Hard starting after warmed up

[Skreamnchkn]

Hello, need some help I have an 84 m1008 6.2. I can’t seem to get it started when warm unless I cycle the glow plugs. Cold or hot I have to cycle the glow plugs every time. Is there a cure for this? Tia

 

[Skreamnchkn]

Crickets.....

 

[Tinstar]

Sounds like a modified electrical system.

A stock system operating properly will not cycle the glow plugs when engine is warm.
The GP temp sensor will tell the GP card not to activate them.
No wait light illumination either.

Has the wiring been modified?
Are you giving it any throttle while starting.
Is the engine Turing fast enough during start?
Etc.

Pics are always welcome.

 

[Skreamnchkn]

The glow plug system has been modified to push button. any time I have to start it Turn key off hold glow plug button down count to 10-15 depress accelerator pedal to the floor release and crank
turns over slowly and fires up. puff of black smoke and she is runnin.

 

[Skreamnchkn]

running two optima red top batteries

 

[Skreamnchkn]

I will try and upload a video later today

 

[NDT]

“Turns over slowly” is your problem

 

[Tinstar]

“Turns over slowly” is your problem

X2

 

[Tinstar]

Fully charge each battery separately, then do a load test.
If they check out ok, you have a dying starter.

 

[NDT]

Or bad connections. After cranking feel all the connections, if there is high resistance it will burn your hand, likely suspects are the barrier strip on the firewall and cable end terminals between the terminal and the cable strands.

 

[Barrman]

The 6.2 is an indirect injection engine. Any temperature below 150° is considered cold to this style of engine and glow plug use is needed. Keep that in mind once you get the batteries and starter right.

 

[Curtisje]

A few paragraphs from my 6.2 troubleshooting guide...

 

[Curtisje]

I also found this excerpt from a GM bulletin on another site;

Some customer comments have been received regarding no cold start capability or hot restart difficulty during mid-range engine temperature. Cases of no cold start may be the result of the glow plug inhibit switch not operating correctly. Reference Corporate Service Bulletin #866001 for glow plug system diagnosis.* Meanwhile, cases of poor hot/warm engine startup may be the result of starting system degradation, and may require glow plug assistance for engine starting. Replacement of the existing glow plug inhibit switch with a new service switch without a coolant temperature sensor (listed below) win provide glow plug assistance upon engine start, regardless of engine coolant temperatures. This feature will not reduce glow plug life.

Hope something here helps.

 

[Skreamnchkn]

I’ll check them this week when the wife gets home. Thank you for the pointers.