Failed Evap Test

[cmotes]

Hello - failed the "evap test" last week here in Calif. Any suggestions on what to look for/replace in order to pass this thing?

 

[blubuckaroo]

What year?

 

[justinoshea]

usually the gas cap. also check the hose that goes from the tank to the charcoal canister.

 

[oleguy74]

what did the paper work say?smog guy should have told you what was wrong.gas caps tested only on computer vehicles.gota be a 76-77.might even be just a hose from canister to air cleaner.if carbed vapor line from carb to canister.

 

[cmotes]

It's a '77. Smog guy suggested the hoses from cannister to tank. How about tank/sending unit gasket?

 

[oleguy74]

so that means they are missing or bad?get a book on emmisions eq.for your year and check every thing.

 

[cmotes]

Not missing. I guess I'm just going to replace the hoses and check the seal on the sending unit. Just looking for any suggestions. Thanks.

 

[justinoshea]

my 77 failed first time though and it was the gas cap. Inspect the rubber seal on the cap. if it looks 30 years old and cracked buy a new one.

 

[cmotes]

Gas cap was good and even replaced it with a different one during the test. So far I replaced hoses from the cannister back to the last one connecting to the fuel tank. Can't get to it without dropping the fuel tank... later today... pain in the butt!

 

[Baja71]

I agree that the cap is the number one culprit. Also, Ford says you can rejuvenate the charcoal by baking it for a couple of hours. Don't know the proper temp though. I'd also check the lines for blockage. They aren't all metal, so you may have a breach in the rubber bits.

 

[904Bronco]

Evap test is generally checking the gas cap and then doing a visual on the tank to canister hoses. I do not believe that they will pressurize the system. Did you go to a smog test only station or other?

I just went through this last year at a test only station, I knew more than the Tech about 77 emissions for Broncos. Both gas caps failed, no other tests were done on evap other than visuals.

Doug

 

[mitzel]

904Bronco
> I do not believe that they will pressurize the system.

FYI, I was talking to someone a couple weeks back and he mentioned
pressurizing gas tank to test evap system has been added as a new test
this year. This might be region specific; guy I talked to was in
SF Bay/San Jose area.

 

[cmotes]

Got all the hoses switched up and was also going to replace the main fuel line hose and noticed each end is a different size - larger at the gas cap. Are these available at most EB parts places? They didn't have them at Napa Auto Parts. I'm in Nor Cal...

 

[Viperwolf1]

I had the steel vent line near the rear tank get a hole rubbed in it from decades of rubbing on the top of the shock mount. I cut it and slipped some rubber fuel hose in. Should last another while.

 

[904Bronco]

904Bronco
> I do not believe that they will pressurize the system.

FYI, I was talking to someone a couple weeks back and he mentioned
pressurizing gas tank to test evap system has been added as a new test
this year. This might be region specific; guy I talked to was in
SF Bay/San Jose area.

Well if that is the case then California is doing their best to keep 30+ y/o rigs of it's roads. Seriously, I had a hard time finding engine smog parts to get mine legal a year ago. The fuel tank smog stuff is just not made any more...

Fuel filler hose: buy from a vendor or buy a standard size from a Napa and put a little silicon lube on it to get it to fit on the larger end

 

[Brinco]

Pressurizing the evaporations sytem is new and is now part of the CA smog test. I just had it done to to my vehicle last month and they charged me extra for it. The smog tech showed me the new law and it says it is done to every vehicle 1990 and older. Check all the hoses into and out of the tank and make sure they are not cracked and the connections are tight.