Stalls Intermittently

[ssdvc]

It is never ending, isn't it. Oh well, I volunteered for this.

Hot or cold, my 09 has now developed a very intermittent stalling issue. It mostly happens when I take my foot off the throttle. I can be backing up when I first start her up, lifting off the throttle to shift into drive and she can stall (but it doesn't happen all the time). It can happen if I am cruising down the highway at 65 or cruising through Main street at 25. She will alway fire right back up afterwards. And, after sitting for a month, while I was dealing with my radiator issue, she fired immediately on the first crank of the motor. New fuel filter and fuel system has been gone over (the only thing not replaced is the IP and Fuel Pump.

Please tell me this is just a simple adjustment or minor repair.

 

[wheelspinner]

Mine was the IP

 

[Barrman]

Sorry, but if you can make it stall while playing with the throttle. That points to an IP needing attention. I had one like that too. Very frustrating but the IP is a wear item and you have no clue when it was last replaced if ever.

 

[cucvrus]

Did you try to lube the shaft on the passengers side of the injection pump. Does that move freely? That pump was replaced during the time I rebuilt the truck. I am thinking 2011 or 2012. I don't remember. I was doing so many back then. When did you buy it from me? Figure a year or 2 before that date the pump was rebuilt. Like I always say. It never ends. It must be a hobby and you must like it. If the need arises you can handle this also. Good Luck.

 

[Barrman]

What does lubricating the shaft on the passenger side do? I don't think I have seen that advice before is why I ask.

 

[Keith_J]

While it is possible the light load advance plunger can stick, this can be observed in the drive way.

Since the engine has been in storage, I would first look for metering valve sticking. This will cause stalling on coasting since this valve is fully closed on coasting until engine speed is under about 1000 RPM. Below this speed, the low speed governor spring is the only force opening the metering valve.

 

[cucvrus]

What does lubricating the shaft on the passenger side do? I don't think I have seen that advice before is why I ask.

That shaft on the passengers side is attached by a rod and it can get stuck in the on/compressed position. I don't know all the technical terminology of these parts but I seen this M1009 truck in person and everything under the hood was dry and sticking. I know the eccentric on the throttle shaft has a roller follower that rides on it and that can stick and drag. I seen them stuck open compressing the valve on the bottom of the pump. Again no correct terminology from the valve or lever but I know how it is supposed to work enough to keep my CUCV's running over the past 27 years. So that has to count for something. After thinking about this particular vehicle I think I would clean and lubricate all the moving parts on the injection pump and give that a try. Of course then you get into removing the VCV and starting over with the shift intervals. I say mark it remove it and clean everything. What do you have to lose? Good Luck. But it will always be something. The military worked on stuff that didn't need worked on and messed up many of these CUCV's within a few months after delivery. I seen the stuff they done when I worked at the GM dealer back in the 80's. They would drag and carry them poor M1009's and pickups behind an M819 or a 5 ton wrecker and drop them off for warranty repair at the dealership after someone at the Gap tried to fix them. WOW. Good Luck. SSDVC Scott.

 

[ssdvc]

Thank Rick. I picked her up from you after I got back from my last round of fun in the sandbox, so I am thinking mid-2016. I know you sold it to a guy around you after the full rehab, but he wanted something "more comfortable" sold you helped him sell it to me (THANKS !!).

I lubed everything yesterday, took a two hour drive and only managed to stall her out twice, both time maneuvering back and forth or at idle. When I had my fuel issues a while back, I remember I "fiddled" with that screw at the top of the throttle assembly. When I got back yesterday, I gave her a turn or two. Seemed to smooth things out a bit (maybe low idle??). I will try and "test and tune" over the next few days.

Just to note, she doesn't seem like she is loosing any power. I have experienced an IP on another 09 I had a while back and this doesn't feel anything like that. Not to say it couldn't be short in coming, but this feels a bit different (hopefully).

 

[ssdvc]

Keith, it does only happen at low or no speed, so I'll look up where the metering valve is and check on it and the governing spring, if possible.

Thanks.

 

[Barrman]

That makes sense about the advance arm to throttle shaft linkage roller needing lubrication.

I drove one of my M1009’s today for the first time in a few months. I have had it for 12 years. When I first got it running it would barely idle. It would die when the fast idle turned off and sometimes when I just gave a little throttle to back up or something similar. We waited to do the IP while we did the body, paint and interior. Somewhere in there it stopped stalling. We never did get to the IP and all seems good. However, that is the only truck I am aware of that got better without an IP rebuild. Do everything you can but know an IP rebuild is probably in your future.

 

[Keith_J]

Most pump diesel contains a small percentage of biodiesel to replace lubricity lost from removal of sulfur compounds to achieve <15ppm sulfur. Unfortunately, biodiesel oxidizes easily and allows far more water to dissolve in mineral diesel. This fact means diesel injection systems will have storage problems.

