pressure build up in fuel filler tube

[brackie1]

I am getting excess fuel pressure build up when the weather is hot. It has been doing it for a while but finally caused the rubber filler tube to rupture. I drilled a hole in the cap it relieves the pressure but I get fuel vapors. anyone else have this problem.

Gene
North Carolina

[So Cal Mark]

has your vapor canister been removed?

[brackie1]

no. would that cause pressure to build up in the fuel filler tube?

[So Cal Mark]

the tank is vented to the canister. Unless the hoses have been plugged off you shouldn't have pressure build up

[lglade]

I recently replaced my low pressure rubber fuel lines (everything to and from the gas tank) because I could smell fuel around the car in the garage. And while replacing the vent line that connects to the two-way check valve, I found that the valve was plugged with what looked like a gray-colored grease--other Spider owners have described similar findings.

Anyway, I cleaned the check valve and reinstalled it along with new ethanol resistant fuel lines and my fuel smell issue was resolved. If your own tank isn't venting properly, you may want to pull you check valve (a fifteen minute job once you have the car on jack stands) and check to see if it's plugged. While you're down there, check out all your fuel lines. Mine were showing signs of cracking and were in definite need of replacement.

[beater]

This is why I started reading this forum again! All my pollution stuff has been taken off my 77 including the canister. Never really knew what the hell it was for but since my gas filler cap pops off when I unscrew it I'm guessing my canister line has been plugged. I'll have to check that out before I blow a rubber line!

[brackie1]

Do you have to replace the lines that run all the way the tank to the engine compartment or just those in the engine compartment? where is the valve you are talking about?

[lglade]

Unless they've already been changed, the fuel lines on your care were made from rubber nearly forty years ago. And even then they were never intended to be exposed to the ethanol fuels like we have today.

So you should plan to change them all. For that matter you should plan to eventually swap out every possible piece of rubber on your car if they show wear and age. Many of the problems you'll find described in this forum can be traced back to a failing rubber part: e.g suspension bushing, vacuum leaks, brake issues, engine stumbles, cracking giubo, etc...if it's not a bad ground issue, then it's a bad rubber part issue (well almost).

I did my high pressure lines first (everything in the engine compartment), and then I did the low pressure lines a few months later. But all of them looked bad with visible cracking and other signs of age. My car is an '84 with only 65K miles, so I'd bet that your fuel lines are in a similar condition, if not worse.

It should be a simple matter (and not very expensive) to restore the vapor canister in your car and get your tank venting properly once again. Unfortunately, I think some owners have mistakenly assumed that these parts were power-robbing smog devices, and they removed them from the car without first investigating their purpose.

The valve is on the driver's side of the car, just forward of the fuel tank by approx 12 inches--near the rear coil-over.
http://www.fiatspider.com/f15/viewtopic ... e#p2014370
Access is fairly easy if you can get the car up on jack stands.

[rjkoop]

You pretty much had this answered but in case this helps...

I had fuel pressure build up on mine when I unscrewed the fuel cap (a sucking sound). I removed the vapor check valve (located under the car above the rear axle with fuel hoses going in and out of it) that apparently allows vapors to be taken out of the tank and, I think, though the charcoal canister. The check valve was blocked up (I couldn't blow through it in either direction) with what looked like grey crud. Here's a pic.



Once I cleaned it out, was able to blow through it, and replaced, no more fuel pressure build up.

This was the part I cleaned out.

http://www.autoricambi.us/product/FU0-0 ... eck-Valve/

[brackie1]

Thanks for all of the info and advise. I had already replaced all of the hoses in the engine compartment. I will now begin the process of the fuel lines.

[brackie1]

well thanks to all of the post I completely re-did the vapor system and everything is now great. I found the same thing as others have posted with regard to the gray putty material in the vapor valve. it is really strange.

Gene
North Carolina

[rjkoop]

Great news. Glad to help


Richard

[brackie1]

but that gray putty in the valve is a mystery. wonder if it is caused by the fuel

[rjkoop]

but that gray putty in the valve is a mystery. wonder if it is caused by the fuel

Not sure but I had the exact same crap, cleaned it out and now runs great

[lglade]

My wife didn't want to ride in my car because of the gasoline smell that seemed to follow it. But all of that went away when I swapped out the fuel lines and sorted out the vapor canister; she now loves my car.