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Help with wiring

Keith_J

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Schertz TX
If you could post the injection pump model number, it would help in getting it running. T he model number starts with DB28..DB2 is the series, a DB28 is for an 8 cylinder. The next 2 digits are plunger diameter, all 6.2 use a DB2829. CUCV from 1986 use a DB2829-4520, the others I don't remember.

Like I previously mentioned, the pump in your CUCV is from a HMMWV which means a 24 volt solenoids. There are 2 inside, under the cover which could be swapped but it would be best to get a CUCV cover as it looks like the position of the fuel return check valve solenoid is different and would get in the way of a stock 6.2 air filter housing.

If your injection pump is a DB2831, that is for a 6.5 and might be too much if for a 6.5 turbo. It can cause piston damage. But it has value if not seized so with the right source, you should be able to swap covers. And it can be adjusted down to reduce maximum fuel rate if a 2831.
 

Keith_J

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Well, studying the injection pump image more also reveals you are missing the vacuum regulating valve necessary for proper shifting of the THM400 transmission. Hillbilly Wizard has used ones for $25. And an injection pump core for $125 which would be a good source for the IP cover with 12 volt solenoid already installed. Most places charge $200 for a core, if the IP in your CUCV needs replacing, you can send in this core for a proper overhaul. The IP in the vehicle might have greater value if a DB2831..
 

ezgn

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Location
Lake Elsinore Ca.
Well, studying the injection pump image more also reveals you are missing the vacuum regulating valve necessary for proper shifting of the THM400 transmission. Hillbilly Wizard has used ones for $25. And an injection pump core for $125 which would be a good source for the IP cover with 12 volt solenoid already installed. Most places charge $200 for a core, if the IP in your CUCV needs replacing, you can send in this core for a proper overhaul. The IP in the vehicle might have greater value if a DB2831..
Man Keith, you are on top of it. Good work on figuring out all that is going on with the injection pump. You are truly a wealth of information. Good job and Thanks for your time and help on this site. Good man!
 

Toddbo35

Member
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62
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Location
Hitchcock, Texas
Thanks for all the replies. Keith I'm in Hitchcock, TX and welcome any help offered. The truck came from Fort Hood about 6 years ago. It's been stored inside the whole time I've had it. Clearly I know very little about Diesels or this truck. Today I will go back and go over and respond to all the questions. I sincerely appreciate all the time effort and help.
 

Toddbo35

Member
41
62
18
Location
Hitchcock, Texas
If you could post the injection pump model number, it would help in getting it running. T he model number starts with DB28..DB2 is the series, a DB28 is for an 8 cylinder. The next 2 digits are plunger diameter, all 6.2 use a DB2829. CUCV from 1986 use a DB2829-4520, the others I don't remember.

Like I previously mentioned, the pump in your CUCV is from a HMMWV which means a 24 volt solenoids. There are 2 inside, under the cover which could be swapped but it would be best to get a CUCV cover as it looks like the position of the fuel return check valve solenoid is different and would get in the way of a stock 6.2 air filter housing.

If your injection pump is a DB2831, that is for a 6.5 and might be too much if for a 6.5 turbo. It can cause piston damage. But it has value if not seized so with the right source, you should be able to swap covers. And it can be adjusted down to reduce maximum fuel rate if a 2831.

First off thank you. I think you must be the 6.2 wizard. I'm clueless with these. You are correct the injection pump is DB-2829-4520. Both the pink wire and green wire have 12 volts when the key is on. As far as the starter I have 25 volts on main lug and nothing when the key is turned.
 

Toddbo35

Member
41
62
18
Location
Hitchcock, Texas
First off thank you. I think you must be the 6.2 wizard. I'm clueless with these. You are correct the injection pump is DB-2829-4520. Both the pink wire and green wire have 12 volts when the key is on. As far as the starter I have 25 volts on main lug and nothing when the key is turned.
Nothing on the starter lead that is.
 

Keith_J

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Location
Schertz TX
OK, I now see the IP has the vacuum regulating valve installed and since it is a 4520 pump but a 1985 year model, it was replaced. Why the HMMWV IP cover I cannot explain.

I need to break out my HMMWV TMs to see if it is possible to install 12 volt CUCV solenoids with HMMWV connections. Since the pump case pressure is 10 PSI, the electrical connections can leak as they age which is the most logical reason it was replaced. That also smells of a less than motivated shade tree mechanic. Which could be the starter issue too.

