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Fuel issue , bad injection pump?

MDF1017

New member
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Texas
Well first post and some background about a week ago I ran my truck out of fuel on the way to work. (Fuel gauge is not working) Put 10 gallons of diesel in it and tried to prime the system and no luck.

Got it home where I could better try and diagnose it. The truck needed a new lift pump before this happened so I changed it out once it was home prior to troubleshooting. After the pump was on I pressurized the tank and cracked fuel lines along the way to make sure I was getting fuel. Found out I wasn’t getting fuel past the fuel filter housing inlet.

My fuel filter housing was leaking anyway and I already had the parts for the spin on modification so I did the mod. Primed the system again and was finally getting fuel past the filter to the injection pump but the engine still won’t run. I cracked the injector lines and cranked the engine until the fuel came out of all injector lines. Still won’t start. Glow plugs all test out and are working, and I don’t see any smoke out the exhaust when cranking. Charged the batteries to ensure enough power.

I have the TM and I’ve been following and I’ve also been searching on these threads and following different ones similar to issue. I know the IP can be an issue.

My question is, is there a way to tell if my injection pump is bad based off of psi while on the truck? Or does it require special equipment?
Am I overlooking something ?
 

Barrman

Well-known member
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Giddings, Texas
If you have fuel at the the 8 injectors. Then the pink wire is connected and the solenoid is working. It also means the engine should start. Are you getting any dirty white smoke out the exhaust while cranking? If so, that means fuel but no heat inside the engine. Back to the glow plugs to see why no heat.
 

MDF1017

New member
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Location
Texas
If you have fuel at the the 8 injectors. Then the pink wire is connected and the solenoid is working. It also means the engine should start. Are you getting any dirty white smoke out the exhaust while cranking? If so, that means fuel but no heat inside the engine. Back to the glow plugs to see why no heat.
I’ve checked glow plugs, both resistance and and checked if they heat up while connected to the controller. They all check out.
Do the injectors need to have a certain PSI to properly deliver fuel? Could the injectors be blocked ?
 

cucvrus

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Jonestown Pennsylvania
I am going to guess that you have the incorrect lift pump. I seen it more time than I would like to mention. It happened to me a few years back and drove me crazy. Sorry to say you may be removing the lift pump again. The correct pump has resistance immediately on compression of the lever arm. The incorrect pump will fit like a glove and you will swear by it being correct but it has a 1/2" to 3/4" of free play in the compression of the arm. It does not pump fuel until the arm is deeply compressed. The 6.2 diesel does not have an eccentric high enough to compress the lever into the pump cycle. I posted this many times ad sound like it should be noted in all the other important information list. But I guess it was over looked as usual.
Check it out. It is complete with real pictures in living color. https://www.steelsoldiers.com/threads/cucvrus-repair-projects.192437/page-8
 

MDF1017

New member
9
4
3
Location
Texas
I am going to guess that you have the incorrect lift pump. I seen it more time than I would like to mention. It happened to me a few years back and drove me crazy. Sorry to say you may be removing the lift pump again. The correct pump has resistance immediately on compression of the lever arm. The incorrect pump will fit like a glove and you will swear by it being correct but it has a 1/2" to 3/4" of free play in the compression of the arm. It does not pump fuel until the arm is deeply compressed. The 6.2 diesel does not have an eccentric high enough to compress the lever into the pump cycle. I posted this many times ad sound like it should be noted in all the other important information list. But I guess it was over looked as usual.
Check it out. It is complete with real pictures in living color. https://www.steelsoldiers.com/threads/cucvrus-repair-projects.192437/page-8
I’m at work now, I guess I missed this that thread on the pump. I got mine through autozone I’ll get the part number when I get home. I know it wasn’t a Delphi pump.
 

