Just having the injector pump (VP44) die on me, I've shelled out $$$'s to replace the VP44, and instead go with a FASS fuel pump, and 1/2" Vulcan Drawstraw. I so do not want this to happen again. I also had the mechanic install a mechanical fuel pressure gauge - a DiPricol right on the steering column - nice. Upon inspecting the work, I could not find where the fuel pressure gauge was connected into the fuel system when I had thought it would have been at the VP44 test port?
The mechanic informed me that the port on the VP44 was not AN standard, so he connected the gauge back at a port coming out of the FASS? Is this acceptable, or should the gauge be connected into the VP44 as I had thought? When starting the truck, I hear the FASS engage, the gauge registers about 15 PSI, then gradually drops off in pressure while the grid heaters time out - the truck fires up fine, and the pressure returns to 15-17 PSI? Is this standard? Thanks, DD

 

Its on the VP44 side of the FASS?? Then it should be fine, maybe a psi or two higher than at the VP44..

Did he use an isolator?

 

thanks ah64ih, when I asked why not straight out of the VP44 test port, the mechanic mentioned something about non-standard fitting. He did mention making the connection to the FASS at the fuel port the manual indicates? Yes to there being a fuel isolator - this came with the mechanic fuel pressure gauge as a kit, and looked to be a the cylindrical type? Not sure, but I thought I read somewhere that eventually, the isolator will fail, and that a snubber is a better even though this would mean diesel at the gauge? DD

 

While it may be a straight shot to the VP44, I still feel that's the best place to put a gauge, then you know what pressure you have going into the pump. The VP44 inlet is a 12mm x 1.5 fitting. You can get a tapped banjo bolt, it replaces the test port.

 

My FASS, 150/150 came with all the fittings to install the pressure tap right before the VP.

 

i dont have a fass , i have my gauge on the test port mine reads 19 psi at idle.

 

You could use a snubber with the isolator, but I wouldn't leave the isolator out of the loop. All the snubber does is dampen any pulses or spikes from its input side. This would help keep your isolator from getting damaged.

Give the guys at Vulcan a call, they have adapters there.

 

I came across this problem as well with my AirDog 100. Being as it replaces all lines to the IP and uses a 90 at the VP I wasn't sure what to do. Then I remember reading through the AirDog Instructions about the port they use when you run a low pressure light. Looked at the port and it is right near the outlet running to the VP. Figured this would be an alright spot and installed an 1/8'' compression fitting and away I went.

I'm going to email PureFlow and ask them if this is an alright port, or if this port will not work due to maybe the internals of the AirDog block is plumbed differently for that port.

 

For those that are running straight from the FASS or Airdog straight to the injection pump, there are 90*swivel adapters that the hose hooks right to as well as barbed inline fittings available.

Dave