You mentioned 25 volts at the main lug so it should not be a conversion to 12 volt. The ignition switch is 12 volt, when turned to engage the starter, this 12 volt signal triggers a relay under the dash making a 24 volt signal travel down a purple wire to the starter. This engages the pinion gear to the ring gear, then connects the 24 volt main lug to the windings of the coil. If fuel is injected at the proper time, the engine should start.

So, you need to look under the dash for the relay panel, the starter relay has a purple wire which goes down to the starter. This relay is a skinny rectangle, unlike the other cube shaped relays. This starter relay is often switched to a cylinder shaped type, known as the Doghead modification (named after a member here ). This relay can stick, causing starter run on and other electrical damage.
 

Keith_J

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Location
Schertz TX
Here are some.more pics.
That injection pump cap looks like off a DB2831-5209 which is a HMMWV with the JP8 modifications (1.2 cST, low viscosity fuel of 1.2 centi Stokes). It delivers 52 mm^3 maximum so it will be fine on a non turbo. But it also has max fuel at 3200 RPM so it will limit top speed with 4.56 axle ratios. It still delivers 44 mm^3 at 3600 RPM where a 4520 is 48mm^3.

The IP cover is missing the rear screw. The prior owner may have lost it or broke it off. Which means you should take off the other two to investigate. This will let you test the solenoids to see if they are 24 volt. Cannot hurt to put 12 volts on a 24 volt coil but 24 volts will burn a 12 volt out.

I realize you are being flooded with information, let me know if you need any other help.
 
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Toddbo35

Member
41
62
18
Location
Hitchcock, Texas
On the starter relay..https://www.steelsoldiers.com/threads/doghead-starter-relay-modifcation.60960/
Well I found the factory relay. However the whole harness was disconnected from it and cut off even with the other harness. Looks like I will be buying the doghead relay. I bought this truck directly from the military base in Fort Hood Texas. The body is in excellent shape with the exception of the passenger door missing. I guess they were starting to rob parts off of it for some reason. I sure hope I don't sink alot of money in parts just to find out the motor has a knock. The truck only has 20770 miles on it.
 

Keith_J

Well-known member
3,657
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113
Location
Schertz TX
Knowing the current state is half the battle. You don't need the relay to start it, it can be hot wired. But it won't run with the injection pump electrical situation. This too can be hot wired IF you can test the solenoids. Preferably with the pump cover removed.

The bare Packard connection post on the back reduces case pressure when cold, that isn't needed for your climate these days. The Packard post up front is needed to run, when not energized, a spring loaded plunger shuts off the metering valve.

Pull the cover and test it with 12 volts first, if the lever moves forward all the way, it is probably 12 volts. Make an adapter from a 1/4" male spade into the pink wire, connected to 2" of 12 AWG insulated wire and then a female bullet connector.
There is yet another reason for pulling the pump cover, that is to inspect the pump function. The most critical being the metering valve. It has been in storage for nearly a decade and the valve is probably stuck shut. Diesel Mechanic in a Bottle works very well in cleaning the metering valve without further disassembly. Notice how the shut off solenoid pushes on the governor arm, the metering valve is in the center bottom of the governor housing. See this video around the 6 minute mark:


See how the metering valve functions? It must be free to move because idle speed is controlled by idle spring force balanced by governor flyweight force. The idle spring force is tiny, the flyweight force is proportional to engine speed and it will close the metering valve overcoming any varnish drag, causing the engine to die.

With Diesel Mechanic in a Bottle in the governor housing, work the throttle shaft while watching the metering valve arm movement. It must not stick in any position. Massage it if it sticks.

When reinstalled, the cover must be set on the pump in a forward position, then slid back against the governor arm. There is slight spring force from the shut off solenoid arm.
 

ezgn

Well-known member
650
1,039
93
Location
Lake Elsinore Ca.
Well I found the factory relay. However the whole harness was disconnected from it and cut off even with the other harness. Looks like I will be buying the doghead relay. I bought this truck directly from the military base in Fort Hood Texas. The body is in excellent shape with the exception of the passenger door missing. I guess they were starting to rob parts off of it for some reason. I sure hope I don't sink alot of money in parts just to find out the motor has a knock. The truck only has 20770 miles on it.
These vehicles have gone up in value considerably. Whatever money you spend, will be a good investment. The doghead relay will not set you back much. Breath life back into that truck and you will be glad you did.
 

Toddbo35

Member
41
62
18
Location
Hitchcock, Texas
Knowing the current state is half the battle. You don't need the relay to start it, it can be hot wired. But it won't run with the injection pump electrical situation. This too can be hot wired IF you can test the solenoids. Preferably with the pump cover removed.

