Send power to the fuel pump from the starter solenoid for starting purposes and once it's running the fuel pump gets power through the oil pressure switch. If the engine dies for any reason, the oil pressure switch will shut off the fuel (safety).

And WELCOME to the forum!
Joe

[American Thunder]

Does the '94 have a fuel roll-over-shut-off switch? I can't remember. If the '94 parts truck had it, then perhaps the switch circuit is open and the computer sees it as the switch being tripped, therefore, it's not sending power to the fuel pump circuit?

I like the idea of an oil psi switch, because it also won't let the engine start until there's oil pressure, which is very nice during cold startups and after oil changes when the filter is mostly empty. Otherwise, the fuel injection cold start mode will high idle the motor with or without oil pressure.
Plus, if you ever spring a leak in the oil pan, the motor shuts off immediately, saving it from a catastrophic fail.

p.s. I wonder what the oil switch minimim was set to in the Vega? 2 psi?? Those 350s sometimes run *really* low pressure at idle. haha
Chevys..

[Lazy JW]

I like the idea of an oil psi switch, because it also won't let the engine start until there's oil pressure, which is very nice during cold startups and after oil changes when the filter is mostly empty. Otherwise, the fuel injection cold start mode will high idle the motor with or without oil pressure.

The Chebbie Vega had it wired so that it WOULD start without oil pressure due to the power from the starter solenoid. No reason you couldn't wire it as you suggest, though; it would merely require a slightly extended cranking period to build up oil pressure. I don't see this as a bad thing either.

On my diesel tractor I use the compression release to allow the engine to spin up and get oil pressure. I can hear a noticeable increase in cranking speed when the oil gets flowing, then I let go of the compression release handle and she fires right up.

IIRC the Vega oil pressure switch only required about 5 PSI to activate.
Joe

[American Thunder]

IIRC the Vega oil pressure switch only required about 5 PSI to activate.
Joe

HAHA!! I edited my post, and asked this question before I read your response.. I guess my estimate was pretty close.. that's funny

[Lazy JW]

The Vagrant had a 2300 cc (140 ci) inline Four-banger.
Joe

[American Thunder]

The Vagrant had a 2300 cc (140 ci) inline Four-banger.
Joe

My buddy had a pretty quick 355" pro-street Vega, if I recall he went 9.30s on the bottle, and 11.50s on the motor. But he ran cheap gas in it when he drove it on the street, as the compression was only about 8:1.
I actually like the cars, they remind me of my Mustang II, cheap and very light, but.. they're still GM. I always think of them as having a 350 in them, due to spending so much time around my buddy's car, too.

[SK83f150]

After working over what i did so far and checking it against the wiring diagram it turned out that i didn't hook up one of the grounds up very well. i moved it and now everything works fine . Now I just have get everything tucked away and looking like it is supposed to be there.
Thanks for the input and big motors in little cars is always a fun idea.