CUCV starting problems

[Indyharleyguy]

Hi All you Mechanic Guru's. I have a starting problem on my 1986 6.2L. If it were a gas engine I'd think it was a carburetor choke high idle problem. But have no clue on my diesel. It used to start almost immediately even at 0 degrees. Both batteries are fairly new.
I turn the key half way until my glow light goes out. I hold the accelerator down all the way. After a second or so it starts to start then a second later it doesn't fire and i get a big puff of dark smoke. This happens with temps around 55 degrees so I don't think it's a glow plug problem? After I crank it for 5 seconds I keep my foot on the accelerator but turn the key off then back on half way, the glow light goes off almost immediately then I try again. I do this 3 or 4 times then it catches but just seems like a high idle isn't catching?
Once it starts and I drive it it starts up immediately even after it's set for 5 hours.
I am not a mechanic by any stretch of the imagination but would like to try and fix it myself if possible.
Oh it only has 64K miles on it.
What's all your thoughts.
Thanks in advance.
Charlie

 

[cucvrus]

If it were me the first thing I would do was pull all 8 glow plugs out and bench test them. That is of course knowing that you have power going thru the glow plug solenoid and getting to the glow plugs. Secondly I would see if the valley under the injection pump is wet or under the fuel filter assembly. I am assuming you have the stock Stanadyne cartridge filter. From afar this is all guess work and speculation. Report back.
I will attach my bench test method. I like to see things working as designed. I eliminate the guess work that way. Good Luck.

 

[dependable]

If it fires up and immediately stalls, then can be started after several tries, I would guess an air leak in fuel system. If truck is stock, the first place to look is the fuel pressure sensor in the fuel filter base. This sensor is pretty much useless unless you have a bit of obsolete test equipment called and STE/ICE, and prone to air leakage. Remove sensor and plug the hole with a screw with JB weld or similar on it. Sensor is the quarter sized disc w two wires under the fuel filter.

The air leak could be somewhere else in line too, but the filter base sensor was/is a very common problem.

Of course it would be a good idea to check glow plugs too, and while fuel filter if off, replace it. I usually fill them with diesel before putting them back on for easier starting.

 

[Indyharleyguy]

If it were me the first thing I would do was pull all 8 glow plugs out and bench test them. That is of course knowing that you have power going thru the glow plug solenoid and getting to the glow plugs. Secondly I would see if the valley under the injection pump is wet or under the fuel filter assembly. I am assuming you have the stock Stanadyne cartridge filter. From afar this is all guess work and speculation. Report back.
I will attach my bench test method. I like to see things working as designed. I eliminate the guess work that way. Good Luck.

Thanks. That assume's I know how to pull them out lol. I'm trying to get your attachment and for some reason can't?

 

[Indyharleyguy]

Thanks. That assume's I know how to pull them out lol. I'm trying to get your attachment and for some reason can't?

 

[Indyharleyguy]

If it fires up and immediately stalls, then can be started after several tries, I would guess an air leak in fuel system. If truck is stock, the first place to look is the fuel pressure sensor in the fuel filter base. This sensor is pretty much useless unless you have a bit of obsolete test equipment called and STE/ICE, and prone to air leakage. Remove sensor and plug the hole with a screw with JB weld or similar on it. Sensor is the quarter sized disc w two wires under the fuel filter.

The air leak could be somewhere else in line too, but the filter base sensor was/is a very common problem.

Of course it would be a good idea to check glow plugs too, and while fuel filter if off, replace it. I usually fill them with diesel before putting them back on for easier starting.

Thanks I'll see if I can find it. I do have a brand new fuel filter but have never replaced it.

 

[cucvrus]

Thanks I'll see if I can find it. I do have a brand new fuel filter but have never replaced it.

Well that can be the problem also. Do you know how to replace it. Not the book way. I will tell you if you want to know. This is the right time.

 

[Indyharleyguy]

Well that can be the problem also. Do you know how to replace it. Not the book way. I will tell you if you want to know. This is the right time.

Sure I'm all ears.

 

[cucvrus]

OK. If you pull all 8 of your glow plugs and bench test them. While they are out I would unplug the injection pump red wire and replace the fuel filter. This way you can open the bleeder on top of the filter housing and crank it over easily and bleed the new filter. It is best to have a helper so you can avoid fuel leaking all over and close the valve when pure fuel is coming out. Now plug the red wire back into the injection pump and reinstall the proven good tested glow plugs and start as usual bring the idle up about 1/2 throttle a few seconds to purge the air from the system. Good Luck. Report back. I always change the fuel filter when ever I have any other issues that involve glow plugs. If it has no issues I have run fuel filters a few years and never had any issues. Clean pump fuel is the key and not using fuel cans that are not clean. The old metal ones are notorious for having paint flakes and rust particulates in them. Good Luck. IMHO gas cans are dirty most times and pumped from a reputable fuel service area is a better way to get fresh clean fuel. No savings in burning heating oil and cheap fuel. It's not a chain saw you don't need to add 2 cycle oil. Straight clean diesel always got it done for me.

