occasional engine stall

Cincyken · Post by **Cincyken** » 02 Jan 2013, 15:24

This only happens when I fill the gas tank of my 1995 T5-R.
I fill the gas tank, i drive for a while, then if i do a normal stop - no problem.
But if i stop with a little more than normal breaking force, the engine stumbles and sometimes will stall.
When I use up some fuel and get down to approx 7/8ths of a full tank, everything is normal again reguardless of how hard I
break.
If I only fill the tank 3/4th, there is no problem with the engine stumbling or stalling on hard breaking.
Any idea what could cause this?

Post by **jblackburn** » 02 Jan 2013, 16:06

A stuck purge valve.

Find the valve on the radiator shroud near the battery. 3 fat rubber black lines connect to it. Next time you get gas, remove the one from the valve to the intake manifold. Duct tape off both ends so as to not cause a vac leak or fuel vapor leak and drive it as you would to normally make it stall. If it doesn't act up, reconnect the lines to vent the fuel vapors and search for a new valve. Some of these use a round valve and some a rectangular one.

Cincyken · Post by **Cincyken** » 02 Jan 2013, 19:27

Are you refering to the Evap purge valve that is held in the rubber bracket by the two torxs?

Post by **jblackburn** » 02 Jan 2013, 20:02

I don't think so.

Lower left corner of this picture...just under those wires. Yours may look different.

Post by **cn90** » 02 Jan 2013, 20:10

If this is truly from Purge Valve, then the computer should have set a code P0440.

Anyway, cleaning it is easy, see the update I posted on Dec 23, 2012 in thread below, clean it with carb cleaner (no need to take it apart).
For the last 2 weeks, it has worked well for me. Very very simple repair.
BTW, get the hose ready before taking out the Purge Valve (I think 8-mm fuel hose should work fine, cheap at autoparts store).

https://www.matthewsvolvosite.com/forums ... 1&start=14

Post by **jblackburn** » 02 Jan 2013, 20:11

cn90 wrote:If this is truly from Purge Valve, then the computer should have set a code P0440.

Sometimes; not always.

Cincyken · Post by **Cincyken** » 17 Jan 2013, 05:26

I believe I found the problem. The hose connections to the purge valve, fuel tank and charcoal canister are all wrong. There are two ¼” hoses connected to my intake manifold, one goes directly to the fuel tank vent, the other to the purge valve. The purge valve is then connected to the canister but the two other fittings on the canister have nothing attached to them.
I think there should be a normally open vent valve connected to the canister as well as the fuel tank vent and the purge valve.
Question 1: How do I know which fitting on the canister to connect the purge valve to, which to connect the fuel tank vent to, and is there really a vent valve or just an open fitting?
Question 2: is a side question, the literature says the vent valve is N.O. and the purge valve is N.C., and computer tells the purge valve when to open. What is the computer sensing to know when to open the purge valve and for how long?
Hope y'all don't mind my obsession with details, but as a 65 year old mechanical engineer, i love details.

Cincyken · Post by **Cincyken** » 22 Jan 2013, 13:39

Well i did not hear back from y'all about the hose connections to the charcoal canister......
So i left the purge vavle connected to the top of the two fittings, and hooked the fuel tank vent to the fitting below it. The other fitting must be the vent to atmoshere since it has a metal clip on it that prevents a hose from being connected to it.
The car now runs better than ever so i guess i did it correctly.

Post by **jblackburn** » 22 Jan 2013, 14:00

Sorry...I've never fooled with the canister lines before. I do know it has a vent to the atmosphere (I believe it even says it on some models), but I don't know the right connections.

Good to hear that it's running well again though!