transamice

Running an 87 GTA 350 TPI auto using EBL 255 LPH Walbro pump, hot wire to pump from batt, removed all evap system and AIR system, a new aeromotive regulator set at 45 psi new injectors and filter.
Problem Im having is the fuel lines are pulsing like a none consistant flow of fuel which is causing the engine to surge at idle till it sometimes dies.
Fuel pressure holds for a few mins after the car is off but drops to around 20 psi and holds.
I still have an issue of fuel pressure dropping after running the car for a while and have to add fuel manually to stop surging.
I have tried pluging the evap line and it builds pressure in the tank, the breather vent on the drivers side allows air both ways but with some force. ( probably not good)
Up till now I have been running the car with the evap line open with no difference except building pressure in the tank.
Is the tank suppost to be pressurized and has anyone experienced this before?
Any ideas please?

Atilla the Fun

Yes, but you removed the evap system. Why? Get a new vent valve.

transamice

I still have it but which part is the valve, is it on the canister itself or the part that has a bunch of hoses connected to it?
Is there a link to a picture of the valve and which part connects to the line from the fuel tank.
I removed it a while back, kept it just in case.
Even so the pulsing in the lines is a concern but I will hook it up tomorrow to get that out of the way.
Should I consider a dorman fuel pump pulsator?

Atilla the Fun

In the rear, where the sway bar end link attaches to the sub-frame rail, on the driver's side, there is a plastic thing on a hose. That is a one-way valve. It is supposed to let fresh air in, but not let gasoline vapors out. The vapors are supposed to be stored in the charcoal cannister until the computer signals another valve to let the engine's vacuum draw those fuel vapors into the intake manifold to be burned. This is the evap system, and while it may not look sexy, it only adds about 2 pounds to the car, and doesn't hurt power, MPG or handling. Removing it creates hassles. That cannister has a replaceable filter on the bottom, and that needs replaced, but nobody ever does unless they fail a Cali emissions test.

transamice

Where do I buy a new one way valve or what is the proper name for it if I were to ask for one at a parts store or dealership?
Is there a part number?

Atilla the Fun

I don't know. I just checked RockAuto.com, '87 'bird 5.7L, not listed in emissions or fuel categories.

ZZ28ZZ

Have you monitored the fuel press while eng is surging? It would have to change a lot to cause surging at idle. I have an adjustable fuel press regulator and I've adjusted it down to 25-30 psi without any change to idle quality (and very little change to the BLMs). I normally run 42 PSI with vac hose connected.