loch

I'v been workibng on my sisters truck, got every thing fixed but one thing. Also thanks to Dave and others for the code help. When the trucks revved quickly and let off the engine drops below idle speed, almost dies. It seems to not be very responsive to pedal pressure, how ever it still runs ok, any ideas ?

93 dually cummins, i think it has pump tweaks but not sure, since collar is gone i'm taking that as yes.

G1625S

Were is the low idle screw set at? The throttle could be indexed wrong with the idle screw compensating though still not providing enough initial tension to smooth the idle after a rev. Maybe the idle spring on the tophat is missing/broken?

IraPatterson

My truck does this too. If I have to stop fast the truck will almost die (and sometimes it does). I have not been able to diagnose it any further than a fuel problem. I know the low sulfer diesel is having an affect on it, because mine has gotten worse since I started running the new LSD fuel. You would think with a name like LSD it would be better for the trucks... Give them a nice buzz and all... J/K. I have heard that if the lines from your fuel tank to the injector pump are plugged at all it could cause this... Just one thing I heard though. I will look into it.

One Tree

i was lucky enough to have a cummins guy come to my house one day, and i picked his brain all i could. He told me that the low sulfer doesnt give the fuel lines the proper lubrication as the old stuff did. You can buy a fuel lubrication additive bottle at most any parts place, he told me to use the stuff every other fill up to keep proper lubrication....

loch

DAVE !!!!!!! the codes are back, I'm really starting to hate this truck.

Today I fixed broken motor mount, replaced valve cover gaskets, new brake pads, fuel filter and washed engine down. The light wasnt on, till I ran to town.

I'm getting a 12--41--46--55, now I know what they mean, but does it have be the computer or could alternater be the cause ? The computer is from dodge and only been on it a week and the alternater was put on new the same day.

keithplacervill

i think 55 means end of codes that is how a gassser is

keithplacervill

chiltons 12 battery disconect 50 start or less 41 generator field not switching right 46 charging to low

JimmieD

1990 FSM:

12 - Battery disconnected within last 50 key cycles

41 - Open OR shorted alternator field circuit

46 - Battery voltage sensor input ABOVE target charging voltage during engine operation

55 - end of codes

With a combination of 41 and 46 I'd look to see that the field wires are properly connected and in good condition. A grounded short [41] in field wires might make it try to overcome the charge loss giving the 46 code. Also check any engine/chassis grounds.

keithplacervill

maybe when you washed the motor water got where it should not be

KRB

I agree, water could be causing some erroneous readings.

Mine gave those codes once and I traced it down to a bad/poor connection on the driver's fender. Very frustrating in the mean time.

wannadiesel

Check out the ASD relay. Just swap the front and middle relay on the fender and see what happens.