Won't start after filling tank

[dkdeford]

Here's a weird one:
1989 EFI
When I fill the gas tank all the way, the engine won't start for 10 minutes or so. Let it sit, then it starts and runs fine.
If I only fill the tank halfway, no problem.
I suspect something to do with the evaporative emissions system, but ... what?
Any thoughts?

Update:
Various sources suggest I was on the right track with evap canister purge valve - or whatever it's called on a 1989 Festiva. I'm trying to decipher the vacuum routing diagram... Does anyone have experience with what the parts are called and where they are on the car? Thanks

[WmWatt]

Sorry you're not getting any responses. This doesn't sound like a problem which would be peculiar to Festiva's. I did an Internet search on "car won't start with full tank" and got quite a few hits. Suggest you try that while waiting. Good luck.

[RayRay]

Sheesh...that is an odd one! Any chance it has something to do with the vent solenoid or the purge valve? Maybe it's stuck open? Let us know what you find.

[1990new]

Purge Canister solenoid valve.jpg
Here is a picture of my 1889 "Trixie" showing the purge relief valve, canister, hoses and intake manifold.
As you can see the valve controls an opening between the canister and the intake manifold (although the hose going to the opening in the intake valve is not shown).
The canister purge relief valve for the 1989 EFI is located on the firewall on the same cowl access cover that the windshield wiper motor is attached to.
A duty cycle timer in the ECM computer controls the opening and closing of the valve. (I'm assuming it's based on engine running time but not positive.)
If a problem occurs with this valve.. such as solenoid freezes, wires broken, ECM malfunction etc. this is what can happen:

1. The valve remains closed and does not open at all will cause no problems with the running of the engine, but fuel vapors that would have been burned will be released
to the atmosphere instead of into the intake manifold to be burned and could show a very slight reduction in mpg.

2. If the valve remains open all the time, the symptoms will be like a vacuum leak and will result in difficult starting and/or rough engine running.

3. The third issue of a valve remaining partially open is a remote possibility.

The good news is that the usual failure that occurs is number 1.. the valve remains constantly closed.

So better for you to have a purge valve solenoid locked closed instead of open (but the EPA might disagree).

It's may be possible that your description of having to wait 10 minutes after a fill up before the engine stars could have something to do with the purge relief valve... a situation that comes to my mind would be where the spring that closes the valve gets weak to the point where it takes several minutes to close the valve after it has been opened. First thing I would try is remove the hose from the canister where it is connected to the intake manifold and pug that intake manifold opening.
If this fixes your problem you will know for sure that the purge solenoid is your problem.


You might want to check the fuel pressure regulator. I added a post to the forum about how it works a while back which explains it a little better:

The outlet of the injector is exposed to manifold vacuum/pressure which varies depending on throttle movement, but the flow of fuel from the fuel pump is constant, the pressure valve needs a reference to continuously change the amount of fuel bled to maintain constant fuel pressure to the injectors. The spring force in the regulator closes the valve when there is no vacuum in the intake manifold. When you start the engine the difference in the ambient air pressure and the vacuum pressure caused by the piston suction is present in the intake manifold and that vacuum pressure that is carried from it to the pressure regulator increases the pull on the regulator valve opening it up. The vacuum is greatest at engine idle and least at wide open throttle. So what the regulator is trying to do is to maintain a constant pressure difference between the inlet and outlet of the injector.
So to answer your question... Yes the volume of fuel return to the tank is constantly changing based on the constantly changing manifold vacuum.

This is just one of multiple reasons why it is so important that you detect and stop any vacuum leaks that you may have before you try to troubleshoot other problems.


Trixie has just over 100K on the odometer and all systems are still working great on her.