transamice

Hello,
I have an 87 GTA 5.7 TPI auto new Walbro 255 pump filter with 10gauge wire, I have a fuel issue for some time now and cant figure it out.
Seems like I have air in my fuel line, I have the pump wired to run all the time when I turn key on.
With key on on a cold start you can hear the fuel rushing up the fuel line to the rail and once its filled it still sounds like there is air in the lines.
I ran the pump with the car off, and pinched the schrader valve, sounded like the lines were more or less filled.
I have no leaks, injectors are fairly new, using an aeromotive regulator on the return line, the fuel line going to the charcoal canister is vented.
Im not sure what to look for but my fuel delivery isnt right and I cannot tune my car.
The fuel line from the pump to sending unit isnt ripped.
Any suggestions would be appreciated.

paulo57509

What are the symptoms that make you think your engine has a fuel problem?

transamice

I cant tune my car, using the EBL and it always learns.
Car can surge when Im at a stop for a long time.
After a while of running the car it seems like the pump is tired, wines, this is my 5th pump in 3 years.
However, all the pumps performed like this.
The first 2 Walbro pumps were faulty and covered by warranty but even the 2 replacements act the same.
I even tried a Delco pump for a cyclone and had same results, so I dont know what else to check, with no leaks and no smell of fuel.

TTOP350

iTrader: (8)

WHich pump is in your car now?

I recomend Racetronix with thier "hot wire kit".

My cars sound just like your discribing when the system primes. (thats normal).

Check your grounds and do voltage drop tests.

transamice

I have the hot wire kit from Racetronix, even got the bulkhead connector that replaces the stock on the sending unit.
I have no prime anymore, pump runs as soon as I turn key on, takes around 7 seconds for the line to fill.
Running Walbro pump at the moment.
Voltage stays at 13.4V at pump.
I disconnected all my lines checking for bad o-rings leaks, blew compressed air threw the lines make sure there is no gunk stuck inside and changing to another new Walbro pump.

transamice

Made no diff.

TTOP350

iTrader: (8)

Do you have a charcoal canister hooked up and the little valve still working? How is the gas cap? the little gas tank check valve on the frame rail ok? It almost sounds like you may have a vacuum condition in the tank after it has run for awhile.
It does sound like your fuel psi is bleeding down a bit when shut off but that shouldn't be a problem.

transamice

Charcoal canister is removed, the line is vented, gas cap is fine, the mushroom vent is good.
After running the car for 30 min or so I have no pressure build up in my fuel tank, only when I plug off the line that goes to the canister it builds pressure.
I was just watching this video on youtube:

He was having tuning problems due to heating, was running same temps as I am, which are normal temps 95c.
I dont know how he solved his problem but Im sure he is on the forum because he mentioned it in another video he posted.

87hellbird

Alright the problem seems like when the engine gets warm it may overheat the fuel lines. Make sure you have all the heat shields for the exhaust and trace fuel lines and make sure they aren't near anything that gets hot. Its like vapor lock on an engine.

ATX-Iroc

If you've got ebl you can datalog. Check your 02 values, a small exhaust leak next to the o2 sensor will cause surging. The air you hear is just the fpr doing its job.

transamice

All the heats sheilds are on, I dont have a crazy setup, just stock with rear mount turbo, headers are wrapped but I thought to turn on the fans around 80c.
Both NB and WB o2 sensors are in tight.