 

[Indyharleyguy]

Thanks I'll need to read the best way to remove glow plugs as I've never done that either. If I need to replace them what kind do you recommend?

 

[dependable]

3/8 deep socket usually does it, unless they are swollen. If they are swollen there are a few approaches to removing, all of which have been discussed many times here. Try to see if they come out normally before you worry about that.

I would recommend AC 60 glow plugs, which have are somewhat self protected against burn out. CUCVRUS like to use the AC 13s which were the original plugs, and work fine. But they are more likely to fail in my experience, but may glow a little faster.

 

[cucvrus]

Thanks I'll need to read the best way to remove glow plugs as I've never done that either. If I need to replace them what kind do you recommend?

You got this thing. Just get a 3/8" socket and crank them out just like you are changing a spark plug on a lawn mower. We will cross that swelling bridge if we get to it. I don't think we will. And yes 13G A C Delco. tried and true. Tell me what you are taking out? And is the resistor pack still hooked up? Good. Report back please.

 

[cucvmule]

When starting you said that you hold the throttle open all the way. Why?

 

[Indyharleyguy]

OK I'm replacing the glow plugs this Saturday. Replacing the fuel filter also.
I hold the pedal to the floor when it's cold outside and half way when its warmer outside.
After I've driven it and it's warm I don't touch the throttle and it starts just fine if it doesn't sit for more than a few hours.

 

[Icorps1970]

If it fires up and immediately stalls, then can be started after several tries, I would guess an air leak in fuel system. If truck is stock, the first place to look is the fuel pressure sensor in the fuel filter base. This sensor is pretty much useless unless you have a bit of obsolete test equipment called and STE/ICE, and prone to air leakage. Remove sensor and plug the hole with a screw with JB weld or similar on it. Sensor is the quarter sized disc w two wires under the fuel filter.

The air leak could be somewhere else in line too, but the filter base sensor was/is a very common problem.

Of course it would be a good idea to check glow plugs too, and while fuel filter if off, replace it. I usually fill them with diesel before putting them back on for easier starting.

Have an M1009. I have a similar start then die issue. Recent Standyne rebuild on the IP. It was leaking at the throttle shaft. It has had the cold start issue for some time, starts, then RPM zooms up then dies. Figured air in the system but all rubber lines under the hood are new. It was OK for a time last winter then in the spring it started again. This was my Dads truck and was owned by the state of AK after the military it has been doing this pretty regular for some time, several years, but now is worse and I am finally fed up. The batterys are new but it ran them pretty low trying to start after setting a couple of weeks had to jump it. Usually it does not take so long to refire. So will pull and work over the filter housing tomorrow due for a filter anyway. Hope this fixes it. Thinking of junking the stock filter but would rather not. Thanks

 

[cucvrus]

Carefully check all the hose clamps. Lately I found a hose clamp that was gorilla tight and had made a small pin hole in the rubber. This allowed air to bleed in and make the vehicle drop the fuel prime. Check that bottom clamp on the bottom of the lift pump. I seen this twice in the past. And just recently. Good Luck.

 

[Indyharleyguy]

Hi Everyone. I did replace the glow plugs with AC 60 glow plugs and replaced the fuel filter. Same problem. I'm wondering if I'm not getting the fast idle set right? I am now turning the key on then I'm pushing the accelerator all the way down then releasing. Same exact problem. It starts for a second then dies. I can only get it to start after cranking it 2 or 3 times while holding the accelerator all the way down. I now the engine block heater is fine because as soon as it does start it's blowing out warm air. What is the lift pump?

 

[cucvrus]

The lift pump is located on the passengers side of the engine very front part. Check this out. https://www.steelsoldiers.com/threads/cucvrus-repair-projects.192437/page-8

 

[Indyharleyguy]

OK thanks I'd call that a fuel pump LOL
Am I doing the correct steps to start it?

 

[MarcusOReallyus]

A diesel has two fuel pumps. The lift pump gets the fuel from the tank to the injector pump at maybe 10 PSI. The injection pump produces the high pressure needed to spray the diesel into the cylinders at maybe 10,000 psi, or more.

But unlike fuel-injected gas engines that inject fuel at 10-60 psi, diesel fuel-injection systems run in the 10,000-30,000-psi range.