Fuel Pressure Question?

[damesta]

I'm having some problems with my fuel pressure. I have been using a cheap fpr off of ebay and I have a walbro 255. I got my pressure set to around 36.3 psi with no vaccum attached like the fsm says but when I attach the vaccum line to it the pressure will only drop to around 32 psi. According to the fsm it should drop to around 28. If I set it to 28 psi with the vaccum attached, it will only raise up to about 32 when the vaccum is removed. My vaccum is good, its around 20hg at idle. I'm guessing the only thing that can be causing this is a crappy fpr, right? I guess thats what I get for buying a $30 fpr on ebay, lol, you get what you pay for. If anyone has any other opinions let me know.
Modified by damesta at 1:12 AM 2/12/2006

[originalsin]

you get what you pay for

[damesta]

Yep, but just to be sure, everyone does agree that the fpr is at fault, right?

[damesta]

BTW, I'm thinking about picking up the sard adjustable fpr, any opinions on it?

[jt15833]

got something against nismo?

[damesta]

lol, no, I just like the sard, I aleady have a gauge I can mount on it, my ca is already set up to use an fpr seperate from the fuel rail and its actually a little cheaper.

Does anyone think this could possibly be anything besides the fpr? Please tell me before I spend money on the sard one.

[damesta]

BTW, I checked it with a vaccum pump as well. Does the same thing, if I set it to 36.3 psi with no vaccum and then put about 20hg of vaccum on it (good idle vaccum), it will only drop to about 33-32 psi. Since it is supposed to be 28 psi at idle its making me run rich until the car starts to hit boost but its fine anywhere above 0 psi when theres no vaccum on it. Just the opposite if I set it for 28 psi @ 20 hg of vaccum at idle. Then it will idle and be fine until the engine hits 0 psi of vaccum/boost, at that point the fuel pressure will only raise to 32 psi instead of 36 and cause me to lean out.

The fpr is the only thing that could cause this, right?

[top_secret]

yeah sounds like the fpr. is it supposed to index at a 1:1 ratio cause I believe thats the stock ratio.

[damesta]

So it should automatically drop 8-9 psi when 20 hg vaccum is added then right? I guess I'm gonna order the sard one tonight.

[top_secret]

I don't know how much it drops but you should see fuel increase 1 psi for each psi of boost once you hit 0 psi.I had an adjustable fpr on my ka24de and I had the same problem, that if I set it with vac it wasn't right without, and vice versa.

[damesta]

I guess I'll see if the sard one works, its on the way, if not I'll resale it.

[top_secret]

yeah I got the nismo one with rail adaptor. didn't feel like messing with other ones.

[damesta]

Allright, the sard one is out of stock, so I guess I'm going with the nismo. One question though, the nismo one is supposed to be adjustable from 28.4 to 85.2 psi but the stock pressure at idle is supposed to be 28 psi. Does everyone with Ca's just turn them all the way down or what?

[top_secret]

I don't know I haven't put it on yet.

[damesta]

Can someone actually running a nismo fpr give me some opinions, is it just cranked all the way down or what?