Engine stalls after 30 minutes

[68chrgrguy]

Hi All,
Question for everyone. My Cordoba developed a problem that I can't seem to troubleshoot. After about 30 minutes of driving, the engine stalls. Sounds like it runs out of gas, in other words, it doesn't just shut off. Then, it stalls about every five minutes after. Each time, I wait a few minutes and it restarts.
Engine specs: 408 stroker, Indy LA-X heads, Holley 750 vac secondary, Holley blue pump and return style regulator with 3/8 lines to and from. MSD 6AL (about 15 years old) MSD pro billet distributor
Things I've tried: New fuel pump. New cap, rotor, mag pickup, wires. Rebuilt the carb and new filters.
Everyone is probably thinking vapor lock, but, it has NEVER vapor locked before. Hot days, hours on the road, never had the problem. With the elec fuel pump and return regulator it shouldn't be a problem.
Reason I put this in the Electrical & Ignition is I think it could be the ignition switch under the column.
Any ideas or suggestions would be great! Thanks.

 

[ruffcut]

I would try a new coil.

 

[Don Frelier]

Could be junk built up on the sending unit pickup screen.
Have you ever had the sending unit out of it?

 

[WileERobby]

I would check the sock inside the tank. I would check the choke operation as well.

 

[68chrgrguy]

I would try a new coil.

I forgot to mention. I did a new coil too.

 

[68chrgrguy]

I would check the sock inside the tank. I would check the choke operation as well.

I'm not using the stock pickup tube. Have a rear sump welded into the tank with a pre-filter to the pump.

 

[68chrgrguy]

Could be junk built up on the sending unit pickup screen.
Have you ever had the sending unit out of it?

Not using the stock pickup tube, I put in a welded rear sump.

 

[Red63440]

Check your starter and starter relay.

 

[68chrgrguy]

Check your starter and starter relay.

Never thought of that. Do you think it maybe loosing voltage at the relay and then to the MSD box?

 

[Nevada dan]

I would check where your getting the power for the msd , put a voltmeter on it to see if it maintains

 

[68chrgrguy]

I would check where your getting the power for the msd , put a voltmeter on it to see if it maintains

This is why I was thinking it could be the ignition switch. If it's failing, or corroded, it might drop volt to the entire system.

 

[Red63440]

Never thought of that. Do you think it maybe loosing voltage at the relay and then to the MSD box?

I had pretty much the same problem with mine. I updated my starter and relay and the problem went away. I could drive less than 15 minutes towards the end and would have to have the car towed home. Starter would drain the battery down to nothing but after sitting and cooling down it would start with a jump. Starts right up now with no issues.

 

[68chrgrguy]

I had pretty much the same problem with mine. I updated my starter and relay and the problem went away. I could drive less than 15 minutes towards the end and would have to have the car towed home. Starter would drain the battery down to nothing but after sitting and cooling down it would start with a jump. Starts right up now with no issues.

Sure have me thinking. Sounds familiar. I also moved my battery from the trunk to back under the hood. Seemed to help a little, but not fixed yet. I built the car 15 years ago, and starter and relay are getting old. I'll have to check them.

 

[70ChargeDodger]

Have you replaced the p.u. in the distributor? Mine was heating up and dying in my 70 Charger, replaced everything else before I tried that, good luck.

 

[dadsbee]

Take the tank filler cap off and go try it again..

 

[BDF6]

Is your wiring in good condition? Notice anything 'iffy' at coil connections?

 

[68chrgrguy]

I did replace the magnetic pickup in the distributor, no change.
I'll have to try the fuel cap, kinda makes sense.
I re-wired the car when I built it, been looking at everything, looks good so far

 

[RGC440]

Did you bypass the inline resistor when you installed the MSD?

 

[68chrgrguy]

Did you bypass the inline resistor when you installed the MSD?

Yep, ballast resistor removed when I put in the MSD distributor and 6-AL

 

[PurpleBeeper]

Well....the 30 minute thing makes all the comments above make sense. You've either got an igntion component heating up and malfunctioning or fuel isn't getting where it needs to go. Do me a favor please? Next time it happens, but your hand on the carburetor and hold it there for a full 30 seconds. It does "sound" like vapor lock.

Fuel (as mentioned by others)
trash in tank that keeps blocking the pickup sock, then falling back off it when engine is off
vapor lock
fuel pump fading
fuel filter
tank not venting
dirt in needle/seat of carburetor

Ignition (as mentioned by others)
pickup
ignition box
coil

I hadn't thought about the ignition switch...hmmm.. I'd expect if the igntion switch was the problem the "time" wouldn't always be 30 minutes.....maybe doesn't happen for a week, then twice in one day....more randomly