Electric fuel pump on '85 carb'o

thaduke2003 said:

Ok, next dopey project- I'm looking into swapping an electric fuel pump onto my '85 5.0 carb'ed. I have a few questions:
1. What fuel pressure range do I need to be running?
2. How should I wire it in? (As a professional bonehead, wiring diagrams would be lovely!)
3. Besides a pre-filter and b-off plate, what all do I need?
4. What do I do about fuel lines?
5. Is the Mr. Gasket pump any good? Otherwise, reccomendations- budget is very tight, but can be expanded slightly.
The car is a street car for now- if I go big, I'll be re-doing this, but for now, rather stock 5.0 that'll be getting bolt-ons (Edelbrock 600 carb, IM, headers, pipes, etc.) as a STREET CAR with a few auto-cross runs here and there
Thanks! Mark W.

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1. low pressure should be around 2 psi. high should be around 9
2. find any key on 12 volt source just make sure it is not hot when the key is off. i do NOT recomend hard wiring it.
3. HERE is the block of plate you will need.
4. seeings how its a carbed car and has such low pressure, just cut the line somewhere near the tank and splice in a piece of rubber fuel line from the parts store. just run it from your pump to the old line and hose clamp it on good.
5. and im sure for your needs the mr.gasket pump will be fine.

The numbers on the drawing refer to the numbers on the relay housing of a typical automotive relay.

I thought all the carbureted engines had an excess capacity mechanical fuel pump with a return line to the tank from the pressure compensating relief valve just like the injected engines?

At least my 2bbl '82 did. So for me it was simply a matter of installing a 4bbl carb+manifold with a pressure regulator matched to the carb's recommended limit of 6psi (120gph). I stuck with a mechanical high flow Carter pump that had more than enough flow to run a flat out 750cfm carb. The pump cost about $70 new from Summit. I got the carb and matched edelbrock intake off ebay for $200 nearly new. I didn't need the 750 as it is way over kill for a 306 but the price was right and this car was not a daily driver so didn't care about economy.

Obviously all you would need is the pump and regulator for less than $100 total.

Most external electric pumps are more than that. Then there's the wiring/shutoff issues.

Unless the drive lobe is worn off and you can't use a mechanical pump that's about as cheap as you can get? And still be new. Originally I was looking for only a 650cfm max. carb but you get what's out there don't you when on the cheap? At least you don't have to buy a new manifold. BTW I had to adjust the floats/the carb factory tech to keep the car from bogging coming out of hard corners with gummy tires pulling big lateral g's while autocrossing and sudden stops. Like I said the 750cfm was way overkill for the 306 so required some adjustments to perfect it. But it can certainly be done easily with no additional expense.

i run my fuel pressure at 6 PSI at all times, didnt really ever try to tune it, but the plugs burn rich soooo u could go lower for sure

87Mustang351 said:

i run my fuel pressure at 6 PSI at all times, didnt really ever try to tune it, but the plugs burn rich soooo u could go lower for sure

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Its not the psi on your engine that is causing your plugs to show rich condition. All the fuel pressure is doing is filling your carb float bowls. As long as the fuel pressure is not too high it will not force fuel into the engine. The reason your spark plugs show rich is because your carb is jetted 2 rich for your application.

thanks man, i was going to get a 650 for it this year, but im going with a 408 stroker, so i will probly need a 850 for that i would say..what do u run for psi?

I run at 7 psi. Seems to keep everything happy. I also run rich but once again its jetting. As for needing a 850 on the stroker. I doubt you will. If you plan on running past 7500rpm then maybe but I bet that 750 will work just fine.