Hard Starting when warm

[T.C.Mac]

A little input?

I have a 1998 6.5 TD with so far a unique issue. When the truck is stone cold or hot, (withen 5 minutes of being shut off ) it starts right up. inbetween times it starts but needs to crank for at least 45 seconds before it will fire. I have replaced the controller, all the glow plugs ( with the AC60G's )and the thermal sensor in the thermostat housing. When stone cold the plugs seem to energize for approx 8 to 10 seconds and it fires right up, after about 15 minutes of being shut off the plugs only energize for about 5 seconds or less.
It seems like the PCM may be sending the wrong signal to the controller telling it the engine is still hot when it is not? Is there another sensor that may be bad giving the PCM the wrong data? any help would be greatly appreciated. Mac

[It\'s a Dry Heat]

I have only tractors to compair with. But Glow plugs on, crank for 45 seconds. The eng is not getting fuel. Fuel pump only makes fuel avaliable to controler. I don't see the computer coming into it. I think you have a controler problem.

[HUMTECH]

Let me get this straight, hot or cold if you shut it down it will refire if you try it right away? If you let it sit for 15 minutes it has an extended crank? Is there lots of smoke when it fires after the extended crank? If so you may have leaking injectors causing a flooded condition, which if left overnight the fuel will seep past the rings and into the crankcase. Can also check for fuel contamination in the oil which can confirm leaking injectors.

[T.C.Mac]

no excessive smoke when it does finally fire, checking the glow plugs with a infrared thermometer the glow plug is 660 degrees f stone cold. after the 15 minute cool down the controler only stays on long enough to bring the glow plugs to approx 440 degrees F?
doesn't seem to be any fuel in the oil?

[HUMTECH]

Any codes set? tough one to diagnose over the internet. As far as the glow plugs not coming on as long they are set on a timer and will come on for shorter periods of time with a warm engine. Possible leak in the fuel return system and after it sits the air bleeds out? You can always put a piece of clear hose in place of the return line at the pump and check for air bubbles while the engine is running.

[Yetti]

if it helps the lead going to each bank from the controler should pull 55 amps. each plug pulls around 15 by it self. if your having issue with plugs its one thing, but your discribing a pump issue. under the right conditions the check valve on the pump can pick up debrie. problem is the debrie is coming from the innereds of the pump. if the check valve is leaking then it will loose its prime by drawing air back into the pump from the over flow line. the valve screws right into the top of the pump and looks like a brass nipple with a small hose attached. if the pump goes real bad it can and will over advance the pump timing. once the head presure reachs 10 psi it will quit starting. if you suspect the pump/valve after all is said and done remove it and put in a straight fitting with no check valve. if it fires and runs the pump is going bad and will need rebuilt.

[T.C.Mac]

OK GUYS, THANKS FOR ALL THE INPUT ALL GREAT IDEAS, BUT I FOUND IT... GLOW PLUG CIRCUT A OK, FUEL DELIVERY A OK.. INJECTION PUMP A OK....
THE PROBLEM WAS WHEN THE VEHICLE GOT TO 160 DEGREES OR HOTTER THE STARTER MOTOR WOULD DRAG, LOSE ABOUT 100 RPM BUT STILL CONTINUE TO CRANK. IT JUST WASN'T CRANKING QUITE FAST ENOUGH TO CATCH. TOOK MY STARTER IN TO A REBUILDER AND $450.00 LATER IT FIRES FIRST TIME EVERY TIME.
SO YOU GUYS KNOW, IT DIDN'T "SOUND" LIKE THE STARTER WAS ANY SLOWER SO BE WARY...
THANKS AGAIN FOR ALL YOUR INPUT
T.C. MAC...