I've searched the site, and can't find any other thread with this issue. The LP and IP were both replaced in my '99 three weeks ago. This is my second LP -- this time it took out the IP! At 115000 miles I guess it was due based on what I'm reading. Now I notice it idles rough and feels like it's also rough while at highway speeds. Something just isn't quite right. I took it back to the shop to have the pumps checked -- they claim the pressure is where it should be, and couldn't find anything wrong. Ironically, while pulling out of their driveway the map sensor dumped on it so I went around the block and dropped it back off for more repairs.

Not being a diesel mechanic, I don't know where to start checking. Has anyone else had this issue after getting the IP replaced? Is it possible that the timing may be off since the IP runs off the timing chain? Could the injectors have been effected? I've used Howes faithfully for the last 80k miles so they should be clean. Is there another sensor that should be checked?

After finding this site and spending many hours reading through all the information, I've decided to start with a few (safe?) bombs. Gauges are a must. I'm also seriously thinking about the Banks Stinger performance package with the Banks break -- for now I only need extra power when fighting a head-wind, but must have extra stopping power while towing my RV. I'm not looking to start a lengthy discussion on performance options -- only that I have already considered these mods.

 

VP (injection pump) is all electric and electronically controlled on the 24valve engines.

So, no on that.

Other than that I don't know, unless you got a bad VP.


phox

 

cam sensor or crank sensor can cause problems like that. I believe on the 99 you've got both.

 

Thanks for the feedback. The "bump" while idling reminds me of a gasser with a bad plug wire. I've learned enough about diesels to know that can't be the problem . I've also noticed it is not consistant -- sometimes it's really bad and others it's hardly detectable. I also noticed it doesn't matter if the engine is cold or warm -- initial startup or been running a while.

Are the cam/crank sensors easy enough to replace? I grew up working in a auto body shop so I know which end of a torque wrench to hang onto, and don't mind getting my hands greasy. Also, does anyone know a good source -- all I know of locally is a NAPA store.

Thanks again!

 

No! Neither is easy to replace!

The cam sensor is just below the injector pump in about 2-1/2" of space! It takes an allen wrench and about 1-1/2 hours 'cause it's a pain to work in that small of a space.

The crank sensor is slightly above and behind the starter. Pull the starter to get to it and it's easy. Just plan on being patient with the starter bolts. Only one has enough space around it for a standard socket, the rest are pretty much wrench only. This one really isn't hard, just time consuming.

Now, I'm trying to remember.....and of course I can't. One is a signal to the PCM for injector timing. The PCM seems to be just a cog in the wheel as it passes the info to the ECM. The other is a signal to the PCM for cruise control etc. Hopefully someone who remembers this correctly will chime in, but I'm kinda thinking the cam sensor is for the injector pump timing while the crank sensor is used for cruise control??????

 

Here's a thought. When you were replacing the injector pump, did you loosen or maybe even mostly unplug the cam sensor? It's easy to reach in there and make sure it's plugged in. Just follow the wiring harness right under the injector pump to the back of the timing gear cover.

 

here is what I have seen with the vp44 , the pump is bolted to a gear and gear driven , the pump shaft is tapered and keyed , sometime during installation with the VP 44 , with the gear in time the key way is at the bottom and the key can fall off during the installationm , and the timing could be off , I always superglue the key to the pump shaft and set the keyslot on the gear at 12 o clock and install the pump , and then still check for the key with a mirror from the front , I would also hook up a clear line from the VP to the filter outlet with a clear line and check for air.

 

There is a possibility of the wrong key being in the VP44. I cannot explain why, but I noticed in my instructions for replacing my VP-44 that you have to use a key with the same number as part of the serial number of the VP44. I do not know why this is since, as I understand it, the timing is all computer controlled. I did check both my pumps and the key for each has a number stamped on it that is part of the SN on the pump.
If this were happening to you, you'd probably notice a difference in power.

Below is a pic of the cam sensor, I took when I had the VP44 out.

Chris

 

Well, I didn't get a chance to check anything out due to having surgery on my foot (made it kind of difficult trying to crawl around under the hood). I had the truck back into the shop a couple times, but they couldn't find anything. About a week ago, I noticed the rough idle just stopped. No more bumps or thumps -- feels smooth. Gremlins?

