68 Mustang Convert. Just had a 96 302 explorer motor put in. Everything in the engine compartment was redone. New gas tank. The car was run with the old tank while it was in the shop and I had the carb apart and cleaned last week after another starting issue. Car ran great for one night. Then had a fuel leak from the filter. That is fixed now but this morning after 3-5 min of warm up it slowly stalled out again. I noticed fuel leaking from an area on the linkage just in front of the banjo fitting (a spring of some sort) Seems like an odd place for a leak but it was wet to the touch. I restarted the car kept the throttle half way down got it to idle on its own didn't notice the leak at the carb again but then it slowly stalled out again. Spent a boat load of money on all this work and starting to get a bit frustrated. Towing it down to the shop tomorrow but anyone have any ideas?? Vacuum Leak?? I messed around with the mixture screws on the carb...do these have a starting benchmark? all the way open or all the way closed? Would they have anything to do with this issue?? Also the electric choke is set at the medium setting.

Has an edelbrock 600 carb electric choke

 

As Sheriff Buford T. Justice says, "Hold up on that car wash boys." Take a breath, smoke a cig, drink a beer, and thing logically. Was the car running well and then stop working, or is this a fresh install? Don't just start changing a bunch of stuff if it was working right. If this is a fresh install, then you need to tune the car methodically and logically. Set/check something and move on to the next thing in a logical order.

Check the bowl levels like I said in the other thread. Check the fuel pump and fuel pressure. If you are jacking with idle screws, then you probably need to tune or have the carb tuned. FYI, start with the idle screws a turn or so out from all the way in and tune for the right AFR from there. I doubt the idle screws have anything to do with the car running and then dieing, but they do need to be set right. A vacuum leak can cause terrible problems especially since the carb's "computer" is vacuum based. Make sure all of your vacuum ports are connected or plugged and the hoses are all in good shape. A poorly installed/tuned choke can cause issues, but when the engine is at running temp and the choke is open, it is no longer a factor and should be ignored if your car is dieing under those conditions.

 

This was a total motor replacement. The shop used what they could out of the engine compartment but anything critical was replaced with new or rebuilt. It's odd it ran great on Thursday night after the carb cleaning. Then had the fuel filter leak. Now this. I guess when you do a major overhaul like this there will be bugs to work out. It's a really good shop that specializes in classic mustangs. It will get figured out. Thanks for the input..

 

How did you clean the carb?

 

Actually the owner of the shop came by and did it...had a can of carb cleaner..we soaked up what gas was in the bowls. There was a small amount of rust residue in there from when they ran it with the old tank. The car fired right up...sounded great after that.

 

wow, this sounds exactly like what happened to me, I just put in a spanking new 351c and used the carb from my old 351c (Holly Avenger 670) I started this project back in late October. Anyway after redoing everything in the engine bay except the carb I put it on and fired it up to break in the cam. It worked well during break in but when I went out on Sunday it would not idle and gas was coming from the T connector that fed the front and back of the carb. I pulled the carb drained it and pulled both covers to expose the floats, carb had dirt so I cleaned it and the jets put it back together and it still didnt want to idle so I had it towed to the shop. I should find out tomorrow what the problem is, I had minimal fuel in the tank and added 2 gallons of premium but when I drained the carb it smelled more like varnish then gas. I can tell its getting fuel but just not good fuel or something else is clogged? I should have replaced the tank but tried that before with another 71 and the damn fuel float was a pain.

My frustration factor was pegged as well so it was better for cooler heads to look at it and set the timing/tuning and to get the AOD cable setup.

 

Talked to the shop this morning. It sounds to them like it is flooding. Going to replace some things. He said Edelbrock had some issues with some bad jets. Leaked again this morning at the carb fitting shown in the below pics.
http://www.jonbalinkie.com/MForm/68mustcarb2.jpg
http://www.jonbalinkie.com/MForm/68mustcarb3.jpg

Here is a pic of the car now..

http://www.jonbalinkie.com/MForm/68must.jpg

Here is a link to the "rebuild" process
http://jonbalinkie.com/68Mustang/

 

A common place for problems on old cars is the throttle shaft bushings. Unseen by the human eye a leak can cause all sorts of running problems.

To check for worn out bushings leaking:
with the engine running take an unlit propane torch open the valve and point it at the bushings. If the engine picks up speed then you need to replace the carb as they don't sell repair kits for these they do that at the rebuild factory.