As some of you may know, I have been chasing an annoying, throttle position sensitive, whistling/squealing noise on my recently purchased 2001 BMW Z3 2.5i.
https://grassrootsmotorsports.com/forum/grm/bmw-mystery-noise/107019/page1/
After checking the brakes and the driveshaft bearing, I decided (with some help) that it might be the vacuum controlled fuel pressure regulator. Today's plan was to replace it. As part of the process of relieving the pressure in the fuel system, I wanted to open the gas cap.
The gas cap will not come off. In fact, I broke the cap with a pair of Channel Locks in a failed attempt to remove it. I was able to remove it easily a few days ago when I bought gas.
Good news: I know that the fuel pump works.
This happened to a friend a few years ago on his five series BMW. They towed it to the dealer and found that the fuel tank had collapsed in on itself. Fortunately, I'm not at that point yet. He's not a car guy and can't remember what caused the problem on his car.
Is this a common problem with BMWs? Any idea what parts I should be checking? I'm assuming that a vent line somewhere in the evaporative control system is plugged, but I could use some help on this one.
Thank you.
I've never encountered that, but I'd think you'd want to open the system somewhere to relieve the vacuum and open the cap, then start testing for obstructions. A collapsed fuel tank seems like something you'd want to avoid.
Hmmmm...
I'm seeing a few things that indicate the cap itself might have a lock on it on the early cars, but obviously that is not the case with yours.
Lefty loosey, Woody.
Seriously, I've never had that problem.
In reply to Harvey:
Nope, no lock.
Here's the funny part: The real reason that I was opening the gas cap was to replace it, but only because the little tether was broken. So I have a new one ready to go on, but it did seem a little odd that Bavarian Autosport had one in stock when I ordered it.
Most of the threads I see the people just rip the plastic part off the cap and then use a pliers or other tool to remove the metal portion from the opening. The issue being that the plastic part disconnects somehow from the metal part and if you get the plastic part off you can then turn the metal part to remove it.
Aspen
Reader
11/12/15 10:01 a.m.
They stock the caps because they lose their seal after 6 or 7 years and cause a CEL to appear.
Harvey wrote:
Most of the threads I see the people just rip the plastic part off the cap and then use a pliers or other tool to remove the metal portion from the opening. The issue being that the plastic part disconnects somehow from the metal part and if you get the plastic part off you can then turn the metal part to remove it.
It's more stuck than that. This is vacuum.
Do you still have the whistle? Maybe the whistle was the vent line that was almost clogged and now it is fully clogged?
Anyway, what about drilling a tiny hole in the gas cap to relieve and pressure difference and then try to remove?
I think I would look for a vapor line to the tank that can be removed to release the vacuum that is apparently in the tank.
The one thread I find that matches your story has the cap coming off normally after a few days of sitting. Presumed to have leaked the vacuum/pressure away.
Someone on here had a trouble removing a gas cap recently.. Driving a drywall screw into it to lock it together, then remove and replace was the solution.
Good luck!
A clogged vent valve on the DMTL (evap pump) could cause the tank to create vacuum.
As for the vacuum controlled fuel pressure regulator- it's not actually vacuum controlled. That is just a vent line just in case the regulator diaphragm breaks. That hose goes to the intake boot rather than to manifold vacuum.
KyAllroad wrote:
Someone on here had a trouble removing a gas cap recently.. Driving a drywall screw into it to lock it together, then remove and replace was the solution.
Good luck!
Just came to write the same thing that I l;earned from an earlier GRM thread. I also learned in that thread that melting the cap off was not a good answer...in case you were considering.
Do not put the screw in the center of the cap but rather toward the edge so as to be able to gain leverage if needed.
https://grassrootsmotorsports.com/forum/grm/99-miata-gas-cap-stuck-arggghhhh/106168/page1/
BMWs also have great access to the fueltank pump.. if need be you can open up the panel over the tank and easily unscrew the ring that holds the pump/sender in place. This will quickly take care of any vacuume.
Problem I had with my old 318ti was the opposite, my tank would get pressurized. When you popped the cap to refuel, you could feel the air (and smell it) coming out the opening
Woody even replied to that thread.
Bumboclaat wrote:
Shotgun.
Only for lugnuts.
http://www.nbcnews.com/id/21758302/ns/us_news-weird_news/t/they-taught-us-shop-class-use-right-tool/
TYhe best part of this story is the last sentence:
It was not immediately clear whether the shotgun blast loosened the lug nut.
Geez, that story is from 2007!
Screw is not an option as the outer plastic part of the cap has broken off.
I just replaced the fuel filter / fuel pressure regulator. I suspect that that would have relelieved the pressure. I'll find out once I get everything cleaned up and get the car off the lift.
wouldnt opening any of the fuel lines relieve the vacuum? especially a return line i would think.
Update:
The cap came off easily after I changed the fuel filter and released the pressure in the tank. After examining the broken cap off of the car, it looks like there is a little rubber vent valve in there that had gotten stuck. You can't see it from the outside of an intact cap.
This car had sat for a long time before I bought it, and last time was the first time that I filled the tank. Who knows how long it had been before that. For now, I'm going to blame ethanol and the old fuel cap. I took the car for a ride with the new cap installed and was able to remove it easily after that, but I'll be checking it often just to make sure.
Probably just a fluke.
Woody wrote:
This is vacuum.
Is there a vent - return line from the metal filler tube to the tank?
Cut it.
To get the cap remnants out, make up something like a bigass easy out. Two bolts screwed into a center union, sharpen the ends and tighten inside the cap, turn counter clockwise.
In reply to 914Driver:
Woody wrote:
Update:
The cap came off easily after I changed the fuel filter and released the pressure in the tank.
Thanks for the suggestion, though.
You might want take it for a test drive with the cap off and see if your noise is affected.
In reply to Tyler H:
That would throw a code and I'm not sure if my code scanner will work on a BMW.
