Skip to main content ↑ ↓
Topic: lift pump psi on an 8.3c (Read 8684 times) previous topic - next topic

Re: lift pump psi on an 8.3c

Reply #50 –
The lift pump has to keep the interior of the injection pump full of diesel at full load plus a bit extra. Checking the pressure at idle may not show any restriction in the filters, etc. The little ball on the return valve develops microscopic canals as it ages so replacing the valve at high mileage may be a good idea. The injection pump is a positive displacement pump and nothing will be gained by exceeding the manufacturer's recommended pressure.

Bosch P pumps are rugged but CUPS pumps don't tolerate low diesel pressure well.

Cummins lift pumps do fail so keeping an eye on fuel pressures via boost pressure is a good idea. A failing lift pump can also leak diesel into the crankcase diluting the oil. Check oil frequently and give it the sniff test at the same time. Never good to "make" oil.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: lift pump psi on an 8.3c

Reply #51 –
Where is the lift pump on an 8.3?
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: lift pump psi on an 8.3c

Reply #52 –
On the passenger side just below the engine mounted fuel filter.
96 U270 BUILD 4810
85 380SL
Drummonds TN.
 

Re: lift pump psi on an 8.3c

Reply #55 –
The Forum link just posted show our surprise how much better our coach ran after replacing C8.3 lift pump and return valve. We must have been light starving injector pump.

Should have installed our fuel pressure gauge before making any fuel changes to have a baseline to which we could compare.

Barry & Cindy