Evap Purge Valve Assembly?

[kazoospec]

In the past few months, I've started having low/rough idle and even occasional stalling issues after filling up the fuel tank. These issues have been getting progressively more noticeable. It's a 2017 Fiesta ST, but for reasons I've never been able to figure out (2nd owner), has an April 2019 "in service" date and about 45K on the clock. Since I believe it's still under the powertrain and emissions warranty, I'm having my local Ford dealer take a look at it. I've read enough here and on FB groups to guess it's likely the evap purge valve/harness that's causing the issue. (If I am/could be wrong about this, let me know)

It seems like this is a "well known" issue, but "everyone on the internet knows this" in my experience with other dealerships doesn't carry much weight. SO FAR, despite flat stalling the car on a couple of occasions, this issue hasn't tripped the CEL (which, quite frankly, surprises me a bit). Anything I can do to get ready for the inevitable argument with the dealer? I can't seem to find any TSB's on this issue, but that may just be the inherent weakness of my google-fu.

I'm already planning to fill the car just before hitting the dealership in hopes of avoiding "we can't replicate the problem".

 

[NOVA_Ranger]

Noticing similar issues here as I get familiar with my car (2019 with 37k miles). My plan is replace the valve and also swap out the rigid plastic lines with rubber hose, so it will be easier to replace the valve when it inevitably goes bad again in another 30-40k miles. It looks like a pretty cheap and easy solution to me, and any input is appreciated.

 

[NOVA_Ranger]

Last week I topped off my tank and left the nozzle in the car for over a minute, as I ran into the store to grab something. That was the first time I didn't have the stumbling or stalling issues after filling up. Seems to be a temporary 'fix' until the valve is replaced.

 

[Capri to ST]

Last week I topped off my tank and left the nozzle in the car for over a minute, as I ran into the store to grab something. That was the first time I didn't have the stumbling or stalling issues after filling up. Seems to be a temporary 'fix' until the valve is replaced.

There's a graphic on the car near the fill hole which says to leave the nozzle in for 5 seconds after filling, and I always leave it in there for about 30, and I've never had a stalling issue after a fill up, and only once had a little bit of stumbling in the six and a half years I've owned the car.
Also, just as general information for people about this, never add any more gas after the pump first clicks off. Some people do this to get the last little bit of gas in there or round up the dollar amount, but this can add to the problem.

 

[kazoospec]

There's a graphic on the car near the fill hole which says to leave the nozzle in for 5 seconds after filling, and I always leave it in there for about 30, and I've never had a stalling issue after a fill up, and only once had a little bit of stumbling in the six and a half years I've owned the car.
Also, just as general information for people about this, never add any more gas after the pump first clicks off. Some people do this to get the last little bit of gas in there or round up the dollar amount, but this can add to the problem.

I always try to leave the handle in for at least a minute or two after it clicks off. I never add after the first click and usually slow the pump down as it gets close to full to try to keep if from getting a surge up the filler neck. I think I'm doing everything I can to mitigate the problem, but it keeps getting worse.

 

[Alkoran]

I always try to leave the handle in for at least a minute or two after it clicks off. I never add after the first click and usually slow the pump down as it gets close to full to try to keep if from getting a surge up the filler neck. I think I'm doing everything I can to mitigate the problem, but it keeps getting worse.

Did you try without slowing down the pump? Slowing it down will only make your tank get more fuel than it's "supposed" to contain. You're basically doing what people who tops off their tank do.

 

[Dialcaliper]

I had the same stumbling issue consistently following every fill-up. Not to the point of totally stalling, but I noticed the RPMs didn’t actually drop much, just the engine stumbled like it was going to.

I have never “topped-off” when filling, and never got a CEL nor any stored codes (checked with Forscan). Car is a 2016 with <60k miles.

Long story short, I replaced the Evap harness including the valve (with a 2014-2015 version) and the issue disappeared entirely.

My theory (with no evidence to support it) is that when the valve starts to gradually fail, it gets sticky and responds too slow. Because there’s a connection in the harness from all 3 intake points (induction hose, cold side and manifold after the throttle body), whenever there is vapor or liquid in the Evap line from the gas tank, you get a “short circuit” around the throttle plate and the idle control valve. When the idle rises from the extra air and fuel vapor, lean, the idle valve and ecu try to compensate by closing and backing off fuel. When the purge valve finally closes later than the ECU expects, it has cut off too much fuel and air, and the engine stumbles.

Something like that anyway. In older engines, the EVAP canister purge would only open under stable cruise conditions, but newer engines do the Evap purge constantly, especially after fillup to limit emissions of unburied hydrocarbons.

 

[kazoospec]

Did you try without slowing down the pump? Slowing it down will only make your tank get more fuel than it's "supposed" to contain. You're basically doing what people who tops off their tank do.

I've actually tried both ways trying to avoid the problem and had issues both ways. I tried slowing the pump on the last few fill ups after I had issues following several "run the pump at normal speed until it clicks" fill ups. I've done the last few fill ups slowing down the pump, but not only is that not helping, the issues have gotten worse, going from low idle/shudder to a flat out stall, so you're probably correct about the observation. I assumed that was a mechanical/system problem getting worse, but maybe my fueling practice isn't helping. I'm also trying to figure out whether it might somehow be related to ambient temps, but haven't seen any correlation there.

All that said, it seems to me that any system that causes the vehicle to stall is dangerous and any system that can't handle a slight differences in flow rate doesn't belong in a consumer vehicle. Around here, it's not unusual to get vastly different flow rates for different pumps at the same station.

BTW, very much appreciate the feedback so far. I'm going to have the dealership look at it since I have some other scheduled maintenance they're doing at the same time. If there's anything I can do to minimize the issue going forward, I want to give that a try as well.

