Hi all,

I have a 68 GT500 with the PI428 in it and have had this issue with it over the past few weeks since I had the engine rebuilt. The car starts right up, idles smooth and runs strong...but once it gets hot, say over 210 degrees it starts to idle a little rough.. (stopped or at low speeds), then most of the time it begins to stall and I have to keep the rpm's high or it will stall. Then it wont start back up.

Now when I say wont start... I mean nothing! No clicks, no turning, no noise or anything...even the engine light is very, very dim. Now if I let it sit for about 30 minutes and it cools down, it starts right up again and runs great. But once hot, it starts this all over again. The car for the most part has all new parts and there is only about 750 miles on the rebuilt motor. Any thoughts?

Thanks

Skeet

 

Strange indeed.

Heat is a killer of many things, including electrical, however, if it's a heat related issue, the electrical wouldn't just come alive again. Hot running issues points towards fuel delivery. I'd start at the choke and work backwards. As far as the electrical issue, you may need to start at the battery with a meter and start testing things till you trace the gremlin.

Have you put a meter on it when it would not start? Does the battery have 12+ volts? You may just have bad electrical connections causing (all) your issues.

Keep us posted.

 

Have you checked the negative battery connection at the block to insure it is clean metal to metal contact. Also clean you battery posts and terminals.

BTW: That's pretty hot for a Ford. You really want to keep that thing about 180*F.

Good luck,

 

As for not starting I would look at the starter they get hot and will not turn but after they cool off they will. As for the running rough I don't have a clue. I would put a cooler termastat in it 210 is to hot for these early motors

 

This is the darnest thing. Car ran great until this rebuild...then this crops up.

Battery is about 5 months old and always has a full charge. I have placed it on a charger serveral times when this has happened and it just goes to trickle due to having a full charge.

Not sure if fuel delivery or choke is an issue as it actually does not turn over nor crank...no click when key is turned, no starter sound...nothing....kind of like a dead battery.

Block was cleaned and freshly painted during the rebuild. I may remove the ground and scrape some of the paint off and reapply to see if that helps.

Any thoughts on soleniod? Thanks

Skeet

 

Try shorting across the solenoid when it is hot and see if the starter turns her over. If so, replace the solenoid. You may also have a weak or bad coil. These cars run about 190-210 degrees at operating temperature, so you are not overheating.

 

Hi I have a friend with a GT 500 and has the same problem, he thinks that the problem is common on GT500 s because of the compression of the engine, that it what he blames it on, as the engine cools down you have less compression so the starter manages to turn the engine, that is the explanation he gave me while waitin for his engine to cool down.

 

Do you really believe that crap?

 

Yeah that's what I thought...the car does run 200-210 normally even before this all started.

I will fire her up tomorrow, run her around until she starts to act up and stalls. Then I'll try the old by-pass soleniod trick to see if she starts. If she does, I"ll be looking for a new solenoid.

I'll also redo the ground and check all connections as well. I'll keep you posted. Thanks everyone.

Skeet

 

As someone suggested when the temp under the hood gets high some main connection is coming loose.

Since the problem is connected with an engine in and out and it is a general power loss the first thing I would check is the body ground. There should be a braded wire ground strap between the back of the engine and the cowl. Usually in the intake manifold area or possibly to the back of the right head.

It had to have been disconnected during the engine work and possibly it was not re connected.

The other obvious place as someone else mentioned is the ground cable between the battery neg terminal and the engine. Check this carefully