I have a Px 8 and it starts hard on the first start of the day. Fuel rail pressure is good a 21,000 psi. It acts like fuel drain back problem. Electric lift pump works, but has air at first.... So there must be a check valve somewhere between the electric pump and tank. Any body know where the buggers located? And I just know your gonna say under the Ecm. Thanks in advance for any help.
Hard starting
- Thread starter Grandpa
- Start date
First off, all px6 and 8's are just rebaged cummins. The only real paccar engines are the Mx series.I have a Px 8 and it starts hard on the first start of the day. Fuel rail pressure is good a 21,000 psi. It acts like fuel drain back problem. Electric lift pump works, but has air at first.... So there must be a check valve somewhere between the electric pump and tank. Any body know where the buggers located? And I just know your gonna say under the Ecm. Thanks in advance for any help.
I would start by checking fuel pressure decay. Enable the leak test in insite and the turn the key off. Fuel pressure should not drop too fast. Cant be more then 6000 psi in 30sec?? Dont qutoe me on that, the spec is close though.
Whats probably happening is the high pressure fuel is leaking somewhere, making it hard for the pump to build the required pressure to start. Fuel pressure can leak in the injector to tube connections, the relief valve, or the fuel pump head. A quickserve subscription helps with the diagnosing as the procedure is quite long.
I realise you made this post quite a while ago but if you still need help I can try my best!
Thanks pushbroom.... I installed a new lift pump and that took care of the starting problem. But I will take the liberty to ask you another question. This truck has never been capable of initiating its own regen per the switch. Ive always had to use Insite to force it. I've been up and down the diagnostic tree until the limbs are worn off. The only thing I can find that may inhibit the regen is the parking brake does not show function when tested in the switches window. I've tested the switch, and it seems fine, the light on the dash comes on showing the brake is set, but yet Insite says its not.... it there another switch somewhere im missing.... thanks in advance Grandpa.
What chassis is this? Normally the switch will only function when the DPF/regen required lamp is illuminated. Otherwise, it will not start a regen anytime you want it to because the start button is depressed, only if conditions allow.
Another thing that is common is vehicle speed registering. Normally this will even kick out the regen in Insite too however.
Another thing that is common is vehicle speed registering. Normally this will even kick out the regen in Insite too however.
Insite has to see the truck is parked for the regen to happen. However, if it doesnt see that its parked it shouldnt start one even if it is forced with the laptop. Weird. Enable the park brake then go to j1939 parameters and park brake source should be on cab controller primary.
Will it idle up with the cruise switches? If it does it is seeing the park brake signal. SHould only be one park brake switch that is datalinked to the engine. Are the regen switches enabled on j1939 cab controller primary?
Will it idle up with the cruise switches? If it does it is seeing the park brake signal. SHould only be one park brake switch that is datalinked to the engine. Are the regen switches enabled on j1939 cab controller primary?
theironoracle
New member
pushbroom,
I have a px-9 in my 2014 kenworth t-370. 25,000 miles, 900+ hours. my diagnostic screen on the dash says I have a plugged egr and low boost pressure. 1) are these probably related? 2) how do I clean the egr? does it matter if I clean the egr? I have been driving it like this say for 2000-3000 miles it has no performance problems at all, same as new just a couple lights on the dash. Thanks............TIO
I have a px-9 in my 2014 kenworth t-370. 25,000 miles, 900+ hours. my diagnostic screen on the dash says I have a plugged egr and low boost pressure. 1) are these probably related? 2) how do I clean the egr? does it matter if I clean the egr? I have been driving it like this say for 2000-3000 miles it has no performance problems at all, same as new just a couple lights on the dash. Thanks............TIO
pushbroom,
I have a px-9 in my 2014 kenworth t-370. 25,000 miles, 900+ hours. my diagnostic screen on the dash says I have a plugged egr and low boost pressure. 1) are these probably related? 2) how do I clean the egr? does it matter if I clean the egr? I have been driving it like this say for 2000-3000 miles it has no performance problems at all, same as new just a couple lights on the dash. Thanks............TIO
These engines are horrible with plugging EGR issues, the higher the idle time the worse the buildup. The EGR cooler and the cross drillings in the intake to the EGR differential pressure sensor are common problem areas. The valves can accumulate buildup as well and are cleanable. Check with your local Cummins dealer on warranty as you are new enough even if its out of warranty you may be able to get some help given the low miles. There has been an update to the cooler that changes it from a horizontal to a vertical plate. Many parts are needed for this update as it changes the coolant flow/lines to and from the cooler. The low boost is likely related to the EGR fault.
HTH
Goody