waiting for the tow truck

[Crash_AF]

Where are you checking for voltage for the glow plugs? Did you check all 8 plugs to make sure they are all working?

And no, there are no safety switches on a CUCV. If the pink wire has 12V and the solenoid in the pump clicks when power is applied and removed, then it should be getting fuel unless there is a problem.

When you cracked the lines to bleed them, how much fuel came out? Was it a lot or just a little?

If you do decide to cheat with ether, disconnect the light blue wire from the glow plugs to disable them. Hot glow plugs + ether = very bad things.

I'm going to lean towards the glow plugs not functioning and not getting the cylinders hot enough to fire.

Later,
Joe

 

[watkinssr]

well, a safety switch would cut out the IP, and the IP is running, so it's not that. I'm very hesitant to use starter fluid. I mean, it's a diesel...it has fuel, it has air, it should run. I need to put an ohm meter on all the glow plugs in the morning.

 

[watkinssr]

Where are you checking for voltage for the glow plugs? Did you check all 8 plugs to make sure they are all working?

And no, there are no safety switches on a CUCV. If the pink wire has 12V and the solenoid in the pump clicks when power is applied and removed, then it should be getting fuel unless there is a problem.

When you cracked the lines to bleed them, how much fuel came out? Was it a lot or just a little?

If you do decide to cheat with ether, disconnect the light blue wire from the glow plugs to disable them. Hot glow plugs + ether = very bad things.

I'm going to lean towards the glow plugs not functioning and not getting the cylinders hot enough to fire.

Later,
Joe

well, when I cracked the lines I just barely cracked some till I saw fuel. Should I open them up more? Some of them it sprayed out pretty good.

Ether is a last resort IMHO. I've never used it on a diesel before, but if I have to I have to. I'll be sure to pull the power to the plugs if I do. My plan was to ohm out each on e of the plugs...and I only checked that voltage was getting to one of them.

Hope I'm not boring you guys with all the updates, just thinking outloud, so to speak. I appreciate the advice and the help.

 

[watkinssr]

Well, disconnected the glow plugs, and did a short shot of starter fluid. It fired off immediately and ran.

Put an ohm meter on the glow plugs...first 6 all read open. At that point I said screw it, all of em are probably bad, so it's off to get new ones.

 

[Crash_AF]

Congratulations. I'm glad that it started out for you and now it's running. Definitely get those GPs replaced soon so they don't take out the controller card. Other than that, have fun enjoying your new CUCV.

BTW, if you haven't figured it out yet, as long as it gets up to temp, it should start without the GPs so you can drive it around or work on it all day even with them bad.

Later,
Joe

 

[watkinssr]

lol...it was running. got 7 of 8 glow plugs out...one is swollen and giving me ****. Also, it appears our friend was right, put it in gear, and it dies. So that's next.

 

[linx310]

Does the engine respond to throttle ok when its in park?

My M38A1 did some thing similar and it turned out the fuel pickup line in the fuel tank had broken and was sucking air.

It would run fine when in park but as soon as I would put a load on it it would die as the gas would move around.

Probably not the same issue but I was just trying to think of an easy test you could do by maybe running an alternative fuel line to a small portable gas can.

Also I have seen M38A1s do this when the timing was off.

 

[linx310]

Wanna bet this is the original owner making this post

6.2 dies when put into gear - Diesel Place

 

[Crash_AF]

Yea, I'd bet it was.

On to the problem at hand. I'd bet that the transmission or torque converter is seized up somehow and that's causing the engine to stall when it's moved out of park. To make sure it's not electrical, put a test light on the pink IP wire and see if it shuts off when the shifter is moved out of park. if it doesn't, then something mechanical is stopping the engine dead. That 'something' has to be transmission related.

Luckily TH400s are easy to rebuild and are fairly cheap to get parts for. Or, you could upgrade to a 700R4/4L60 transmission to get an OD.

Later,
Joe

 

[T_F_E]

I saw one guy who welded the flexplate to the torque converter... it lead to a broken crank.

 

[linx310]

And no, there are no safety switches on a CUCV.

Isnt this a safety switch? The neutral safety switch.

It doesn't allow it to start unless its in Neutral. If its messed up it might be telling the engine to cut out when it should not. Perhaps when he puts it in gear it cut the engine out.

NSN - 2920-01-150-1610

 

[watkinssr]

Boy, this is turning epic. Got the last glowplug out with a pair of vice grips and rather long Snapon pry bar.

Got the new glow plugs installed, tried to start it...it tries, but doesn't quite catch. joy.

 

[K9Vic]

Boy, this is turning epic. Got the last glowplug out with a pair of vice grips and rather long Snapon pry bar.

Got the new glow plugs installed, tried to start it...it tries, but doesn't quite catch. joy.

