Did you know the previous owner or anything about the trucks history? Do you know if anything has been done to the truck? Do someone change the VP44? The P1693 companion code means there's another code in there and your scan tool might not be reading it. I cant say for sure but it sounds like your injection pump is out of time but that would mean that its been changed and someone botched the reinstall job. But dont let me miss guide you either. You might want a good mechanic or shop who knows about the ISB try and pull all the codes.

 

the computer should control the timing so it shouldnt be out of time

 

Even though the VP is a electronically controlled fuel injection pump, it is still mechanically connected to the engine. If upon installation, the installer misaligns the VP's shaft key into the timing gear, the injection pump will be out of time with the engine and cause problems. One being a loping engine at idle.:thumbsup:

 

I had two problems like that, both were on 99 models, and were automatics, they would miss at idle but as soon as you put it gear it ran smooth.I changed the VP44 on the first one and fixed it, it had no codes, and a new lift pump.The second one was a friends truck,and he put some fuel in that had a lot of water in it, it started missing bad and finally quit.He tried, and tried to start it, but the water done it's damage and I put a VP44 on it, and fixed it, and now not a day later his does he same as the first miss at idle stops in gear, and it's a brand new VP44.I'm going to do some checking and see if it's something else, I wouldn't think a new VP44 would be go bad that fast, but it is electronic so will see,so it could be your VP44, and if your lucks like mine you may have to change it twice,but you need to check you fuel pressure to start, and find out what codes you have now.If you need to know fuel pressure reading, or were to check let me know.

 

The second one was a friends truck,and he put some fuel in that had a lot of water in it, it started missing bad and finally quit.He tried, and tried to start it, but the water done it's damage and I put a VP44 on it, and fixed it, and now not a day later his does he same as the first miss at idle stops in gear, and it's a brand new VP44.

Please tell me someone pulled the bad fuel out, and changed filters with a good Baldwin to assist with water separation? I wouldn't be surprised if the injectors need replaced if water was pushed through them in operating conditions.

 

Ya it was one of cummins northwest service rigs,however i know nothing else about it.

As far as i can tell its completely stock.

So as of now i have no codes..cuz i cleared the crank position sensor one.,Put a new CPS in and it hasnt thrown another code for that yet.

Thanks for ur reserch 5.9 rail.

Im gonna let me friends friend who is a cummins tech listen to it and test the usuals for me.

 

Leaking fuel anywhere? :confused013:

It like your sucking air into the VP44 causing the knockin' lope. That what it sounds like on the first fire up of a fresh VP44 that is pushing air out.

You might want to check...

Lift Pump Diagnostics
(Look for air bubbles in your test)

Fuel Pressure
(Since you never mention fuel pressure in the first place)

 

i'm gonna bet it's bad fuel....where do you buy fuel from?? stay the hell away from Wal Mart.....

 

I use only shell and chevron ..however the truck still has fuel from when i got it left in it..so it is a possibility,day off today so ill do some testing.

update.

So i havnt done the remove rubber hose and bump starter and check the output of the lift pump but i checked the filter and it seemed fine.

ALSO i noticed the black electronic part on top of the VP says re manufactured on it,with some part/serial numbers?

 

So i did the test where u put some clear tube on the output of the filter.and run the lift pump..it had some bubbles but then cleared...so i then put a piece of clear tube in place of the black tube(in between the filter and the VP,to see if it made bubbles under normal operating load...and IT DOES.

A steady stream during idle and at higher rpm/s

So my next step is finding where air is being sucked into the system..

any pointers??

Thanks guys

 

Check the banjo bolts coming into and out of the fuel filter canister. They should washers on them. Make sure theyre clean too. If youre running a stock lift pump remember that the whole section of line from the tank to the pump is under vacuum. You can sometimes find small holes by looking for dirt accumulations.

 

I did drain and clean the tank,and changed the fuel filter(that would't be smart on my part) its not getting any air in the fuel lines,but I talked too my friend, and he says it's not any better and he noticed that it stops missing when the a/c clicks on, and starts again when off,as long as the engine is under load it doesn't miss. I talk to cummins, they said that they have seen the fuel temp senser fail and cause one too miss under a no load condition, so he's going to check with them to see, sinse there the only one too check the VP44 in that way. I'll let you know what they say.

 

I did drain and clean the tank,and changed the fuel filter(that wouldn't be smart on my part) its not getting any air in the fuel lines,but I talked too my friend, and he says it's not any better and he noticed that it stops missing when the a/c clicks on, and starts again when off,as long as the engine is under load it doesn't miss. I talk to cummins, they said that they have seen the fuel temp senser fail and cause one too miss under a no load condition, so he's going to check with them to see, sinse there the only one too check the VP44 in that way. I'll let you know what they say.

 

thanks 5.9,i really appriciate the update.. it seems all my air got out of the system..i left a clear tube in between the filter and VP and no air..and it still runs the same .

I tried listening to the injectors with a screw driver and none of em are popping off right at no load idle..then when u rev it up they sound good.

 

So i was reading about water contamination and it ruining the VP44.

i noticed today when refueling for the first time in day light my fuel cap is incorrect and the metal fill tube is all rusty..so this truck may have been running contaminated fuel for a long time..could this have ruined the VP?

put power service in and made no diff.

 

Water in fuel will definitely ruin a VP44. VP44 is fuel lubricated, same effect as water in the oil- bad news.

 

Did you ever check to see if the VP was replaced on this truck? You can tell because usually the new VP will be black and/or have printing on the id tag that says its been re-manufactured.

 

lets not over think this here. where are you located? was it cold out when you started it? It could be the 3cyl high idle. look it up on you tube and make sure its not that before you actually make yourself a problem/spend money

 

Read the original post. Runs good cold, bad warm.

 

ya the vp says re manufactured on it.

 

Hmmm.....I dont want to be the one to say it but since you've really exhausted most possibles, you may have a truck that someone screwed up the install on the VP shaft key into the timing gear. ONLY, of course, if your trucks been running like this since the day you bought it. The sad thing is that its a job which is very easy to do wrong but if the truck came from an actual Cummins service shop, I'd hope to shout that they would know what they heck they're doing, if they did it. I'm not even sure if you can redo the install and exchange the key because when the key is misaligned it gets smashed between the timing gear and the VP shaft as the VP is torqued back on the block.
The only other possible problem I can think of is that maybe one of your injectors is bad. Have you thought about going back to the place of purchase and asking them what the heck it may be? They are a Cummins service shop. Maybe they'll look at it for nothing because you just bought it there.
The last thing I can advise is this, call the only shop I know which works ONLY on injection pumps and has a wealth of knowledge about the VP44 injection pumps. Their web site is Blue Chip Diesel Performance Specialists. The person you want to talk to is Chip. Even though you didn't buy anything from him, he will take the time to help you out with possible diagnosing your dilemma. I'm not knocking anyone else either because there is plenty of other places who sell VP's and possibly work on them too but Chip is the only one I've talked to who actually helped. Believe me, when my VP went out, I called many of them too.

 

katoom,

Thanks so much for that site!,it was super informative and basically what his diagnosis page says is the miss at idle and under light load ussualy is the computer module ontop of the VP is partially bad.

SOOOOO ..looks like i got worst case scenario lol

 

Glad it helped and sorry for the bad news.