Hello everyone! Recently my car has had trouble starting, well sometimes it turns on and sometimes it doesn’t and i have to either wait a few minutes or sometimes it won’t even turn on anymore. I changed the starter and even got a new battery as the problem continued. I had the vehicle checked out by a mechanic twice but it just so happened that each time it was checked the car started without a problem >.> they said that maybe the battery was starting to go bad so I got a new one. What seems to be the problem? It does make a sound like a little vacuum noise when I try to start it and the radio and lights work when its on.I even took it out for a long drive and it didn’t break down or have a problem.All in all I’m looking for a solution as I want to sell this car soon and I honestly don’t know what to check.
What do you mean by “turns on”
You turn the key to start and nothing happens?
You turn the key to start and starter spins but doesn’t engage?
You turn the key to start and the engine cranks over but fails to start?
Or is this a key in your pocket and push button to start, Replace the battery in they key.
When I put the key in and turn it sometimes the car starts and other times nothing happens at all except for a little vacuum like sound.
The next time the engine won’t start, with the dash light on, step on the brake pedal and shift the transmission into neutral and then try starting the engine.
If the engine starts, it points to a problem with the transmission range/neutral safety switch.
Tester
Battery connections are the first place to begin when you have a “No Crank” situation. Even
if you have a new battery, if the connections are loose, dirty or corroded, you will not be
allowing the full flow of current to pass thru the connections. The connection may be
enough to turn on the lights, but not enough for the huge flow that is needed to operate the
starter. This is where many people say that they know the battery is good….”because the
lights come on”. This is no more a battery test than licking a 9volt battery. It only tells you that there is electricity…not how many volts or the amperage that flows from the battery.
Jump starting may have wiggled the terminal just enough to allow the current to pass and start the engine, but tomorrow you have the same problem.
First remove the cables from the battery and use a wire brush to remove any corrosion and dirt from the battery posts and the cable terminals. There is a tool with a round wire brush for this purpose, found at any auto parts store for less than $10 http://shop.advanceautoparts.com/p/kd-tools-terminal-battery-brush-kdt201/25980576-P?searchTerm=terminal+brush.
Before connecting the cables, apply a coating of di-electric grease to the battery posts this will keep oxygen away from the connection so that it will not corrode as fast.
It is just as important that the other end of the cables also have a clean connection. Remove the negative cable from the battery again so that you do not short anything out. Follow both cables to their far ends, remove this connection and wire brush the connection and the cable terminal clean and retighten these connections.
If there was work done recently, there may have been an “engine to body” ground that was not installed following the work. These grounds normally run from the rear of the engine to the firewall and are uninsulated and most are a braided wire. If any of these are found unattached…reattach them.
Remember….this is not a “Sherman Tank” don’t over tighten the connections.
Tight…tight………………too tight…broke!!!
Yosemite
Hey Tester, I have tried this a few days ago and nothing happens so I think that’s not a problem
Hey Yosemite, I cleaned the connections to the battery and well I’m going to try and clean the other ends hope it helps! 
I don’t know how Ford built the Fusion but old Fords used to ground the negative battery cable to the inner fender which was metal. That “extra” point used to rust. Check the cable along the length to see if there is a connection on metal somewhere between the engine and battery. Then wrench the bolt back and forth and see what happens.
Connecting a jumper cable from engine to frame may help as a test for a bad ground. By frame I mean to a strut bolt or nut. If the blower fan or power windows seem to move too slow, a bad ground between engine and body could be the cause. Mostly not, but it could be, and often was in the past.
I have an 07 with the same problem, battery had been checked multiple times and this, according to other forums, send to be a common problem. Trying to move the wheel back and forth sometimes helps start the car. But let the car sit for over 30 mins and it usually will start up, with or without a’ check braking system’ message which indicates like battery. However, you can get a jump if you need to get going asap. I’ve had it not start as soon as I turn off the engine then try to restart less than a minute later, but then leave it sit for a while and when I go to get a jump it starts up like nothing wrong. If I ever trade down the problem I’ll post back on here, but for now have a quick disconnect I use at times which works fine, although getting a jump box so you don’t have to home from another car is another option. Sorry there send to be no known solution that I know of, and I’ve check countless boards and forums searching for what is the cause to this problem. I’m soon heading down to a battery store in my town where they said they’d look at tracing the electrical problem to find the cause, but am waiting on another fusion owner to get back with me on whether a different place found the source to the same problem. Best of luck, and please post, whether here or in a new discussion, if you ever get a solution, it’d help so many fusion owners.
This would indicate that the problem is with the battery or it’s connections.
I would follow my instructions above to clean the terminals and battery clamps.
It’s not enough to just brush off the surface from built up corrosion, but you have to remove the clamp and either wire brush wherever the clamp and battery post make a connection.
Yosemite
Update it was the starter fuse.
Basically I called my mechanic again and guess what…? The car started when he checked it >.> so he checked everything and predicted it to be a starter fuse so he swapped it out and so far no problems have occured. Hopes this helped anyone with this problem.
Your mechanic probably replaced the starter relay.They rarely go bad but when they do,the car will never start.
Hey COROLLAGUY1, Yea he changed a little black box in the fuse box. I saw videos of people changing them but it never occured to me that it was that.
Maybe the “vacuum noise” – which I presume means something was sounding like small vacuum cleaner was running — that was a failing under-dash relay buzzing. That part is a probably a rare failure item so if it fixes the problem for you long term, good time to make a trip to Las Vegas, you got lady luck on your side 
If the problem returns, make it clear if the problem is a no-crank, or a cranks ok but won’t start. “Cranking” is that rrr rrr rrrr sound you hear when you turn the key to “start”, before the engine catches and runs.
Hey George_San_Jose1, the "vacuum noise " can still be heard but only for like half a second when I start it. It sounds like it’s coming from the passenger side of the car. No idea what it means or what got messed up.
If the sound is coming from the passenger side, near the glove box, it may be the heater/AC fan that has a bad bearing. Once the bearing warms up the sound stops.
I don’t know about the Fusion, but some fans never shut off but run very slowly. This may be only on Defrost though.
To test this; you could pull the fuse for the Heater Fan and see if the sound is still there after you start up.
If the sound disappears, then it is the fan on it’s way out.
Yosemite
I will definitely do that,thank you. this may seem off topic, but what would cause so much corrosion on a newer battery?
Many cars make a sort of humming noise that lasts a second or two when the key is first turned to “on”. That’s the electric fuel pump priming the fuel system, and is normal. That may be what you are hearing.
Sometimes the seal where the battery post protrudes is not as good a seal as they would like.
Thus “offgassing” can occur and cause a lot of corrosion.
Yosemite
Update: The car again did a no crank and i was left waiting for 5 minutes until it started again. Now a lock and a car icon appears in my dash and it just flashing like every other second. When the car starts it disapears but when the key is out it keeps flashing, even though I have not locked the car.