6.2 Revving and Missing

[motormayhem]

Hey Guys,
I'm having some engine trouble with the M1009 that has me a bit stumped. I drove it to work the other day and everything was swell. When I started it to go to lunch as soon as it started it revved way up to ~3k like the throttle was stuck open, but before I had a chance to acknowledge what was going on it came down to idle. Everything seemed good so I proceeded to leave for lunch. About 10min later pulling up to the light before the lunch place it started making a knocking nose from the engine bay and was running rough at idle like it had a miss. I limped it over to the lunch place and it was running / had some power but was making a very loud knocking from the engine that is hard to pinpoint. I took the air filter off with it idling and noticed that the rear cylinder on the right bank seemed to be backfiring into the intake a bit. When I put my hand over the other runners it was only air into the engine that runner seemed to be air in and out. In addition to the loud knocking and miss, whenever I start it up it wants to rev like I'm starting it with the pedal floored. If I feather the key on and off for a few cycles I can keep it from revving to high and it eventually calms down to a rough idle with throttle control.

The revving on start makes me think its a fuel issue like a stuck injector or governor, but the intake makes me think its a valve train issue (but maybe timing?). Its not making any abnormal smoke that I have noticed like its running away on oil or anything and it responds immediately to key off when it tries to rev. At idle both pipes sound about the same and don't smoke. ​

I tried cracking each injector line with the engine idling and none of them seemed to make a huge difference. Maybe the rear 2 cylinders on the right bank had less impact when cracked, but it wasn't night and day.

What is going on? Where is the best place to start as far as troubleshooting this goes?​

 

[rsh4364]

Is the knock worse while under load? Then less severe when you get up to speed and ease off throttle? Is it smoking more than normal under load?

 

[Chaski]

Something else to look at its the three screws that fasten the top cover onto the injection pump. If one of the screws has a little metal tag with the letter "E" stamped on it the pump has been worked on some time in it's life and it has had the old plastic governor weight retainer replaced with the new style that has no plastic. No tag most likely means it has the old style weight retainer. The old ones are known to break apart inside the pump and fowl things up.

 

[nyoffroad]

The surge sounds like you have a air leak in the fuel system, the knock could be the engine swallowed a glow plug. That's all I can come up with.

 

[motormayhem]

I did some more work today and found some stuff. First off, no smoke (other than black). I have to start it and throw it in gear to keep the revvs down. When it sits there trying to go in gear both pipes are blowing some black, but nothing out of the norm.

I pulled the drivers side valve cover as running it with the intake off the drivers side #3 cylinder was not sealing on the intake valve and blowing exhaust out the intake port. Looks like the rocker arm shaft is cracked and the intake valve spring on that cylinder is broken.

So with that news, how would that explain the fact that it is trying to rev when starting? That is for sure what is causing the miss and I can't imagine two major issues popped up at the same time out of the blue. It didn't drop the valve (looks like there is a second spring), but with a broken spring should I be worried about piston/cylinder damage? I was planning to sell the truck basically now, so I'd rather not pull the head, but also don't want to pass the buck with a quick fix. If there a way to get into the cylinder to take a look through the head? I have access to a bore scope if needed.

 

[rsh4364]

Doubt if you damaged the cylinder piston or rings, but you can pull the injector and bore scope through there.

 

[nyoffroad]

"

#3 cylinder was not sealing on the intake valve ​

" that could be your problem, it's sucking engine oil and running (surge) on that. Just my .02

 

[motormayhem]

That's what I originally thought, but since it doesn't blow any white / blue smoke or look like there is oil leaking from the valve guide I'm thinking it might be something else. Once I have a chance to get the valve spring changed out I'll post an update.

 

[motormayhem]

Well I put a new valve spring in there and she runs normally now as far as the knock and misfire go. Still revving when started. Now that its back to a working engine I can start troubleshooting the rev issue, but Ill start a new thread for that since its pretty specific.

 

[motormayhem]

Engine Over Revving When Started

Hey guys,
I'm having a problem that just popped up recently and resulted in a broken valve spring. Now that the valve spring is taken care of I am back to troubleshooting the original issue. When I start the truck it acts like the pedal is floored / its running away. If I start it and throw it in to gear at the same time it prevents it from revving higher than I can stand, but sits there like its has the throttle depressed. If I push the gas pedal down it will respond with a little more power and when I let off it will then return to a normal idle and I can then put it into park and have it idle normally. It sounds like it might be surging very subtly, but its hard to tell since the intake manifold is off right now. The tach only varies by about 20rpm which isn't noticeably different than before it started having this issue. Any ideas on what is going on that would cause it to act like a stuck throttle until I depress the pedal and then it returns to idle normally? Its being started with no throttle input and high idle solenoid unplugged. I haven't taken the top off the IP yet as I was worried about getting it back together, but I can only think its the governor asy. The injection pump was done about 8 years ago and probably has 15k on it so its not that old. I pulled the return fitting on the IP and it was free from debris. Truck shuts off with the key no problem.

 

[Kaiser67M715]

Sounds like a governer issue. BUT can be a very bad air in fuel issue.

