Subaru trouble starting first thing in the morning

subaru
legacy

#1

2014 Legacy: (wife’s car)
First thing in the morning I have intermittent trouble starting the car. It cranks just fine, but sometimes the engine won’t turn over. Sometimes it starts right up, and sometimes it will take several seconds of cranking until it starts. The battery is brand new. I brought it to the mechanic and since it only seems to do it in the morning we weren’t able to replicate the problem. He put it on the ‘machine’ and it showed there is nothing wrong with the car. It has done it when it is cold (16degrees F), and also when it is warm (50 degrees F). Any ideas as to what the problem could be?


#2

I don’t see that as a problem… assuming several is two…


#3

Yes, 2 seconds would be what a normal start would take. But this takes roughly 5-7 seconds.


#4

The next morning, turn the ignition switch to the run position so the dash lights come on for two seconds, and then turn the ignition switch off.

Repeat this a half dozen times and then try starting the engine.

If the engine starts right up, it indicates a problem with the anti drain-back valve on the fuel pump assembly.

Tester


#5

+1 to Tester.


#6

ok, I will give it a shot. I am not much of a mechanic, but if i understand correctly this is a check valve that keeps the fuel from draining out of the pump. A faulty anti drain back would cause the extra 5-6 seconds of cranking for the fuel to get to where it is supposed to be. Correct?


#7

The anti drain-back valve prevents fuel from draining out of fuel rail(s)/fuel line back into the gas tank.

Each time you cycle the ignition switch, the fuel pump runs and this refills the fuel line/fuel rail(s) and rebuilds the fuel pressure.

Tester


#8

Yes. Sometimes the fuel pump won’t catch up with the engine’s need for fuel unless you do the key dance to bring fuel and fuel pressure up to spec.

I have had this on my 1999 Honda Civic and now that I know this procedure I have avoided repair costs. It happens more often when the tank is low on fuel.

Another factor could be a leaky injector: fuel leaking into a cylinder would have a similar effect to fuel leaking back into the tank.


#9

Great. Thanks for the explanation. So can this valve be replaced by itself, or would the whole fuel pump need to be replaced. I just surpassed the 36,250 miles. (Warranty expired only 250 miles ago).
Thanks.


#10

I’ll defer to Tester or other professional mechanics on that question.


#11

The fuel pump assembly is replaced.

https://www.rockauto.com/en/moreinfo.php?pk=6436668&cc=3305964&jsn=350&jsn=350

Tester


#12

I will try the ignition key dance method and let you know how it goes. Thanks.


#13

Tried the ignition key dance 2 days in a row. So far so good. Thanks Tester, and Shanonia.