Hey guys my girlfriends 99 Cummins 24v is running really sluggish lately it just feels like its not building any boost at all. She used to work as a secretary for a guy that did car and truck restoration and I am starting to wonder what this guy knew. He pretty much did a full restoration on her truck it had 220,xxx miles on it when he got and rebuilt the motor and redid the whole body put a lift on it and so on. Well he told her he did all kinds of work to it and I am finding out that half the things were straight lies. Yesterday I was checking all the fluids in it popped open the air cleaner and saw possibly the worst air filter I have ever seen in my life. It had a K&N in it that was so plugged you could barely see the individual pleats in the filter. Well we spent about 4 hours getting it cleaned and re-oiled, and cleaning out the lower portion of the airbox that was covered in a later of like dirt greasy oil. He recently told us that he changed the filter and just added a simple in line filter after me and her had problems and i changed the stock filter about a 1000 miles ago cause it wasn't good enough since i did it. Well I am a classic car guy I can figure out what is wrong with an old emissions free motor but when it comes to a diesel I am clueless. Now I am wondering where to start to look for problems it seems like the truck has just slowly been loosing power and it hardly ever puts out any black smoke from the stacks anymore like it used to. So any ideas what to check for?

Also how do I check the level and add transfer case fluid to it? It has a small leak that I plan on fixing when the weather gets a little warmer but for now I would like to just top it off. The truck has the 24v cummins and an automatic transmission.

 

I'd check the fuel pressure off the lift pump and make sure it is pushing enough to the VP44. lack of fuel can realy kill the 98.5-02 model years.

 

If the air filter was that bad, I'd bet the fuel filter isn't any better.

Check it because if it is a lack of fuel you'll soon be looking at a $2000+ repair bill to replace your VP44. the filter is only $15. If he did put a cheap $5 in-line filter on there, I'd yank it off real quick, it can't handle the flow that the diesel engine needs and it is so small it will clog easily. It also would not hurt to get a fuel pressure gauge so that you can monitor the fuel pressure. Like Drew said, the 98.5-02 trucks had the VP44 lift pump and any lack of fuel will ruin them.

 

Your mechanic friend may have either cracked or not tightened up a boot when working on it. Check those as well.

 

Well I have a fuel/vacuum gauge at the house and we will be up there next weekend so I was wondering where would be the best place to hook into the fuel line to check? And how many lbs of pressure should it have?

 

This is where I screwed the sensor on my Autometer. Hopefully someone will confirm that your gauge will work there as well. As far as lbs go, I'd like to see you over 10lbs.