Put a clear line on the return side, make sure there are no bubbles when starting or after sitting.

It might not be the miles, but rather age making it act up.

As to air in fuel, my truck did same sort of thing, except it would burble and stumble with lots of smoke first, then it would clear and I would press the accelerator to get to high idle, and the thing would scream...not really, less then 2,000 rpm likely. Fixed the air leaks, and now when I press the accelerator, it goes to a normal high idle (roughly 950/1050 rpm) also got rid of the stumbling and smoking.


Sent from my SM-S920L using Tapatalk

 

[Chaski]

Here is a bit of info again.

The DB2 pumps had a urethane weight retainer on the governor weight ring inside the pump. The urethane bit would come apart and cause all sorts of havoc. Stanadyne made / makes an upgrade kit that used a totally different governor weight retainer that was all steel. The upgrade kit came with a small stamped piece of aluminum with the letter "E" stamped in it. The little aluminum tag was supposed to be installed on one of the three screws that holds the pump lid on. The identification tag would allow easier identification in the future.

So, if you have the metal "E" tag you have the retrofit kit.

If you don't have the metal "E" tag it is very possible that you have the older style weight retainer that has decided to come apart inside your pump. Not saying that it is your problem for sure, but it could be an indication.

 

[motormayhem]

Good info. Sorry, I didn’t see your post in my other thread. Just took a look and no tag on the pump. It was supposed to be a new rebuilt one when the shop did it 8 years ago but I was 400miles from home so I was more focused on getting up and running than what specific updates were done. I’m pretty confident it’s not an air leak as it runs strong just won’t go to idle. No smoke or sputtering, it just lights off and shoots for the moon. If I take the top cover off can I see if the retainer is broken? I know the gov weights are housed below the little sump under the cover, but can you see any part of it?

 

[Chaski]

You can clean everything up and pull the top off the pump if you are curious. Read up on placing the top back on, when you do make sure the shaft is at the idle position, and you place it on with sort of a swooping motion to make sure you don't get the shutoff solenoid wedged behind the metering valve and have a runaway. There is a little illustrated drawing in the TM... I think.

With a flashlight if you look around you might see clear / clear white / clear brown bits of the governor weight retainer. If you see chunks then you know it is time to take the pump off. The governor flyweight is towards the front of the pump, and on the main shaft. It is hard to see from the top, but with a good flashlight you should be set.

 

[motormayhem]

Well after replacing all the valve springs on the drivers side bank I pulled the injector pump cover off and there are a bunch of metal shavings in there. They are ferrous and stuck to the solenoids. From what I could see the governor assembly looks ok, but with the shavings in there something is not having a good day. Looks like its time to pull the pump. Anyone have a shop they recommend to do an IP or should I just take it to the local injection pump shop? Looking in the TM, re-timing the pump is a matter of just aligning the timing marks? That seems too simple. I know some people play with the timing a bit and mine is currently set about a line width to the drivers side of the timing cover mark, but if I pull the pump I don't need to pin the engine at TDC or have any special tools to time it when I re-install?

 

[Keith_J]

No special tools needed. No locking the engine either. The pump hub has an alignment pin, fine tuning usually isn't needed.

The metal shavings could be from the worn out urethane flex ring causing the governor drive pins to wear on the cage.

 

[motormayhem]

Ya I think the ring has failed and it just hasn't run enough to see debris from the ring. The local injection shop quoted $900 to do the pump so I guess I'll be finding one online since that's pretty steep for a POS rotary pump.

 

[antennaclimber]

I have used Oregon Fuel Injection with good results. But there are other shops out there as well that can rebuild them.

 

[Chaski]

Ya I think the ring has failed and it just hasn't run enough to see debris from the ring. The local injection shop quoted $900 to do the pump so I guess I'll be finding one online since that's pretty steep for a POS rotary pump.

Doh!

$900 is pretty steep.
There are lots of internet options, one being Badger diesel...I think.
I have used both Oregon Fuel Injection out of Medford and Redding fuel injection out of Redding CA with good results. That being said... no garuntees of positive results for you implied...

My word of warning is this, if at all possible have a Stanadyne authorized shop do the work. I had a shop do one for me with a grey market seal kit. While they did bore and sleeve the advance piston bore and it did work great it only lasted 10 months. All the rubber parts used were total garbage and self destructed. I kid you not, the little rubber triangular shaped gasket under the timing inspection hole on the drivers side crumbled and turned to mush when I took it off. One of the shaft seals was about 200% of original size. Total knock off garbage.

 

[Keith_J]

The governor drive ring damps rotational oscillations just like the torsional damper on the crankshaft. This keeps the governor from hunting. This damping device "evens out" the rotational speed. When it fails, the governor cage can move about 20° of cam travel (40°of crank rotation) which is why the idle speed suffers with the throttle blip will cause the engine to die.

It is a simple piece to replace with the new Pellethane part which will last much longer. But in my opinion, this part is junk like rubber torsion springs or crankshaft torsion dampers. It should be magnetic leaf dampers which use diesel to dissipate the energy hydrostatically. I have a design in works but need to open a pump to get dimensions.