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car shuts down when i'm driving it!

Philip Ferguson

Philip Ferguson

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Mississauga, Ontario
Thanks for everyone's help on my cam situation. I actually did go out and buy an FSM for the car...nice guide to have handy in restoring and maintaining these old cars! As a reminder, I've got a numbers matching/original drivetrain '68 Plymouth GTX.

OK, I know these engines give off a lot of heat...especially with the hot weather we've been having here. But just today after the car had been sitting for a good 30 minutes, it started up and as I was driving along it just lost power and shut down on me. It happened to me a couple of times before. Usually after waiting about 15 minutes I was able to start it up and drive off - same case as today.

Is it possible that the engine is experiencing "vapor lock"? Or, maybe it's time I should be recoring the rad...it's likely been in the car since it rolled off the line in 1968.

The ignition and battery has been recently updated...I checked the PCV valve and it moves freely. I did notice that the needle on the factory temp gauge was definitely to the right of the mid-point but even just left of the mid-point, the car had shut down on me.

I appreciate any advice on getting this fixed in case I end up somewhere I don't want to be with this issue!

Phil.
 
Don't give up on original core unless there something wrong. I had a radiator recored (26" 3 rows) in the 80's and ran hot in traffic in hot weather, 90's. Found a correct 948 radiator never recored cured the over heating . The fins between tubes were S shaped not V shaped like on recore.
Weak fuel pump. There will be more suggestions .
 
Many things possible. Is this a new problem, or has you car done this since you owned it? You mention engine temperature, and right side of middle and left side of middle. Does the engine puke coolant or steam when it shuts down? You said it typically starts back up in about 15 minutes. Fifteen minutes is not a long time for an engine to cool down. So if waiting 15 miuntes and it starts again, does it shut off again or it is okay? To me the 15 minute thing indicates other things that could be wrong. Fuel pump itself. Crap in the fuel tank. Plugged fuel filter if you have one. Coil overheating and quits. Fuel tank vent not functioning. When this happens, have you tried cranking the engine and have someone look to see if there is spark?
 
You mentioned recoring the radiator, is it getting hot... 200 or less isn't a problem. What your describing sounds like boiled fuel in the fuel line except the fact that it starts after 15 minutes (boiled fuel in the lines usually just requires a few seconds of cranking the motor)? If it is it will usually happen most often after you've either been in stopped traffic or after a short stop. If it's firing right up every time then it sounds like the carb isn't boiling.
 
Is it like someone turned off the ignition and threw the keys out the window? Check bulkhead connectors. Gently. Or does it stumble first. Get a digital temperature gauge to be sure of temps.
 
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Two things to check for when it quits running
1 is the coil producing a good spark?
2 is there fuel in the carb?
Start there & see what is missing.
Coils have known to get hot & quit
No fuel could be float level,boiling fuel
or fuel pump
 
Did you convert to electronic ignition
if so the pickup could be bad
 
If you get a sudden shutdown, it's fuel or spark. As stated, check immediately if you have any squirt of fuel in the carb. If not, probably vapor lock. Otherwise, a loose bulkhead connector, loose primary wire, bad ground, reluctor faulty, etc. Like Alfred e. Newman said previously.
 
my rad is oem from 67 and and is perfect. it sounds like vapour lock , i would check that you have spark when it happens.
and then you know where to go.and it was 98 degrease here today , and sticky , felt like 113 they said on the radio
 
It sounds like an electrical issue to me. Did you upgrade to electronic ignition? If so, probably a grounding issue. (lack of a good ground) If the engine doesn't have a good ground, the coil will overheat and open the circuit. When it cools down it will run again for a while. Same thing will happen with an electronic ignition. The plate coil in the distributor can open when it gets too hot from a bad ground. Or the spark controller will overheat and open if the box is not grounded on the firewall. Check those grounds with a digital ohm meter from the neg post on the battery. A good ground is .3 ohms or better.
 
Thanks for the comments thus far. Because the cam pushrod that works the fuel pump is worn, I'm using an electric fuel pump for the time being...it was in the car prior to me upgrading the ignition but we re-installed it correctly with its own relay. I don't think its the ignition - we checked the grounds and everything was good when we installed everything...including a brand new coil.

I'm wondering if that electric fuel pump is pumping strong enough though...I'll check that out. I've experienced vapor lock up here before especially with the temps we had this past week...the other two times it happened to me was when it was also hotter than usual and extremely muggy...
 
Do you have an aftermarket temp gauge? If so, at what temp was this shut down happening?
What temperature thermostat are you running?
You never answered the question "points or electronic" ignition?
And again, are you getting fuel squirting from the accelerator pump after this shut down occurs?
All these answers will lead down a different path.
 
No, I don't have the aftermarket temp gauge so I'm unsure as to the temperature that the engine is shutting down. It happened with the old points ignition and it's happening with the new electronic ignition. I'll need to check and see if fuel still squirts into the carb when I try to start it again.

On one occasion though, I noticed the fuel filter was dry (it's an old glass type)...that's why I'm wondering if the fuel pump is operating effectively.
 
I'm sort of a novice when it comes to electric fuel pumps but they are man made so failure sure is a possibility. I do understand placement and positioning can impact how well (or not) the pump runs. Since this problem seems to happen mostly during higher temperatures I wonder if the pump itself is maybe too close to exhaust pipes or something else heating it up.

I though about going electric fuel pump but it seems to me there just isn't enough room to mount one back close to the gas tank and stay clear of the exhaust pipes so I'll just stay with the mechanical pump for now at least.
 
I might have missed it, but I havent seen where you describe how its shutting down, spit sputter or like the ignition was turned off like @Dennis H asked???
If its instantanious like the ignition being turned off, 99% sure it's electrical. Electrical components/connections are affected by heat and can cause gremilins as you have described. If your electric fuel pump is wired into the switched side of your fuse block it (problem) can be 2 fold. Switch or bulkhead connections are loose/bad, when they heat up, the contact required is broken....the heat is created not only from ambient temps but the amp draw, the less contact pressure you have causes the amps to increase which causes even more heat until the circuit opens. When it cools down it will have enough pressure to make the system act normal until it heats up again.
 
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Gold Rush said:
Reread the first post.
Click to expand...
His description of losing power, IMO isn't as clear as it could be. If the car is down on engine power still running an dies fuel, which what it sounds like. Most electrical problems car just shuts off.
 
Philip Ferguson said:
Thanks for the comments thus far. Because the cam pushrod that works the fuel pump is worn, I'm using an electric fuel pump for the time being...it was in the car prior to me upgrading the ignition but we re-installed it correctly with its own relay. I don't think its the ignition - we checked the grounds and everything was good when we installed everything...including a brand new coil.

I'm wondering if that electric fuel pump is pumping strong enough though...I'll check that out. I've experienced vapor lock up here before especially with the temps we had this past week...the other two times it happened to me was when it was also hotter than usual and extremely muggy...
Click to expand...
Not sure how "new" the electric pump is. Exterior (not in the tank) electric fuel pumps are less reliable than in-tank pumps. But, here are some pointers for electric pumps (not mine):

Do not run them dry. Run a filter before the pump. Keep them as close to the tank as you can (electric pumps push fuel much better than they can pull it.) Keep them away from heat sources such as exhaust. Electrical power, need to have the correct wire size to it, relay is preferred. Grounding of it is critical. This will kill pumps real quick.

Good luck!
 
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