Calling out to 6.2 Diesel gurus, need help

[ZooMad75]

Ok guys, I got a local buddy struggling with his 6.2 oil burner. He's not on here, but he has hit a point of frustration where he might bail on his project. While he might want to go switch to gasoline he's got too much money stuffed into the project in total to just unload it. Going EFI gas isn't a cheap way to go either as he'd have to change everything from the fuel tank forward, exhaust, wiring, ect.

So here's the gory details. The truck is a 84 GMC Suburban, factory 6.2 diesel/700r4. It started out as a half ton, but it's rolling on 1tons, 37's with 6" lift. He picked up and installed a unused Banks Sidewinder turbo kit for it and installed it with the stock injection pump. As far as I know the engine was a reman/rebuild shortly before he got it but I'm a little fuzzy on that detail. Here's an idea of what we are working with.




He ran the Banks turbo with the stock IP and found it was lacking for power. Doggish. More than a turbo'd 6.2 should be at least. He got his hands on a military J-code IP and swapped in with the bigger/better injectors than the stock civvy 6.2 stuff. I'm told he pulled the 12v stuff off of the original IP and swapped out the 24v parts off of the J-code pump before installing it. That's where the proverbial crap hit the fan I'm told. He fired it up with that combo and it instantly went into a runaway scenario. Couldn't shut the damn thing down. Turbo wound up and all. By some stroke of luck he got it shut off, checked out some stuff and fired it up again. Yep, you guessed it the 6.2 ran away again. After a couple of panic phone calls to another guy he got the idea to pinch the fuel line off and sure enough, it shut it down.

He called the guy he had got the IP from and was told to send it back to him, he'd go through it and send it back. He pulled it, sent it to the guy and got it back. The IP was fixed (don't know what he did) and my buddy installed it. Fired it up and yet again it ran like it had a brick on the throttle.

He's totally frustrated right now and considering dumping the whole truck after putting the stock IP and injectors back on it. He's capable in swapping parts on and off, but he just lacks the ability to diagnose the problem.

I openly admit I know jack squat about the 6.2/6.5 diesels. But I don't want to see my buddy dump the whole truck over the problem as he's going to take a bath on it. I'm open to suggestions, ideas or if there is one of you that is fairly local (Colorado front range) we could get the truck to and he paid somebody to fix it right. I know there are a few of you guys on here that know what you are doing around one of these. @AgDieseler @tRustyK5 @KirsL @imiceman44 @Truckman4life @GWeakland620 @K5wrench You guys came to mind but I know I may have missed some, tag anybody else that have more of a clue than I have.

I appreciate the help that anybody can provide and will pass it straight to him. Thanks guys!

 

[K5wrench]

Military 6.2 has 12 volt shutoff solenoid just like civys.
Only the starter and starter solenoid are 24 volt, volt gauge, and secondary side of starter solenoid key solenoid.
The glow plugs, glow plug card, and everything else is 12 volt on a cucv.
Glow plugs are fed through a resistor bank to bring operating voltage down.
Both alternators are even 12 volt.. isolated ground.
One charges the front battery.. both alts together charge both batteries.



If the cutoff solenoid is installed incorrectly, it will run and not shut off but it wont run away from that alone.

Either: ip pump is messed up.
Throttle cable to ip pump is messed up.
If he was sucking oil it would run with the fuel line pinched or not so that is out.

Just tell him to put the original ip pump back onnit.
When adding a turbo, you have to turn up the ip pump a little.
Lots of info online.
Basically involves removing the housing off the top of the ip pump and turning a screw inside the governor assembly.. like 1/8th of a turn.
Which he should do amyways to figure out why the cut off solenoid isnt working.

If all else fails.. sell your turbo kit to me cheap.

 

[AgDieseler]

Either: ip pump is messed up.
Throttle cable to ip pump is messed up.

Same thoughts - only the IP modulates the fuel feed. Swap back to control for the IP variable, and document results.

It’s easy to incorrectly rebuild a pump. He might consider going to a Stanadyne dealer and spec’ing a 4911. I ran a “value rebuild” for a good while until I saw the light.

David

 

[K5wrench]

Same thoughts - only the IP modulates the fuel feed. Swap back to control for the IP variable, and document results.

It’s easy to incorrectly rebuild a pump. He might consider going to a Stanadyne dealer and spec’ing a 4911. I ran a “value rebuild” for a good while until I saw the light.

David

I used Oregon fuel injection.
Flawless.
About 600 bucks with exchange and other parts/gaskets etc.

 

[AgDieseler]

I used Oregon fuel injection.
Flawless.
About 600 bucks with exchange and other parts/gaskets etc.

That’s probably a good reference mark. I paid 650 here in Dallas for my 4911 update/rebuild.

David

 

[ZooMad75]

Military 6.2 has 12 volt shutoff solenoid just like civys.
Only the starter and starter solenoid are 24 volt, volt gauge, and secondary side of starter solenoid key solenoid.
The glow plugs, glow plug card, and everything else is 12 volt on a cucv.
Glow plugs are fed through a resistor bank to bring operating voltage down.
Both alternators are even 12 volt.. isolated ground.
One charges the front battery.. both alts together charge both batteries.



