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lift pump pressure .

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I read alot about the pumps but never read what the min. presure was . On my 98. 5 the lowest by Cummins is 10 psi. . I went to the dealer today to have them comfirm what my little 16 psi gauge said 8 psi at idle. It cost me $76 and they said it was at 13psi and every thing was fine. I went to local Cummins it tested 7 psi, I was told it was defective. I went back to dealer and asked to see the gauge as they tested 2nd time, it showed 11 psi. The gauge he used was ( zero to 100 psi ) cheap looking and had black tape around it. The gauge at Cummins was a large MAC brand (zero to 35 psi) . FYI.
 
I believe the 2000 FSM states, minimum pressure: 10 psi pre-filter. A maximum differential pressure of 5 psi.



It is not uncommon to have two different gauges (both being fairly accurate) read two different pressures however, the difference should be minimal. I would like to know how you can accurately check our fuel pressure with a 100 psi gauge:confused:



Where is your gauge measuring pressure? Pre or Post Fuel Filter.
 
I said the same thing . To me the 100 psi guage has more room to give an inaccurate reading. The point is the gauge at Cummins was better to measure lower pressure. I used a Holley brand zero yo 15 psi. On the road wot take off 4 1/2 psi. (all measurements pre filter)



Thanks for the info.
 
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When reading pressures from any source it is most accurate to use a gauge where the reading will fall in the middle of the scale. In fact in certain critical applications, such as boilers, by law the maximum gauge reading must be no more than 2 times the normal working pressure and no less than 1. 5 times the working pressure.
 
Demand your $76 back! the idiot used an incorrect gauge and obvioulsy didn't test at WOT which is where you need to run it to see if the pump is good.
 
Originally posted by CUMIN2pass

I read alot about the pumps but never read what the min. presure was . On my 98. 5 the lowest by Cummins is 10 psi. . I went to the dealer today to have them comfirm what my little 16 psi gauge said 8 psi at idle. It cost me $76 and they said it was at 13psi and every thing was fine. I went to local Cummins it tested 7 psi, I was told it was defective. I went back to dealer and asked to see the gauge as they tested 2nd time, it showed 11 psi. The gauge he used was ( zero to 100 psi ) cheap looking and had black tape around it. The gauge at Cummins was a large MAC brand (zero to 35 psi) . FYI.
Looks like a letter to zone rep is what you should do . Bad service like that is not to be taken by anyone . If you do not have a copy of the bill request one before you write the rep. Don't let them get away with that crap . If zone rep don't get your money back post the reply here for all to see . Then name the names let them see what we can and will do . Know how you feel after a rip off like that . Worked with guages for about ten years testing things for the US navy and Know that the readings at end of scale are most inaccurate mid scale is best 11to 1 on the clock . A small scale gauge o to 16 is best for 98. 5 or later Rams . Hope this helps Ron in Louisville KY :eek: :eek: :eek: :D
 
Thanks guys for this info. Please help me if I'm wrong, My understanding was min. 10 psi at idle and no more than 5 psi drop after that. The information about the gauges is great!



I showed the man at dealership the paper from Cummins (7psi)

but reiterated that his mechnic had normal pressure.
 
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