I installed the raptor 100 to replace the in tank pump last weekend. All went well and I have much more steady pressure but the fuel pressure is either 17 @ idle dropping to 13 @ 2000 rpm and sometimes it 13 @ idle dropping to 10 cruising at 2000 rpm. The raptor sounds steady and does not sound like it is pulling air. The lower pressure is usually after a warm start and it will dip down to 10psi for a second when I first touch the throttle and bounce back to 13. I have an electric glow shift at the bottom of the filter to the vp44 and everything else is stock. What should I look at to steady this out?

 

I would try a different gauge. Even just a mechanical test gauge to confirm the pressure. Glow Shift doesn't have a good reputation for quality.

 

Your gauge more than likely is junk. I went through 3 sending units on my old truck in 2 months because it would start bouncing then pin at 30psi no matter what was going on

 

That's what I was afraid of, I knew I should have paid a couple more bucks for ole reliable A. Meter or isspro. I will give it a whirl on a mechanical gauge before I dig into more.

Sorry for posting this two times, grumpy iPhone.

 

I checked with my test gauge and it follows the electric gauge but I cannot get them to do the sudden drop when they are both on. It only happens after I start the truck, let it warm a bit and start to drive. It will drop down to 7 psi then recover and sometimes it will do this 2-3 times. Yesterday as I was driving home, it was reading lower and lower pressure and the pressure drop got worse with a little throttle. I started off at 14psi at idle with 12 at 1200rpm, by the time I got home it was 13 at idle and 9 cruising at 1200rpm. I confirmed it when I parked and hooked up the test gauge. I turned the pressure up a bit on the Raptor andstill the same thing

This morning read 16psi idle dropped a couple times to 9 after pulling out of the driveway but only goes down to 12 with 3/4 throttle. I will change the filter for kicks to see if that is it but it has less than 200 miles on it. Any ideas?

 

I am on my second Raptor and it is not looking good. Same problem as you describe but worse. My pressure drops to zero. When parked and drawing from a fuel can the best I saw was 7 psi when yesterday it read 15 on the highway. Called warranty and they now say they are sending me a Viton ball that will cure the problem. We will see....

 

After reading your reply, I read this on a couple different forums and they said it helps. I will call pureflow tomorrow and see if this will help me out. Don't loose faith, the product seems good, they seem to back it up and always fine tuning for improvement. Let me know how it goes as I hear it should be a simple fix.

 

Well, the viton ball came in and installed it an hour ago. I drove around with o/d off to simulate highway rpm, rolled on the throttle easily until wot. Pressure went from 17psi and only dropped to 14.5, sweet. Rolling along at 2,000 rpm, 15psi. I am going on a trip next weekend and that will be the ultimate test. So far I have to say what a difference changing from the piston to a ball makes.

One big detail if anyone has to do this, make sure you have o-rings on hand - replace them - GENTLY install the regulator cap/set screw to not tear the o-rings or it will not behave properly. The o-rings will get damaged on the threads going out and back in. If the o-ring is gnarled up, you will feel the threads are not nearly as smooth going in.

Contact Kyle at pureflow and he will take good care of you, great customer service.