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Discussion Starter #1
ok this truck starts rough. you have to give it a little gas when the truck cranks to get it to fire. the truck runs ok when warmed up but will hold a high idle or will idle really low. a few people seem to think that the governer spring s stuck or broken. whats everyones thought on this? truck is completely stock. planning on doing some work to it with in the next week with the fuel plate and maybe change the timing a bit


any idea on why it may be stalling when in reverse if we dont keep it revving?
 

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whats your rpms at in park just sitting there...you probably just need to bump up the idle a lil bit, i would also change that fuel filter if it hasnt been done in awhile... and also it is normal for having to tap the throttle for it to start, this engine and pump are mechanical and you may need to on occasion
CumminsDatabase.com :: 12V Idle Adjust
 

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Discussion Starter #3
thank you for the info. im sure it hasnt been changed in sometime. was bought for a grand in running driving condition. my buddy cant . not to much rust either. a few of the things that i have planned to do to the truck is a 16 degree timing and a 40 pound governer spring. any major issues with those mods?
 

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Discussion Starter #4
idles about 750 or so.
 

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Don't trust the dash tach.
I do it by ear till it runs smooth.
 

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yea, mine did this too, bump up the idle.
 

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Definately dont trust the dash tach, mine varies by a couple hundred rpm every time i drive it, sometimes its off almost 500rpm!

These old pigs dont really like a low idle at all, just bump it up a bit and see how it goes.
 

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Discussion Starter #8
i will do this first thing in the morning and report back. this is for a buddies truck im just the wrench. new to the cummins world.
 

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Discussion Starter #9
would it be worth while to get a cheap sunpro tach you think?
 

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x2

you should be able to find a laser tach for next to nothing, maybe even borrow/rent one somewhere.
 

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What about using a OTC scan tool to read and set the RPM?:confused013:
 

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another option (if it does work on these PCMs), but i would still opt for a laser tach for accuracy
 

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Discussion Starter #14
ive worked with a laser tach before. fairly new to them. what do i need to do to get one to work??? i guess i dont understand them. how can a laser read the rpms of the truck?
 

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Sorry. Im having the same problem, wondering if my scan tool is as good as a laser?
 

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how can a laser read the rpms of the truck?
You stick piece of reflective tape that comes with the laser to the lower engine pulley, start the engine and fire away with the laser.
 

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Discussion Starter #17
You stick piece of reflective tape that comes with the laser to the lower engine pulley, start the engine and fire away with the laser.
no .

ill have o get one on order
 

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mine was doing that a couple days ago, i took it in, there was a leak at the fuel heater so they pressurized the fuel system fixed the leak. and it didn't kill in reverse anymore, and if it still runs rough i would check you injector pressure, my pressure was also lower then it should be. my truck also has about 228 thousand miles.
 

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mine was doing that a couple days ago, i took it in, there was a leak at the fuel heater so they pressurized the fuel system fixed the leak. and it didn't kill in reverse anymore, and if it still runs rough i would check you injector pressure, my pressure was also lower then it should be. my truck also has about 228 thousand miles.
I second that,
When I change my fuel filter/clean pre-screen/replace fuel hose, (let air in the system), if I let in a bit of air (7 PSI fuel pressure) then it will idle low and take a little longer to start. but as long as it's above 13 psi then it will start almost like usual, and will idle the same (very slight miss here and there, but you have to listen for it). But if you rev it up and let go it will die MUCH easier.

http://www.cumminsforum.com/forum/94-98-powertrain/559333-how-test-air-your-fuel.html
http://www.cumminsforum.com/forum/94-98-engine/58777-joe-gs-fuel-system-writeup.html
 
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