Success! Finally fixed the hard start while hot and fueling issues.
 

I was having a fairly common problem. The car was hard to start once it was hot and l left it resting for about 1/2 hr to an hr. When fueling, the gas would shut off well before the car was full, sometimes turning the fuel nozzle upside down helped, but not always. And then, to start the car after fueling sometimes took over a minute of cranking with the throttle partially open before it caught.

There are all sorts of posts on how to correct the hot hard start problem and its clearly something in the evap system, but there are several very expensive solenoid valves, carbon canisters etc. and I read posts about people spending thousands and not solving the problem.

When I hooked it up to the durametric, I noticed that the fuel trims were at the rich limit and the MAF was reading way below spec, classic case of a vacuum leak. So at the throttle body, I pinched off the hose that comes from the evap system and magically, the fuel trims went back down towards normal, MAF was reading correctly and no more hard start when hot.

So I confirmed it was the evap system but I still hadn't figured out which component it was. Online searches revealed that some said it was the purge valve, a solenoid under the front fender, or the fuel vent valve attached to the gas fill tube or the tank vent valve under the right hand intake manifold. So I dug into the evap sytem under the fender and was able to apply voltage directly to the purge valve and it worked fine, fuel vent valve also seemed to be clear so I took a chance on the vent valve ( $130 at the dealer) under the manifold and viola-all is fixed. No more hot hard start. And when I filled up the tank, it filled completely and then the car started immediately.

I like my car again.

Excellent detective work! This is the valve buried under the left intake manifold? How did you get to it?!

Bravo! Thank you for posting that. I have never had that issue but will definitely print this into my notebook, just incase.

Its not too hard, but a bit time consuming. You have to take off both engine covers and jack the car up. It also makes it a lot easier if you take off the trunk hatch so that you can climb in the trunk which gives much easier access to everything.

Under the left side intake is the valve, it has an electrical connector that has a wire spring that holds it on. just push down on the wire and the connector comes off. Then, with 45 degree needle nose pliers, loosen the clamp that holds the hose going to the throttle body and slide the clamp well clear and take off the hose. You will probably have to use a screw driver to help pry the hose off the valve.

Next is the most difficult part. There is a plastic piece that holds the hard plastic hose on the valve against the underside of the intake manifold. It is absolutely impossible to remove the nut that releases the hose. I ended up jut breaking it off, but beware, the plastic piece is molded into the intake manifold and you might crack the manifold, but I had no problem.

Next, you have to get under the car and release the connector at the end of the hard plastic hose. Its against the firewall way at the bottom. There are two similar hard plastic hoses so be sure you get the right one. Now fish the valve and hose out from the trunk side and put in the new valve/hose. Be sure it threads through correctly along the bulkhead, there's a lot of hoses and wires in there.

I just zip tied the valve to the underside of the manifold.

Great info,I have not had that problem with my 06 Boxster s but my winter beater a toyota Echo did,couldent get fuel in tank,ended up bypassing the charcoal cannister and voila works again,but gasoline fumes will come into the garage now if its left inside.I was told that this problem with fuel not filling and destroying the cannister or parts leading to it is trying to over fuel the tank,fuel will drain back down the overflow into the cannister and destroy it as its only ment for fuel vapours,so when the pump clicks full,pull it out,dont try and squeeze that last few dollars in.

I am having the very same problems, every time I fill up the tank I'm having a hard time to start. But no problem at all with hot engine. The valve you are talking about looks like this?

Excellent Post
 

I just changed the regeneration valve on my wife's 00 Boxster using this post!

It cleared up the hard to start problem after the engine was hot and after gassing her up at the pump.

I would like to inform those that want to not have to crack the clamp / housing that hold the regeneration valve up to the manifold - use an 8mm wrench and take deep breath. I got mine off and back on.

thank you San Rensho for an excellent post.

Fern

Way to go guys, great DIY fixes!
That's what it's all about :)

If pinching the hose solved the problem, why can't you just do that or am I oversimplifying things with a dumb question?

Not at all, good question. It will probably fix the problem, but you will likely still throw codes and possibly not pass inspection if you have emissions testing in you state/country.

Try it and report back if it works or you have any problems.

No emission testing in my neck of the woods. Now I need to figure out which line to pinch.

Theres a rubber hose that goes from the throttle body then under the driver's side intake manifold. Just pinch it off at the throttle body.

Thanks for the info!

Good information anyone care to post some pics to bring additional insight to this issue?

san rensho, what was the part number? From the part number I can probably locate it in one of my photos.

left side air intake distributor
http://986forum.com/forums/uploads01...1400158510.jpg

now a closer look
http://986forum.com/forums/uploads01...1400158644.jpg
http://986forum.com/forums/uploads01...1400158726.jpg
http://986forum.com/forums/uploads01...1400158766.jpg
http://986forum.com/forums/uploads01...1400158798.jpg
this is the left front side of 2004S.

San Rensho is this the part your referring to?

Thanks for the pics- This really helps!!

electrical connection
 

this is what the connection looks like. Squeeze in on curved metal wire which will release securing metal wire on sides, pull/wiggle out connection.

http://986forum.com/forums/uploads01...1400251327.jpg

http://986forum.com/forums/uploads01...1400251364.jpg

That's the one. Its a two part hose, one is hard plastic, the other a rubber hose. Pinch off the rubber hose and if your problems go away, then change out hard plastic hose.

Thanks for the tip.
I had been having the no start after fueling up with my 2000 boxster S plus irregular fast rough idle with cel error codes P0507 P1128 P1130 & P0446.

There is no emission testing in my area so I made a small clamp to clamp off the vacuum line .... worked great !!
No more rough or fast idle & car fuels up with no problems now.
Its been 3 days now with aprox 300 km driven & no cel or error codes yet.