When we start the truck lately, when shes cold, the speedometer wont register and it will only tach to 1600. This has just started recently and after a while it will kick on. We have a n14 Cummins. Any ideas

 

This is an easy fix.......Get rid of your Cummins and get a nice big yellow motor. :lol: :lol:

I had this problem a few years back, was interment at first and then became steady after about 300 miles (I was going to limp home but had to goto the dealer) Turned out to be a speed sensor on the back of the transmission. If I remember correctly, and I seldom do, the motor goes into a protect kinda mode when it can't sense all the things it wants too.

 

try putting on a new Fuel filter

 

changed the fuel filter right off, but the sensor................ah

 

what sensor ?

 

I put her in the shop today to check all fuel lines and that sensor( the speed sensor on the trans)
Will let you know if thats the problem....thanks.

 

before you change it ;

back off the jam nut,

turn it all the way "in", careful not to break

then back it off 1/2 turn, tighten jam nut.

this re-sets the sensor air gap. as long as you have a threaded sensor, you will have to set the new one as well.

 

Any answer yet?

 

I will second that.

Had that happen a few years ago on a Mack.

Speed sensor on trans output shaft failed. Speedo registered zero MPH, engine was totally devoid of power.

I would assume that without a MPH signal, the ECM thinks the truck isn't going anywhere, and wont allow the engine to receive full fuel.

Replaced the speed sensor and all was well.

 

I appreciate the responses, but she is still at the shop . We are going to get her on Monday. The shop did replace the sensor and all the fuel lines were fine. So we'll let you know>
Thank you