need help with testing adjustable bbk fpr
 

ok iv had this really bad lag, bog, hesitation at lower rpms so i am checking the fuel pressure regulator i pump the regulator up but the vacuum just bleeds right out but if you have the car running and you pull the vacuum line off to set the wot pressure it will rise so im lost do you think the regulate is shot or is that the way adjustable reg's work the car also doesn't hold feul pressure in the system after the engine is turned off

Your fuel pressure should go up when you pull the hose. Also your pressure should drop after your car has been off for a while.

How long has this been happening? Any mods since? Have you tested for a vaccum leak yet?

I installed a Paxton FPR once and it didn't hold pressure. It went south because of additives I added so I replaced it with a stock FPR. It held pressure. I replaced that with a BBK adjustable and it didn't hold pressure again. I think it's just something with the adjustable FPRs.

As for your problem, what is your fuel pressure set at? What size injectors do you have. What kind of modifications have you made to the engine? Have you pulled your fault codes from the ECM? Have you done a MAF conversion?

How fast does your fuel pressure bleed down after the key is off? That's a bad thing.

hmm you guys scare me, mine drops off pretty fast, i dont see why it shoud be a problem, there is a return line?

i have no vacuum leaks the pressure bleeds right off after i turn the engine off its done that since the regulator was new so i don't know if that's just the way its made. i just need to know if it should hold vacuum when i pump it up because right know i just pump it up to like 20 and it just bleeds right down and doesn't change the fuel pressure from 0 that's with the engine off key on and does any one know what size fitting i need to hook a fuel pressure gauge up to the schrader valve im going to try the stock regulator but right now the gauge is hook right up to the regulator thanks for you help

My adjustable BBK does the same thing. When the key is turned off, it drops right down. If you turn the key to prime the motor, the pressure will hold around 20-25# for a while and slowly drop, but if the car was running and you shut it off, the pressure goes away. I've talked with several people who experience the same thing with adjustable regulators.

--nathan

The shrader valve is 1/16 NPT but standard fuel gauges are 1/8 so you will need an adapter, I had mine custom made so it may be hard to find. I think places like steeda sells them.

The dropping of fuel pressure when the engine is turned off is normal, however the speed it all going to depend on several factors including what modifications you have made and hot hot your vehicle is, I think on hot days it takes several minutes to drop all the way down, but it slowly starts dropping after the engine (fuel pump) it turned off.

Applying vacuum to the regulator OPENS the restriction, it doesn't close it. When you add vacuum it will cause the pressure to drop.

You should use the fuel pump test lead to run the fuel pump when adjusting the pressure and then when you stop the pump, that's when you should do the leak down test.

and you are not pulling out any gas past the diaphram?did you buy a ghetto one that looks like the stock one or did you get a kirban/areomotive billet alumn style one?

i had nothing but problems with the stock style Holley ones(all 3 of them they suck!)..i ran Kirban on my notch and now its on my 2.3T and my car will hold 20psi for 2 days

check your FP to see if that is it and not your pump on its way..hesitation down low is a sign of a worn pump and the fact that the sytem bleeds out so fast also points to it..

duh you got a BBK reg..ok i think your pump is bad..same thing happend to the other matt's car when it was still mine

i bought a 255 FP from D&D for $99 for my turbo car

i have no gas leaking past the diaphragm and i have a 255lph from D&D its only a year old but it could be bad but i don't think that's the problem i have good pressure i don't know the volume though i have no way to tap in. my real question is should the reg be holding vac or is that the way after markets are

if it is tight on there i do not see any reason why it should not..where would it go?put a ziptie around the vac line and see if it holds vacum..if it doesnt and you are sucking gas threw then the top 1/2 of the regulator has a crack,bad gasket or something

unless....it is just sucking the diapram up and up and nothing is stopping it..i mean you car makes say 15hg..the engine will allways have that at idle providing there is no vac leaks and will only pull the diapram so far out becasue the TB/IAB really controlling the fact that you have vacuum..get it kinda

ok i just got back from a good 40 min drive down the highway the car is a slug from 2000 rpm to 3000 and the powers not smooth if i punch the gas it just lags really bad and then slowly builds and then goes and if i beat on it it smells real bad like something is burning not oil or coolant but something else i also checked my plugs and wires plugs are clean wires are getting to the limit any ides

also the lag gets worse as the car heats up so im thinking i mite try getting new wires but would wires make the car lag i have had a wire go and had a miss

Is the smell like rotten eggs by any chance?

If so, then your cats may be breaking up or melting. That would create a big restriction in the exhaust making the engine seem sluggish when in fact a lot of the power is being used to push the exhaust through the cats.

The root cause may still be your FPR, as too much unburned fuel causes your cats to break down quicker.

Does this make sense?

Good luck,

Rich D.

no it doesn't smell like bad cats i know that smell and i don't have cats so that can't be it but thanks for trying

For the record, your fuel pressure should not drop at all for several minutes, at least, after you turn the key off. If it does drop faster than that, you have a problem, and it's going to make the pump work harder than it should, which will shorten it's life span considerably.

Also, yes, your regulator should hold vacuum. If it doesn't, you will have a vacuum leak when running.

:)

Take care,
~Chris

Chris,

My Paxton and my BBK FPRs do not hold pressure like that, but the stock one that I had installed after the Paxton and before the BBK did. That tells me that there is nothing wrong with my fuel system as far as leaks go and that certain FPRs behave differently. I'll check again, but I'm pretty sure that that's how they behave. I thought maybe it was my gauge leaking at the Schraeder valve, but like I said, it held with the stock type regulator. My A/F curve was pretty much perfect when I put it on the dyno, too. As I said, I'll check it again to see if I just have a lousy memory.

Is there anyone reading this thread with a BBK or Paxton FPR that has had a different experience?

As far as vacuum goes, it took 2 minutes for my vacuum to drop from 20 down to 6 inchs-Hg. My pump didn't leak at all when I just put my finger on the end of the hose, so I know that pressure leaked from the regulator.

jimberg,

I've experienced the same thing. The stock regulator held pressure (until the fuel pump died...replaced the fuel pump and it still held pressure). When I put on a BBK AFPR, the pressure dropped right away when the car shut off. However, I also put on a set of FRPP injectors at the same time (tried a set of nearly new 30's...bad idea, and currently have a set of new 24's). Maybe the injectors dump the fuel??

I assumed it was normal. If it truly isn't normal, I'd sure appreciate an idea of what would cause it. It's not the lines or the pump since it held pressure with the stock regulator.

--nathan