Carb & fuel filter dry up overnight

When my jeep sits overnight, the fuel is completely gone (evaporated maybe?) from the carb to the fuel pump. It takes a good 10-15 seconds on the starter to get it flowing again, and runs perfectly after that and all day in between starts & stops.

I figure it must be either evaporating, or leaking, but If it is a leak, it's not severe enough for me to observe.

Anyone else have this problem, or any idea on how to correct it?

Thanks,

 

Just guessing on your equipment.. If you have a mechanical fuel pump and your carb has a vent in the top then it is possible your pump which has a back-flow valve built in, is leaking back to tank. However, your float bowel should have sufficient fuel to start up in morn providing there is no crack in the carb.

 

does the oil smell of fuel?had a holley that had a bad leak and found the gas was going out ,down the in. runners, and into the pan?

 

So, looks like two possible sources of the problem:

1. leaking back-flow valve in fuel pump = new fuel pump.
2. leaking/cracked carb = new carb.

I suppose I'll replace the fuel pump first, since it isn't that expensive, and see what happens. The fuel pump is the same one that was installed when I bought the jeep 6 years ago, so who knows it's condition. Probably wouldn't be a bad idea to replace anyway.

the carb is the stock Motorcraft 2100, and the only vent is into the air cleaner housing, no exposed vent on top of the fuel bowl.

 

If you put your model/year/engine etc. in your message or in your sig, it will help with answers to questions like this.

It could be evaporation, but IMO if you have the factory air cleaner and the carb gaskets are in good shape, evaporation won't be a problem. With no air cleaner, the bowl will dry out pretty fast. An open element air cleaner will make the bowl dry out faster too.

 

I don't think it's evaporation. I just went outside and checked and it's definitely carb leaking. I rebuilt this thing a year or so ago, with new gaskets and all, but maybe I did more damage than good. Seems like it's leaking around the accellerator valve.

Here's some pics:





You can see fuel dripping from the screws at the bottom of the power valve cover, and it is wet all the way up to the accellerator valve. This being the highest point, I figure this is where the leak is.

Guess it's time to operate...

 

LOL I just had this problem last week. I got another crab overhaul kit, the only way to get a Power value for the jeep MC 2100 quickly. It takes only 30 min to 1 hr to do MC 2100 overhaul. I also got a one way fuel filter, cute clear one at the parts store.

 

Found the problem...a pinhole in the accelerator pump diaphragm. A dab of superglue fixed it for now.

Anyone know if these are available without buying a complete rebuild kit? FLAPS search turned up nothing.

 

NAPA Online shows it. CRB24295
http://www.napaonline.com/MasterPag...=24295&Description=Accelerator+Pump+Diaphragm

Your local independent parts store should be able to get a kit for less than Napa, probably around $20.

 

Hey, thanks. I guess my online parts searching needs improvment.