If the cutoff solenoid is installed incorrectly, it will run and not shut off but it wont run away from that alone.

Either: ip pump is messed up.
Throttle cable to ip pump is messed up.
If he was sucking oil it would run with the fuel line pinched or not so that is out.

Just tell him to put the original ip pump back onnit.
When adding a turbo, you have to turn up the ip pump a little.
Lots of info online.
Basically involves removing the housing off the top of the ip pump and turning a screw inside the governor assembly.. like 1/8th of a turn.
Which he should do amyways to figure out why the cut off solenoid isnt working.

If all else fails.. sell your turbo kit to me cheap.

Good info. The fact that they swapped stuff from the old civvy IP to the military one might be the variable that is the problem. Not because they may be the same just the fact that the opened up both, fiddled with it and possibly did something wrong. I would have thought the guy they sent the IP to would have caught it though.

My thought was to get a solid unmolested pump and install.

 

[tRustyK5]

I would agree to swap on an unmolested IP.

 

[K5wrench]

Definitely worth one last look at the throttle to make sure it is at idle, nothing holding the linkage, tv cable, etc.
See if it is resting on the screw stop.

Then, if it is..
There is no other action to take but remove that ip pump and have it rebuilt (by a professional this time) or put a known good one on.

 

[ZooMad75]

Same thoughts - only the IP modulates the fuel feed. Swap back to control for the IP variable, and document results.

It’s easy to incorrectly rebuild a pump. He might consider going to a Stanadyne dealer and spec’ing a 4911. I ran a “value rebuild” for a good while until I saw the light.

David

Ok for the 6.2 stupid, what is the 4911 spec?

 

[AgDieseler]

Ok for the 6.2 stupid, what is the 4911 spec?

Last mechanical 6.5 IP for 92-93. It’s a good option for road driven trucks.

David

 

[ZooMad75]

Last mechanical 6.5 IP for 92-93. It’s a good option for road driven trucks.

David

I assume that works well with the added turbo too?

 

[tRustyK5]

The 4911 was the highest flowing mechanical pump that fits the 6.2. It is able to provide more than enough fuel for a boosted 6.2 and is a "stock" part somewhat easily available. 1993 was the last year for the mechanical IP, so if someone was to ask for a reman pump for their 1993 K2500 with a 6.5 TD they'd get themselves a 4911 pump.

All that said, your friend should try for modest expectations. Even turbo'd the 6.2 isn't going to come close to any modern diesel he may have driven. It will just be less gutless, and have a new thing to worry about (EGT's)

 

[ZooMad75]

The 4911 was the highest flowing mechanical pump that fits the 6.2. It is able to provide more than enough fuel for a boosted 6.2 and is a "stock" part somewhat easily available. 1993 was the last year for the mechanical IP, so if someone was to ask for a reman pump for their 1993 K2500 with a 6.5 TD they'd get themselves a 4911 pump.

All that said, your friend should try for modest expectations. Even turbo'd the 6.2 isn't going to come close to any modern diesel he may have driven. It will just be less gutless, and have a new thing to worry about (EGT's)

Thanks. The expectations aren't to get modern diesel levels. The internals are stock, no intercooler so the power levels are going to be better than stock NA. Just not radically higher than stock. When you factor in the 37's it's probably going to be back to adequate with turbo.

 

[K5wrench]

When i got my m1009, the injection pump was leaking.
Called Oregon Fuel Injection.
Described how i use the truck.
My climate being very cold at 9,000 ft, winter temps of minus 40 degrees.
Then sent them my pump.
I got an entirely different pump back.
Rebuilt to spec.
It did not magically turn the 6.2 non turbo j-code into a fire breathing dragon.
To some degree, in a non turbo 6.2, it is simple; less fuel, less power.
More fuel, more power.. until the air at a given rpm runs out and then.. black smoke.
But it does not leak.
Starts and runs at minus 40.
Gets 17 mpg with 3.73's and 33's between 5,000 and 9,000 feet elevation where i live.
And even without the turbo, it manages the 10% grade on 14A just fine, albeit in second (turbo 400).
But the higher i climb, the more black smoke i make, and less power i have.
In my case, i am overfueled.
If you think an n/a j-codes 160 hp and 275 lb ft of torque is sad.. try one at 9,000 ft.
A turbo would help.
However, the more fuel and air.. the higher the exhaust gas temperatures.
You don't want to exceed 1,100 degrees or you risk damaging your valves and pistons.

So, your friend can get that pump rebuilt.
Turn up the pump until the egt under full load approaches 1,100 degrees.
But you gotta watch out.
Where as the non turbo 6.2 like mine can not really hurt itself.. a turbo combined with too much fuel can absolutely destroy the engine.


I recommend reading up on the subject.
Tons of information on the web.
But that pump would be first.
Then adjusting the pump based on egt would be next.

