I'm stalling too, different issues

[machm1970 180]

My '70 302 stalls randomly, not necessarily accelerating, decelerating, etc. I will be driving and it acts like the ignition just acts like it shuts off, sometimes it will quietly diesel for a few seconds before it dies. It had a pertronix ignitor on it, the tech at pertronix thought it was a bad ignitor, so I swapped back to points. I have an Autolite 4100 with everything set to specs. Everything is new in the last year, rebuilt carb, new fuel lines, new battery, regulator, solenoid, pmg starter, wiring all looks good. I also replaced a leaking pertronix coil a a new gas tank last week. I do have shorty headers, but the fuel line isnt close, when it stalls it restarts usually right away.Any ideas are greatly appreciated, I'm all out.

Thanks,

Matt

[barnett468 418]

I would set the float levels to 1/2" to start with although i doubt that has anything to do with your problem.

 

disconnect and plug the distributor vacuum line.

 

try to turn the dist rotor to make sure it moves properly and has some spring preload on it . if it iitially moves with no resistance, it may have a broken spring but this should not cause your prob.

 

park in a shady area then pull the coil wire out of the distributor and hold it 1/4 to 3/8" away from a carbureor not or unpainyed bolt then jump the solenoid to see what the spark looks like . if it is weak and pale yellow, your coil is weak but that still may not be the prob . if it is pale blue, your coil is very good. the

 

If you have a electric choke and it is connected to a wire that eventually powers the coil, i would disconnect it then connect it to the proper post on the back of the alternator then turn the key on when the engine is cold and see how long it takes to fully open . if it opens in 3 minutes or less, it is "ok" if it opens in slightly less time it is better if it takes more than 3 minutes, you might try adjusting it . you could also disconnect the wire then fully open the choke for now until your prob is resolved but the wire sould not be connected to the coil power wire.

 

if your car starts right away, it may have rust in the gas tank . the rust can get sucked up around the in tank fuel filter and stop the gas flow . after the car dies, there is no longer suction so some of the rust can fall off which will then allow the fuel to flow again . i have had this particular problem several times on different mustangs.

[MichaelJames 12]

Can I ask why the choke wire should not be connected to the coil? Is this only for a setup where the coil is not getting 12v due to the resister wire?

 

My electric choke is connected to my coil, but I bypassed my resister wire completely so I have 12v going from ignition switch directly to the coil. Of course I am also having some stalling problems myself only when accellerating from stop position. I'll be watching this thread closely. :)

[machm1970 180]

Thanks guys, I will have to mess with the technical aspects later on. I do have an electric choke, it's connected to the stator terminal on the alternator. I replaced the gas tank last week as well as the sock filter inside. I will check on the other things tonight or tomorrow and post the results. I do really appreciate your help.

Matt

[Dave R. 85]

I like barnett's ideas. I'm in favor of the coil being bad. Check it first. Sounds electrical to me since the fuel tank and filter are new.   Dave R.

[barnett468 418]

Can I ask why the choke wire should not be connected to the coil? Is this only for a setup where the coil is not getting 12v due to the resister wire?

 

My electric choke is connected to my coil, but I bypassed my resister wire completely so I have 12v going from ignition switch directly to the coil. Of course I am also having some stalling problems myself only when accellerating from stop position. I'll be watching this thread closely. :)

the choke wire takes voltage from the coil wire if it is connected to it . this can cause a misfire . had it happen a few times.

 

it is less of a problem when the resistor wire has been bypassed, however, the correct way to connect it with an orig ford electric choke is to the alternator but those were 9 volt chokes and the alt terminal is 9 volts . sometimes a 12 volt choke will open slowly when connected to the 9 volt post and sometimes it will open nearly as quickly as it would if it were connected to 12 volts . its just something that should be checked if connected to 9 volts.

 

your acceleration problem is not likely electrical . it is either jetting, power valve, and/or ignitiontiming and we can tell you how to diagnos and fix it if you want to start a new thread . very common problem that is usually easily fixed.

 

.

[machm1970 180]

Is there a way to test a coil? The one in there now is a brand new Accel unit, the Pertronix one was definitely bad and was leaking oil.

Thanks,

Matt

[1969_Mach1 333]

Have you tried rebuilding the carb to be certain it is clean inside and didn't get any crud in it from the old fuel tank?  When ignition coils fail it is usually a abrupt turning off of the engine or violent on and off conditions while you are driving.  Make sure your Accel coil is connected with the correct ballast resistor. original resistor wire, or a combination of both, whatever the instructions for it indicates.  Make certain the inside of the distributor cap is clean, no carbon tracking, and the rotor is good.

