destroyerSS

iTrader: (2)

Just trying to get some idea's what a bad pressure regulator would act like. I have a new pump, wiring is good,new injectors. Thanks

KillerSS

usualy they cause hard start run rich or lean check your fuel pressure i think it should be 48psi

Nasty N8

iTrader: (33)

They will not hold pressure at the set point. up and down pressures as the engine is reved or leaking through the vacuum port.

Nate

DarkAzNite

iTrader: (2)

Ok so I discovered I was running real lean at a dyno, I finally got ahold of a Fuel Pressure Gauge. Of course first step in diagnosis since with adding 5 points richen on predator had no effect at all on A/F while on dyno.
I connected gauge today and read approx 43lbs when first turning key over and it slowly dropped, I then started it up and it jumped back to 43lbs pressure, I blipped the throttle and each time it the needle would bounce down to 30lbs and it would quickly recover to 43lbs. Held throttle at about 3k and stays constant just seems to drop after the instant punch of throttle.
This sounds like the pump is ok but maybe a bad regulator?
What do you all think. and also where can I get a regulator, how much and how difficult to install. I searched some and seems like every thread has the common answer just upgrade to the Racetronix pump. Can't afford right now.
Hoping for a simpler and cheaper solution.
Car is a 99, mods in sig.
Thanks

DarkAzNite

iTrader: (2)

anyone????

99PontTA

fuel pressure should be around 58psi...maybe drop to 55 under wot.How old is the fuel filter? If you don't understand much about fuel systems i would take it to a good shop to have it tested.1st test involves blocking off the return line after the fuel filter and measuring max prssure the pump can generate with engine off...should be aprox 75 psi.If it passes that test next test would be checking the fuel pressure without starting the engine with the regulator unblocked.Turning the key on should cause the pressure to build to 55+ and stay there.If it doesn't then the regulator is most likely the trouble.I seen the stock regulator for 3 bucks on fred beans webstite.Its probably best to find a good shop to do all this testing...if you can find one...most shops today are in a rush.

DarkAzNite

iTrader: (2)

What do yo mean by with the regulator blocked? Are you referring to removing/blocking the vacuum line which simulates heavy load situation (low vacuum pressure)? I also can't afford to take to a shop, and would rather work on it myself.
thanks

99PontTA

there is no vacuum line on a 99 TA..is the fuel filter new?to block the regulator on a 99 ta you need to disconnect the nylon return line from the steel return line after the fuel filter and cap the steel line.PLEASE GET EXPERIANCED HELP BEFORE DOING ANY OF THIS!...

DarkAzNite

iTrader: (2)

Yes the filter is brand new. First thing I checked. I have a used pump coming in the mail and am going to put it in. The car has 83k miles on it so a new pump with 3k miles for 40 bucks isnt too bad. If if fixes it then great. I will let you know. I am going to do it myself with the help of a lot of reading. I can't be experienced without doing it myself.
thanks

DarkAzNite

iTrader: (2)

Question:
Since there is no vacuum line, is the regulator part of the pump unit in the tank itself. In other words if the regulator is bad, you will need to remove the tank and replace the pump anyways correct?

99PontTA

the regulator is in the tank...it a cheapo 5 dollar part........its not really part of the pump...but its mounted with it.

DarkAzNite

iTrader: (2)

Excellent. I think I am going to replace it when I put the new pump in. I got a used factory pump from an 02 for 40 bucks, might as well slap a new regulator on as well. Do you happen to know the part number?
It is strange, I hear pump, regulator and sending unit.
Forgive my ignorance on this but Isnt the sending unit the pump?

99PontTA

before you dig into this i would test the fuel system using a pressure gauge.A bad pres regulator could cause low fuel pressure but until you test everything its hard to say whats wrong.What are your troubles?

DarkAzNite

iTrader: (2)

I tested with a fuel pressure gauge. Earlier post in this thread:
Ok so I discovered I was running real lean at a dyno, I finally got ahold of a Fuel Pressure Gauge. Of course first step in diagnosis since with adding 5 points richen on predator had no effect at all on A/F while on dyno.
I connected gauge today and read approx 43lbs when first turning key over and it slowly dropped, I then started it up and it jumped back to 43lbs pressure, I blipped the throttle and each time it the needle would bounce down to 30lbs and it would quickly recover to 43lbs. Held throttle at about 3k and stays constant just seems to drop after the instant punch of throttle.
This sounds like the pump is ok but maybe a bad regulator?
What do you all think. and also where can I get a regulator, how much and how difficult to install. I searched some and seems like every thread has the common answer just upgrade to the Racetronix pump. Can't afford right now.
Symptoms are some pinging at high RPM's, horrible gas mileage and loss of prolly 40 horse. Dyno'd at 300 hp, and 300tq, with dyno showing lean conditions even at idle.

99PontTA

fuel pressure should be 55 lb +...maybe a couple things.To test the fuel pump output you need to take it to a pro OR be prepared to get messy with dangerous gasoline.1st test is a pump pressure oiutput test...this involves blocking the return off,then running the pump with the engine off.This will test the pump..should be 75 psi.....if it passes that test....its time for a fuel volume test...how much can the pump push through the line in 30 seconds....it should move ALOT of fuel.Next test is pressure leak down test with the regulator blocked off....should hold pressure for a very long time.If it passes that test next is the regulator...you can see by checking each part of the system you can narrow it down.
I seen the regulator at Fredbean's web site...i'm not sure if they are a sponser on this site.ONMO THINg...if you had this dynod don't they know how to diagnose fuel systems?

DarkAzNite

iTrader: (2)

I dyno'd on a Sat. and all the mechanics tool boxes were locked and didnt have a pressure gauge handy.
Also that seems to be a lot of potential cost as opposed to getting a 40 fuel pump and 15 dollar regulator and doing the install myself. If it still is a problem after that I would have spent less than 75 bucks and then can take to a shop to have it tested. Not to mention I don't really trust anyone very easily to work on my car.
Once took in for a pinion seal replacment, they never tightened the cover bolts and after a 2000 mile road trip, bang goes the rear.
Happened across country so got the complete run around from the shop, ended up costing me 800 bucks.

99PontTA

i hear that.....well do yer testing and at least you will know exactly whats going on.I would also do the trap door to change the pump-regulator.I would stay with the stock pieces too.So many people upgrade to other brand pumps then end up with all kinds of werido troubles.I know where you can buy just the pump replacement kit..its around 75 bucks new.The regulator you need to get from a dealer.Be sure before you test that the fuel filter is NEW.

DarkAzNite

iTrader: (2)

Thanks.
I purchased a used pump with 2k miles on it from an 02 off a forum member, I saw this write up on the trap door.
http://www.taekwondoplus.org/z28/fuelpump.html
It is the best one I have found.
I replaced the fuel filter less than 1k miles ago. I guess I will grab a regulator and start on it next week sometime if it warms up any here in Texas.
Thanks for your help.

99PontTA

that is not for a 99 up fbody...thats for a 98 maybe....the 99 up uses a plastic fuel tank and the trap door you nned to make is more to the rear of the car....be very careful cutting into that area...i would use a hand nibbler...if i can find the 99 up instructions i'll post a link.

99PontTA

http://community.webshots.com/album/70099731hGvNzx 99 up