Agis8
Member
- Joined
- August 24, 2015
- Messages
- 11
- Reaction score
- 0
- City, State
- Chicago
- Year, Model & Trim Level
- 2000 Explorer 4-Dr SOHC
I had a code for Small EVAP System Leak, and then it evolved to also having a Check Gas Cap light being on. Replaced gas cap with genuine Ford part. Light went off; but still the Small Leak code. So I checked the whole EVAP system's lines, valves and connections while under torch oxygen pressure at 1 PSI. No bubbles anywhere from soapy water. Probably mistakeningly, I replaced the purge valve up front. The vent valve, above spare tire, was a rust sculpture but still working, so I cleaned and repainted it. Lastly, after seeing a YouTube video on a guy discovering his leak due to a gas tank check valve deteriorating from ethanol (he presumed), I decided to go to the trouble to check my tank check valve. And of course it wasn't checking. The great AH HAA! moment. Here's what I did (from a previous email write-up to a mechanically-oriented friend & fellow fisherman):
Valve is $50 to $100. Didn't want to spend more on the darned system or drop the tank twice. So, how to fix... well, the new OBD-II specs indicated that the test system checks and provides trouble codes for leaks of 0.010" to 0.020" dia. (small leak) and for 0.020" dia. or larger (large leak). Thus a leak below 0.010" dia. is allowable.
So, at the bench I did this.
Crimped the nose of a small bullet sinker closed and then drove a sewing needle into closed end just enough to get minimal airflow (mouth blow test). Probably was about 3 to 6 thousands of an inch dia. Then installed it in check valve outlet tube using a couple 1/4" to 3/8" lengths of 5/16" vinyl tubing to hold and seal it in place. Fit like a glove. Check valve below.
Reinstalled in top of gas tank. Despite unorthodox nature of fix, it still provides the necessary:
Caveat: Now some may object to this fix as dangerous, but consider: the valve is plastic and ongoing fire exposure would soften it probably about the time that the tank developed enough back pressure to blast the deformed valve out the top of the tank anyway. It's the initial minutes that count, and the lead sinker wouldn't deform until after the plastic valve is already badly softened and shrinking (if the tank pressure transducer -- also plastic -- didn't already blow out first). Thus these plastic sensors & valves can also be viewed as inadvertent tank emergency pressure relief valves. And one could always make an orifice plate, say out of copper tubing soldered shut, to install inside the EVAP line to the valve, or in the valve port tube itself.
5 days and the Check Engine light is still off...
Valve is $50 to $100. Didn't want to spend more on the darned system or drop the tank twice. So, how to fix... well, the new OBD-II specs indicated that the test system checks and provides trouble codes for leaks of 0.010" to 0.020" dia. (small leak) and for 0.020" dia. or larger (large leak). Thus a leak below 0.010" dia. is allowable.
So, at the bench I did this.
Crimped the nose of a small bullet sinker closed and then drove a sewing needle into closed end just enough to get minimal airflow (mouth blow test). Probably was about 3 to 6 thousands of an inch dia. Then installed it in check valve outlet tube using a couple 1/4" to 3/8" lengths of 5/16" vinyl tubing to hold and seal it in place. Fit like a glove. Check valve below.
Reinstalled in top of gas tank. Despite unorthodox nature of fix, it still provides the necessary:
1) Gas tank vapor venting to charcoal canister - though at a very slow flow rate (it'll get there)
2) Car crash roll-over protection - fuel would just barely drip into vent hose if tank inverted [and there is no guarantee that the liquid-blocking feature of the valve would still be working as the OBD tests only for pressure integrity against the closed check valve - and does allow for some minimal leakage]
3) Allowable EVAP system pressure-test air leakage - below threshold of OBD-II concern
2) Car crash roll-over protection - fuel would just barely drip into vent hose if tank inverted [and there is no guarantee that the liquid-blocking feature of the valve would still be working as the OBD tests only for pressure integrity against the closed check valve - and does allow for some minimal leakage]
3) Allowable EVAP system pressure-test air leakage - below threshold of OBD-II concern
Caveat: Now some may object to this fix as dangerous, but consider: the valve is plastic and ongoing fire exposure would soften it probably about the time that the tank developed enough back pressure to blast the deformed valve out the top of the tank anyway. It's the initial minutes that count, and the lead sinker wouldn't deform until after the plastic valve is already badly softened and shrinking (if the tank pressure transducer -- also plastic -- didn't already blow out first). Thus these plastic sensors & valves can also be viewed as inadvertent tank emergency pressure relief valves. And one could always make an orifice plate, say out of copper tubing soldered shut, to install inside the EVAP line to the valve, or in the valve port tube itself.
5 days and the Check Engine light is still off...
