Curtis T look here.

[TORN]

I couldn't help but see your post about the gas tank problem you have. Yes you should have a non vented gas cap. Sounds like you have the same problem I had. We have a gas canister on our cars that the gas vapors collect into and the computer opens a relay and draws into the TPI setup via the pentium so it can burn the gas vapors. I am going to go take pics so I can explain how the system works, But you need to fix this so gas is not spraying out the gas cap.

[TORN]

Gas info 002..jpg

ok this is the canister and as you can see there is a relay that the computer opens and closes at certain times.
Gas info 004..jpg
This is the vacuum pot/solenoid it opens when the motor is at a certain vacuum
Gas info 006..jpg
So to fix your problem you need to test the relay and the vacuum solenoid. To test the relay get a multimeter and OHM it out and make sure its not open or shorted. I used a vacuum pump to test the solenoid. The vacuum pot/solenoid was what was bad on mine and was the reason my gas tank was building pressure. If you don't fix this you will burn up your fuel pump.

[TORN]

Almost forgot there is also a check valve by the axle that might be stuck and could be causing that build up too.

[TORN]

From the Chilton book:

charcoal canister ECC - Evaporative Emission Control (EEC) Systems

The Evaporative Emission (EVAP) control system used on all vehicles is the charcoal canister storage
method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage
device (canister) to hold the vapors when the vehicle is not operating. When the engine is running,
the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal
combustion process.

Removal of the vapors from the canister is accomplished by a solenoid operated bowl vent or vacuum
operated purge valve mounted on the canister. In addition to the fuel system vents and canister, the
fuel tank requires a non-vented gas cap. The domed fuel tank positions a vent high enough above the
fuel to keep the vent pipe in the vapor at all times. The single vent pipe is routed directly to the
canister.

These systems commonly use an in-line EVAP pressure control valve as a pressure relief valve. When
vapor pressure in the tank exceeds approximately 0.7 psi, the diaphragm valve opens, allowing vapors
to vent to the canister. Once the in tank pressure drops below 0.7 psi, the valve closes causing
vapors to be help in the tank.

If the EVAP system is not functioning properly, any one of the following conditions may be as result:
Poor idle, stalling, and poor driveability can be caused by:

Inoperative purge solenoid valve
Damaged canister
Hoses split, cracked or not connected to the proper tubes
Evidence of fuel loss or fuel vapor odor can be caused by:
Liquid fuel leaking from the fuel lines
Cracked or damaged canister
Inoperative canister control valve

Disconnected, misrouted, kinked, deteriorated or damaged vapor hoses or control hoses.
If the solenoid valve is open, or is not receiving power, the canister can purge to the intake
manifold at the incorrect time. This can allow extra fuel during warm-up, which can cause rough or
unstable idle.


Operation

This system reduces the amount of gasoline vapors escaping into the atmosphere. Some models employ a
purge control solenoid which is controlled by the ECM, to open and close the EEC system. Other models
use a canister mounted vacuum purge valve; when the engine vacuum reaches a certain pressure, the
valve opens allowing the gas vapors to be drawn off to the carburetor for burning.
Carbureted models use an exhaust tube from the float bowl to the charcoal canister; fuel injected
models eliminate the fuel bowl tube (as no float bowl is used on fuel injection systems). Fuel vapors
from the gas tank travel from the tank to the vapor canister, where they are collected. Although the
system varies from vehicle-to-vehicle, the operations are basically the same.


Testing Tank Pressure Control Valve

Using a hand-held vacuum pump, apply a vacuum of 15 in. Hg. (51 kPa) through the control vacuum
signal tube to the purge valve diaphragm. If the diaphragm does not hold 5 in. Hg. at least for 10
seconds, the diaphragm is leaking. Replace the control valve.

With the vacuum still applied to the control vacuum tube, attach a short piece of hose to the valve's
tank tube side and blow into the hose. Air should pass through the valve. If it does not, replace the
control valve.

[Curt_irocz]

Wow thanks for the big heads up. The only thing is mine looks a little different, Just because mine is a 1986, But I think it has the same basic setup. I will test the vacuum solinoid, Is it supposed to hold vacuum? And how many ohms resistance does the relay have? THANKS!

Also My car does have a poor idle, and sometimes does have a stalling issue.

[TORN]

Well I can OHM mine and yours should be close, I don't remember what it OHM out to. To test the vacuum solenoid just blow thru the big hose and rev the moter if you can't blow thru it than its bad. The vacuum from the motor should open it up.