AggieJustin

I'm running a Raptor 100 on my '01. When I first installed it, it was rock solid predictable on fuel pressure. I had it set to 20psi at idle, it would highway cruise at 17-18psi and dip to 15psi only under hard acceleration.

A while back, I noticed that my idle pressure had dropped down to 17psi and my highway cruise was anywhere from 12-15psi. At first I thought I had picked up some trash in the fuel filter, so I swapped the filter and cleaned the canister. The filter looked normal and even with the new filter in place, the pressures were still down. So the next thought was that my regulator adjustment must have slipped. I dialed the idle pressure back up to 20psi, however I noticed that my cruise and acceleration pressures were still lower than previous. After a week or two, I started to see lower idle pressures again. Sometimes it would be at 17psi at startup, sometimes it would be 20psi. I e-mailed AirDog and they suggested adjusting the regulator all the way open, then all the way closed before setting the pressure again.

I followed those instructions, but I've noticed that the regulator is now very erratic. I had set the pressure to 20psi, but after a couple of starts it had crept up to 25psi. I was adjusting it yesterday and it was all over the board. I was doing it solo, so it was a lot of crawling under the truck to adjust and then back into the cab to check the pillar gauge. I dialed it back a 1/2 turn and it dropped from 25 to 17. I went back up a 1/4 turn and it was 21. I moved back slightly and tightened the adjustment nut down holding the screw steady and when I checked the gauge it had fell to 16. I loosened it and turned it forward an 1/8th of a turn, and the pressure jumped past 25psi. I had to turn it back over a 1/2 a turn before it finally started to fall back closer to 20. I finally hit right at 21 consistently, so I just left it there.

I guess my question is, should this regulator be that touchy? Or should it be more linear? On the original install, it was easy to get it set right where I wanted it. Now it's a guessing game where the pressure will be whenever I get the gauge after touching the adjustment. Any ideas on things I should check?

Sea:\>Drive

Very typical for a regulator to act that way. You'll have to keep adjusting it until you find the sweet spot. I've only really adjusted mine twice but I'm do again as it is starting to drop again. After quite a few years of use (10 to be exact) I may have to look into a replacement too.

SIXSLUG

Stuff wears out. Something inside is possibly broken or weakened, like a spring or seal etc.

As long as you are over 8-9 psi you should be good. but fluctuating pressure may be a sign of impending failure...

AggieJustin

Thanks guys! I'll keep tinkering with it till I get it right where I want. It's been holding pretty steady for the last week, just a little higher than I want at idle (22psi).

KATOOM

It may not be part of your issue but I've heard before that the Raptor inlet pre-screen can get clogged up and restrict the flow coming in the pump. Generally if this is the case then the fuel module pre-screen has to be torn somewhere to allow the garbage to be sucked up into the fuel line.

I have an older Raptor 100 too. Even though my idle and cruise fuel pressures are rock solid, my WOT pressures can act weird and cause the FP gauge needle to bob around a few psi while under heavy throttle. As soon as I come off the throttle the gauge needle smooths out. I've thought this may be an erratic pressure regulator too not handling the large quantity of fuel supply very well.