95' cheyenne 6.5 problems :( lots....

[cheyenne1500]

Hi guys! Well i have a 95 cheyenne with 120xxxkm..not too much i'd say. I'm pretty new to deisels but i've been doing some research. Anyways here my problem...Higher than normal fuel consumption, running rich (more black smoke than usual). But heres where it gets weired....when the oil temp is up to operating range the eng starts running really funny. Low power, struggles to go more than 50 mp/h or 80km/h. At idel the rpm will drop sometimes like a cyl is not firing. When under braking the rpm goes back to idel-ish but surges up to 11-1200 3 or 4 times while under braking. AND when feathering throttle while crusing it knocks like crazy and under full throttle, but not accel. None of this happens while the eng is still warming up. I've just replaced the lift pump and fuel filter...it fixed the problems for a week but now they back!!!!!

Also i think the thing on the turbo side valve cover its the pcv valve i think its spitting alot of oil in to the compressor, and there is about a 1/8 -1/4 inch coating of black sooty crap all in the intake and down into the head and valves. But ya i've got some work to do :(:(

[tommac95]

>Also i think the thing on the turbo side valve cover its the pcv valve i think its spitting alot of oil in to the compressor, and there is about a 1/8 -1/4 inch coating of black sooty crap all in the intake and down into the head and valves.

Keep in mind , but leave for now... you have other priorities!

>I've just replaced the lift pump and fuel filter...it fixed the problems for a week but now they back

Both the LiftPump and the PMD/FSD share power supply elements {including the IgnitionSwitch} ; both are also noted for occasional failure within a month of renewal, indicating related problems not cured by the renewals. The cause of the LP's second failure could be either sucking more crud up from a dirty old FuelTank (which has a worn-out filter screen/nylon-sock, and some sludge from a bad load of fuel , and accumulated condensation), or sucking air through a corrosion-perforated pickup assembly, or , more likely {since the symptom correlates with a warmed-up engine} , the LP loses its power feed when oil pressure drops following warmup, particularly at idle/low-throttle. The LP is fed power via the OilPressureSwitch when engine running on '95 model year.
If the fuel filter is also clogged , that can also cause the PMD/FSD to choke , and make engine stumble. Strictly electrical issues [worn IgSw , bad harness ground at rear psgr head , and frying driver transistors in either/both the LP and PMD/FSD] can also prolong symptoms.

So , ENSURE clean fuel at good pressure , and clean steady electrical supply [IgSw, grounds, OilPressureSwitch] , before other things.