6.2 wont start when warm

[OzzyGMC]

Help please guys. I have a 6.2 in a 83 Sierra 1/2 ton. She will fire up fine from stone cold and at a temp where the GP system operates. but when she is warm just below 200 on temp gage she will just turn over and not fire, If I leave it for 1/2 hour to an hour she will fire again no worries.

Is this a problem with the GP or is there something else. Air Temp today was around 75. ( I'm Downunder in Australia)
Cheers
Terry

[Robyn]

WELCOME TO TDP

With about 1/2 tank of fuel, dump a couple quarts of motor oil in the tank and allow it to slosh around and mix, or better yet, add the two quarts of oil to a jug and then add some diesel to mix it, then dump in the tank.

Allow to mix well then see how this starting issue goes.

If there is improvement, the issue is that the rotor head in the injection pump is worn out and at high temps the plungers are leaking too much and not making enough pressure to "POP" the injectors.

If this is the case, its time for an injection pump.

Missy

[OzzyGMC]

Hi Robyn, thanks for the welcome, you certainly seem to be a wealth of knowledge when it comes to these engines.

I went to try your suggestion today, put the oil in the tank and took off to town. Unfortunately I didn't get to see the result as my starter motor decided it has had enough.Waited until I was 30 miles from home of course!:mad:
I think it is the solenoid, it clicks but is blowing the 20 amp fuse I have in the pull in circuit. So my truck got to ride home on the back of a tow truck.

It does make me wonder if it is a cranking speed issue that I am having. have to wait til the starter is rebuilt, I guess.

In my original post I said that the Temp gage was sitting just under 200 deg, I realized this morning that I miss read the gage and it is actually sitting just under what I believe would the 150 mark. Does this change your thinking on what could be?

Thanks again for letting me pick your brains, it is much appreciated.
Terry

[Robyn]

A warm engine should "POP" right off with very little starter time.

Get your starter fixed then check it again.

The other thing could be that the POP pressure on the injectors is very low and the spray pattern is poor.

This condition will cause some tail pipe smoke (blueish) at idle even when hot.

Give it a go when the starter is back up and going and keep me posted.

Robyn

[JohnC]

You can try manual glow plug activation to see if that makes any difference. It won't fix anything, but it might mask the symptom for a while.

[OzzyGMC]

Hi guys sorry it has taken a while to get back to you. I got my starter motor back with a new solenoid and brushes. boy its cranking a lot faster than it was. Its taken a while to make sure the oil is out of the fuel but it appears that the cranking speed (probably combined with some wear in the fuel pump) was the problem. Thanks for all your help and advice

Terry

[Robyn]

Good deal

Glad things are working better

Missy