Won't start when warm

D

damo605

Member
Hi Everyone!

I hope someone here can help - I have a '68 Buick LeSabre 400 which starts OK from cold but will not start when hot. This started happening a few months ago but was only an issue on really hot days (Rare here in Ireland) but has now progressed to the point where she won't start at all, no matter what the outside temp, once engine is warm! After spending well over an embarrassing hour this evening stuck in a supermarket car park trying to start her it's time to solve this problem once and for all :angry:

This is a weird one: Plenty of fuel getting to the carb. Spark to the HT leads. Pulled the plugs and they don't get wet even after lots of cranking (Look almost bunt). Originally thinking the fuel wasn't getting from the carb down into the engine but not sure now....

Here is the thing - When it eventually does start warm - it's at the exact instant when I let go of the key from the cranking position. The rest of the time when she won't start (Which is most of the time when engine is hot) when I let go of the key (From cranking position) the engine gives a cough/rattle/bang as if it just caught and tried to start.

She's tucked up in her garage now and won't move again until this problem is sorted - If anyone has come across something like this before or has an ideas I'd greatly appreciate your input!

Thanks a million,

Damo.
 
damo605 said:
Here is the thing - When it eventually does start warm - it's at the exact instant when I let go of the key from the cranking position. The rest of the time when she won't start (Which is most of the time when engine is hot) when I let go of the key (From cranking position) the engine gives a cough/rattle/bang as if it just caught and tried to start.
Click to expand...

Makes me wonder if it is related to the 12V wire running to the coil in the start position. Maybe try getting it warm to where it is having the problem, then "hot wire the coil", run a wire from the + side of the battery to the + side of the coil and see if it starts. If it does, then it will be a break in the 12V start wire. It may be that it has a connection at the starter motor and has just fallen off or broken.
 
Could/may also be the starter solenoid is not making an internal contact to the Yellow wire going to the coil in the start position.
 
Thanks a million Bob & Telriv for your suggestions, really appreciate it!
Have her booked into my mechanic for this week so I'll give him this info ;-)
I'll update when I have news!
Thanks again....
 
Bad Ground or Bad Ignition Switch????

Some other things you might want to check:

1. A few times that I had hot restart problems - It turned out to be a bad ground from the engine to the frame or body. Sometimes ground straps get disconnected and never reattached. Check them - it can't hurt!! There should be a braided ground strap on the passenger's side between the engine and the frame or the firewall. Check it!!!

2. Since the engine wants to start when you release the ignition key - check the ignition switch itself - could it just be worn out????

Thanks,
BluesBrothersBuicks
 
There should be a braided ground strap on the passenger's side between the engine and the frame or the firewall. Check it!!!


the 'better than factory' solution is to run the primary battery ground to one of the starter mounting bolts. then you ground strap the rest of the car to that.
 
Hi - Just to update this... You guys were spot on with your replies! Hotwiring the coil as Bob suggested worked and turned out to be worn ignition switch as BlueBrothers suspected which gave poor current to the coil when hot.
As spare parts not easily to hand here my mechanic just fitted a relay to give a solid feed to the coil when starting and problem solved so happy days :))
Thanks for your input and direction, much appreciated!!
Damo.
 
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