Can't Fine Miss At Idle

[icanfixall]

For some time now I have had an idle miss. I can drive the rig with no noticable miis. If I get just about 1000 rpm its gone. I have checked and cracked each injecter loose and felt a very noticible lope from that cylinder. Really didn't feel a cylinder that barely changed. May have to do it again. Or remove all the injecters and pop test them.. I really don't want to do that. If I go that far I'm changing all of them. Only other choice I see is to run a compression test and we all know thats no joy too. I really can't see this miss being a mechanical issue like a broken ring or a bad lifter. Its got me wondering whats up.Any ideas guys...

 

[argve]

delivery valve in pump is what I found on mine years ago. it sits behind the vane pump in the nose cone of the injection pump. fairly easy to get to you can do it on the truck but you have to work across the rad and junk. Mine wouldn't be noticable until you got the engine warm then it would make it's self known. after talking with my pump builder he thought it was the likely suspect. the delivery valve has to slam shut everytime an injector gets pulsed with fuel so if it leaks by it will stumble or miss. I called it my hot idle shake/miss back in the day. I wrote a thingy up on it years ago on how to perform the swap and demo'd it at the 2nd IDI weekend.

 

[Bashby]

My old engine had a rough idle also and I couldn't really tell much by killing cylinders either. Are you getting any abnormal smoke from the TP at idle?

 

[gingrass179]

wheres the infrared temp gun?

 

[icanfixall]

Thanks for the answers guys. Travis. What you described is whats happening to my engine. I probable will look into checking out what you posted. I have two spare pumps here I can rob parts from. I have had the front of the pump apart before seeing that small impeller and screen in there but no further into the pump. Guess I need to look at an exploded view of a pump now. Thanks guys. I apreciate the help. Its not often I ask for any here.

 

[icanfixall]

So has anyone got a pump breakdown of this valve. I don't know what it looks like so it sure would be nice to know before I get into this. Any o-rings that might be needed are nice to know of too. I do have a really nice injection pump repair shop about 5 miles from me. I'm sure they will have what I need. I just don't know whats needed yet.

 

[gandalf]

Good morning, Gary. It's 0430 here, and there, and it's real dark outside. I really hope you're not awake also. Come to that, I wish I wasn't awake.

I have a picture which might help. It doesn't have a delivery valve marked, but it does show the internals of the pump. I'll toss it in here.

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I also have a 27 page instruction manual on rebuilding the DB2 injection pump. This manual is written, believe it or not, by the USMC, as a training manual. It's in pdf format. I'd be happy to send you a copy if you'd PM me an email address. Useful? I really don't know. But I'd be happy to send it along.

 

[icanfixall]

Thanks Ken. PM sent...

 

[icanfixall]

Well I opened up a spare parts injection pump. Removed the allen screw with a hole in it. Then used a small pencil magnet to reach in and draw out the valve and spring. Is there are seat this valve seats on or am I done.. Waiting on more information fro others sucks but its how it goes. Its really interesting getting into the fuel feed end of these pumps. In that cone there is a very fine filter. Behind that is the feed pump with the 4 vanes and the 2 springs that keeps the vanes pressed outward to the pump shell. As careful as I was I thought I lost a spring. They are about 1/4 inch long and about 1/32 diameter. I thought I heard it hit something on the floor so I dragged a magnet around.. Nope.. No joy but found plenty of other treasures... I still have another useable injection pump for parts too but will probably just pay the two bucks and take what I need or want from a wrecker engine in the yards. I really hate loosing parts like this...

 

[dgr]

Did you look at this thread? There is a 48 page DB-2 manual and a DB-2 torque specs manual at the link.
http://www.oilburners.net/forums/showthread.php?65029-6-9-manual

 

[icanfixall]

Did you look at this thread? There is a 48 page DB-2 manual and a DB-2 torque specs manual at the link.
http://www.oilburners.net/forums/showthread.php?65029-6-9-manual

Thanks for this information. I did not have it. Gosh am I learning lots about whats ahead of me. I have more to remove now.. I kinda thought this was not as easy as I thought it was going to be...

 

[argve]

You got it gary. Replace that valve and enjoy.