dualfuel

Hi guys,
2004,5.4 F150,7700, bi-fuel.
we are unable to use all the CNG fuel, it switches us over to gasoline, when the CNG still has about ½ a tank full still left in it. A full tank of CNG will usually run for 180 miles but now we don’t even get 100 miles.
If you have any suggestions of what component could be the problem, appreciate to hear what you think.

techrep

iTrader: (1)

Is there a sending unit for the CNG tank ?

PerryB

I would think the tank "level" is monitored by a pressure transducer, and that would be my first suspect.

dualfuel

I don’t think there is a sending unit in the tank, but I am not sure about much on this system.
I have read there is a pressure regulator, and alternative fuel control module.

nrivera04

Did you buy the truck in that configuration or did you do the conversion? I haven't seen too many of us on the board who are running alt fuels. I don't know how much help you'll be able to get.

dualfuel

I have read there is a pressure regulator, and alternative fuel control module.,
also, fuel rail pressure transducer sensor,
fuel tank pressure sensor,
fuel rail temperature sensor
I am not too sure they are all for the CNG,

tcp2

I would suspect the Fuel tank pressure sensor.

dualfuel

Yes, I did buy this truck in this configuration,
now I see tcp2 say
(fuel tank pressure sensor), sounds like the one thing, that controls the problem I have, sensor must be out of calibration I agree,
I was hoping someone would say they had the exact same problem, but like nrivera04 said, there are not too many around.

tcp2

Years ago, I also had a propane powered vehicle that I bought used. It would buck a bit in steady state driving and I was told by a mechanic that the "filter" was plugged. Sure enough there was a white disc shaped fiber filter inside one of the carb parts. I exchanged the filter and everything was good. The filter housing looked similar to this:

https://www.propanecarbs.com/impco/vff30filter.html

Maybe you have something similar that is not flowing properly and shutting the system off early.

Edit:
The filter element was more like this:

http://directparts.eu/en_US/p/LPG-fi...pco-VFF30/5786

scobar

iTrader: (4)

I owned a propane beast very shortly, I'd also wonder about a filter perhaps it's causing the line pressure to drop. I don't recall a sender being in the tank but it was also an early 90's chevy WT.