M1009 Starts great cold - hard to start warm

rossbart

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Waurika, Oklahoma
Have a seemingly odd issue with my M1009 that is so repeatable that I hope someone can give me some insight.

Vehicle is a 1985 in excellent condition. I'm not sure it is the original motor as it is awefully clean, no leaks, uses no oil, etc.. I got it a few months ago from GL and have put about 4,000 miles on it. It doesn't have an excess of power (but I don't know what is normal). Once started, it runs smoke free and drives great.

But, when I start it COLD I can hear the glowplug solenoid cycle and the 'wait' light comes on as normal and it starts on the first pop even in cool weather. But, after it warms up, if I try to restart it in the next, say, 15-20 minutes it restarts pretty well. However, if it sits much more than that - say an hour or two - the glowplugs do not seem to cycle and it has to cranks for a good while before it will start and once it does start it has alot of white smoke.

Do I have an injector problem, fuel delivery (i.e. delivery pump or filter) problem, injector pump problem or glowplug system problem?

Any help is greatly appreciate.

Thanks,
Ross
 

Westech

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you answered your own question.

But, when I start it COLD I can hear the glowplug solenoid cycle and the 'wait' light comes on as normal and it starts on the first pop even in cool weather. But, after it warms up, if I try to restart it in the next, say, 15-20 minutes it restarts pretty well. However, if it sits much more than that - say an hour or two - the glowplugs do not seem to cycle and it has to cranks for a good while before it will start and once it does start it has alot of white smoke.


glow plugs not working... could be temp sending unit(s) or control card. I betting on sending units. One on right side rear of head.. on on top of head on left rear side. the one on left side front lower if for light and does not control anything. Replace the two sending units and see whats up.
 

rossbart

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Waurika, Oklahoma
Where can I get these senders/sensors?

Thanks a million Westech. If I may inquire, do you know where I might go to find these sensors? Is this a NAPA kind of part or do I need to go to the Military suppliers?

Thanks again,
Ross
 

Westech

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there civy parts... take them out and match them up to make sure but there the same as the civy units for a 1983 chevy J code 6.2 diesel.

I just replaced them in my pop in laws truck.. I cant seam to find them at the autozone web site, but napa had them. Just take them out and the can match them up in the book. one was like 12 and the other 19 bucks.
 
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rossbart

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Location
Waurika, Oklahoma
Where is the pass side one?

Thanks everyone for the help. The one on the upper rear of the drivers side head is obvious. I'll take it out and take it to NAPA to match up. However, you seem to be saying that there are two and I need to replace them both? Westech mentioned that one controlled nothing but the wait light and mine seems to be functioning correctly. But, I'm all for replacing both. But, where is the other one?

I referred to the -20 manual on the glowplug switch and it just shows the one on the drivers side top rear. I do see some kind of sensor at the front of the engine and low (drivers side) that has a single green wire (same color as the glow plugs). Is that it or something else.

Please direct me to the other one...

Thanks again,
Ross
 

Westech

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that one is the the warrning light... the one in the front of the head. There should be a two pin sensor in the rear of the passanger side of the head. That one also controlls the glow plug card.

here is the autozone # SU183 for the rear lower right side one. you have the top one already.
 

rossbart

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Waurika, Oklahoma
I'm a little confused. The sensor on the top, rear of the drivers side head on mine is not a two pin. It has a single barrel connector although the wiring connector does have two wires. I'm attaching a picture. For now I have just plugged the hole and layed the sensor on top of the intake so that it cools off quicker than when in coolant. Do I need to use the two-pin sensor and just splice blades on those two wires on my connector harness? If so, does it matter which wire goes where?
 