Check to make sure you are getting 12volts to the glow plugs when the ignition is first on as they are 12v and not 24v. If they are above 14v, then you may still have a GP issue. The relay may be bad, I had that on I had and after changing out the plugs. If you need one, they are not a standard civi part, but easy to get at O'Reilly. There is also the resistor block on the firewall behind the engine, I recommend bypassing this to the 12volt side to avoid any 24v spike issue that may destroy your new GP.

Did you get the AC 60G as these are the recommended ones and work best?

 

[watkinssr]

Check to make sure you are getting 12volts to the glow plugs when the ignition is first on as they are 12v and not 24v. If they are above 14v, then you may still have a GP issue. The relay may be bad, I had that on I had and after changing out the plugs. If you need one, they are not a standard civi part, but easy to get at O'Reilly. There is also the resistor block on the firewall behind the engine, I recommend bypassing this to the 12volt side to avoid any 24v spike issue that may destroy your new GP.

Did you get the AC 60G as these are the recommended ones and work best?

Yeah, 60g. Getting 12 volts at the plugs.

 

[Crash_AF]

Isnt this a safety switch? The neutral safety switch.

It doesn't allow it to start unless its in Neutral. If its messed up it might be telling the engine to cut out when it should not. Perhaps when he puts it in gear it cut the engine out.

NSN - 2920-01-150-1610

Ok, if this comes out sounding patronizing or like I am being snippish I apologize, but did you read the wiring diagram instead of the parts manual? I realize that that component is called a 'Neutral Safety Switch', and in a civilian vehicle that's what it would be used for, but it only turns the backup lights on and off in the CUCV. Nothing more. The CUCV (and all other GM trucks of the era AFAIK) has a mechanical block in the ignition column that prevents the key from being turned while the shifter is in any position other than Park or Neutral.

Attached is the starting circuit wiring diagram for the CUCV, and the colored lines represent the path of electricity. Yellow is from the starter switch on the column to the starter relay under the dash. Red is the path from the battery to the starter relay to the starter solenoid. Nowhere in that path is there a 'neutral start switch' listed that breaks the connection.

There is no 'safety switch' anywhere in the CUCV from the factory that will interrupt power from the ignition to the injection pump. The only thing that controls the pump is the ignition switch.

Now that that is settled, let's move on.

The starting problems could be any number of things. First off, is the vehicle getting fuel in appropriate quantity to start? The lift pump on the side of the block might be getting weak. You should pull the rubber line off of it and do a flow check to see if it's delivering enough fuel to the IP.

On the transmission issue, I had a thought. The parking pawl might be jammed, keeping the transmission locked down. When you put the transmission in neutral with the transfer case in 2HI can you push the truck?

Later,
Joe

 

[watkinssr]

Still will not start, I'm getting fuel definately, is it enough? I'm not sure how to test. My fuel preassure guage is in storage with a lot of my tools (long story) . Just tried to start it again, and the starter started making funny noises...I'm going to let it cool off a bit and go out and try again.

I'll try the push it in 2h thing.

 

[linx310]

Ok, if this comes out sounding patronizing or like I am being snippish I apologize, but did you read the wiring diagram instead of the parts manual?

Na don't worry about. That is why I am on this site to learn, I just remembered seeing it in the parts manual when I was looking to see if the key/lock cylinder could be replaced and recalled seeing it labeled as a safety switch. Now I know it isn't.

 

[Crash_AF]

Still will not start, I'm getting fuel definately, is it enough? I'm not sure how to test. My fuel preassure guage is in storage with a lot of my tools (long story) .

The description of the procedure is in the -20 under Mechanical Troubleshooting: Engine cranks but won't start. Table 2-3 Section 15 Step 6.

Check fuel pump operation. Disconnect input fuel line at the fuel filter. Disconnect pink lead from fuel injector pump. Use a quart capacity container, and crank engine for 15 seconds. Container should be at least 1⁄4 full or contain 1⁄2 pt (0.231) of fuel. Install low pressure gage in fuel line. Crank engine for 15 more seconds. Fuel pressure should be 5.5-6.5 psi (38-45 kPa). Reconnect fuel inlet line to fuel filter, and reconnect pink lead to fuel injector pump.

Later,
Joe

 

[watkinssr]

Joe, thanks for the info. I've about decided that thats where the problem is. I re-shimmed the starter and the bad noises went away, then I turned the key and fired right off...ran for about 10 seconds, then died. Wouldn't start again.

When I opened the vent on the fuel filter it took several turns to get fuel out. Batteries are starting to wind down and so am I, so I'm letting it charge overnight and I'll get a lift pump tomorrow if it doesn't check out. Glad this thing has 3/4's of a tank of fuel in it, otherwise I wouldn't be able to afford the fuel to drive it after all the money I've thrown at it the last few days.

 

[choll]

I have an 85 that was doing the same thing. Would not start with out assistance from starting fluid. I know your not supposed to use it but I used very little. Anyway I traced it back to the little electric thing on the fuel filter assembly, bought a new assembly from ebay and have not had one issue in over a year. What ever that thing is called it was sucking air.

Chuck