Dual carb dilemma...?

[white64]

I've got a 8BA, with an offy two carb intake and two rebuilt ford 94's on it.

It was running great. I just replaced a badly leaking '34 fuel pump for one with the glass bowl, '46 maybe...

It now runs like crap.

Accelerating is not an issue! ...when running at a steady speed it runs rough, stumbles, sputters... hit the gas and off she goes smooth as can be, but back off the gas and it runs rough again...

Tried messing with the timing but it doesn't seem to change much other than losing the acceleration aspect.

suggestions?

[Johnnydidd]

Sounds like a carb is running over, maybe dirt got in needle valve during replacement of fuel pump or pressure may be to high, pressure should be around 2.5 lbs. Good luck John

[Mart]

It might be that the fuel pump is delivering too much pressure. The pressure output of the pump is controlled by the big spring in the pump underneath the diaphragm. the spring in the new pump may be too strong. I had the same problem and replaced the spring in the new pump with the one from the old pump and it worked ok.

Mart.

[B-O-B]

If it was running fine before the fuel pump replacement WHY would you mess with the timing? Check your fuel delivery & pressure.

[George/Maine]

I know the tank side of fuel pump has different fittings.
There is 2 part #s for 46-48,and 49-53
They may not be interchangeable.

[zzlegend]

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Yes what B-O-B said. If it was running perfect before the fuel change, then work the problem. Don't create another worry with the timing.

[scooder]

First thing to look at is the bit you changed. Do as Mart did.
Martin.

[white64]

Thanks guys, thought it may have been the pump, that's why I mentioned it, but then I got to thinking maybe it was just a coincidence! But that's why I wrote you guys, I knew someone would have the answer!! The pump comes apart tomorrow!

[Bruce Lancaster]

Give it a pressure check before you remove it. Many newer pumps have crazy high pressure, probably because fuel pump springs are mostly about the same size and they have a ton of SBC ones in stock...
If pressure is high try borrowing the diaphragm spring from the leaker. Also compare diameters of your 2 pumps...actual '34's are pretty rare, if diaphragm diameter looks same as new one it might well be a '41-46 type and so perhaps might be fine with diaphragm transplant from the new one...

[B-nut]

On a dual carb set up ,what pressure should white64 be looking for? Around two pounds? What would you consider too high?

[white64]

Got it! ...it was a bad condenser. And the distributor cap where it contacts the rotor was eroded badly

[scicala]

Originally Posted by white64

Got it! ...it was a bad condenser. And the distributor cap where it contacts the rotor was eroded badly

I love it when the carburetors turn up innocent for the problem. They get their fair share of blame for running problems. Easiest thing to blame I guess.

[chap52]

Thanks for the "got it" update.
We all learn from each others adventures.