The bare Packard connection post on the back reduces case pressure when cold, that isn't needed for your climate these days. The Packard post up front is needed to run, when not energized, a spring loaded plunger shuts off the metering valve.

Pull the cover and test it with 12 volts first, if the lever moves forward all the way, it is probably 12 volts. Make an adapter from a 1/4" male spade into the pink wire, connected to 2" of 12 AWG insulated wire and then a female bullet connector.
There is yet another reason for pulling the pump cover, that is to inspect the pump function. The most critical being the metering valve. It has been in storage for nearly a decade and the valve is probably stuck shut. Diesel Mechanic in a Bottle works very well in cleaning the metering valve without further disassembly. Notice how the shut off solenoid pushes on the governor arm, the metering valve is in the center bottom of the governor housing. See this video around the 6 minute mark:


See how the metering valve functions? It must be free to move because idle speed is controlled by idle spring force balanced by governor flyweight force. The idle spring force is tiny, the flyweight force is proportional to engine speed and it will close the metering valve overcoming any varnish drag, causing the engine to die.

With Diesel Mechanic in a Bottle in the governor housing, work the throttle shaft while watching the metering valve arm movement. It must not stick in any position. Massage it if it sticks.

When reinstalled, the cover must be set on the pump in a forward position, then slid back against the governor arm. There is slight spring force from the shut off solenoid arm.
Thank you for all the great info. I have to work all day tomorrow. I will get back at it Tuesday. In the mean time I will just buy the Napa doghead relay and get it installed Tuesday as well.
 

Keith_J

Well-known member
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Location
Schertz TX
I wish I had the energy to make the drive..I am doing cylinder head gaskets on my CUCV while recovering from a bad accident. I have about 2 hours endurance before I can't bear the pain. Damaged brachial plexus and lost feeling in half my left hand.

I will help online as much as possible. Getting my memory back so I may be a bit slow. Getting better.

I'm also doing a twin turbo on the engine. 10 years in planning, 3 years buying parts and tools. 3 months training my left hand how to feed filler wire for GTAW. Almost done with the intake side, less than half done on exhaust and oiling systems.
 

Toddbo35

Member
41
62
18
Location
Hitchcock, Texas
I wish I had the energy to make the drive..I am doing cylinder head gaskets on my CUCV while recovering from a bad accident. I have about 2 hours endurance before I can't bear the pain. Damaged brachial plexus and lost feeling in half my left hand.

I will help online as much as possible. Getting my memory back so I may be a bit slow. Getting better.

I'm also doing a twin turbo on the engine. 10 years in planning, 3 years buying parts and tools. 3 months training my left hand how to feed filler wire for GTAW. Almost done with the intake side, less than half done on exhaust and oiling systems.
I see you live in Schertz. I use to pass through there all the time heading to deer lease. What in the world did you do to yourself? I've had a few bad accidents myself and have been through 3 different spine surgeries. I know it's no fun. It will get better though.

Where did you learn so much about the CUCV? I assume you were military? At one time I had 6 of them. Mainly was buying them for axles . None of the others were in very good shape. I currently have 5 square bodies. Send me some pics of your turbo project.
 

Keith_J

Well-known member
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Location
Schertz TX
Car accident. Road racer clipped my left rear, flipped and my arm got dragged out the window. Still have 6 pieces of glass under the skin. Tired of surgery. Bad concussion but I am getting my memory back.
Yes, I learned some of the CUCV while in the US Army. Last unit still had the Dodge M880 contact truck, I took care of the Hobart welder-generator and air compressor. When the M1031 came along, the PTO generator was a awesome addition as it cut nearly 500 pounds from the package. Along with power steering and a proper, 1 ton rated front axle. The 880 has a Dana 44, with the contact truck body and generator-welder, it always ate brakes and bearings.
10 years ago, I liberated a very low mileage M1031 SECM via GL from Ft McCoy WI. 9009 miles on the odometer. So I learned the CUCV all over again. I've brought a few back on the road since then and got a few ideas..hence the twin turbo and eventually 4L80.

My project is in the hot rod CUCV section. https://www.steelsoldiers.com/threads/m1031-to-rv-tug.182098/
 

Keith_J

Well-known member
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Location
Schertz TX
Here's the cut wires
Easy fix. The purple with white trace is 12 volt from ignition switch. Solid purple is solenoid output 24 volt to starter. Red is 24 volt supply. This red wire is protected by a fusible link at the 24 volt bus, right side of firewall engine compartment. You need a wire to ground from the other coil terminal.
 
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