My '91 190e 2.3 has had this problem since the day I got it. Every time I fill the gas tank all the way up, the check engine light comes on shortly afterwards and I have to reset it (battery disconnect). I bought a new gas cap from the dealer, but it made no difference. Any ideas??



-irieite

My guess is that you are getting too much fuel in the tank and effecting the EVAP/ purge system.

Do you "top it off"? If so, Try filling it till the gas nozzle shuts itself off, ( thats WHY it shuts itself off, its FULL) and see if that corrects the problem.

Do you fill with the engine running? That may cause the light to come on.

Thanks for the replies. I have topped it off a couple of times. Mainly before a long trip. I'll try and avoid that from now on and see if it makes a difference. Does the "EVAP/purge system" tie into a sensor that could trigger the engine light?

-irieite

Oh, and Yal, no I don't fuel it up with the engine running. Thanks

-irieite

Inspector 1, I'm wondering ... Where does that extra fuel go?
I remember early 1970s GM cars had charcoal cannisters that would get saturated with fuel vapors. Can the extra vapors richen the mixture somehow and waste fuel?

I take it, that it's better to just fill up until the gas pump shuts itself off THE FIRST TIME when refueling? In other words, don't try to squeeze in another gallon or so.

I know in NJ (full serve only) they will top it off to the next higher dollar amount.

Tonight I filled my 300TE and got 19.5 mpg, not topping it off. I had been getting 17 mpg. I'll track this over several tankfuls to see if it's a statistical fluke. If my mileage improves, I'd rather pay $20 than $25 any day

Thanks, Bob

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic

I tried filling up once just letting the pump auto shut off, but ended up with only 3/4 of a tank. I've also had it auto shut off near the beginning of a fill up on this car, so I guess I just don't trust the auto shut off at all times on this car. BTW, I'm in Tucson, AZ and the pumps don't have vapor recovery here, if that makes a difference.

Anyway, I've found that the fill up actually has nothing to do with the engine light coming on. What causes it to come on (after reseting it) is when I floor the accellerator and let it accellerate for a few seconds that way. It'll seem uneven, then the light will come on. It seems as if the car accellerates beter and smoother at 3/4 throttle.. I'm gonna post this in a separate post to see if anyone has an idea what might be wrong.

Thanks for the reply.

-irieite