Hard Start When Warm

forcarlb · October 1, 2008

Hello, I recently purchased a 1982 GMC pickup with a 6.2 diesel in it. It turns over and starts fine when it's cold, but after I've driven it long enough to get it warmed up and turn it off, I go to start it back up and it turns over slowly and is hard to start.

Any ideas?

Thanks,

Carl

merlin5577 · October 2, 2008

Ok.......... Bit of advice...........when posting on a website like this, the more information you give the better. How many miles are on the truck? Transmission type? Etc... Since posters cant see the truck we rely on this kid of stuff to help.

With what you have given I can only guess. Have you changed the fuel filter? Or even know when it was changed last? That would be my first order of business. The 6.2s are really picky about fuel pressure and a clogged filter will cause that kind of trouble.

forcarlb · October 2, 2008

Ok.......... Bit of advice...........when posting on a website like this, the more information you give the better. How many miles are on the truck? Transmission type? Etc... Since posters cant see the truck we rely on this kid of stuff to help.

With what you have given I can only guess. Have you changed the fuel filter? Or even know when it was changed last? That would be my first order of business. The 6.2s are really picky about fuel pressure and a clogged filter will cause that kind of trouble.

Hello again, sorry about the sparse info on the 1982 GMC. It was said to have 99,000 miles on it, but of course it's hard to tell with old odometers only going to 99,999 and it has an automatic transmission.

I haven't changed the fuel filter, which I'll do now that you mentioned it. So, even though it turns over easy and starts fine when it's cold, a bad filter would cause the engine to be harder for the starter to turn the engine over when it's warm? I'll change the filter today. Thanks for the advice. Have a great day.

Carl

95Sierra2500 · October 2, 2008

Booster pump or injection system. My dad had an '86 that had the exact same problem you are describing. He wouldn't shut it off unless it was going to be off for a long while and GM techs couldn't figure out what was wrong. Took it to a place that used to be Detroit Diesel in Saginaw and those were the two options he gave 'em. Replaced the booster pump and the problem went away.

merlin5577 · October 2, 2008

Ok.......... Bit of advice...........when posting on a website like this, the more information you give the better. How many miles are on the truck? Transmission type? Etc... Since posters cant see the truck we rely on this kid of stuff to help.

With what you have given I can only guess. Have you changed the fuel filter? Or even know when it was changed last? That would be my first order of business. The 6.2s are really picky about fuel pressure and a clogged filter will cause that kind of trouble.

Hello again, sorry about the sparse info on the 1982 GMC. It was said to have 99,000 miles on it, but of course it's hard to tell with old odometers only going to 99,999 and it has an automatic transmission.

I haven't changed the fuel filter, which I'll do now that you mentioned it. So, even though it turns over easy and starts fine when it's cold, a bad filter would cause the engine to be harder for the starter to turn the engine over when it's warm? I'll change the filter today. Thanks for the advice. Have a great day.

Carl

Yes, the engine is starting because it can burn the fuel already in the injection pump. If the filter is clogged (a lot or a little) the lift pump cant push enough fuel through the filter to the injection pump to keep the engine running.

If you change the fuel filter and that doesnt work pull the fuel line running from the lift pump to the injection pump off and check the fuel pressure. As 95Sierra2500 stated the lift pump might be on its way out the door. Since your in there already, have someone key over the engine to start it while you put voltmeter on the lead to the lift pump. If the pump isnt getting 12volts you have a electrical issue.

Welcome to the site, hope you stick around. We need pictures!

Edit; If all else fails you can always sell the truck to me cheap.