Pre-start Fuel Pump Power

[MorePower]

I let my fuel tank get below 1/4 and the "near empty" idiot light came on. Normally when I turn the key to ON, the fuel pump runs for a few seconds and gets the fuel pressure up to about 10psi. The next time I started it, the fuel pump didn't do ite pre-start run. The engine started normally and had normal fuel pressure. I filled the tank, the idiot light went OFF but the fuel pump still didn't do its pre-start run. A few starts later, and everything was back to normal. Is this a feature or a failure?

[Mopar1973Man]

That little pulse is meanless really... Because in some ECM flashes its disabled completely and others run longer. What matters is your cranking fuel presure, idle fuel pressure and WOT fuel pressure...

[MorePower]

Thanks, I guess I can relax a little now. I'm just a little nervous about any potential stress on my new VP44.

[Mopar1973Man]

Most critical numbers in my mind is... 1. HFRR score of the current fuel meeting the requirements of the VP44. (Lubricity value) 2. The fuel pressure at wide open throttle operation. Bosch requires the fuel lubricity to be of a score less than 400 HFRR for long life of the injection pump. But todays fuel averages right around 520 HFRR. I'm using 2 cycle oil to beef up the fuel lubricity but there are several products that do a really good job of adding lubricity. http://mopar.mopar1973man.com/cummins/general/2-cycle-oil/hfrr/hfrr.htm Then since there is only fuel to lubricate the injection pump during its maximum amount of stress at WOT operations should be enough fuel pressure to keep it lubed. Dodge/Cummins suggest 10 PSI as a minimum I suggest a minimum of 14 PSI. Beyond that enjoy your Dodge Cummins Truck...

[MorePower]

That 2-stroke diet was one of the first things I learned from your site. As far as enjoying my Dodge...I'm starting to. I'm definitely enjoying the Cummins part more.