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Car crank but won't start *Help*

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New User

Oct 24, 2021, 12:57 PM

Post #1 of 4 (220 views)
Car crank but won't start *Help* Sign In


I have a Subaru Forester 2010, standard. 200 000 kms, 4cyl. Since a couple of weeks, it had problems starting. I tried a couple of things but nothing worked.

The symptoms:

Every morning, the car can take a good 15 second cranking to start or not start at all. It cranks fine, got electrical power, but doesn't start. Usually during the day, it starts fine (maybe 2-3 seconds of cranking, which is still not the best), with the exception of a couple of times here and there.

When I plug my jump starter on the car, it starts right away, even in the morning BUT it's really weird, as the jump starter doesn't use any of it's charge. Only the fact that the jump starter is plugged makes the car starts like a charm, but the battery of the car doesn't seems flat, and I would say looks full, since the jumper starter is always full of charge after use. What can cause the jumper starter to make a difference while not using it's charge? I just think if I figure that out, I can find the overall problem.

What I tried to do:

First, I changed the old battery for a new one, I cleaned the battery wires and the grounds from corrosion, and I added a new ground. Then, I changed the spark plugs, the coil and the wires are new.
I've also changed the crankshaft position sensor as one morning that the car didn't start, the check engine light when on afterwards with a code for a faulty crankshaft.

I ve removed the battery from the key knob, as maybe it was sending a faulty message to the car immobilizer. I didn't knew what to try at that point.

What I didn't do:

Change the fuel pump but it seems to work just fine. Starter seems fine since it's cranking no problem. Maybe a ECM problem?

My friend who owns a shop will look at the timing belt tomorrow. It was changed in the last years, but he thinks they might have missed a tooth or 2 while changing it. I just wonder why the problem would have started now, since it must have been off a tooth since at least a year or 2.

Thank you, I don't know what to do anymore.

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 24, 2021, 1:35 PM

Post #2 of 4 (206 views)
Re: Car crank but won't start *Help* Sign In

OK, first the key fob has nothing to do with starting.

Stop throwing parts at it aimlessly.

Perform ALL these tests and post the results here.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 24, 2021, 1:50 PM

Post #3 of 4 (204 views)
Re: Car crank but won't start *Help* Sign In

? Quote you ">When I plug my jump starter on the car, it starts right away<"
That was your clue to test battery for voltage drop IMO first as THE only problem. It would then require finding out why, an old battery would he high on the list. The other things you did all at once it seems now confused the problem now.

This is struggling to relearn as I'm sure you didn't use a memory saver for swapping out battery may be the trouble AND CPS not done right both in question - they were not before - bummer.

Allowing a long cranking time takes a toll on starters not meant to crank long if you count seconds 15 is a lot! All that time voltage is dropping like a rock too. Actually 3 whole seconds if you count or watch a watch is too long.

New battery doesn't mean it worked out test the new one with your jumper box maybe if that works just do that this time charge new battery first before installing it.

I question the crank sensor's installation now so see what you can do to verify it's done right. No pinched wires or things out of place - double check.
Up top in this section is locked a "CRANKS but NO START" locked thread to read but I'd go back first with items you apparently didn't need and check everything.

Side note on tossing more that one thing at a time is now that they are new you think must be good or done right just adds to diagnosing it now. Frustrating but best for this type issue when you hit it first time, properly diagnosed stop till it proves itself then do other routine things later.

In short - go back to where it was if at all possible, parts and all if needed used again,


tractorboy profile image

Nov 5, 2021, 6:18 PM

Post #4 of 4 (101 views)
Re: Car crank but won't start *Help* Sign In

yep guessing seldom works when trying to figure out why a car does not start.
you need to find out if it is the ignition or fueling

you can use a spark plug tester as mentioned above , the preferred way or take the plug out put the wire back on and lay the plug so the threaded part is touching metal of the engine that is grounded best to do in the shade. either have a friend keep bumping the engine or use your cell phone /camera on a tripod to record the spark if no assistant. May need to wait for night. If you use a garage be careful about carbon monoxide...really dangerous.

to test fueling get some SENSOR SAFE carb/throttle body cleaner. either remove a hose going into the intake boot to the trottle body or remove the whole intake boot squirt in some TB cleaner into the Throttle Body , this too can be potentially dangerous 1. TB cleaner is flammable if it starts flowing out of the TB onto say hot exhaust pipes and 2. if your timing belt is off and a plug fires when the intake valve is open you can explode a plastic intake manifold...why do they use plastic intakes, see if the car starts momentarily

are you noticing that you are using coolant? as stated above do a compression test,
what does your oil look like? is it milky looking?
what is the history of the car
any issues like it overheated
maintenance done etc
best to first get a nice pair of protective eyewear from the hardware store like ones made by 3M especially if you are going to be working on your car regularly.

over and out

(This post was edited by tractorboy on Nov 5, 2021, 6:35 PM)

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