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Trouble starting subaru in morning at low or change in temperature

I love my Subaru Outback 2007 but recently its been having trouble starting in the morning either when it’s cold or the temperature has changed significantly overnight. I recently moved to Louisiana so we’re not talking extreme cold, just cold for here. 50/40 degree weather. The car cranks and cranks but won’t turn over for several minutes. Once the car has started it runs perfectly the rest of the day, until the next morning. When it’s warmer (60s/70s), the car starts right up without any trouble.I’ve replaced the battery and the crankshaft position senor and it’s still acting up. Can anyone help??

It could be a coolant temperature sensor, an air temperature sensor, or a MAF (mass air flow) sensor.

Since your description says that it is limited to cold temperatures, then this leads me to believe that the computer is not getting a correct reading from one of these sensors, and is not adding enough fuel in order to start the car.

The air temp sensor might actually be part of the MAF sensor, so if one is bad, the whole unit would need to be replaced.

I would start with those items.


I think that Bladecutter has covered the likely problems very well, but (as usual) I want to add a couple of hints for the OP:

If the car is not up to date with maintenance items, such as spark plugs, you should make sure to do so.
A car with old spark plugs will be harder to start when conditions are less than optimal.

And, when you take the car to your mechanic, please don’t tell him that the car, “won’t turn over for several minutes”. Since you tell us that the car “cranks and cranks”, you are telling us that it DOES turn over. (Cranking=“turning over”)

The engine apparently does not start and run on its own when the ambient temperature is low, but it does turn over. If you give the mechanic bogus information, he will go off on a wild goose chase that will result in much higher labor costs for you.

Thanks for your help!


This car has spark plug wires, I would suggest replacing them and the plugs.

Question. You state that it runs perfectly the rest of the day. Does this mean during repeated starts or do you mean that the car will start right up after sitting all day long? (As in working all day and then attempting the start, etc.)

The hard part is starting it in the morning. I drive to work and at the end of the day, 99% of the time it has no trouble starting.

Well, 99% is not a 100 so I’ll throw a possibility out. Maybe this issue is related to a residual fuel pressure loss. Fuel injection is designed to hold fuel pressure while the car is parked and this allows an instant start when the key is turned.

If pressure leaks off (leaking injector, fuel pressure regulator, or the more common fuel pump check valve) the engine will be slow to start and may run rough for a minute.
Think of a garden hose in the sun on a hot day. When you turn the water on the hose may sputter for a while before air is purged out of the hose. It’s the same principle with fuel injection lines.

You might try this. In the morning before attempting to start the car turn the key to the RUN position for about 2 seconds. Do NOT operate the starter motor. Now turn the key off. Repeat this process 4 or 5 times and then operate the starter motor.
If the engine starts right up and runs fine then the problem is likely the loss of residual fuel pressure and most of the time this is due to the check valve in the fuel pump. (This means pump replacement of course.) Hope that helps.

If the trouble isn’t with the check valve in the fuel line as OK4450 suggested then there may be trouble with the cold start valve. I believe the engine has one to help with cold starts.

Ok. Someone else told me about this trick too. It did work 95% of the time for a few weeks. In the last week, the trick hasn’t helped start the car at all. Does this mean that the fuel pump is just slowing dying? or could there be something else at work here.
I took it to get a fuel pressure test and it failed, indicating that I need a new fuel pump. But another mechanic said that it’s not the fuel pump cause the car starts quickly once it does, instead of a slow accelerated start. I am now thoroughly confused. The car is so young, why would the fuel pump fail?

I don’t know if this has to do with it but for the last 4 years before this year, I was living in Maine and didn’t drive the car too often, maybe 2 to 3 times a week. When it got very very cold, into the teens, the car had the same trouble starting. Same symptoms except that sometimes, more often than not, when I finally got it started, it was as if the car was rebooting because all of my radio station settings were gone. strange. Again, this only happened a few times each winter in extreme cold so I never took it in or got it examined. But could the problem I have now be anyway related? curious.

To see if there is a fuel shortage problem try spraying a small amount (a 1 second shot)of starter fluid into the air intake and see if that helps get the engine going first thing in the morning.

Elise, just curious as to how this is all working out?

I have a very similar problem, and was wondering if you or anyone else had any ideas.

I have a 2004 Subaru Forester that, for the past 3 years (bought it used; so may have done it with previous owner too, but I don’t know), will ~2x per winter, not want to start. Similar symptoms to yours - endless cranking, but will not catch/fire. However, the difference is that I can’t get it to go after a few minutes. I have to let it sit for ~8 hours, and then it starts fine.

This happens in very cold weather (~5 F), so more akin to your problems in Maine than Louisiana. And it only happens on the second start. Meaning, it only happens when I start the car fine the first time, then park it after a short drive (~5 mins), and let it sit for ~2 hours. That’s when the endless cranking kicks in. If I let it sit for only 10 minutes after the initial drive, no issue and it starts fine. And like I said, leaving it for 8 hours has it starting fine the next time also. It’s just the weird limbo amount of time in between when it’s not happy and won’t start.

Problem is that bringing it to a garage never has them coming up with an answer because they let it sit too long and it works fine for them after the 8+ hours of sitting. After the first instance, spark plugs and air filter were changed, but to no avail - the problem still occurred again.

I know very little about the workings of cars, but the two ideas that have been tossed my way in the past are the fuel pump relay or a temperature sensor.

Any thoughts?

ETA: it’s sort of like the symptoms of a flooded engine, except there is no gas smell associated with the problem. Plus the Subaru book fix for flooding of pressing down the gas pedal all the way does not help. They also said there was no evidence of flooding the first time I took it into a garage.

I am having a similar problem in a 1999 Subaru Forester. I’m in the Boston area. It starts in the morning but after a 2 mile drive when I try to re-start it will turn over but not fire. If I let it sit awhile it starts up. After this happened yesterday I drove it straight to the garage Sunday and left a note. The mechanic told me in the morning it started right up. I tried the car and it /did/ start up. I forgot to say drive it 5 miles. So I drove it that long and you can guess what happened when I got home. No start. It has new battery, sparks and wires.

I got a 99 subaru legacy L and in cold temperatures car will crank but wont fire up. After a few minutes it finally starts…here now its Thanksgiving, I’m stranded and my battery is now dead. Charging it and jump starting it wont work. I was just driving the car yesterday to. This is the 2nd time my battery has died. And it’s a brand new battery. New spark plugs, all new wires, new temp sensor, new timing belt, new fluids, new head gasket and seals. When I went to get the new timing belt they wanted me to buy the fuel pump bit I rejected because they then wanted to charge me $700. This is just pushing me off because with all the money I spent it’s still no good.

The key dance might help, once you get a fully charged battery: Turn the key to On (not all the way to Start.) The fuel pump should run for a couple or few seconds then turn off. You may hear it. Turn the key to Off and back to On and wait a bit. After a few cycles of this, there should be good fuel and fuel pressure at the engine. Turn key to Start. Good luck and please let us know how your results.

Having similar problems with my 2007 Forester. Cranks over fine but will not start in cold weather. We have replaced the battery, plugs, wires, water temp sensor and mass air flow sensor. Still no luck. I have found that if I put on my battery charger and put the charger on “engine start” mode it will start every time in the cold??
Next logical step in my mind is to go after battery cables and connections. Any advice or comments appreciated.
Thanks !

If it cranks over fine, the battery is strong enough to power the fuel pump and the ignition.

When it doesn’t start, do you have fuel and fuel pressure at the engine? Spark? Those are the things to test for early on in the process.

Dang, 53,000 views in 10 yrs. lots of folks with poor running Subaru’s