I've seen this multiple times with various types of injection systems. In the DB2 pumps, the sensitive parts are the metering valve and the plungers. Idle speed is governed by the balance of idle spring and flyweight forces. Both of these forces are quite small, any varnish or corrosion in the metering valve will cause unstable idle.

When the engine is cold, significantly more fuel is required to maintain idle speed, both cold high idle (increases spring force) and timing advance are needed. Likewise, idle speed would be much higher when throttle is closed after a hard pull. This could cause control problems if not for the idle spring to lower injected quantity when the precombustion chamber is hot.

How to clean this biodiesel varnish? I've found Diesel Mechanic in a Bottle to be the most effective solvent, both on the bench and in the fuel system. A few drops will clean a used piston, removing all but baked on gray ash. I had a John Deere diesel which had compression pressure under 200 PSI in all cylinders, ran an ounce in each cylinder and next day, spun it over without glow plugs until most had cleared out. Compression pressures were over 400 PSI on all. Ran about 4 ounces through the injection pump and the tractor was back at 100%

 

[ssdvc]

So, I went to adjust the idle so I could get a few more RPM's while off throttle. I think I have found that the idle screw is upside down and it is not accessible, at least to me, right now. Does this look right AND, is that the idle adjustment screw (I did look in the TM, but just checking to make sure) ?



So a bit more on the stalling. It stalls if am am cruising and decide I need to stop (like at a light or stop sign) and I let up off the throttle, but only if I do that abruptly. It also sometime does it when I am sitting there, idling, with no foot on the pedal. Otherwise she is running well and very strong.

 

[ssdvc]

Just an additional data point. I drove around today AND, if I keep my foot on the pedal (bringing her up by only a 100 RPM or so) she does not stall.

Given the pictures in the post above, how can I bring up the idle without disassembling a ton of stuff (or is that a must) ?

 

[ezgn]

Just an additional data point. I drove around today AND, if I keep my foot on the pedal (bringing her up by only a 100 RPM or so) she does not stall.

Given the pictures in the post above, how can I bring up the idle without disassembling a ton of stuff (or is that a must) ?

Bringing up the idle will not correct your problem. Personally, I would never drive a vehicle on the road with a stalling problem. You could be putting your self and others at risk of serious injury.

 

[Barrman]

You just need a long slotted tip screwdriver to adjust the idle. The screw is under the fast idle solenoid. Shine a light in there and you should see it.

 

[ssdvc]

LOL ! Thanks Barrman, I found it ! Went to make a small adjustment, and she is frozen in there pretty good. Sprayed some Kroll in there, waiting a while so it can work it's magic.

In the mean time, I heavy poured some HOWES Diesel Treat in the tank. No one around here has "Diesel Mechanic in a Bottle"in stock, so I had to order that.

Another observation. Sitting in the driveway, if I rev her up a few times, then left off the throttle abruptly, she'll stall. Not always, but about 2/3's of the time. Fun times.

 

[Keith_J]

LOL ! Thanks Barrman, I found it ! Went to make a small adjustment, and she is frozen in there pretty good. Sprayed some Kroll in there, waiting a while so it can work it's magic.

In the mean time, I heavy poured some HOWES Diesel Treat in the tank. No one around here has "Diesel Mechanic in a Bottle"in stock, so I had to order that.

Another observation. Sitting in the driveway, if I rev her up a few times, then left off the throttle abruptly, she'll stall. Not always, but about 2/3's of the time. Fun times.

Classic sticking metering valve symptom. Idle speed is set by a very weak spring force as the flyweight centrifugal force is also weak. The spring force opens the metering valve, flyweights close the metering valve.
When the accelerator pedal is slightly pressed, the idle spring collapses and the metering valve is then directly controlled by the accelerator pedal, all flyweight force is then opposed by the accelerator pedal force. Sudden release of the accelerator pedal causes the flyweight force to fully close the metering valve. It then sticks and requires more force than the idle spring can provide.

 

[ssdvc]

Thanks Kieth. If the "Mechanic in a Bottle" doesn't do the job, is this "metering valve and spring" internal to the actual IP body or this a replaceable set of components I could do myself? Or does this require a rebuild of my IP (new in 2014, less than 15,000 miles on it).

 

[Keith_J]

The metering valve is an internal part of the IP which can be serviced after removing the cover (3 screws), guide stud, throttle shaft and governor arm. See pages 4-62 through 4-64 on the GM manual GM_STG_16015_05_1C_1987_The_6.2_Liter_Diesel_Engine.pdf available from the TM section here. It is illustrated and well written.

GM 6.2 Liter Diesel Engine Service Manual 16015.05-1C

I found this PDF service manual from GM, searched forums for dups. Haven't found any...the CUCV is considered the "D" truck version in the manual. Hopes this helps all that require additional info on these trucks.

www.steelsoldiers.com

 

[MrMikey4026]

Try some Stanadyne Lubricity Formula additive in the fuel.