My car was having stalling problems and shaking on start up. I took it into the dealership. It is a 2003 Subaru Forester. The dealership found that both my mapping sensors were out plus a bunch of other issues, costing me 2,100.00. A week later I drove it off the lot, after paying of course. I went to the grocery store and the same issue happened. I took it back to the dealership. They drained the gas tank and said that someone had put water in the tank, with a 50/50 ratio. I made an insurance claim for vandalism. Now the fuel injectors need replacing and the fuel pump. The dealership told me that the initial issues were also a result of the water and that the could not see the other problems until they replaced the sensors, etc. The insurance company only wants to pay on the second set of repairs which will cost 1,900.00. I find it hard to believe that they are not related. Any advice?
During the initial problems you were having (stalling and shaking on startup) how did the car perform AFTER it had been running a while?
When you drove it off the lost 2100 bucks later (Ouch!) did it run fine when you left the lot?
Did the dealer save a sample of this 50/50 ratio water/gas and show it to you?
I’m really leaning towards some major league incompetence or possibly even outright fraud here but there’s not nearly enough info known to be sure.
I know who put the water in the tank- messy divorce and instability(police are involved but there is no proof). The car ran ok, while driving, all issues were at start up and turn off. The day I first took it in it also was not shifting out of first very well. Very slow up hills. They do have a sample of the gas and showed that to the insurance adjuster. It seemed ok when I left the lot, but I drove it 2 miles away, went to the grocery store and it stalled again. It just seems hard to imagine that it just happened to have major electrical issues at the same time it had water in the tank that knocked out the fuel injectors, fuel pump and possible some coil.
Unless the insurance company thinks that your tank was watered at the dealership, or during your drive to the store, then obviously your tank was watered before the first repair. It may be that the dealership failed to correctly diagnose the problem and made a bunch of unneeded repairs, but I think you would need to take to another mechanic to review exactly what was done and give you an expert opinion. Then you are going to have to decide whether to spend $500-$1000 on an attorney to get the other $2000, if that’s how it turns out.
And get a locking gas cap 
If the gasoline was diluted to a 50/50 gas/water mix (even a 80/20 gas/water split) the engine will not even run “ok”. It will not run at all.
The reason is because water and gas will not mix and the water will settle on the bottom of the tank. The fuel pump siphons from the bottom so this means the only thing being pumped is water.
Maybe the tank was contaminated to some degree and there’s still a lot of unknown here, but my gut feeling is that you’ve been the victim of some needless parts replacing and wild guessing. In other words, they were throwing mud against the wall and hoping some of it sticks.