spn 157 fmi 18

[730Industries]

(01-19-2023 )Rawze Wrote:  Here is the correct way to test the rail. Seems no one does this any more properly and then does nothing but guesses at their issues, wasting moneys. Putting this here as a reference.

ref: http://rawze.com/forums/showthread.php?t...2#pid69262

So I've got the truck and started diagnosing it.

We cleared the code and drove it up here and the 559 code doesn't appear until i get into the throttle.

Cleared it once again and followed the above video for testing the pressure, and the pressure peaks slight above 29000, after shutting it off and watching it, it doesn't dip below 29000. Stays within 100psi of the final mark. For over 1 minute. For almost 3 minutes until i stopped observing it.

So if the truck is asking for fuel and its not losing any once its supplied.... is my issue the pump itself? If there was a leak and thats how the truck wasn't getting what it was asking for, then i should see it with this leak down test, correct? The pump was replaced a hair over 300k ago by the previous own, and there has been a plethora of work done to the fuel system.

As a final point, the fuel pressure hasn't dropped 300psi in the 6 minutes i've typed up this response....

Give me guidance and direction please. :)