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Hi all I have a western star 4900fx with a cummins cm570 it has intermittent hesitation under load the power drops off and then back on as quick as a light switch. Any one know if fuel solinoids will do this ?

could also be the accelerator pedal.

(11-05-2017 )Red Wrote: [ -> ]Hi all I have a western star 4900fx with a cummins cm570 it has intermittent hesitation under load the power drops off and then back on as quick as a light switch. Any one know if fuel solinoids will do this ?

I doubt it is solenoids/ actuators. Does it completely drop power or just limit it . Does it do it in all gears or only lower ones ?

(11-05-2017 )Rawze Wrote: [ -> ]could also be the accelerator pedal.

Thanks mate I tryed that no luck I think the next step is see if i have leak by on the injectors. I have looked at every thing else i can think of

(11-06-2017 )AussieISX Wrote: [ -> ]

(11-05-2017 )Red Wrote: [ -> ]Hi all I have a western star 4900fx with a cummins cm570 it has intermittent hesitation under load the power drops off and then back on as quick as a light switch. Any one know if fuel solinoids will do this ?

I doubt it is solenoids/ actuators. Does it completely drop power or just limit it . Does it do it in all gears or only lower ones ?

It seems to be only under load and in any gear on the high gears mate. It completely drops power then kicks back in . It repeats this untill your coasting or back off the accelerator

(11-06-2017 )AussieISX Wrote: [ -> ]

(11-05-2017 )Red Wrote: [ -> ]Hi all I have a western star 4900fx with a cummins cm570 it has intermittent hesitation under load the power drops off and then back on as quick as a light switch. Any one know if fuel solinoids will do this ?

I doubt it is solenoids/ actuators. Does it completely drop power or just limit it . Does it do it in all gears or only lower ones ?

You were right about the solenoids mate had another truck in to change over and the fault was still their

I seem to have air in the fuel return hose. I set up a test tank to eliminate sucking air from hose or truck tank and still have air. So this might be the course of my problem although id exspect the fault to be more consistent if this was the case and i have no hard start or shut down or ruff idle??. I have ordered a cummins tool/part to preform a injector leak by test as I have seen on Rawze you tube, exspensive in Australia but $500 for the tool. This I hope will let me determine if its sucking air at the IFSM system or injector.

I suggest you check the vehicle speed sensor

(11-06-2017 )hhow55 Wrote: [ -> ]I suggest you check the vehicle speed sensor

Thanks mate will do any chance you know how i know their a VR style pick up