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A couple of weeks ago our 1985 245 "Daisy" failed the evaporative emission system test on the California Smog Check. The test, at least as it applies to this model and year vehicle was performed as follows:
1. The evaporative line from the gas tank to the evaporative (charcoal) canister in the left front wheel well is pinched off just before it enters the canister.
2. Nitrogen was introduced to the fuel/evaporative system via a fitting that replaced the gas tank cap. The system was pressurized to 0.5 psi.
3. To pass the test, the system had to hold pressure for 2 minutes, dropping to no less than 0.45 psi.
After a bit of study, I elected to troubleshoot and repair the system. Should you follow this path, I would advise attention to at least 2 points:
1. Introducing air to the fuel system may result in a hazardous condition, use your own discretion and caution here.
2. It is probably best to keep any pressurization of the fuel tank/evaporative system below the release pressure of the gas cap (about 3.6 psi).
My approach was to test the system in two parts. In the photo below you can see that the hose, which leads forward through the car to the rollover valve and onto the evaporative canister, was disconnected from the fuel filler pipe. The test rig was attached in its place. The gauge is a cheap vacuum/fuel pump tester that allowed measuring pressures of 0-10 psi. Approximately 2.5 psi was introduced and then the pressure line was clamped with visegrips to insure there was no chance of further pressurization from a leaking blow gun valve. This part of the system held pressure for 5 minutes with no loss.
Though not involved in this repair, the area at the top of the fuel tank (next photo) has potential problem areas. Leaks have been found at the bung nut/o-ring seal. Also, the cap on the unused port could be a leak source. You can see the new section of evaporative hose, labeled "To Roll Over Valve", that was ultimately replaced.
The photo below shows where I found "Daisy's" problem. The new hose replaces the original which had completely broken in half at the point where it and the fuel hoses pass through the bulkhead opening.
The curved metal line exiting the top of the roll over valve is joined at either end with 2 short lengths of hose which are also potential problem points. The line leading from it at the top of the photo is 1/4" hard plastic line and leads to the front of the car, paralleling the fuel line.
"Daisy" has an oil leak so its a bit hard to make out the 3 lines that go to the evaporative canister. Here is how to identify them:
"From Roll Over Valve" - 1/4" hard plastic, then enters a rubber hose near the canister. This is the one to pinch off to test the system.
"Vacuum from Intake" - 1/8" hard plastic, joined with a short rubber hose at the top of the canister.
"Vent to Intake" - Rubber hose 5/16" ID (about 1/2" OD) all the way from the canister to the intake manifold.
Here's a photo of the connections at the top of the canister which may clarify things a bit.
The following photo shows where the other 2 lines from the canister end up. Intake manifold vacuum actuates the purge valve to allow fuel fumes to be drawn into the engine and burned.
Testing the evaporative emission system is simple enough and the repairs inexpensive. I'll check the others in the fleet before they go in for their next test. Hope this info helps keeps a few more older 240s on the road.
Regards,
Tatra Mike
San Diego, California
1985 244 "Alfsen" (the first - the flagship)
1984 245 "Buster" (with the relatives in Seattle}
1985 245 "Cosmo" (enjoying retirement in the side yard)
1985 245 "Daisy" (back seat down, full of tools, the work truck)
1985 245 "Earl (hoozah, another stick shift!)
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