After a heavy rain storm my Subaru forester either wont start, or runs very ruff. and the check engine lite comes on. This has happened several times in the last year or more. The first time it had to be towed to a dealer. I was told I had gotten some bad gas. the drained the tank. When I got it back it had rained that night, and it had to be towed again to the same dealer. they had know idea, but after it sat for a couple hours it started. And thats the way it has been. Now again this spring we’ve had a lot of rain. Does any one have an answer? This is frustrating!
This is generally a problem in the secondary ignition; plugs, wires, coils, etc. Bad gas is seldom ever the culprit and anyone who ever tells you this is the problem should be able to back it up with a gasoline sample. If that diagnosis is correct and the shop is reputable then keeping a sample is an absolute MUST.
How long has it been since the spark plugs were changed and how many miles on the car? Old plugs can exacerbate the problem and based on your complaint this is the first thing they should have considered. They were wild guessing, and guessing badly, IMHO.
If the check engine light is on, it should be storing a code. If the dealership didn’t notice that the check engine light was on and/or they didn’t read the code, then they aren’t a very intelligent group of people and shouldn’t be servicing people’s vehicles. It sounds to me like you have a bad spark plug or coil wire that when it gets moisture on it, it doesn’t work properly. I would bring your vehicle to a different Subaru dealership and have them check the problem out. If you want to bring it to an independent mechanic and he figures out the problem, make sure you put nothing but Subaru parts in it and no aftermarket parts because Subaru is very fussy on issues like that. Especially if you need warranty work done. Let us know how you make out.
About a year ago had a similar problem with a '99 Outback. City car that sat idle for a while, and the weather had been pretty wet. Low power and CEL solved by some new plugs.
This sounds very similar to the problem I’m having with my 2004 Forester except mine dies in heavy rain and when sitting in traffic for several hours. It takes a jump start eventually and then is totally fine. Based on everyone’s advice here plus that of my mechanic I’m going to change spark plug wires and see what happens. Other thing we’re going to try (just to see if it is the wires) is to douse the engine with water while it’s dark out, with the engine running and look for arcing (before getting the wires changed).
Have you had any luck figuring out your problem?
My vote is for bad plug wires. They can look good and be bad. Unless you have a leak in the fuel fill system I can’t buy the bad gas idea. In any case getting the computer checked to find out what that CEL is would be a good step. Post a reply to your original message with the code (it should be like “P0123”)