Cummins 5.9 12 valve towing issues

[DonDee]

Air brakes? On my 24v w/air brakes there's a 1in hose that feeds the air compressor with clean pressurized air from the int manifold. Ours was cracked we lost boost.

[retired long]

Originally Posted by rseibenick

1994 Diesel pusher. P7100 pump.

Those p pumps are almost bullet proof ;However long time ago instructions from Case tractor manual was to never replace the final filter for many thousand hrs.Reasing is ALL Diesel pumps are very alergic to minute dirt,So on our Case tractors that wass practiced an never had trouble.So my recomenddation is to never replace the second or final filter,It is too easy to get dirt in replacing filter. However i always cut first filter apart when changing first filter.Cant emphise enough cleanlesss is vitally important .

[Buly]

Originally Posted by Scepter40

By far the easiest way to install a fuel pressure gauge on a p-pump is to drill and tap a 1/8” pipe thread into the head of the banjo bolt for the fuel feed right on the side of the pump. Then run a line to a glycerine filled gauge using a needle valve. The mechanical lift pump thumps pretty hard, so it’ll destroy a gauge in short order if you don’t. Then just crack the needle valve enough to get a reading. You will probably want to get an adjustable overflow valve as well to keep your fuel pressure up. Here’s an adjustable one that I run on my 12V:

https://www.torkteknology.com/cummin...rk-tek-ofv010/

I find that the stock mechanical lift pump works fine with no issues and folks have been running them more often than not, especially at stock power levels.

Here is how I did it. Tells me if the filter is starting to load, and the pump is struggling to suck fuel thru it. It is a Racor vacuum gauge.
No drilling or tapping. Used the spare ports of the filter mount.

[captbrown]

change the fuel shut-off solenoid if over 10 yrs old and make sure it has full travel.

[Billbob]

Originally Posted by rseibenick

Having issues when going up long hills after driving for over 2 to 3 hours with the RV and trailer. The RPM's drop from 2200 to 2000 to 1700 . Stay there for a short time ,then go back up. Some times have to drop into 3d gear to get the RPM;s back up to 2000 and craw up the hill at 35 MPH. When entering the Hill , try to increase the RPM,s and the engine will not respond, just start to go down. The 5.9 is inter cooled and turbo charged. Anyone having the some issues. Thanks.

I had same problem.near flagstaff. Ki ked out a lot a black smoke. No power. Found out egr was plugged. Cleaned it out, runs great. Just a thouhht

[Scepter40]

Originally Posted by Buly

Here is how I did it. Tells me if the filter is starting to load, and the pump is struggling to suck fuel thru it. It is a Racor vacuum gauge.
No drilling or tapping. Used the spare ports of the filter mount.

I dig that! Nice way to do it! I originally had mine hard plumbed at the banjo bolt on the pump and it lasted 40K of daily driving miles and cracked from vibration. I went to a copper oil pressure line and left the coils in it to dampen the vibrations (and relocated the gauge).

[1320Fastback]

I daily drive a 12 valve and tow with it 4-5 times a year. I run Baldwin filters and change the fuel twice a year when I do the oil change.

OPs issue sounds like a fuel pressure issue time. Either a simple filter change or lift pump.

[Ray,IN]

Originally Posted by 1320Fastback

I daily drive a 12 valve and tow with it 4-5 times a year. I run Baldwin filters and change the fuel twice a year when I do the oil change.

OPs issue sounds like a fuel pressure issue time. Either a simple filter change or lift pump.

I'm thinking the lift pump of a 12V 5.9 runs all the time. My 1995 had a screen inside that was coated over with dirt. Cleaned and replaced that screen and usual performance returned.
The Dodge truck fuel lines from frame to lift pump were flexible, the outside appeared fine but the inside was wrinkled with loose pieces.