I've been concerned that the new lift pump was defective but the shop insists it's good. I have a 32' travel trailer that will be towed into Colorado and Montana Rocky Mountains this year. Knowing I need more stopping power, and a little help while bucking head winds and long uphill climbs, I ordered the Banks Stinger and Brake systems. While waiting for them to arrive, I installed a DiPricol fuel pressure guage (with the isolator). What I found is 12psi at idle, 10 at highway speeds (no load), and 8 WOT. These seem low to me. I also noticed the pressure goes up to (around) 10psi with the lift pump when I turn on the key, but drops back down to 0 as soon as the LP quits running (if I don't hit the starter). Is this normal or do I have a leak? Once I start the engine, it runs smooth and seems to have the same power as pre-guage. I'm heading to Colorado on the 23rd -- I really appreciate any/all help! Thanks in advance!

Franklin

 

Your fuel pressures are fine. The spike you see when you first turn the key on is the pump priming the system. It's perfectly normal.

 

Flack, did you take your truck to a mom and pop shop or a dealer sometimes, tech's will take short cuts and not disconnect the batterys, after installing any new electronic device on these trucks it is a good idea to disconnect the batterys for a hour or so. after restarting allow the run the truck for 20 miles to allow a complete relearn process, in reference to the cam sensor, it is used as a diagnosis sensor and has no impact on preformance, all pump timing is controlled by the speed reference sensor inside the pump. I installed a rebuilt VP-44 on my ram and had the speed sensor go bad in 2000 miles. fought it for 2 weeks before i figured it out. Also if you loose a crank sensor the truck will run pretty much normal, a code will be set, the tach will die and the check engine light will come on.

 

BigBlue, thanks for the reassurance! I dred the thought of breaking down on the highway with the camper, wife, two kids, and a dog -- been there, done that, don't want to do it again!!!

Mouse, thanks for the feedback. The shop is "NAPA Certified" and performs warranty work for the various dealerships in the area. I've trusted them with my gassers over the last 10 years -- very honest and won't perform work unless it is really needed. I'm not sure how qualified their mechanic is in regards to the CTD. The check engine light has not come on since the MAP sensor was replaced. I'm installing the Banks systems this weekend and will make sure the batteries are disconnected long enough to perform the reset.

Thanks for the feedback!
Franklin

 

I think I found the problem... I didn't trust my LP so I installed a FASS last month before heading on vacation. Even with the FASS, I noticed rough engine performance on several occasions. This last weekend I noticed the fuel pressure gauge was very slow to come up when starting the truck. Once going, it would stay at 13 lbs. I unhooked the fuel line from the VP44 and put it into a fuel can, and had my wife bump the starter -- lots of fuel being pumped, but I could also feel and see air being passed with the fuel. I remember reading several threads about people with pick-up assembly problems causing air to get into their fuel systems. Since the tank was below 1/2 full, I filled it up. Now the FP "snaps" up to 10+ lbs when the FASS primes the system and snaps up to 13.5 lbs when I bump the starter -- engine runs smooth again.

Looks like I have a leak in my pick-up assembly inside the fuel tank. Chances are the leak caused the last LP and VP44 failure too. Now I need to decide if I want to go with a new pick-up tube (like the 1/2" stand pipe from Advanced Diesel) or with a bottom port as Haulin_in_Dixie and TxDieselKid described on another thread. I'm looking for feedback on these and/or other options members have used.

Thanks, Franklin

 

well my 2 cents...there is no chain and if it was timing it would be across the board not 1 cyl. I think you should do a cyl drop test manully or with the ob 1 tool and see which injecter is not at avg with the others ( kind of like pulling a plug wire).

 

Try to notice if after starting, especially after sitting for a couple of days, does it make a surge or miss after running for a second or two. That would indicate air in the system.

You might also go over the banjo bolts for tightness. Remember air will enter where fuel will not leak.

Also I wonder if you just got a bad tank of fuel? Now and then I get lumpy fuel. A bad tank could have helped the vp44 to go when it did. I will add this though. The current engine (complete ready to run) sat for a couple of years in storage. When installed it was not quite smooth but had good power and economy, seemed to be only at idle, after 20,000 miles it is glass smooth.