Engine/Transmission (1994 - 1998) pre filter or lift pump?

[cop0110]

my 1997 3500 sometimes acts like it misses while going down the road. around 2200 rpm it cuts in and out blows white/blue smoke and stalls. it does not do it all the time but seams to be getting worse. when it died the other day i pushed the primer plunger several times and it started and ran fine for a few miles. i was thinking it could be the pre filter but i cant locate it. or could it be the lift pump? i did change the fuel filter and it still does it. any help will be greatly appreciated

 

[Todd T]

its in the bottom of the fuel heater which resides just forward of the transfer pump. the bottom of it is a bowl that will unscrew. The pre filter is in there. a Cummins center will have a kit to replace the screen O ring and gasket for about $10 bucks.

 

[illflem]

Pre filter cleaning instructions here -

http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

 

[cop0110]

Well it was the filter in the tank it was gunked up bad. cleaned it with brake clean and it runs great.

 

[illflem]

The tank filter is usually kept clean enough by fuel sloshing around in the tank. If it plugs it means things are really gunked up. Good idea to drain the tank completely, flush it out and use a biocide for a couple of tanks or the problem will reoccur. Just using boicide isn't enough as the dead bodies of the diesel algae plugs things up just as bad as live ones.

 

[cop0110]

Well I replaced the lift pump. I replaced the supply and return line's. truck ran great for 3 days and this morning I started it to warm up and it died. I pushed the plunger on the lift pump several times and started it back up. it ran rough white smoke and wanted to die. I drove it 150 miles and it ran fine. After the drive I turned it off and let it sit started fine. Let up warm UP went in the house came back out and it had stalled. What the $%#%! I am really getting discouraged and mad. What good is a truck that is not dependable? Any sugestions?

 

[akline]

Do you have a fuel pressure guage? My truck had somewhat of a similar problem, turns out it was the fuel overflow valve. (pressure regulator in the return line fitting on the front right corner of the injection pump) It doesn't sound quite exactly like that would be your problem, but who knows, it might be worth a check. I would tend to lean towards the dirt/algae/fungus explanation. Sometimes I think these things have minds of their own.

 

[cop0110]

I drained and flushed the tank. I do have a pressure test gauge but where and how to I hook it up ? what did your 95 act like to make you change your overflow valve? I heard that if you push on the lift pump plunger and it makes a hissing sound that its good. Is this correct. At this point I am ready to hang parts just to get it fixed. Thanks for the help.....

 

[bmoeller]

Overflow valve check-http://www.dodgeram.org/tech/dsl/troubleshooting/injector_pump.htm#Overflow



Fuel psi check- http://dodgeram.info/tsb/1996/14-07-96.htm



Engine specs- http://www.dodgeram.org/tech/dsl/Facts/96specs.html

 

[illflem]

cop, it will cost you about $25 just to connect up a FP gauge unless you remove the injection pump inlet banjo bolt and tap a 1/8'' port in the top of it. Easy job but it might be easier/cheaper just to buy a new overflow valve here.



Precision Diesel Injection and Turbo Inc.

Marty Tompkins

toll free 888-734-7349

$20 + $5 shipping and handling.

 

[cop0110]

After all that it was the fuel overflow valve... 81 bucks for a banjo bolt. Oh well its fixed. thanks for all the great advise and information...

 

[akline]

I guess my post about the fuel overflow valve was actually helpful for someone. I spent 2 years trying to find the problem on my truck. I was actually convinced it was time to rebuild the fuel pump, and purchased a cheap beater vehicle to drive while this was taking place. Thankfully I read my TDR and found just a small reference to the problem, and saved about 2 grand. Am I understanding you to say that none of the other things you did fixed it, and replacing the valve was the answer? I think this item is one in the small handful of little known gremlins on these trucks that need to be kept in mind when troubleshooting!

 

[cop0110]

akline you are the man! saved me a pump rebuild. Runs G R E A T Oo. Oo. Oo. Oo. Oo. Oo.

 

[cop0110]

Well here I am again... . I started my truck today and while idling it started sounding like it was missing... . It did it 3 times did not die and cleared up cant get it to do it again. You think its just a flook or may-bee a bad of clogged injector. Any ideas greatly appreciated. :{ :{ :{ :{ :{ :{ :{

 

[akline]

score: pickup 1, akline 0! My ideas are all out... it's up to the crowd on this one.