(M998) Hard To Start With Cold Engine

[WhoMe08721]

Hey Guys,

My (M99 is always hard to start with cold engine in colder weather. I have replace all glow plug last year. I have tested the system by connect a amp meter across the batteries and with the glow plug cycling I see a draw around 89 amps. Also check ohms resistance on all glow plug they check out good. When I turn the start switch to run the wait to start light comes on for around 9 Sec. and I can hear the relay clicking under the dash too. When the truck dose final start the Glow plug system is cycling normal with pulse for 1 second and an off pulse for 15 seconds. I have also replace the fuel filter and checked the cold advance solenoid switch and solenoid there is power to both and I can feel and hear the solenoid pulling in. The only way I can get the old girl to start is by pushing on the accelerator pedal. Final the truck dose blow white smoke at first but that cold be it is cold out and diesel don't like cold.

 

[WhoMe08721]

 

[WhoMe08721]

 

[Milcommoguy]

I guessing you didn't connecting the Amp meter across the batteries??? 89 Amp is a good ballpark for in series current when energized. What is the cold start outside temperature? Initial glow plug on time should be a longer (based on temp, say +/- 10 sec.) Cycling a good sign too. Little more data need... Compression and IP pump pressure would be nice.

That's my end of the year guess's, CAMO

 

[REF]

Based on the statement that finally it blows white smoke,
It could be a problem similar to one I had. After my truck would sit overnight the next morning when I went to start it, it would hit on a couple of cylinders / try to start but then nothing and I would have to crank on it to get it to start. As I worked the problem I replaced both the inlet and return line check valves down by the fuel tank, ( Didn't help ) but when I replaced the check valve on the inlet of the fuel filter the problem was solved. When the unit sat the fuel was leaking down. So if your not getting smoke as soon as you start cranking it, you may have a fuel leak down issue and remember there are 3 stand alone check valves in the fuel system to prevent drain back. Hope this 2 cents helps

 

[TOBASH]

You can always glow plug twice before starting

 

[papakb]

Even though you have power to the cold advance solenoid it may be sticking and not opening on a cold start. They're not that expensive. Try replacing it.

Your comment on stepping on the pedal reminded me of when mine was doing the same thing and that was what solved my issue.

 

[gimpyrobb]

I had lots of issues getting my motor started in the cold. Everyone said to swap glow plugs, so I put new ones in- in the fall. Still had issues with cold starts. I had finally had enough and put an aftermarket GP wire harness in. IT WAS AMAZING the difference in start ability. Before I was lucky to start if I left the block heater on. Now, at -16, it would start like a champ with no block heater.

 

[Milcommoguy]

Did you ever check, ohm them to see if they were in spec. ? What is the aftermarket GP wire harness that made it work?

Amazing questions, CAMO

 

[86humv]

most 80's Hmmwv's don't have fuel check valves.