Topic: Need to Rebuild Carb? Fuel leak around front diaphram

[sdgrant]

Doesn't it just figure? Haven't had the PC at a show in almost a year, and I got invited to the Concours d' Elegance at the Trump National golf course in Rancho Palos Verdes. I was detailing the engine area today, and I noticed a small pool of fuel in a recess in the manifold. It appears to be leaking at the front diaphram where the accelerator toggles. I'm not carb pro, so I have to have my buddy come get it, fix it, and put it back on. He's out of town this weekend, so it won't be ready in time for the show.... Rats.

[2V8s]

I had this problem. It was the pump diaphragm on the front. Was easy to change. A rebuild kit isnt much money then just change the bit you need to. Can leave the carb in situ for this. Just need a 1/4 socket and take off the 4 bolts you can see at the front where the lever goes in. If it isnt that one, it may be the one underneathe the float chamber. Mine had a slight weap, I tightened the bolts and it was OK again.

You might find it also causes starting problems as the fuel level in the float chamber drops too low.
Over here in the UK, we are blaming these more frequent problems on increasing levels of ethanol in the fuel. It eats certain types or rubber!

[sdgrant]

Thanks to advice from the forum and a mechanically gifted friend, I was able to replace the accelerator pump diaphragm with no complications. I was able to take the car to the Trump Concours d'Elegance on Sunday, and it turned out to be a good day:

1. Although not part of the Indy 500 display of vintage racers, they somehow parked a $400K 2012 Lexus LFA next to me. I think the PC looks better...

2. The organizer of the Indy 500 display was one of the dignitaries from 1964 that drove one of the Mustang dignitary convertibles! He said his car was a 4-speed with a red interior.

[Bill Cabaniss]

2V8s. From what you describe you might have a carb. problem as well. The cover you described that is underneath the float chamber is the power valve access cover. That side of the power valve is for full manifold vacuum only. There should never be fuel in that area. If there is, the power valve diaphram is cracked and leeking fuel down from the fuel bowl. While the engine is not running the leak will fill the bottom cover area and run through the vacuum port and drain the fuel bowl contents onto the intake manifold. This will cause the hard starting situation and some black smoke out the exhaust when starting up. It can also cause a rough idle from the extra unmetered fuel leaking into the engine. According to my carburetor manuels a fully open power valve ads as much fuel to the motor as 4 more jet sizes would. Power valves only open under hard acceleration when engine vacuum is low and fuel demand is high. If you have fuel seeping from the gasket area at that plate you need to replace the power valve,round power valve gasket, and square 4 hole cover gasket. You will get better fuel mileage and have a smoother running mustang!! Hope this helps you. Bill.