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rossbart

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Location
Waurika, Oklahoma
Okay, I'll look closer over there but I didn't see anything? If that's not the glow plug inhibit on the drivers side rear that I pulled out of the water passage, it is ironic that the glow plugs are operating now when the engine is warmer than before? Oh well, attached are some of the pages I found on the -20p manual pages that lead to my confusion. Is there somewhere that outlines narratively how all of the sensors work in the glowplug system. . As you can see from the attachment, the manual seems to define the sensor that would be located at the rear of the passenger side as the "cold advance switch". The one that I pulled from the drivers side is described on the manual page under the glow puls and temperature sensor parts section? Wonder what it does?
 

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Westech

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well I think you got it correct.. the one on the driver rear is stated to be the glow plug inhibit ..(per auto supply houses) but that could be the wrong description. If its working then it the correct one.
 

rossbart

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Location
Waurika, Oklahoma
Yes Sir. I ended up replacing the glow plugs, controller card, one battery and drivers side alternator. But, I think my problem with hard warm starts was caused by and resolved by replacement of the temperature sensor at the top rear of the drivers side head...
 

Lild

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Nashville,nc
Like to bump this. I am having the same issue. 10-20 mins after shut down starts fine, hr later & it takes a while to start. After 2 hrs the wait light comes on, & it fire right up. Have new glow plugs, as well as the relay, I feel one it's the same issue as the op. So Dear op, where did u get the glow plug inhibit switch @ & did u have replace original plug with 2 female spade connectors & which wires went to which connector or does that not matter.

I found 2 @ advance for a k30 for 15 bucks & another listed for 4wd @ 70 bucks
& I ALS found one @ autozone for 15 listed or a k30 4wd
Can't decide if it maters if there's a difference for the 4wd or not

thanks for your help!
 
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rossbart

Member
54
3
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Location
Waurika, Oklahoma
Hi Lild,

Yes, replacing the inhibit sensor on drivers side top rear of head did resolve my problem.

I got it at Napa. I don't remember part# but I think it would be one listed for a K30 J-code 6.2 diesel.

The replacement sensor did have a 2 pin connection unlike the original. So, I had to replace the wire ends with a couple of solderless blade connectors. You might want to check me on this, but as I remember, it did not matter which wire went where. I think it is just a variable ground sensor inline on a ground wire.

Hope that this helps,
Ross
 

Warthog

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Here is some info I dug up a couple of years ago.

The GM part number for the GP inhibit switch/sensor on the driver side rear is: 10045847.
Stock it is a two wire center pin unit. The replacement unit is a 2 wire 2-pin unit

Oreilly part numbers

old style: WT5133
new style: WT3000
new style require pigtail: PT191

Napa numbers
old style:TS4032
new style: TS4052
new style requires pigtail: TSC200

You may need a bushing to install the switch/sensor: 0.500-14 x 0.375-18 NPT
 
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Lild

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Nashville,nc
So what is the difference in the one you listed oreilly new style wt3000 & auto zones part #su183

& my next question is how do I convert from single wire to the newer two prong style.
 

Lild

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Location
Nashville,nc
Never mind on the 2 wire conversion. I just went out checked mine, & saw that it is a 2 wire plug. How ever i think i found.Temporary fix until imget a new sensor. I will know for sure in 30 mins.
 

Lild

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Location
Nashville,nc
Well i found out if i wait 30 mins, it won't start. I know i at least have to wait 2 hrs beofre it will. So as i looked @ new sensors, checked mine, it has been 30mins since i cranked it, no dice. So i unplug the sensor, the wait light comes on, i wait 5-10secs. then it fires right up. But u have to plug it back up as the light won't go back off, as well the relay will turn off.
Amazing how a simple little temp sensor can keep from cranking.
 

pdub58

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Negaunee, MI
Lild, I had the same exact situation as you going on, and then I changed the sensor. It still wouldn't fire when it was warm, but would start as long as I let it cool off enough for the wait light to come on.
My truck was Cranking over pretty slow so I decided to pull the starter off and had it rebuilt. I reinstalled the starter and now it starts perfect at any temperature weather the wait light comes on or not.
I guess it was the starter after all!
 
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