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Fuel Tank Suction Pump Function?

StealthGTI

Autocross Champion
Location
Newport News, VA
Car(s)
2017 GTI Sport
Hello!

I have a question about the suction pump. I think I understand that its primary purpose is to remove fuel from the evap canister and move it to the tank. I suspect that it cannot do that if one "tops off" the tank or "fills it to the brim." I think the pump is intended to address minor over-fills. The recall appears to be to replace potentially faulty pumps or seals. I hope to have the recall done soon; I need to remove some equipment from the car first. Until then, I have a question:

What happens when the pump fails? Does the canister flood and then result in a non-start condition? Does it behave a bit like "vapor lock?" Old-timers may recall that term; I haven't heard it in a while. Anyway, I have an intermittent no-start condition. It hasn't left me stranded (yet) since the car usually starts after a few attempts. I think I've determined that over-fueling may be the cause in my case. I learned years ago to stop fueling when the fuel dispenser clicks OFF the first time. I used to bump another 1/2 gallon into the tank. But I stopped when I considered that it may be causing my no-start issues. No-starts have been rare until this morning.

I had a fuel dispenser that was running just a little slow. It shut off automatically, but it may have been a little late. The car started fine, but I got stuck for about 15 minutes after my second stop. Once I got the car started, I drove about 50 miles to drain the tank down a bit. I burned less than 1/4-tank in those 50 miles, which shouldn't have happened with my current rooftop load. So, I think I was over-fueled.

Here's a video that I shot before burning off the extra fuel; it shows the no-start and slow start. Wear headphones to hear the engine:

What do you think? This post shares a little more detail than the video since I learned a few things after burning some fuel. The car started normally after the burn-off. Could the suction pump be a culprit? Or is this purely an over-fueling issue, faulty fuel station pump in this case? It would be nice if the recall prevented this from happening again, but I understand that's wishful thinking. :ROFLMAO:

I appreciate your input.

Cheers!

PS: My rooftop load, which nets about 25 mpg...

 

Benihana

Go Kart Champion
Location
Socal
Sounds like this is all leading to a faulty suction pump. Topping off will cause this. This happend to me as well after the very first time i topped off the car. It's crazy that the suction pump is that sensitive. I had the sputtering issue that was intermittent and sometimes a slow start as well, then quickly after that fuel starting leaking from the evap tank.

I would get it done before you get to the stage where you can't even fill the tank anymore.

I wish I had the recall option..... mine happened a while ago, but I ended up fixing it myself...cost me around $30 in parts.

Good luck!
 

StealthGTI

Autocross Champion
Location
Newport News, VA
Car(s)
2017 GTI Sport
Thanks for the response! I'll start labeling wires and disconnecting the equipment that I have blocking access to the fuel tank. Oddly enough, my recall should be among the easiest for a mechanic to do. Basically, he'll open the rear door and the fuel tank hatch will be right there. HAHA! I'm also going to mask off the area with plastic since I want to protect wiring and other things that will still be in the car.
 
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