mcratchet1

yes from dash, ill take a look at check valves should i put a gauge on the wet tank itself to see if its losing air somehow? could it backfeed thru a valve?

etec e7

no it was doing it before injectors were installed oil sample says soot%0.4

so getting back to this, i have checked ever where for a leak cant find one truck holds air pressure over night also

i have a 2003 mr688s 400hp blowing black smoke in bewteen gears truck runs great no problems. New turbo and injectors beginning of this year, should i be concerned or just let her roll?

i found it a pinched key switch wire

yes already bypass it

2006 mr688s (032711) under dog box all 4 power relays buzzing when i try to start all fuses good, batteries are good, just changed starter since i had one no difference i check and cleaned grounds no change even new key switch any help would be great thanks!

on all 4 power rely's #30 has power and #87 is ground

whats a typical cause ? rubbed wire?

ok ill check there 70 amp relays

ok found high/low beam relay bad changed been running with no problems for a month now did same thing 2x today also this morning truck would not start. When i turned key only heard buzzing coming from these 4 relays. Does anybody know what these control? im guessing one has to be starter i cycle the key a few times then it cranks i checked to the wire had 11.50 but when i turned key switch dropped to 5.5 volts now truck will not start going to just start tracing wires unless someone could help a brother out Thanks!!!

thats a good idea but they dont work nights here

tell me which ones to take off and i would gladly do so to test it out

yes, the only thing i do not have a pin tester to check relays, but the did have good scratches and fit tight we are a small private pump company we have 7 mack trucks I called mack for a diagram of the fuse and relay layout in the dog box but they said they cannot give me that info they are never helpful 032711 is the last 6 of vin do you have access to fuse and relay location? Thanks