Long story. I took my Subaru Forester in for it’s 35,000 mile servicing. I had the usual oil change but also had the fuel system treated. Up to this point I’ve had no problems with the car. The next day after the servicing, the car started normally in the morning but when I tried to start the car later in the afternoon it turned over but would not start. The next day, it started fine in the morning but again, later in the afternoon when I tried to start it, it turned over but would not start. I took it back to Subaru and they said that there was dust in one of sensors but it was good to go. Started fine so took it back to work but when I tried to start it later that afternoon, it turned over but would not start. Took it back to Subaru and it didn’t start for them in the afternoon so they were able to put it on the computer. They said that a cam sensor needed to be replaced and I had them go ahead and replace it. Took the car home and the next day, it started fine in the morning and in the afternoon, turned over but wouldn’t start. Took it back to Subaru and they kept it for five day but it started every time for them so they were not able to do another analysis of the problem. I took it home and the starting issue continued but not every day. It has started to get worse so that it continues to start in the morning but will not start late in the day. I had a mobile mechanic look at it and he was able to get the error code. He ran through the possible issues and it isn’t related to the battery but when he put the fuel pump gauge on there was no fuel pressure at all. He suggested replacing the fuel pump but was concerned that this may not be the problem. I’m certainly willing to replace the fuel pump but I want to be sure that this is the problem before having a fairly expensive fix done. The starting issues seems to be related to temperature since it started when early in the summer but that’s just a guess. Are there any other senosrs that would impact the fuel pump? Any suggestions or ideas at this point would be very helpful.
The next time the engine won’t start, take something like a rubber mallet and bang on the bottom of the gas tank.
If the engine starts, the fuel pump is the problem.
When you first turn the ignition on, the computer runs the fuel pump for a second or two to build fuel pressure. So, if there was no fuel pressure it would mean there’s a problem with the computer or the fuel pump relay. Which I highly doubt.
Tester
Is this the 2.0L turbo or 2.5L non-turbo? The turbo had a recall for the fuel pump (NHTSA 21V-587). If it’s a turbo, I can’t imagine the dealer would have overlooked that but you never know. Not sure if the recall covered all turbo-motored Foresters so you can check your VIN here.
Good ideas above to start. If those ideas don’t pan out…
Which sensor was it they claimed had dust on it?
Back to basics: For the engine to start it must have these three
- compression
- spark
- fuel
So to get to the bottom of why, those have to be checked one by one at a time it cranks but won’t start. My guess is no-spark. The reason: the 2018 power-tran computer probably has access to a sensor to read the fuel rail pressure. If the fuel pressure was wrong it would presumably flag a low-fuel-pressure diagnostic code. So the only thing left is a spark problem. Spark problems can be temperature related. Suggest to ask the shop to test for lack of spark.
There are other problems beyond the main three above that could cause this same symptom. Next in line is probably an evap system problem that is making the mixture too rich for a hot-start. Faulty purge valve for example. Best of luck. I expect you’ll have to let them keep the car so they can test it when it won’t start. Maybe one of their techs could drive it to and from work as their daily driver.