8.1l hpcr fuel system hard start after it's been running

[rmllarue91]

Hey hef got another one common rail appears to be low rail pressure based on code but I don't have scan tool to verify. Customer wants a pump and injectors 7000hrs. But I want to understand system better I downloaded manual. Says to check pcv powers but didn't give specs with idling valves open I show 8 volts with it running 4.5 volts valves cycling is that normal. ? It will start good cold idles for two mins it starts hard let it run for 10 mins won't start without ether. Seems odd but have no experience with fuel setup let me know what you guys thinking thanks

 

[partsandservice]

That no start symptom is likely a high pressure leak. Identify where the return fuel comes from the injectors. Then run the engine to recreate the the no start condition. When spinning the engine check the fuel flow from injector return , there should almost no return flow with just the starter , same goes for the rail relief.

 

[BigWrench55]

The cheapest and easiest way to try and solve the problem is to change the relief valve and sensor. Also you can pull the relief valve and look for a groove that's been cut from going over relief several times. Other than that you would need to isolate all of your fuel returns and see what is returning to much fuel.

 

[rmllarue91]

Checked relief the over flow valve seems to open around 30 psi pumping hand primer pushes good volume of fuel out over flow valve from pump I'll isolate injector returns pressure sensor was changed prior to me looking at it. Thanks

 

[mg2361]

Serial number of the engine?

 

[rmllarue91]

Ended up being pump after all said and done got to talk to operator and it's been loosing power for awhile and getting harder to start. With a laptop to view pressure and unhooking return rail it should be easy to find leakage in future.