lift pump pressure

[RADdodge]

Bob -



The sending unit on the top is actually a pressure switch that switches on when the suction between the fuel pump (either fuel pump, if the check valve is allowing the fuel to bypass the pusher pump) and the filter indicates that the filter is becoming restricted, i. e. needs replacement. That sensor along with the WIF sensor (Water In Fuel) is wired to a Racor gauge that visually and audibly, warns the driver of either condition.

 

[GGades]

I just installed an autometer 0-15psi electric guage. Used Ray's tapped banjo to mount the sender on the injection inlet. At idle the guage would read between 12 to 18psi at idle. Under hard acceleration the guage would go down then back up. When I put the sender into a short piece of hose it reads the way it should, 15psi at idle, 8-9 psi really getting on it. The sender must not like to be that close to th inlet of the pump( turbulence, pulsing?) guage also works after installing a 90 degree 1/8 pipe fitting into the tapped banjo. Hope this helps someone. Nice filter setup!

 

[zman]

Big Don -



If you can get your hands on a service manual, it states that the minimum pressure should not fall below 10 psi. After I showed my dealer what was in the service manual, they replaced my lift pump without any questions. Mine was showing 10-11 psi at idle and 0 at WOT, and that was without the EZ and the DD2's. With the new pump, fuel pressure never falls below 12-13 psi at WOT with the EZ and DD2's and idles at 16 psi.



Steve

 

[Big Don]

Zman,

Or anyone else, can you show me where the manual states "should not fall below 10psi". The manuals I have seen state 10 psi min at idle and max of 5 psi differential between pre and post filter pressures. I can find nothing stating pressure at any speed other than idle. I would love to find this info and I would demand a new pump.



thanks

Don

 

[Larry Willard]

I am with big Don, can't find any info other than the min. of 10# at idle, so had to replace my own pump. Still looking for the ultimate pump set up.

Larry

 

[zman]

Don -



Mine's an '01, but the service manual states:



"With the engine running, the pump has 2 modes of operation: Mode 1: 100 percent duty-cycle with a minimum pressure of 10 psi except when the engine is cranking. Mode 2: 25 percent duty-cycle with minimum pressure of 7 psi with the engine cranking. The 25 percent duty-cycle is used to limit injection pump inlet pressure until the engine is running. " (2001 service manual, volume 2, page 14-79)



My interpretation of this is that when the engine is running (other than cranking) the pump operates in Mode 1, so there should be no less than 10 psi with the engine running.



Hope that helps.



Steve

 

[Steve St.Laurent]

That's the exact same thing my '98. 5 manual says. That's what I've been using as my reference for what I'm looking for our of my lift pump anyways - I've never seen it stated so clearly anywhere else.