 

[NOVA_Ranger]

I've actually tried both ways trying to avoid the problem and had issues both ways. I tried slowing the pump on the last few fill ups after I had issues following several "run the pump at normal speed until it clicks" fill ups. I've done the last few fill ups slowing down the pump, but not only is that not helping, the issues have gotten worse, going from low idle/shudder to a flat out stall, so you're probably correct about the observation. I assumed that was a mechanical/system problem getting worse, but maybe my fueling practice isn't helping. I'm also trying to figure out whether it might somehow be related to ambient temps, but haven't seen any correlation there.

All that said, it seems to me that any system that causes the vehicle to stall is dangerous and any system that can't handle a slight differences in flow rate doesn't belong in a consumer vehicle. Around here, it's not unusual to get vastly different flow rates for different pumps at the same station.

BTW, very much appreciate the feedback so far. I'm going to have the dealership look at it since I have some other scheduled maintenance they're doing at the same time. If there's anything I can do to minimize the issue going forward, I want to give that a try as well.

Agreed...a vehicle shouldn't stumble or stall after being filled, period. I have never had to tap dance at the pump with any other vehicle that I've owned. If changing the valve every 30-40k is what it takes...

 

[dhminer]

Agreed...a vehicle shouldn't stumble or stall after being filled, period. I have never had to tap dance at the pump with any other vehicle that I've owned. If changing the valve every 30-40k is what it takes...

It’s probably easier to replace the whole harness then mess with the valve.

 

[FiestaSTdude]

Mine is doing the stumbling idle thing after filling up and I always leave the pump in at least 30 seconds and never keep going after the click. The other thing I’ve noticed is that if I fill up from a gas can it will still have the same issue. Im going to replace my purge valve and see what happens.
I have modified the lines where the purge valve is with rubber lines and hose clamps so changing it is pretty easy

 

[Sprinkle_Star]

I've had my purge valve assembly replaced under warranty, and a year later, the issue reappeared. Fast forward two years, I still haven't bothered replacing it because I just have to keep the rpms above 1,000 if I get stuck at a red light for the first ten minutes of driving around after refueling.

 

[Sam4]

As soon as you (all) replace the assy, the stumble will go away.

 

[dhminer]

I had my evap assembly replaced twice under warranty and replaced it myself last week. I always have one on hand. Ordered a 2014-2015 this time.

 

[NOVA_Ranger]

Anybody got diameter and lengths of rubber hoses needed to make this valve a cheap and easily replaceable item? I assume you reuse end fittings from the existing harness and a couple of new clamps at the valve?

 

[kazoospec]

Got a call from the service manager. They think it's the "low side fuel pressure sensor". They're replacing it under warranty. Apparently, they did get it to stumble while they had the diagnostic computer connected and it didn't show an evap code, which is where they came up with the low side sensor. I filled the car up at the gas station across the street from the dealership, so I think that's why they saw the stumble, but the computer doesn't lie I guess.

I still think its the purge valve since it only happens on a recently filled tank, but I've now brought it to their attention while the car is under warranty. The dealership is only about 10 minutes away (and I know the owner), so I'll see if this fixes it. If not, it'll go right back.

BTW - this is why it's important to know your "in service" date. At first, they told me it would be $430 because the car was out of warranty. They assumed that because it's a '17 the powertrain warranty was expired. Had I not known it had an April 2019 "in service", it wouldn't have been covered.

EDIT: I should add that they had a 20 year Ford tech working on my car, so it's entirely possible he knows more than I do.

 

[Capri to ST]

Got a call from the service manager. They think it's the "low side fuel pressure sensor". They're replacing it under warranty. Apparently, they did get it to stumble while they had the diagnostic computer connected and it didn't show an evap code, which is were they came up with the low side sensor. I filled the car up at the gas station across the street from the dealership, so I think that's why they saw the stumble, but the computer doesn't lie I guess.

I still think its the purge valve since it only happens on a recently filled tank, but I've now brought it to their attention while the car is under warranty. The dealership is only about 10 minutes away (and I know the owner), so I'll see if this fixes it. If not, it'll go right back.

BTW - this is why it's important to know your "in service" date. At first, they told me it would be $430 because the car was out of warranty. They assumed that because it's a '17 the powertrain warranty was expired. Had I not known it had an April 2019 "in service", it wouldn't have been covered.

EDIT: I should add that they had a 20 year Ford tech working on my car, so it's entirely possible he knows more than I do.

I'm glad that it seems to be working out.
I'm curious about the discrepancy between your model year date and in-service date. Did the car sit unsold for 2 years?

 

[kazoospec]

I'm glad that it seems to be working out.
I'm curious about the discrepancy between your model year date and in-service date. Did the car sit unsold for 2 years?

I'm not entirely sure since I'm the 2nd owner. We met the previous owner at a credit union to pay off the loan, and he said something about how they had messed up the loan initially and it took him a long time to actually get the car so he was glad to be paying off the loan and to be done with them. I don't honestly know how a loan screw up could add 2 years to the delivery date. I have heard, second hand, that some of these cars sat on the lots for a while when new. I started looking at them around 2020, and there were still a fair number of 19's on some of the local lots, so I guess it could be a combination of those two factors.

 

[FiestaSTdude]

Here’s what my modified evap lines look. I just replaced my purge valve today and that setup made it a quick and easy job. I’ll report back as to whether it stops the post fill up stumbling

 

[NOVA_Ranger]

Here’s what my modified evap lines look. I just replaced my purge valve today and that setup made it a quick and easy job. I’ll report back as to whether it stops the post fill up stumbling

Pretty much what I'm thinking. Let me know how it works out!