GP controller bypass mod performed

[PJL]

So the M1008 wouldn't start last night. Had to be pushed back to it's parking area. Had a peek at it today. Starter was stuck. I smacked it with a hammer a few times and got it to turn over. I checked the batteries and both are good and able to provide about 900 amps CCA. Yeah I know it needs an overhaul. The root of the problem seems to be hard to start warm. I warmed it up and sure enough won't restart. I pulled the temp sensor and it ran the glow plugs. Started right up. But with the sensor out of the circuit the GP's stay on. So I decided to do the bypass mod and leave the controller in as it works fine for cold starts. Wired in the push button where the radio isn't and it fires right up after a 10 second GP burn. So, what I am wondering is what problem am I masking by running GP's to start a warm engine?

 

[tstone]

I had this happen on my 1008. My problem was a worn IP; after the IP fuel bowl warmed up in about 1/2 hour, I noticed that it was difficult to start when warm. When operating it after a few weeks I lost acceleration due to lower compressibility (bypassing of the fuel around the plunger) of the fuel as it became thinner when warm. I had the IP rebuilt and everything was back to normal.

 

[PJL]

Sounds reasonable. That was one of my suspects. So how come running the GP's makes it start?

 

[tstone]

In the situation with my vehicle the GP's wouldn't activate because the engine was already hot; I would guess that whatever fuel that you were getting injected into your was pre-combustion chamber more easily ignited due to the GP's. I guess that you were manually activating your GP's?

 

[Hasdrubal]

I have a manual GP push button set-up. One summer, I noticed it was no longer just firing at the turn of the key when parked for short periods of time. Had to engage glow plugs. Come Fall, the answer was apparent, no heat in cab. Thermostat had failed and engine was always running cool.

 

[PJL]

That's a good tip, I had not considered the thermostat. When we got the truck the radiator was rotted and what little coolant was left in it was like Alabama mud. Took forever to flush clear. The engine seems cool to the touch even after running awhile. Thermostat is an easy fix.