6.2 turning over, but not starting.

[Lonesome715]

My aircraft tug recently made it home and will not start? From what I hear, it does turn over though. So, what would cause this? I know, I know, that is a pretty vague question. But I am only looking for any common problems I should look for. I will be home on R&R hopefully soon and I do not want to spend a lot of time on this. To my understanding, if the engine turns over and is getting fuel it should start. Am I correct, or is there more to it with these old 6.2’s?

 

[AJMBLAZER]

Could be dead glowplugs.

 

[Lonesome715]

Not what I want to hear.

 

[AJMBLAZER]

They're not hard to replace. Sorta like doing spark plugs only a bit more expensive.

 

[Lonesome715]

Oh, then that is okay. I thought it was like my Stroke. I have to pull the valve covers and everything that is above them.

 

[FreightTrain]

Yea,The injectors are outside the VC but below them.I think the GPs are in the valley.Nothing under the valve covers but the valve train.

 

[Lonesome715]

How can I check to see if they are bad?

 

[FreightTrain]

Test light.The light comes on good,light not on,bad.One Bad plug will throw the whole setup off.As they heat the resistance changes and the controler senses it and goes into After Burn mode(atleast on a ford which is basically the same system) where it keeps the hot plugs hot without over heating by cycling on and off.

 

[FreightTrain]

When you turn the key when cold(don't start),watch the volt meter.It should be REAL low and then after several seconds jump up.If it is showing full power then the GPs ain't being warmed and can be bad plugs,bad connection,Bad ground on the controller,bad controller.Check the GPS first,then check all connections and grounds.

 

[Lonesome715]

Okay, that sounds simple enough. What else should I look for?

 

[superburban]

1) Check to make sure that the fuel cut off solenoid on top of the injector pump is working. A quick and dirty test is to turn the key to the KOEO position, then pull the pink wire on top of the injector pump. You should hear a click when you connect and disconnect it.

2) Check that you are getting fuel. Open the top vent nut (plastic disc with an "X" molded onto it) on the fuel filter. Crank the engine over. If you see fuel spurting out of the vent, the fuel pump is working fine. If you do not see fuel coming out, you may have to crank for a little longer, you have an air leak somewhere further upstream on the fuel line, or your fuel pump is shot.

3) Check to make sure the IP is pushing fuel to the injectors. Find the most easily accesible injector, whichever one is convienient. Loosen the injector line to the top of the convienient injector. Crank the engine for 4-5 seconds. You should see fuel weeping out of the line. If you see no fuel, your injector pump is shot.

PS: Dont do step 3 before step 2, or the test conclusions could be faulty.

 

[Lonesome715]

Thanks. That is the kind of information I was looking for.

 

[superburban]

Oh, yeah, if it has been run out of fuel, it is a real b!7ch to re-prime. You have to open the air vent on the fuel filter, then crank until you get fuel spurting out, then close it up. Next, you need to "crack" as many of the injector lines as you can reach and crank until you get fuel weeping out at the injectors. It takes a lot of cranking. You may have to re-charge your batteries at least once.

 

[Lonesome715]

I have ran my Stroke our of fuel before. That was not fun. It seems like these older non electronic deisels are worse when it comes to that.

 

[FreightTrain]

Nah,just that these older trucks don't have electric pumps so you can't just turn the key a couple times to reprime.

 

[dependable]

The Chevy 6.2 is a low compression diesel that needs glow plug to start when engine is cold. regardless of air temp. If fuel delivery is ok, try to take out one glow plug. Take care not to break glowplug if heavely carboned, twist it out slowly. if it breaks, you should be able to retrieve glow plug tip with magnet from preignition chamber. Ground body of plug to engine, if tip dose not get hot when ignition is just turned on, you may have bad glow plug controller or some burnt out plugs, There are some postings under cucv glow plugs that may help.

 

[Lonesome715]

Thanks. That is going to be a big help.

If I do have to replace the plugs and controler, is there a upgrade that I should look for or is stock replacement good enough?

 

[Braunchitis]

If you need to reprime the engine, try hooking up one of those vacuum hand pumps used to bleed brake lines to a fuel line coming off the filter. Pump until you get diesel. Then hook everything back up, and you may have to then bleed the lines as described above.

I did this when I replaced my lift pump. It saves your batteries and your starter.

 

[Lonesome715]

I was expecting to have to do that. I have a hand pump so I should have all that I need to get this done. I just hope that is all it is.

 

[dependable]

R E glow plug control replacement; In my opinion, replacing the controller is a waste of money as the manual ground jump to control soleniod is easy and works well.. But if you have multiple users or want things very original it may be worth it. You can test plugs out of vehicle on a battery charger( low amp). Black to body of plug and red to connector tab. Glow plugs should be replaced in sets. If some are dead, the rest are sure to follow.