Your fuel pressure should read close to 15 psi at WOT. Either the gauge is no good or the LP is no good.

 

Man, I don't know much about the 24V, but that still seems awful low for a pump so prone to fail catastrophically if it doesn't get enough fuel.

 

What is WOT?

Do gauges need calibrated?

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I also had a big drop in fuel mileage....usually when I pull my trailer I will get 13 mpg but since I put on the new LP it's down around 10mpg. Any thoughts?

 

WOT = Wide Open Throttle. Pedal to the metal. Hammer down. Foot to the floor. Generally speaking, maximum fuel, although I'm pretty sure with these trucks in stock configuration that isn't always the case. But for purposes of discussion here, it should be.

Regardless, gauges can need calibration, but I'm not sure how one would go about it. I know a buddy of mine who worked in a speed shop said they once took five Autometer boost gauges off the shelf and hooked them all up to the same air source and they all showed a different reading at the same pressure. Then they did the same test with some high dollar Japanese tuner gauges (Greddy, IIRC) and they were all in perfect sync and dead nuts accurate. I suspect some of those Autometers were a little out of calibration somehow, but the point he was trying to get across at the time is that Autometer "ain't all that". That was many years ago though, before stepper motors and such, and I think all gauges have come a long way.

As for ISSPRO, if you're using an electric gauge, ISSPRO has multiple maps/programs for them that are application specific. If you have a gauge programmed for an electric LP and try using it on your mechanical LP Cummins, it's not going to read properly. I'm sure there are as many programs for the same gauge as there are engine/pump configurations, and it's just a matter of plugging in the gauge to a laptop with the tuner software installed and changing some values, or sending it back to ISSPRO and telling them what you've got so they can set it up with what you need. I would talk to whoever you bought the gauge from and make sure they gave you one programmed for your specific application. I know my ISSPRO FP gauge wasn't right for my truck and I had to send it to ISSPRO to be reprogrammed; I don't think most of the retailers are aware that the EV2 gauges specifically, are factory-match gauges designed to compliment OEM instrument clusters of specific year/make/model trucks. Every combination of face and trim color, lighting color and even brightness of the LEDs are designed to match the factory instrument cluster of a specific truck, as well as the fuel system that truck is known to have. I got the white face/black trim/red pointer/green lighting EV2's for my '98 Ram because I thought they looked nice, but the fact is they were intended for a much newer Ram with brighter backlighting and an electric LP. ISSPRO was able to reprogram it for my older truck and send it back, but if they'd been told what year Ram it was going in when it was ordered the fiasco could have been avoided.

As for the mileage, that is odd. Everyone I know who goes to a FASS, Airdog, etc, claims their mileage goes up not down. This might further suggest something is wrong with the LP, but I'm just guessing.

 

mitchell on demand says on a 24 valve your fuel pressure should be 5 -7 psi not running and 10 psi running. also it shows ur suppose to check it on the inlet side which is ontop the fuel filter housing and is the little port on the right when your facing your engine

 

No wonder the VP44 is notorious.

 

I called tech support at Fass and they said 16 at an idle. They told me to disconnect the supply line and put it in a small bucket of fuel to make sure it's not something in the fuel line or tank. Will this put air in my system?