2011 F250 WEAK CRANK - Ford Powerstroke Diesel Forum
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post #1 of 29 Old 10-31-2016, 08:28 PM Thread Starter
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2011 F250 WEAK CRANK

I have a 2011 and recently it has developed a very weak sounding crank. I figured it was batteries since it had motorcraft batteries in it figured they were the originals and one looked like it was leaking a bit. Went ahead and bought 2 new batteries and when i pulled them out they had 6/15 and 5/15 dates on them. Drove it and am still getting the same thing. It can sit for a week and still start up but it cranks really slow before starting. According to the tuner i am running at 14.2-14.4 volts consistently even after a 2.5 hour drive so i figure it isnt an alternator issue. crawled under the truck and took a look at the starter connections and they look fine and dont look corroded. Next step i think is to pull the starter and get a better look at it. If you drive it for awhile and shut it off like at a food stop on a trip and come out it will crank quick like normal. I am almost at a loss with this thing. Anyone have any suggestions?
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post #2 of 29 Old 11-01-2016, 06:35 AM
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These trucks have "soft start" or some such thing. In other words, it's a computer controlled start. Weak charging system will not cause a slow crank.

My bet would be starter, or accessory drag?
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post #3 of 29 Old 11-01-2016, 06:38 AM Thread Starter
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Would the dealer be able to test the starter if I pull it off?
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post #4 of 29 Old 11-01-2016, 06:52 AM
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I would start by removing the belt and see if that makes a difference. If it still has a slow crank, voltage drop test the cables. If they test good, you have to run an amp draw test on the starting system. If high amperage draw is found, it's either due to a mechanical resistance, or the starter itself. That's when you'd remove the starter for bench testing. If the starter tests good on bench, belt isn't the issue, that leaves engine mechanical resistance.
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post #5 of 29 Old 11-01-2016, 06:56 AM
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You can do a quick check and have someone crank it cold. Feel on the passenger side b+ terminal. See if it gets real hot. High heat is an indication of high amperage
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post #6 of 29 Old 11-01-2016, 07:12 AM
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Yeah kaya is on the right track (usual). The starter spinning slowly has nothing to do with a computer controlled "soft start". Sounds like a starter is starting to get tired or more likely a mechanical resistance.

All the computer controls is the starter solenoid opening and closing on the starting circuit, and the length of it's activation. It cannot modulate power output to make the starter spin slower or faster. No reason to or means to, anyway.

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post #7 of 29 Old 11-01-2016, 07:18 AM Thread Starter
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what kind of mechanical resistances should I look for? I would think I would be able to detect or hear one of the accessories hanging up creating drag. To be honest I have had this truck since last august and it has been problems ever since.
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post #8 of 29 Old 11-01-2016, 09:59 AM Thread Starter
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Drove the truck 2.5 hours home on Sunday. Went out today at lunch and checked battery voltage and it was 12.4 which seems low. Haven't driven the truck since parking it on Sunday.
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post #9 of 29 Old 11-01-2016, 10:21 AM
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12.4 resting voltage is an indication batteries are starting to get weak, or you have a parasitic load somewhere I.E. Phone chargers, inverter, lights, computers, etc running somewhere, causing a drain.

12.6 resting voltage is considered a healthy battery, 12.2-12 and below considered weak.

Check for stuff plugged in, if you have amps for a stereo make sure the turn on wire is wired properly, etc etc


I no longer think you're encountering mechanical resistance on the accessory drive.
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post #10 of 29 Old 11-01-2016, 10:56 AM Thread Starter
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The batteries are brand new so there is probably a draw somewhere. I assume doing a draw test on one of these trucks is the same as a car. Put a meter on ground side and measure current. if there is a draw start pulling fuses until the draw goes away. I know in the audis that Ive worked on a lot you have to hit the key lock and wait for 30 sec or so till the car goes to sleep then measure draw. How do you do it with dual batteries? I guess I can start with this and maybe the voltage drop test.
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