Fuel Pressure

[mwilson]

Can some of you very helpful Cummins owners please give me the fuel pressure spec for my 94? I checked mine today and is running 28 pounds wide open and drops to a wildly fluctuating 20 pounds at idle. Checked it at the fitting on top of fuel filter housing. I know it is in the forums somewhere but I can't get the search engine to dig it out. I have lost a little power and thought the transfer pump might be getting weak. Thanks in advance.

Mike

 

[illflem]

Your pressure numbers are right in there. Might try looking for a boost leak to solve your power problem.

 

[mwilson]

Hi Illflem, knew I could count on you to respond. My highest boost reading has been 14 pounds. What has brought the loss of power to my attention was when I hooked onto the company trailer. The truck pulled well for about the first half hour and then would go numb on slight grades. Acted like lack of fuel. The turbo would quiet right down and more throttle made no difference at all. Didn't miss or anything, just acted numb. If you any input, I would sure be grateful. Oh yes, exhaust temp at preturbo never went over 800 degrees.

 

[nfox]

lost power

I would look for a intercooler hose that has slid off or might possibly have a hole in it. Check to make sure your throttle cable hasn't stretched, make sure it pulls the throttle lever on the injection pump all the way open. Might try switching fuel filters.

 

[mwilson]

Well, as a matter of fact I have an appointment first thing in the morning for the throttle cable and hood safety latch recall. Maybe the darn thing has streched enough to be a problem. The fuel filter only has about 2,000 miles on it and I also changed the prefilter screen that time as well. We are still on winter blend fuel up here also and I don't think I put any Power Service in the tank that time either. You guys have me thinking!



It's quite a thing to be able to sit in the comfort of home and type in a few lines about problems with your truck and get the quality responses that these forums provide. Feel very lucky to have this available to me. I have checked out a few other ones and they don't begin to hold a candle to this one.

 

[illflem]

Some other causes of low boost are loose manifold bolts or a wastegate that is stuck open.

 

[Joe G.]

mwilson,



If you have an auto trans you should check to see that you have wide open throttle after they get done with the linkage recall. In adjusting the TPS they may get the throttle rod too short so that it does not hit the stop at WOT.

 

[mwilson]

Just got back from having recalls performed and they found that old cable was out of adjustment and some body had reversed the transmission rod on a previous repair. He got that all straightened out and new cable installed. TPS checked out OK so he reinstalled it, adjusted it and checked with scan tool. Works like a charm and at full throttle empty exhaust temp is 900 degrees with 16 pounds of boost so a definite improvement was enjoyed by all!!

 

[mwilson]

Almost forgot, THANKS EVERYBODY for your help.