Is there some sort of lag on the Autometer full sweep electic fp gauge?

What would happen tonight is that when I would be at WOT N/A, I would be set at the correct 43 psi and when I sprayed (50 Shot - NOS recommends 60 psi of fp), the fp would go up to 50 psi, but the funny thing was, when I stop spraying and let off the gas, the fp gauge would shoot up to 60 psi for a second then go back down to the correct driving fp.

What was happening? Was I getting 50 psi at WOT? or 60 and it just took a second to register?

Is my fp dead or dying? My N/A idle reading is ~34 psi, but when I'm on the gas it's 40 and WOT it's 43.

I've had nitrous for about a month, I'm on my 2nd bottle, and I've only sprayed 50 shot. I dyno'd last weekend and my A/F was fine.

btw, bottle pressure was constant at 900 psi

Thanks

 

You must be using the stock fuel pressure regulator.

Mine did the same thing when I was using the stock unit. So were other ppl.

 

Hmm. So am I really getting 60 psi or 50 psi?

 

You said you are getting 50psi when spraying, right? So that means you are getting 50psi. Install a smaller fuel pressure bypass jet, and see if you get more fuel pressure while spraying. If it doesn't work, then you will need to replace your stock fuel pump.

As for the fuel pressure jumping up to 60psi when you let off the gas, it's normal for ppl using the stock fuel pressure regulator.

 

Gotcha, well stated. I was going to do that last night and move to the .040 fuel jet but I don't have one. Would that be a good place to start or should I try like a .036?

 

I assume you are currently using a .042 fuel pressure bypass jet. From my experience (but remember, each setup and each car is different), you will definitely need a huge difference in jet size to bump your fuel pressure up 10psi. I'd say go with the smallest jet you have now...and see if that makes any difference. Plus, with a bigger difference in jet size, it'll be easier to notice if there is actually any difference in fuel pressure. If you just go down one jet size, there may be a small difference, but you may not notice it.

 

Did you go to a .036 jet? Did it fix your problem? I seem to be having the same problem. I think I have a .037 jet lying around that I can try.

Or did you just upgrade your fuel pump to resolve this problem?

 

If you want to know if you pump is the problem there is an easy test, just dont even use the whole btpass tee system take the vaccum hose from the nitrous pressure regulator and hook it straight to the fuel pressure regualtor, off the bottle you will run WOT fuel pressure (44psi) constantly, spray with it like this and it will max out your stock pump and show you exactly how much pressure it will push.

 

Llike this?

 

Pretty much, just go ahead and take the vaccum lines off of the bypass tee, then run the one coming off of the nitrous pressure reg. directly on to the FPR, but you have the basic idea in the pic just remove the tee.