Engine/Transmission (1994 - 1998) Engine cutting out

[super38]

I've got a 12 valve 98 that will on occasion without warning will just shut off while driving, usually while coasting in traffic or coming to a stop light, also some times it will drop RPM usually to around 600 or so and bounce back. It is also has problems starting some times, it will just turn over until the pedal is taped then fires right up. So far all it has a 3000rpm kit, and a #10 plate. Anyone have any ideas? Could a bad injector couse this?





James

 

[bmoeller]

What the normally idle speed? If you have an auto transmission, it should be 750 RPMs, in drive, and with A/C on. Check to see if the jam nut is tight on the adjusting screw. Takes a 10mm wrench.



http://dodgeram.org/tech/dsl/adjustments/2nd_Gen-Idle.htm



May also need to adjust the governor spings a tad.



www.piersdiesel.com/TechGSK12V.htm



How old is the fuel filter and fuel pressure?

 

[super38]

The fuel filter is new ( less than 500 miles) I also checked the idle adj. screw and it's tight with a normal idle speed of 750 to 775 rpm with ac on and it has a 5 speed transmission, forgot mention the Prime-Loc but I don't think it has anything to do with it. Don't know fuel pressure, didn't put a guage on it being a 12 valve.







James

 

[ABorchard]

Better put a gauge to it or buy a new overflow valve. The OF valve is the single most common part that wears out on a 12 valve. Your pressure should be 22-26 at idle.

You won't find a better price than here



Precision Diesel Injection and Turbo Inc.

888-734-7349

$35 + $7 shipping and handling.

 

[DBraunig]

Hey Super38, did the truck start acting up after the GSK springs were replaced? if they are not set right it will cause this (too loose). one injector would not cause truck to stall, just develop misfire and run bad. also might check that the throttle linkage move freely and fully, just some ideas, good luck

 

[ata]

5 speed manual bump the idle up to 875 r. p. m.

 

[JGheen]

I would check the overflow valve, like Aborchard mentioned. Also what about the fuel shutdown solenoid, has it been checked for proper operation? That is another easily overlooked part that causes sudden shutdown.

But definately check your governor spring kit as that is also a sensitive piece to make the pump run right.



Joe

 

[super38]

The fuel shutoff solenoid was checked by myself and Cummins, and yes it started after the springs where changed. If it's the springs how do you know where they need to be set? At what RPM should I see defueling with a 3000 RPM kit, right now it starts at about 3600. I may go ahead and change the overflow valve it’s cheap and couldn’t hurt.





James

 

[DBraunig]

some measurements should have been made (repeatedly) before the stock springs were changed to give you a base line for the new springs. mine are set @ . 065 from top of stud to spring retainer. some of the other guys may chime in here with other opinions. you stated that "yes the problem started after the governor springs were changed" common sense says this is where the problem is. remove the afc housing and plate and use a dial caliper to measure what they are set at now. you can try to adjust them a two or three clicks tighter and drive the truck again to see how it acts. make sure that both springs are adjusted the same. i believe the TST and PDR website show illustrations on how to do this. hope this helps