LT67

Well-known member
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501
93
Location
Bowdon, GA
Have you checked to see if fuel is getting through the filter and going to the inj pump?
I am going to guess that you have the incorrect lift pump. I seen it more time than I would like to mention. It happened to me a few years back and drove me crazy. Sorry to say you may be removing the lift pump again. The correct pump has resistance immediately on compression of the lever arm. The incorrect pump will fit like a glove and you will swear by it being correct but it has a 1/2" to 3/4" of free play in the compression of the arm. It does not pump fuel until the arm is deeply compressed. The 6.2 diesel does not have an eccentric high enough to compress the lever into the pump cycle. I posted this many times ad sound like it should be noted in all the other important information list. But I guess it was over looked as usual.
Check it out. It is complete with real pictures in living color. https://www.steelsoldiers.com/threads/cucvrus-repair-projects.192437/page-8
Is there a difference in part numbers?
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
I couldn't tell you the correct part number but 906 does sound correct. I know by looking at it and handling the lever which one is correct. I received 3 different pumps from 3 different vendors and only 1 was correct. The 3rd one I was told to keep. It was incorrect and they didn't want it back. I kept it as Exhibit A : Incorrect CUCV lift pump. I have it marked as such. Like I said the correct one has immediate resistance and the pumping action is complete before the other one even runs out of free play. Good Luck. Like I said you can change it tp side so you don't need to lay in the wet or dirt.
 

LT67

Well-known member
655
501
93
Location
Bowdon, GA
I couldn't tell you the correct part number but 906 does sound correct. I know by looking at it and handling the lever which one is correct. I received 3 different pumps from 3 different vendors and only 1 was correct. The 3rd one I was told to keep. It was incorrect and they didn't want it back. I kept it as Exhibit A : Incorrect CUCV lift pump. I have it marked as such. Like I said the correct one has immediate resistance and the pumping action is complete before the other one even runs out of free play. Good Luck. Like I said you can change it tp side so you don't need to lay in the wet or dirt.
Thank you for the info. The lift pump on my 86 m1008 had to be changed and it's running terrible. I'm already guessing the wrong pump is on it.
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
Thank you for the info. The lift pump on my 86 m1008 had to be changed and it's running terrible. I'm already guessing the wrong pump is on it.
I am surprised it runs at all. Most don't even run with the incorrect pump on them. Like I said this should be listed in the important CUCV details. This is vital information. Unlike some of the stuff they do have listed which is just plain unneeded and not required. Also make sure the motor mounts are still supportive and not allowing the feed intake rubber fuel line to make contact with the frame crossmember. Good Luck. Report back. I'm pulling for you.
 

LT67

Well-known member
655
501
93
Location
Bowdon, GA
I am surprised it runs at all. Most don't even run with the incorrect pump on them. Like I said this should be listed in the important CUCV details. This is vital information. Unlike some of the stuff they do have listed which is just plain unneeded and not required. Also make sure the motor mounts are still supportive and not allowing the feed intake rubber fuel line to make contact with the frame crossmember. Good Luck. Report back. I'm pulling for you.
Yup, the parts house sent #MF0030 which was the wrong pump. The correct CHFP906 has been ordered. Once again thank you for the vital info.

** the inj pump was just rebuilt, so I'm guessing it was somehow pulling a little bit of fuel through the line🤷‍♂️
 
Last edited:

MDF1017

New member
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4
3
Location
Texas
Well update on the issue. Cucvrus you were correct. Wrong pump. Soo got the part number you mentioned and it starts. However it runs super rough and has a very bad vibration, like it’s out of balance. Bled the injector lines once more just to make sure, but still rough running.

I did notice the injection pump is wet on the driver side of the pump, out of what looks like a throttle linkage.
 

cucvrus

Well-known member
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Location
Jonestown Pennsylvania
Throttle shaft seals. IMHO it needs a rebuilt pump. Don't dance around the issue. Fix it once and done. That is my best advice. I changed many and it cures a lot of issues at once. Good Luck.
 

TheMod

New member
16
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3
Location
Southern Illinois
Throttle shaft seals. IMHO it needs a rebuilt pump. Don't dance around the issue. Fix it once and done. That is my best advice. I changed many and it cures a lot of issues at once. Good Luck.
He stated above the injection pump was just rebuilt?

Sent from my moto g(7) power using Tapatalk
 
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