68 big block very hard to start when hot.

[Brandon T.]

I have a 68 big block that starts fine the first time after pushing the gas pedal once. After I drive it for a while and cut it off, it is very difficult to get started. Any ideas are welcomed.

[William F.]

Re: 68 big block very hard to start when hot.

Had this trouble with a '67. Found out corroded solenoid wasn't giving full 12 V to coil as it should when key is turned to "start." Check to see full V going to solenoid and then giving full 12V to coil in start position. Could also be fuel percolation.

[Joe R.]

Re: 68 big block very hard to start when hot.

Brandon,

Is the choke set correctly?

Joe

[Brandon T.]

Re: 68 big block very hard to start when hot.

Not sure, how should it be set? When it is cold i can push the gas pedal one time and it starts good. When it warms up I almost run the battery down starting it.

[Joe R.]

Re: 68 big block very hard to start when hot.

Brandon

With the engine hot, take off the air cleaner lid to see if the choke is closed. I resorted to holding the choke open with my wallet one time on the road in my 65 Chevy pickup when it wouldn't start hot. My ex girlfriend was impressed! It would be more impressive if I knew how to adjust the choke, but I don't. Did you look in the service manual?

Joe

[Michael D.]

Re: 68 big block very hard to start when hot.

Heat soak. My 74 used to do it. As suggested, check the starter solenoid and ensure the starter heat shield is in place.

[Brandon T.]

Re: 68 big block very hard to start when hot.

It turns over fine just acts like it is flooded or not getting any gas.

[Brandon T.]

Re: 68 big block very hard to start when hot.

What do you do about fuel percolation?

[Clem Z.]

Re: 68 big block very hard to start when hot.

if it turns over slowly when it is hot i would use some top engine cleaner to get the carbon off the top of the pistons as that is holding heat causing the piston to expand in the bores. i had a 454 chevy and a 70 caddy that had this problem. there was a GM bulletin on this. this does not apply of you have a SHP 427 engine with forged pistons as their clearance in the bore is greater than the cast . with the caddy i would just pump the gas about 10 times and wait for the cool gasoline to cool off the pistons.

[Richard M.]

Re: 68 big block very hard to start when hot.

Try some Avgas

[Richard E.]

Re: 68 big block very hard to start when hot.

I found that using pure Sunoco high octane race fuel($9.80 a gallon) cured the problem for my 67/435...

[Rich G.]

Re: 68 big block very hard to start when hot.

If you try it with wide open throttle (gas pedal on the floor) and it starts, it was flooded. My 68 427/435 floods itself when it's hot and it sits for a while. Other suggestions above are good. This is an easy way to tell if it's flooded or dry.

It has helped me having to figure out how to start hot Lycoming fuel injected engines on airplanes. They tend to flood themselves when sitting hot. Wide open throttle and mixture at idle cut off is the only way to avoid a dead battery

Rich

[Keith S.]

Re: 68 big block very hard to start when hot.

Heat soak. My 74 used to do it. As suggested, check the starter solenoid and ensure the starter heat shield is in place.

I had the exact same problem on my '74 big block, usually after a long highway drive. Replacing the starter solenoid and installing the missing heat shield made a huge difference. Never had any gas smell or Q-jet issues that I can remember.

[Brandon T.]

Re: 68 big block very hard to start when hot.

Thanks for the information but I don't think I want to buy any $9.80 gas.

[Ken A.]

Re: 68 big block very hard to start when hot.

If you have original TI ignition, then the old amp has a heat problem due to using germanium transistors. They quit above 200 degrees and won't fire the coil.