Diesel won’t start

[SDJunkMan]

Took the CUCV out this morning, started fine. Fired off as soon as I cranked it after the glow plugs light went out, as usual.

Stopped for about an hour, and now it won’t start, cranks fine, but acts like it’s not getting fuel. It’s done this once or twice before, Burt usually starts after a minute. Seems like it does it when it’s hot out (in the 90’s right now).

My powerstroke will do something similar if the voltage is low, it won’t open the fuel selonoid, but my voltage seems fine.

Any ideas?

 

[AyWoSch Motors]

All I can think of, is that it got some air in the line. Maybe it got hot enough that some of the fuel vaporized, and its caused a bubble in the line. The high pressure pump wont pump air.

I have a CUCV blazer. Thing wont start for crap. I've done everything to that truck short of tearing the whole motor down.
Mine will only pop over a little on staring fluid, anything else and it sits there cranking all day. Pretty convinced it has no compression, have to do rings.

 

[Blue Ox]

Took the CUCV out this morning, started fine. Fired off as soon as I cranked it after the glow plugs light went out, as usual.

Stopped for about an hour, and now it won’t start, cranks fine, but acts like it’s not getting fuel. It’s done this once or twice before, Burt usually starts after a minute. Seems like it does it when it’s hot out (in the 90’s right now).

My powerstroke will do something similar if the voltage is low, it won’t open the fuel selonoid, but my voltage seems fine.

Any ideas?

Hard starting hot is the first sign of a worn out head & rotor assembly in the injection pump. If everything else is good, and it starts fine every other time you're eventually going to be looking for a pump.

 

[SDJunkMan]

Hard starting hot is the first sign of a worn out head & rotor assembly in the injection pump. If everything else is good, and it starts fine every other time you're eventually going to be looking for a pump.

Damm, that’s not good. Do you know if a 82 uses the same pump? I have a complete 82 engine that I picked up in a parts truck.

 

[Blue Ox]

Damm, that’s not good. Do you know if a 82 uses the same pump? I have a complete 82 engine that I picked up in a parts truck.

Well, yes and no. They're similar. The engine may or may not notice the difference. I'd need the part numbers off the tags on the pumps to tell you what the differences are.

 

[AyWoSch Motors]

Damm, that’s not good. Do you know if a 82 uses the same pump? I have a complete 82 engine that I picked up in a parts truck.

An '82 would be a C-code civilian 6.2 diesel, the CUCVs used the J-code 6.2 diesel.
Same basic engine. 82 was only 2 years away from the first cucv, I'd say they're probaly the same pump. But like BlueOx said, check the parts code. They may have a different psi rating or something.

 

[SDJunkMan]

Well, yes and no. They're similar. The engine may or may not notice the difference. I'd need the part numbers off the tags on the pumps to tell you what the differences are.

Thanks, I’ll try to get the numbers, but it will probably be a day or two until I get over to the 82.

 

[Bextreme04]

Thanks, I’ll try to get the numbers, but it will probably be a day or two until I get over to the 82.

Agree with the above posts, we used to have this issue in the HMMWV's in Iraq all the time. A little bit of ATF in the fuel seemed to help reduce the occurrences, but that is purely anecdotal and doesn't really help you now. We did find if you pour a little water on the pump it will usually let it start up when this happens. It's just a band-aid though and will eventually get worse and worse until nothing helps.

 

[Bextreme04]

All I can think of, is that it got some air in the line. Maybe it got hot enough that some of the fuel vaporized, and its caused a bubble in the line. The high pressure pump wont pump air.

I have a CUCV blazer. Thing wont start for crap. I've done everything to that truck short of tearing the whole motor down.
Mine will only pop over a little on staring fluid, anything else and it sits there cranking all day. Pretty convinced it has no compression, have to do rings.

Have you checked the glow plugs and glow plug controller? Compression test?

 

[SDJunkMan]

We did find if you pour a little water on the pump it will usually let it start up when this happens. It's just a band-aid though and will eventually get worse and worse until nothing helps.

I'll have to try that next time. I opened the hood so it could get some air, and it started up after a little cranking

Have you checked the glow plugs and glow plug controller? Compression test?

None of that yet, as I said, until it got this hot out, it would fire right off after the glow plug light went off.

It's my plow truck, so I don't usually drive it much in the summer.

a couple of hours later. It's on!y done it a coup!e of times, and always when itbis in the 90's.

 

[Bextreme04]

I'll have to try that next time. I opened the hood so it could get some air, and it started up after a little cranking


None of that yet, as I said, until it got this hot out, it would fire right off after the glow plug light went off.

It's my plow truck, so I don't usually drive it much in the summer.

a couple of hours later. It's on!y done it a coup!e of times, and always when itbis in the 90's.

The glow plug and controller comment was for the other guy that said his CUCV wont start for crap. Generally glow plugs are the main cause of no cold start.

Injection pump wear/failure is the main cause of hot start issues. The head wearing allows it to vapor lock after shutdown.

 

[Blue Ox]

Be real careful about pouring cold water on a hot pump. You can shrink the head onto the rotor and cause it to seize. Tolerances are real close in there.

It's not vapor lock, but the low viscosity that hot fuel has. A worn head & rotor will allow fuel to bypass between the components instead of being pumped through the passages. Path of least resistance and all that stuff.

 

[SDJunkMan]

Be real careful about pouring cold water on a hot pump. You can shrink the head onto the rotor and cause it to seize. Tolerances are real close in there.

It's not vapor lock, but the low viscosity that hot fuel has. A worn head & rotor will allow fuel to bypass between the components instead of being pumped through the passages. Path of least resistance and all that stuff.

Good to know, don't want to screw it up any more than it is. Luckily I have another truck to drive (although it is a Ford). I'll deal with this when the weather cools off, really don't have time to mess with it right now.

Thanks for all of the input everyone.

 

[Raider L]

@SDJunkMan,

No, you have to deal with it now, while it's hot so you can see what is causing it while it's hot. Once the weather cools then it won't do it anymore and it won't, not , start. So you'll just have to make some time and as a matter of a fact, drive it while it's hot. It doesn't matter if you drive up and down the road in front of the house so at least if it stops again you won't be far from the shop and you can just walk over there and get what you need. If it only does it when it's hot and you wait untill it gets cooler, does it do it then to or only when it's hot? Well, there you go.

 

[SDJunkMan]

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.

I haven't got the numbers off the 82 pump yet because it looks like I will have to pull it to read the numbers.

Since this is my plow truck, I probably need to get it figured out soon.