I tried different gauge and it reads the same. I'm assuming that means my gauge is ok. I also took out the snubber and tried it that way too and still no change, except the needle bounces a little more. I called FASS again and he told me I need to switch to a low pressure pump and that was my problem. He claims that the regulator can't decrease the pressure coming out of the pump, they can only increase pressure. This makes no sense to me. I know many of ya'll are running a high pressure pump and regulator. Currently I backed the screw out all the way and then turned it back in a little. At idle I have 3psi. I'm going ot drive it and see where it goes from there.

 

As soon I started driving it climbed back up to 15. Every time I adjust the screw out the pressure climbs back up. Right now the screw is about to fall out and it's running 10-12psi at idle and 15 at WOT. If I knew it would stay there I could live with that. I'm pretty sure the regulator is no good. I'm going to call FASS Monday and see if they'll warranty it.

 

Where do you have your regulator return line hooked to? If you have it hooked to the injection system return, move it to the inlet (supply) of the lift pump.
PS This statement is wrong.
"He claims that the regulator can't decrease the pressure coming out of the pump, they can only increase pressure."
A regulator can only decrease pressure.

 

Stude4x4, you're on the right assumption, especially since the symptoms are erratic and inconsistent.
I'd swap the regulator out.

Mark.

 

It's already been mentioned, but I'll outline it here.
1. A regulator decreases pressure by bypassing some liquid.
2. If there's an overpressure situation, it's either the regulator, or the return line is blocked, or returning to something other than atmospheric pressure.
Regulator could be defective, or too small for the flow.
Bypass needs to be to before lift pump or to tank.

 

My return line goes into the factory supply line to the tank. Since I used the spare bung and the 1/2" draw straw I figured the stock line would suffice for the return. I'm glad ya'll agree on the propose of a regulator. To decrease or "regulate". I was going crazy thinking that I was taught wrong. I'm sure their regulator is sufficient enough. It has three 1/2" NPT ports and its adjustable from 0-100psi. I'll call them tomorrow and see if i can get it replaced. I will keep you guys posted on what happens. Thanks again for all your input!

 

Any regulating device, like a pressure regulator, thermostat, etc. has to have an opening setting and a shutting setting, with some difference between them, called hysteresis. Usually the wider the possible setting is, the bigger the hysteresis.

Also, any regulator will have some dependency on the input pressure. That's why when extreme pressures are regulated and the output needs to be precise, they go to a two stage design.

Translation, this may be a misapplication for that particular regulator.

 

Full adjustability from 0-100psi is probably not accurate with just one spring. Sounds like you need a lower range spring to control as low as you are wanting.

 

I talked to another guy at FASS today. He claims that their regulator is designed to increase pressure. Normally you would set the pressure on the pump and use their regulator to increase it. Still doesn't make sense to me. Why change it and do things differently? He's going to try and duplicate what I have and bench test it to see if he can make it work for my application. If that doesn't work I'll be looking for another regulator. Any ideas on what works the best?

 

It cant increase pressure beyond what the pump will put out when deadheaded.

The only way it can "increase pressure" (inaccurate term) is if it is a back pressure regulator. The pump will push a certain amount of pressure and the regulator is like a valve or bypass to the return back to the tank, close it and the pressure to the IP goes up, open the reg and fuel gets bypassed to the return which reduces pressure to the IP.

 

Just wanted to give an update. I bought a Mallory press. reg. and everything works great. My pressure is around 8-9 at idle and 12-14 at WOT. It hasn't changed or fluctuated one bit. I'm assuming that something has to be wrong with the FASS reg. I still don't understand how they work but I'm not buying the "increasing pressure" bit. Thanks again for everyone's input and expertise.

 

Thanks for updating us on this one!

Mark.