My 351W in my '70 Mustang has been stalling. Goes like this: Last sat, drove it, it would sputter, then hit gas, okay, but would sputter soon again. Finally it just stalled out, couldn't get it started. Couple days later, started right up, but stalled after 25 ft. Turned down pressure on fuel press reg to lowest, played with primaries (carter 625), started again. Drove it about 200 ft, stalled, waited, started back up, drove it about 100 ft, stalled again. A few days later, started it up, no problem. Idled for about 10 mins, ran fine. Done that 3 times now, no prob. Even moved it to a new parking spot, and it was fine. I just don't trust it to drive it...the car has a elec fuel pump, so that means it shouldn't be vapor lock, right? The fuel filter is also new, 3 weeks old. Any clues?

 

Sounds like you need either a carb rebuild or at least a new accelerator pump. Similar thing happened to me on a 170-6 in a 71 Bronco. The carb was ALL the problem. Gas tanks were full, and the pump was working. The whole problem was the carb. Same thing with a 68 1-ton I had. 390 motor, 2 bbl Motorcraft. Would idle like a champ, but try to move, and it would fall flat on it's face. $25 rebuild kit later, it ran like a champ.

 

The carb was just rebuilt 6 mons ago by a very good shop here in Phoenix. This was somethign that just started recently. I can move it, and give it gas, and it's fine. But I'll check out the accel pump, make sure it's working right.

 

Gary
If your engine idles OK and then stalls when you increase RPM then you probablly have a fuel delivery problem.

Vapor losk happens on a hot engine so that is probably not your problem.

With a Carb your fuel pressure should be 5 - 7 psi.

Things to check.
Pull the fuel line from the carb and put the end in a container. Have some crank the engine, and you should see a good steady stream of fuel. If you do not have suffician fuel flow then:
(1) Check youf fuel filter.
(2) You may have a restriction on your fuel line or a crack in the fuel line that is sucking air.
(3) The pick up in the tank may be partially clogged.

If you have good fuel flow then:
(1) Check the inlet to the Carb and make sure the filter screen is not clogged.
(2) The floats may be set too low.
(3) Check to make sure that the choke is opening all the way after it warms up.

 

Alright, thanks for the suggestoins. That's exactly the prob I have, idles okay, low rpm (say 5-10 mph) okay, but at higher it stalled. I'll give those things a try...maybe the fuel pump is starting to crap out or somethings clogged.