Topic: Stuttering and stalling 73 351 Q code

[67foxgt390]

  Hey all!! I had purchased my 73 Q code Conv in 2019. The first two years the car ran great. When I got it out in 21 I would start it and let it run for a bit. When I did drive it it would stumble or stutter for no reason. When I would let it run for a bit in the drive way the idle would slowly drop RPMS and stall out. Due to Covid and house repairs did not have time to deal with it. Now in 22 it's at it again. I replaced the point with a Pertonix unit and coil (hid it really well) and it still does it. From what I read the 4300D is a real pain even from new. Any one have ideas. I do not want to rip it open, and don't want to put a Holley on either. It's my only Mustang and I DO drive it! I don't want to left sit on a cruise night!! Any help would be appreciated. Thank You!!

[Bob Gaines]

  Hey all!! I had purchased my 73 Q code Conv in 2019. The first two years the car ran great. When I got it out in 21 I would start it and let it run for a bit. When I did drive it it would stumble or stutter for no reason. When I would let it run for a bit in the drive way the idle would slowly drop RPMS and stall out. Due to Covid and house repairs did not have time to deal with it. Now in 22 it's at it again. I replaced the point with a Pertonix unit and coil (hid it really well) and it still does it. From what I read the 4300D is a real pain even from new. Any one have ideas. I do not want to rip it open, and don't want to put a Holley on either. It's my only Mustang and I DO drive it! I don't want to left sit on a cruise night!! Any help would be appreciated. Thank You!!

Time to send off the 4300 to have it rebuilt. It is a common story. I am not suggesting this course of action but your situation is why many swap out to a Holley . I have not had good success when rebuilding the 4300 myself so I send them off to others that have.

[Bob Gaines]

https://www.carburetorrestorationyoungstownoh.com/   is who I have used before . I am sure there are many others out there .

[67foxgt390]

I'm not it needs a rebuild, it looks brand new! Entire engine area was very nicely done by the previous owner. Really frustrated. Thanks

[Bob Gaines]

I'm not it needs a rebuild, it looks brand new! Entire engine area was very nicely done by the previous owner. Really frustrated. Thanks

External looks can be deceiving. Many times gas can go bad inside a sitting carburetor causing problems or fuel over time can build up residue inside blocking various internal passages causing issues that get worse and worse until until the car hardly runs. A carb can look restored on the outside but inside be clogged up. A clogged up carb isn't the culprit all of the time but given your symptoms and the kind of carb it is it is a likely suspect. I hope that you find your problem regardless of what it is. 

[67foxgt390]

Thank You for your input. Gonna look into my options. I'm kind of hesitant to send off my carb and wait who know how long or how much it will cost!! Ugh!! If I have to go aftermarket does any one have any recommendations? Not a hot rod, want to keep stock air cleaner assy. Just want reliable cruising. Thank You

[67350#1242]

Wouldn't hurt to try pouring\spraying some carb cleaner into the bowl area and see if any improvement.
I have had good luck blipping the throttle with my hand over the primary of the carb to suck out foreign material also.
Kurt.

[rockhouse66]

Your issue could also be caused by debris in the fuel tank.  If there is an inlet filter on the carb, take a look.

[67foxgt390]

Thanks weather permitting gonna try carb cleaner and have inlet filter on order!

[Bob Gaines]

In case you do not want to wait for a ordered inlet filter for the carb , it s a inexpensive common auto parts store sourced item used on a wide variety of Ford applications over a number of different years.