j0hn_j0hn08

iTrader: (1)

Hey all 99 trans am New racetronix 255 pump, new delphi regulator .


Im gettting steady 61 psi of pressure at idle.. however on Key on engine off the gauge spikes to 58 psi and drops down to 0 in about 20-25 secs...

How can i track down the leak? anyone have any ideas?

_JB_

iTrader: (33)

If this is related to your other thread with difficult starts, make sure there are no leaks from the tank all the way to the injectors. It might even be such a small leak run your finger around any part where lines couple and see if anything gets on your finger. Otherwise ensure the feed line in the pump assembly are tight with hose clamps, the thin hose is snugly connected, regulator is properly seated facing upwards, and double check there is only one o-ring.

Overall 20-30 seconds isn't too bad, I'm assuming if you wait a second after the pump primes you're somewhere around 55-58psi?

j0hn_j0hn08

iTrader: (1)

yes i ended up running compressed air into the fuel tank and found the fitting at the fuel filter was leaking (metal fitting) i removed the fitting replaced the o ring (was in pieces) and added some teflon to the threads.

Now on the pressure test it still leaks down but it slowed down quite a bit.

Is it normal for it to still leak down or is it supposed to hold steady pressure koeo?

_JB_

iTrader: (33)

After prime it will eventually bleed down, mine will take a few minutes to hit 0 though.

j0hn_j0hn08

iTrader: (1)

re tested psi today, it is now showing 30 on key on engine off and rapidly drops to 0 in about 15 seconds... Im thinking my next step will be to pull the fuel rail and prime the system to check for leaks

_JB_

iTrader: (33)

Have you ever smelled gas after priming it, driving, or parking it? Where is your pressure gauge at, the fuel rail?

j0hn_j0hn08

iTrader: (1)

Just pulled rail disconnected injectors and primed key, no fuel squirted, i then connected the injectors and primed the key again (koeo) and still no squirt from the injectors.. running out of ideas.

i used the shradder valve and hooked up a pressure test kit

bigsticksupra

iTrader: (3)

when you say new delphi regulator, what do you mean by that? the regulator is internal to the fuel pump bucket assembly and not replaceable as far as i know

j0hn_j0hn08

iTrader: (1)

Its replaceable i pulled off the stocker from the bucket and i put on an aftermarket Delphi regulator. Its held on by a clamp.

::UPDATE::

Pulled off the rail re installed all new O-rings on the fuel injectors.. Still loosing fuel pressure rather quickly causing me intermittent hard starts.

I sprayed some soapy water on the quick disconnect line that goes from the fuel rail to the fuel hard line on the driverside and found some slight bubbling on the quick disconnect plug that goes to the hard line (connection was rusted pretty bad). I have a replacement hose on the way to see if it remedies anything. Im a bit doubtful because the bubling was very slight and it would only bubble every so often but im hoping for the best.

Really running out of options here guys on what else to check... ive replaced just about everything and my fuel pressure is still dropping almost immediately after i turn the key off, it doesnt hold. However fuel pressure once the car is idling holds at 61-63 psi no problems, also no driveability problems just the intermittent hard starting is the issue.

Orange Juice

iTrader: (3)

I'm still trying to find the cause of mine. One big problem was the clamp holding the small line in the fuel bucket. I dropped the tank and then hooked the pump back up and set it in a bowl of gas. Turned the key on and watched the fuel spray around the line.

bigsticksupra

iTrader: (3)

i would remove the fuel pump bucket assembly from the tank and prime (key in ign) the system in a bucket of liquid with the lines still attached to car but inlet of fuel pump bucket submerged in the liquid to draw fuel. sometimes there may be cracks in the plastic that are semi-invisible but will leak when pressurized. Look at the clamped connections between the fuel pump and bucket assembly and the hose itself. those may leak if improperly clamped or the hose may have begun to degrade and leak/lose pressure.

kingtal0n

iTrader: (1)

I am not sure the fuel pressure is related to your hard start.

Why not wire the pump to 12V directly so it runs constant, then crank the vehicle to see if it gets easier to start?

more likely you have an idle air (starting airflow quantity) or fuel priming/cranking pulse issue, and there are also plenty of other reasons for hard starting out there. Just a thought. Running a stock ecu, stock injectors, stock map/maf?

LLLosingit

iTrader: (4)

I would check your injectors to be sure they aren't leaking, Normally pressure wouldn't drop that fast with a leaky injector(s) but that can cause hard start issues.

klinznilk

iTrader: (8)

Mine did the same thing.

Mine ended up not being the tightest connection on the pump flex tube.

I bought the Oetiker tool to get a better crimp and it seemed to help.

Mine now spikes to 61 on key on... then after a few seconds it drops to 45ish according to my gauge on rail. It holds for approx. 60 minutes before it drops all the way.

Racetronix of course is blaming me and yet I still think its the check valve on the pump. I took that part of and cleaned it etc etc and still didn't help more.

j0hn_j0hn08

iTrader: (1)

Everything is stock, if it was something other than Fuel pressure that wouldnt explain the almost instant fuel pressure drop with the fuel gauge connected ans the car with key on engine off. Thats why i havent suspected anything else.

j0hn_j0hn08

iTrader: (1)

This will be my next step after the new lines install, i did however replace all of the hoses and when i did the pump install but i am not going to rule it out.

j0hn_j0hn08

iTrader: (1)

Hmm thanks for this info i will definetly look into that flex hose connection. I am determined to find this issue ive spent a lot of money on this already

j0hn_j0hn08

iTrader: (1)

.::Update::.

Replaced fuel hose that appeared to bubble, still losing pressure.

Lup

Just a shot in the dark but, can the fuel pressure bleed off in the EVAP system? I don't know how, but it seems like maybe a possibility.

j0hn_j0hn08

iTrader: (1)

I dont think so evap has its own lines.

Ill be pulling the pump back out tonight and re clamping all the hoses, also will probably end up sealing the area around the regulator to see if it makes any difference on the fuel pressure drop.