Diesel won’t start

[Blue Ox]

Well, I didn't drive the CUCV much when it was hot, and it seemed ok, but the last couple of times I took it out, it would just randomly die on me after driving a few mi!es. Would start right up again, then die a couple of more times, then seemed fine. Now that is is getting cold, I'm not able to get it started. Does this sound like the injection pump? It looks like a real pain in the backside to replace.

Maybe.

1982 may still have a "flex ring" which causes those symptoms when it fails by plugging up the pump's internal works. If you take the top cover off the pump and you see little black plastic crumbs. Those would be the remnants of the flex ring.

If it's not that obvious you can try the following. Make sure you have a solid fuel supply to the back of the pump when the condition occurs. If that's okay, see if you can vent the pump housing by loosening the return fitting, the top cover or the side cover bolts. If fuel can escape and relieve the internal pressure and it starts then it's likely a flex ring issue.

Let me know what you find.

 

[SDJunkMan]

Maybe.

1982 may still have a "flex ring" which causes those symptoms when it fails by plugging up the pump's internal works. If you take the top cover off the pump and you see little black plastic crumbs. Those would be the remnants of the flex ring.

If it's not that obvious you can try the following. Make sure you have a solid fuel supply to the back of the pump when the condition occurs. If that's okay, see if you can vent the pump housing by loosening the return fitting, the top cover or the side cover bolts. If fuel can escape and relieve the internal pressure and it starts then it's likely a flex ring issue.

Let me know what you find.

The pump on tne CUCV is the original, I haven't pulled the 82 pump yet. Would the CUCV have a " flex ring"?

 

[Blue Ox]

What year is the CUCV? Flex rings were supplanted around 1985.

 

[SDJunkMan]

It's a 85

 

[SDJunkMan]

Actually just double checked it, and it's a 84

 

[eskimomann209]

I did one of those manual glow plug switches using a Ford starting solenoid for a buddy.
His issue was after sitting for an hour the truck was too cold to start but too hot for the glow plug relay to cycle.

But the water on the IP is a common way to see if the pump is worn out for sure.
I have used cold water and just room temp.
Never had an issue since most of these pumps are older and have probably lost most of their tightness.
New diesel fuel beats these pumps up without additives.

 

[Itali83]

Why has no one asked if when it dies while driving, does it die like you turned the key off? Or like you’re running out of fuel? If it dies like you shut the key off, I’d be looking at the power wire to the fuel shut off or the shut off solenoid itself. I can’t see how a worn/tired pump will not feel like it’s running out of fuel (a slower gradual loss of power as opposed to instant shut down)


Also, what is this flex ring you’re talking about?

Ben

 

[SDJunkMan]

Why has no one asked if when it dies while driving, does it die like you turned the key off? Or like you’re running out of fuel? If it dies like you shut the key off, I’d be looking at the power wire to the fuel shut off or the shut off solenoid itself. I can’t see how a worn/tired pump will not feel like it’s running out of fuel (a slower gradual loss of power as opposed to instant shut down)


Also, what is this flex ring you’re talking about?

Ben

Just like turning the key off. Didn't think about that, like losing spark on a gas engine. Checking power to the solenoid should be easy, but how do you check the solenoid?

 

[eskimomann209]

Just like turning the key off. Didn't think about that, like losing spark on a gas engine. Checking power to the solenoid should be easy, but how do you check the solenoid?

Probably because he mention it not restarting not that it’s dying.
Common issue with the 6.2 DIESEL engine is worn IP causing exactly this issue.
Also an issue with the GPR sensing the engine being hot and not running the relay. So we force it to run for 15-25 seconds to heat them plugs and re fire. Lotta options but to me it sounds like the GPR. But it’s only 25 bucks to check it out.

The pump itself is not electric. It’s either the lift pump mounted on the block or the IP mounted on the intake. Neither have electric wiring.

 

[Itali83]

Probably because he mention it not restarting not that it’s dying.
Common issue with the 6.2 DIESEL engine is worn IP causing exactly this issue.
Also an issue with the GPR sensing the engine being hot and not running the relay. So we force it to run for 15-25 seconds to heat them plugs and re fire. Lotta options but to me it sounds like the GPR. But it’s only 25 bucks to check it out.

The pump itself is not electric. It’s either the lift pump mounted on the block or the IP mounted on the intake. Neither have electric wiring.

Wrong.

The injection pump has an electric solenoid mounted in the housing that shuts fuel off. Like all solenoids, heat is the enemy and can fail when hot. Cool down and work again. Now that we know it dies like shutting the key off and not running out of fuel, my money is on an electrical issue, not fuel.

I don’t know the resistance of a good solenoid off the top of my head but I do know that if you put 12 volts (I’ve never had a cucv but have been told only the charging/starting system is 24 volt? So 12 volts still applies for your solenoid? You can hear the solenoid click if you’re under the hood while putting power to it. You’ll also see a faint spark when you touch the terminal. Try this when it’s cold and when it’s dead if you can. Should narrow things down for you.
On my civilian 6.2, it’s the pink wire probably 12-14 gauge that plugs in on the top of the injection pump. Really should be the only wire as I’m sure the cucv’s didn’t have EFE and I know they don’t have a 700r4 with lockup converter.

Ben

 

[Turbo4whl]

50 cent question, how old is the fuel filter? I did not see this mentioned in any of the posts.

 

[SDJunkMan]

I don’t know the resistance of a good solenoid off the top of my head but I do know that if you put 12 volts (I’ve never had a cucv but have been told only the charging/starting system is 24 volt? So 12 volts still applies for your solenoid? You can hear the solenoid click if you’re under the hood while putting power to it. You’ll also see a faint spark when you touch the terminal. Try this when it’s cold and when it’s dead if you can. Should narrow things down for you.
On my civilian 6.2, it’s the pink wire probably 12-14 gauge that plugs in on the top of the injection pump.
Ben

Pretty sure it's 12 volt, starter and glow plugs are 24. I'll give that a try today, didn't really think about the solenoid before.

50 cent question, how old is the fuel filter? I did not see this mentioned in any of the posts.

I've never changed it, but I've only put a few thousand miles on the truck. Pretty sure the PO changed it before I bought tne truck. Been thinking about upgrading to a spin on filter, this would probably be a good time to do that.

 

[Turbo4whl]

(fuel filter)

I've never changed it, but I've only put a few thousand miles on the truck. Pretty sure the PO changed it before I bought tne truck. Been thinking about upgrading to a spin on filter, this would probably be a good time to do that.

Bio-diesel fuel that they run in our fleet.... No I won't talk about that now...

Changing the fuel filter is very inexpensive, and easy compared to many of the options stated in this posting.

Swapping to a spin-on filter is a fine plan, but right now I would just replace the stock filter or filters if it has two. There might be a small screen filter in the fuel system also. This should be checked if it has one.

 

[SDJunkMan]

I used to make my own biodiesel, ran it in my 7.3 Powerstroke, and TDI Beetle. Never had any pdoblems with tnem. With fuel prices going up, I'm thinking about making it again. Haven't made it in a few years, and don't think I ever ran any in the CUCV.

 

[Blue Ox]

If the rest of the system is 24V the pump solenoids are probably 24V too. The cover should be stamped 24V if it is.

It's rare for solenoids to go bad where they will just let go in the middle of the ride. Frankly I don't think I've ever seen it. Once they're pulled in, they're in. So carry a jumper wire with you to do a direct to battery to see if it's losing power somewhere.