[machm1970 180]

I did some detective work last night and looked up how to test a coil with a multimeter. I looked at Summit's website and it lists the primary resistance for this coil at 1.4 ohms, I got 1.6, so probably good thrre. The secondary resistance is listed as 9.2, I can't get a reading at all. More and more the symptoms do seem like a coil, runs good for a bit until warmed up, then frequent stalling.

[det0326 179]

that 9.2 value is 9.2K ohms. Did you have the meter set on a scale high enough to read this valve, some VOM's are auto detect and some have to be manually changed.

 

Dave

[machm1970 180]

Yep, it was set right. When I pulled off the neg push on connector from the coil, the metal part inside the push on connector broke off, may have been like that before, that would explain alot.

[barnett468 418]

I did some detective work last night and looked up how to test a coil with a multimeter. I looked at Summit's website and it lists the primary resistance for this coil at 1.4 ohms, I got 1.6, so probably good thrre. The secondary resistance is listed as 9.2, I can't get a reading at all. More and more the symptoms do seem like a coil, runs good for a bit until warmed up, then frequent stalling.

I mentioned one extremely easy way to test the coil . The meter will typically only telly you if it is completely dead or not.

[machm1970 180]

I will check that out. I thought I was making a little progress. I made a new wire from the dist. to the coil, it seemed to run better so I went for a test drive, died twice while coming to a stop (this is new as before it was just randomly). One of the times it took me a bit to get it started. I have changed the jets in the 4100 several times, maybe the tab got bent and altered the float level. I will check the coil using the other method too.

Thanks,

Matt

[barnett468 418]

I will check that out. I thought I was making a little progress. I made a new wire from the dist. to the coil, it seemed to run better so I went for a test drive, died twice while coming to a stop (this is new as before it was just randomly). One of the times it took me a bit to get it started. I have changed the jets in the 4100 several times, maybe the tab got bent and altered the float level. I will check the coil using the other method too.

Thanks,

Matt

the coli test method i mentioned is an old school standard, however, it cannot detect an intermittent prob . intermittent probs with coils are nearly unheard of however and will typically show up after around 5 minutes or a little more when the coil gets hot . if it dies in less than 5 minutes from first starting it, it is extremely unlikely that it is a coil prob.

 

you can also try another coil . if you don't have a similar one on another car, i think rock auto has them for maybe $15.00

[1969_Mach1 333]

Intermittent problems are sometimes difficult to diagnose.  Especially in cases like this when the engine immediately restarts.  The approach is often check components to make certain they are okay.  When you find something like the resistance of your coil being far out of range, replacement is the best path.  Otherwise you are constantly guessing which of many items it could be.

 

Theoretically, when electrical component failure is heat related, a cooling time is needed before the problem corrects itself (until heated up again).  But, in reality that's not always the case. 

 

I'd replace the ignition coil like others have mentioned.  If that doesn't fix the problem, are you certain the carb is clean inside?

[machm1970 180]

Carb is clean, I double checked the floats and changed the fuel filter. I noticed the metal fuel line going from the pump to the carb is almost too hot to touch (shorty headers added a couple weeks ago). The fuel line gets pretty close to the t stat housing almost touching it, so I'm rerouting that too. I will keep you posted on the progress.

Thanks again for all your help!

Matt

[1969_Mach1 333]

My fuel line routes close to the thermostat housing as well.  I haven't had any issues.  But I don't drive it on hot days and I have an insulating sleeve over the fuel line.

[albarnett_99 13]

I feel your pain as I have been dealing with similar issues. Start with the coil. My experience is you can have intermittent coil problems.

 

Follow the advice given here and consider adding some heat reflecting material on your fuel line from the pump to carb. Change all fuel filters also. This will rule out fuel related causes.

 

I don't think percolation is your problem here (my experience with percolation is the motor dies at a stoplight when under hood temperature rises). My guess is it's coil failure. I also replaced the solenoid when I changed the coil.

[machm1970 180]

I had time to play today and think I figured it out. I swapped to shorty headers over the winter and switched jets a few times, apparently in doing so the tab on the float got bent, the idle mixture screws needed adjustment too. I adjusted the floats to 1/2" and used a vac guage to adjust the idle mixture. I had time to take it for a 20 min drive, so far so good. On a side note I sent the Pertronix ignitor back for warranty, I called today and they said their warranty claims are 2 weeks behind!