Failed gas cap leak test

Harp · 02-25-2002, 10:10 AM

DMV just failed me for a leaking gas cap. I guess they actually screw the cap onto a tester and presurize it. And it didn't hold pressure well enough. So, who knows where I can buy one that's inexpensive? I have a 944 N/A 1988. Thanks.

Also, anyone ever have this problem?

PorscheG96 · 02-25-2002, 10:32 AM

On a similar note, how difficult is the seal around the gas tank filling orifice to replace...anyone know the cost of the part?

Eturbo924 · 02-25-2002, 11:00 AM

Funny I have never heard of this before. I am checking on a used one out of a 1994 968 for you if you are interested. Send me an e-mail and I will get you a price.

Question. When you go to fill up your tank do you ever have a large pressure release when you unscrew the cap. Hear rushing air? If yes then your cap is fine and the tester is full of you know what.

Eric
Eric.Lynch@itt.com

sd01 · 02-25-2002, 11:01 AM

http://www.pelicanparts.com

Eturbo924 · 02-25-2002, 11:05 AM

Oops yup sorry Wayne
http://www.pelicanparts.com/catalog/shopcart/944M/POR_944M_miscel_pg3.htm#item17

Harp for a new cap take the link above. Pelican offers them new for about $30.

Eric

AFJuvat · 02-25-2002, 11:06 AM

A gas cap shouldn't cost more than about $25. However, is it really your gas cap that is leaking or is it your filler neck that has been bent?

The seal around it isn't "technically" difficult to replace, but it can be a real PITA. You have to access it from the hatch area of the car.

AFJuvat

944pete · 944pete's Garage

Same thing happened to me. I bought an el-cheapo gas cap at the local parts store for about $8.00, passed the test, and put the original back on with the rubber seal from the new one.

Pete

Z-man · Z-man's Garage

Yep: happened to me too. I did the e-cheapo replacement, and passed right away.

If you're a purist, order an OEM from Pelican.

This is a pretty common thing, especially on older cars. The gas cap test has been around for only a couple of years here in NJ.

You'll be set either way.

-Z.

Harp · 02-26-2002, 05:27 AM

I like the cheapo Idea, and then using the cheapo' s seal.

Which parts store would have the cheapo? Thanks

Z-man · Z-man's Garage

If you're in North Jersey, and got the car inspected at the Wayne inspection station on Rt. 46 West, then you know where this store is:

A-1 Autoparts, on Rt. 46 Eastbond, just past Riverview Drive (Home Depot) and after the Nissan dealer after the onramp from Riverview Drive. It's just before the old Hot Dog joint (mmm Hot Dogs....mmmm)

-Zoltan.

JGriff · JGriff's Garage

Besides failing the test due to smog concerns, does a faulty cap cause any kind of driveability problems? I've heard that it does/could on newer cars, but I don't know whether it could on a 12 year old Porsche.

I wonder, because my car has an intermittent problem (although it is happening more frequently recently) where it idles rough when I restart it after driving it (i.e. after it has warmed up).

I'm thinking that it could be the O2 sensor (which is on the way from Pelican as I type this), but I wonder if it has anything to do with the gas cap and the whole vapor recovery system on these cars. (I looked in the owner's manual, and there is a whole page that describes the system. Yikes!!)

When I take the cap off after driving it, to refuel, I do not get a hissing sound.

What say all? Should I try replacing the cap? If so, I'll probably do so after I replace the O2 sensor.

My gas cap is keyed for use with the OEM key. If I order a new cap, is there any way to swap the lock components, so that I don't need two keys?

Thanks.

Jim

Eturbo924 · 02-26-2002, 10:03 AM

Jim the cost for the caps are so cheap that you should go ahead and do it. I beleive you can swap out the lock tumbler for the one in your current cap. That way you can have use of the one key.

Eric
Eric/Lynch@itt.com
Bradford Ma.

Brian J · Brian J's Garage

Quote:

Originally posted by Eturbo924
Funny I have never heard of this before. I am checking on a used one out of a 1994 968 for you if you are interested. Send me an e-mail and I will get you a price.

Question. When you go to fill up your tank do you ever have a large pressure release when you unscrew the cap. Hear rushing air? If yes then your cap is fine and the tester is full of you know what.

Eric
Eric.Lynch@itt.com

I have noticed this. It was my impression that the gas tank vent tube was clogged.

Eturbo924 · 02-26-2002, 11:33 AM

Hmmm. If this is so then my 944, my 924 and my friends 944S2 need some attention.

They all run great with no hot or cold start issues.....

Eric

JGriff · JGriff's Garage

Quote:

Originally posted by Eturbo924
Jim the cost for the caps are so cheap that you should go ahead and do it. I beleive you can swap out the lock tumbler for the one in your current cap. That way you can have use of the one key.

Eric
Eric/Lynch@itt.com
Bradford Ma.

Thanks. I'll look into it.

Jim

Roger Hall · 02-26-2002, 07:31 PM

im not sure if this is correct but a freind of mine has a chevy caviler and he had a loss of power and surging after a complete tune up he decided that he needed to replace the fuel filter a mechanic told him it was caused by the gas cap my freind says it cured the problem i never really belived it though

Eturbo924 · 02-27-2002, 06:27 AM

Yes I know for sure that the new cars have to have a nice tight cap or the engine will not run properly. My wifes Passat 1.8T is just like that. I just was not completely sure if the same could be said about the 924/944 but I believe it is true... that is that you need good pressure int the tank... I.E. good seal on cap.

VW says make sure the cap clicks... three times... that way you are sure it is completely on tight

Eric

fireboss · 02-27-2002, 08:26 PM

I have replaced the cap on mine but I still spill fuel out of the tank at every auto cross. The neck where the cap screws in is out of round just enough to piss me off. No matter how tight the cap I still get a leak. I only run 2 gallons of gas in the tank when I'm on course and it still leaks out the of the cap. This has never caused a problem with the way the engine runs.
I would check the air flow meter "spring tension' before I replace the O2 sensor. A week spring gives a false reading to the computer and you will have an over rich fuel mixture causing it to run really crappy on a cold mornig.

josh912 · 02-28-2002, 10:25 AM

I'm glad I live in California. No annual DMV car inspections. But then again we have 91 octane premium gas and ridiculus smog rules and inspections. The agony, the agony.

p0r2chbyIII · 02-28-2002, 10:35 AM

josh912... guess its been a while since you have had a car smogged here in CA. In January, my 86 was inspected... passed with flying colors but get this, the test station DID test the cap. The test center has a machine for just testing gas caps... so, if my feller neck was bent or not, it would not matter...

guy said that most cars fail this part of the test...