 

[KirsL]

As everyone else has said. Double check all linkages and such to make sure none are binding up.

But from the sound of it. When the shutoff was swapped it wasn't properly installed. The pump is going to full throttle. A true runaway would end up blowing oil out of every seem in the intake. Plus it would rev till it ran out of fuel or exploded.

I would pull the shut off solenoid and check that the governer spring is still there.

The fuel screw needs to be turned up some to make use of the turbo. If you have a decent injection shop in your area I would take the pump and injectors to them and have them gone through and setup for a turbo.

 

[tRustyK5]

A true runaway will exceed the governed max rpm and spin til it blows. It sounds like this one sat at the limiter (3600 rpm) until they starved it for fuel.

Safer to start it without the air cleaner and have a small piece of plywood handy. If it takes off, drop the plywood over the intake hole.

 

[ZooMad75]

When i got my m1009, the injection pump was leaking.
Called Oregon Fuel Injection.
Described how i use the truck.
My climate being very cold at 9,000 ft, winter temps of minus 40 degrees.
Then sent them my pump.
I got an entirely different pump back.
Rebuilt to spec.
It did not magically turn the 6.2 non turbo j-code into a fire breathing dragon.
To some degree, in a non turbo 6.2, it is simple; less fuel, less power.
More fuel, more power.. until the air at a given rpm runs out and then.. black smoke.
But it does not leak.
Starts and runs at minus 40.
Gets 17 mpg with 3.73's and 33's between 5,000 and 9,000 feet elevation where i live.
And even without the turbo, it manages the 10% grade on 14A just fine, albeit in second (turbo 400).
But the higher i climb, the more black smoke i make, and less power i have.
In my case, i am overfueled.
If you think an n/a j-codes 160 hp and 275 lb ft of torque is sad.. try one at 9,000 ft.
A turbo would help.
However, the more fuel and air.. the higher the exhaust gas temperatures.
You don't want to exceed 1,100 degrees or you risk damaging your valves and pistons.

So, your friend can get that pump rebuilt.
Turn up the pump until the egt under full load approaches 1,100 degrees.
But you gotta watch out.
Where as the non turbo 6.2 like mine can not really hurt itself.. a turbo combined with too much fuel can absolutely destroy the engine.


I recommend reading up on the subject.
Tons of information on the web.
But that pump would be first.
Then adjusting the pump based on egt would be next.

He added an EGT gauge with the turbo to keep tabs on it. I'm pretty sure he is aware of the 1,100 degree threshold as he was thinking of going to water/meth injection to keep them down. Again, me being a dummy to this, water/meth still sounds like a bandaid.

As everyone else has said. Double check all linkages and such to make sure none are binding up.

But from the sound of it. When the shutoff was swapped it wasn't properly installed. The pump is going to full throttle. A true runaway would end up blowing oil out of every seem in the intake. Plus it would rev till it ran out of fuel or exploded.

I would pull the shut off solenoid and check that the governer spring is still there.

The fuel screw needs to be turned up some to make use of the turbo. If you have a decent injection shop in your area I would take the pump and injectors to them and have them gone through and setup for a turbo.

Good point. From what I've been told it didn't blow oil out or grenade the engine. Simply pinching off the fuel line was all it took to stall it out. He tried everything else though, shutting it off by the key, nada. Disconnected the battery, nada. Like I said before he's handy enough to swap parts, but may not understand the changes being made or if he put it back together right. He may have tweaked the fuel screw too. From what the guy said that built the pump he may have overtightened it and even though he backed it back off might have got something stuck. That's why it was sent back to the guy, he wanted to make sure my buddy didn't damage it somehow. The guy went through it and said it was ok which tells me you could be right on the linkage or his pump guy is a quack.

Problem we have is the local diesel shop in town won't touch a 6.2 with a ten foot pole. They'd rather fleece bro's with dirtymax's, Cummins and powersmokers. I've not heard good things. So I'll reseach Colorado Springs or Denver.

 

[Scribbles]

A true runaway will exceed the governed max rpm and spin til it blows. It sounds like this one sat at the limiter (3600 rpm) until they starved it for fuel.

Safer to start it without the air cleaner and have a small piece of plywood handy. If it takes off, drop the plywood over the intake hole.

The only thing that scares me is this part

By some stroke of luck he got it shut off, checked out some stuff and fired it up again. Yep, you guessed it the 6.2 ran away again. After a couple of panic phone calls to another guy he got the idea to pinch the fuel line off and sure enough, it shut it down

This is possibly me reading it rather than living it but let’s clarify? What was happening during this phone call?

 

[Scribbles]

Never mind, smarter people than me are chiming in while I was working on my earlier post.

 

[ZooMad75]

The only thing that scares me is this part


This is possibly me reading it rather than living it but let’s clarify? What was happening during this phone call?

The engine was running away, not shutting off regardless of conventional means. He almost took a hammer to a metal line underneath when he saw a section of rubber fuel line he could pinch off with some pliers.