Hello all,

My 72 Mustang started acting up last week. I will describe the problem from a cold start. First off, the engine always starts right up after I give a little gas. FYI the Holley carburator does not have a choke. Since I am in Florida that has not been too much of an issue. I just let it warm up aminute and it is ready to go. So far so good, no change there. Problem starts after about4 minutes into the ride. Engine begins to sputter heavilyand wants to stall. If I do nothing it canstall but will notnecessarily.Giving it gas has for effect of keeping it running more but very roughly and with a lot of hesitations and very loud backfires happen through the exhaust if I give it too much gas, but sometimes I dont seem to have a choice or it will die. After about 2 to 3 minutes of this, engine returns to normal operation. I can now drive the car anywhere from 20or 40minutes until it does it again. Sputtersas described for a few minutes then goes back to run normally. This happens at any RPM but it seems that the warmer the engine the better it runs.

Since we have had heavy rain down here for about 3 weeks in a row, I figured some water may haveseeped into the gas tank through the gas cap somehow. Iputa bottle of dry gas in the tank which was about half full. That did not help. When the tank was less than 1/4 fullI filled it upand put another bottle of dry gas in it.

The weather hasbeen fairly dry in the last week. But no change. The car still does the same. I checked the spark-plug wires which are good new MSDs. I checked inside the distributor cap for sign of moisture or cracks.I verified the wiresconnecting the coil.The gas tank, fuel pump and filter are only 3 months old. I also checked the spark plugs 3 months ago, but the points may be a little weak. The problem started suddenly last week but seems to progressively get worse. I am puzzled and even though this can be several things, I wouldlike to be able to get right to the actual cause without having to replace too many parts in a trial and error fashion. Can anyone point me in the right direction here? Is this an ignition or a fuel problem to begin with? Help would be appreciated.

Cheers,


1972 Mustang Fastback
351 Cleveland 4-V
Holley 750CFM Double Pumper
Hooker Headers
C6 Auto

2006 Mustang (5 Speed V6 Premium)
(14.6 sec. 1/4 mi.)
GT take-off dual exhaust w/ Custom H-pipe
Mac Headers
JLT CAI
SCT Xcal2 93 Octane tune
JBA spark plug wires
NGK Iridium IX spark plugs
Steeda short throw shifter
FRPP T-Lok & 3.73 Motive gears.
Steeda upper & lower control arms
Take-off GT sway bars
SMR Strut Tower Brace

 

Typically, backfires in the exhaust are ignition related. You may have a plug or plug wire breaking down or mis-fire due to point contact crud.

 

Check you fuel filter. It sounds like you are not getting adequate fuel. What is your fuel pressure when this happens? It sounds like you are running lean when you open it wide open, which is the popping you are hearing. How does it smell when it does this? Does it smell like fuel or does it smell like burning oil?

Also, it could be bad gas. An easy fix is to put a combination of HEAT, SEAFORM, STABIL, and known good gasto get rid of water and bad gas.

My bet is an intermittent fuel pump issue or fuel delivery issue. Again, check your filter and check the fuel pressure when it acts up if you can.

 

Thanks guys,

I started with checking the plugs and wires again and they were good. Then I checked the gas itself and there was no actual sign of water in it. Hhhmm, interesting. Since I already had a new fuel pump and filterI decided to go for the points asI already knew they were starting to go (my mechanic told me about 3 weeks ago). But the pointswere a lot worse than I thought, no only that, the plate where the points are mountedseemed allout of wack. So I took everything out of the distributor, cleaned it and re-assembled it with new points.The problem went away. Yeah! Nice car cowboy...

Cheers,


1972 Mustang Fastback
351 Cleveland 4-V
Holley 750CFM Double Pumper
Hooker Headers
C6 Auto

2006 Mustang (5 Speed V6 Premium)
(14.6 sec. 1/4 mi.)
GT take-off dual exhaust w/ Custom H-pipe
Mac Headers
JLT CAI
SCT Xcal2 93 Octane tune
JBA spark plug wires
NGK Iridium IX spark plugs
Steeda short throw shifter
FRPP T-Lok & 3.73 Motive gears.
Steeda upper & lower control arms
Take-off GT sway bars
SMR Strut Tower Brace

 

OK, it has been a few days now, and I am beginning to get a better feel of the car. Thereis still no more backfire or stalling as before. The car is also easier to start with the good points and cleaned up distributor cap and rotor contacts. However, it would seem that if I maintain constant speed on the highway for example, after several miles,when the engine is completely warmed up, it will begin to hesitate like itmay bestarving for gas or there is bad gas. So I guess my original problem was a combination of problems, jlg2002 and urban_cowboy were both right. I will finish this tank of gas and then fill-up with good gas and see what happens. If that doesn't work then I will need to look deeper into the fuel system.

Cheers,


1972 Mustang Fastback
351 Cleveland 4-V
Holley 750CFM Double Pumper
Hooker Headers
C6 Auto

2006 Mustang (5 Speed V6 Premium)
(14.6 sec. 1/4 mi.)
GT take-off dual exhaust w/ Custom H-pipe
Mac Headers
JLT CAI
SCT Xcal2 93 Octane tune
JBA spark plug wires
NGK Iridium IX spark plugs
Steeda short throw shifter
FRPP T-Lok & 3.73 Motive gears.
Steeda upper & lower control arms
Take-off GT sway bars
SMR Strut Tower Brace

 

I am posting this for the benefit of others who may some days experience similar problems with their car. After replacing dist. cap, rotor, wires, coil, points, fuel filter, fuel pump, and rebuilding the carburator the engine was still sputtering and missing heavily, eventually getting to the point of being undrivable. The last 2 parts that were replaced were the solenoid switch and the distributor itself which was pretty worn out upon closer examination. I have also learned that electical wiring and the ignition switch can cause similar issues on this type of cars (related to voltage to the coil). Anyhow, the car is now running great for a few weeks without any sign of trouble. Thank agains to those who have helped me with this. It wasn't an easy one.

Cheers,

 

Cool!

I was having similar problems until I did a distributor as well. Now my car runs like an 08.