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Topic: new lift pump made a BIG difference (Read 2964 times) previous topic - next topic

Re: new lift pump made a BIG difference

Reply #25 –
A quick  note to let others know we replaced our fuel return valve on the back side of the injector pump.

Thanks to others who recommended removing the dash air conditioner compressor and mounting bracket to gain easy access to the valve.  It made all the difference.  I loosened the small side bolt holding the return line so the banjo fitting could be moved, but this small bolt did not have to be loosened.

Old valve and new valve are exactly the same length and both had plenty of space between the top of the banjo fitting and the side of the engine head, and it was no-sweat to remove them without moving the banjo fitting.  We were able to easily change out the rubber gasket between the banjo and the injector pump.

Instructions say the new adjustable fuel return valve is preset for 30 psi and we did not make any changes to the setting.

Before this change, as I noted, our new transfer pump made a big difference in driving power on startup and on up hills.  We installed a dash fuel pressure gauge when we changed our transfer pump, so we don't know gauge readings with original transfer pump. After the new transfer pump, pressure readings were 6 to 14 psi.

We started the engine but have not driven with the new fuel return valve and pressure readings were increased to a steady 20 psi at idle and higher RPM.  We will drive to Quartzsite next week from Yuma, so we will get a real time reading, but only on flat land.

Valve replacement project time was all in removing 4 compressor bolts so it could be swung away with coolant lines still attached and then removing 4 bracket metric bolts that had been in place since day one.  Valve out and in was a piece of cake.  New bolts, nuts and washers were used with anti-seize to put things back together.  I will do a detail write-up with photos at a later time.

Thanks to everyone for their guidance.

Re: new lift pump made a BIG difference

Reply #26 –
Good Morning Barry - looking forward to your write up and photos.  I am beginning to think my 1997 c8.3 may also need this new valve.  Mine starts fine and has power, yet idle rpm is not consistent.  Over the past year, it fluctuates between a very low 500 RPM and 700 RPM.  I have adjusted the idle upward, yet it still will not hold steady.  "Fluctuating" in this case means one time when I start up, it will be around 500-550 RPM and then the next time it may idle at 650.  I have found I now need to put the transmission in neutral when stopped at a red light.  Any thoughts?  THANK YOU, Jeff...

P. S. - if handy, would you mind providing vender and part # info for pump and valve
P. S. S. - will your write & photos be found later in this thread, or __________?
Jeff & Sandy
1997 American Eagle 40' Slide-less
2013 Toyota FJ Cruiser 4X4 Toad
Interested in Foretravel Coaches
 

Re: new lift pump made a BIG difference

Reply #27 –
After the new fuel return valve, stationary psi was about 20 psi.  Today we drove about an hour from Yuma to the Quartzsite gathering and our route had a few hill climbs. 

With new transfer pump and new return valve, our fuel pressures on our trip today did not increase over 21 psi and did get down to a few moments at 11 psi.  We have not changed fuel filters for a while and our next change will be to replace the filters and see if pressures increase.