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Jeep cranks for 10 seconds

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
Recently my jeep has been having this issue where for the very first start of the day it takes about 10 seconds to start. You can hear the starter cranking and sometimes the cranking sounds like it is stopping or struggling. It'll eventually start and run fine though. I noticed that it is worse in the cold and struggles more the colder it is. When I am driving it throughout the day though it starts fine. I don't have any codes other than P0135 (O2 sensor heater) which I plan to fix sooner than later. I also replaced the starter about 7 months ago.
 
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Wtrask

TJ Enthusiast
Joined
Jul 26, 2019
Messages
354
Location
Maine
A few things come to mind. Fuel pressure regulator may be bad or leaking fuel injectors or both. I happened to have both issues at the same time. If you replace your o2 sensors do them in pairs also or all at the same time.
 
OP
DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
A few things come to mind. Fuel pressure regulator may be bad or leaking fuel injectors or both. I happened to have both issues at the same time. If you replace your o2 sensors do them in pairs also or all at the same time.
I plan to do all the O2 sensors at the same time. If I am not mistaken the fuel pressure regulator is part of the fuel pump assembly? If so I replaced my fuel pump with a bosch about 4 months ago. I'll check the fuel injectors
 

Gilaguy23

TJ Enthusiast
Joined
Sep 21, 2021
Messages
257
Location
A'holeville
Struggles in the colder?? Being in Va with the winter it may be a case of 90wt oil in the pan and a cold battery from the sub zero nights ;0. I keep mine in a barn and even when its in the teens I can tell it cranks slower. Not to say the battery or something else is going south but look at it this way. Instant fire up on a 5 degree morn is rough on parts. Id bet in that 10 seconds of cranking the oil is already pumping thru the engine. Kinda like a pre oiler ya know. ;)
 
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DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
To everyone saying it could be my battery, could it also possibly be my battery cables? I got new ones from custombatterycables.com and ever since I got them I ran into a whirlwind of different electrical problems but I am not sure if they were related.
 

Gollywomper

TJ Addict
Supporting Member
Joined
Feb 9, 2019
Messages
2,754
Location
Corning CA
To everyone saying it could be my battery, could it also possibly be my battery cables? I got new ones from custombatterycables.com and ever since I got them I ran into a whirlwind of different electrical problems but I am not sure if they were related.
Yes. A lot of battery problems are actually cable/connection issues. You can verify all this with a meter.
 
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DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
Went to O’reillys for a new meter and the worker did a test verifying 105 amps to the starter and around 14 volts to the alternator. On the tester it said the battery was “good” and it had passed the tests
 
Last edited:
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DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
Update: Had a very hard time starting this morning in the cold and a new code popped up. P0340, which i read is a camshaft sensor circuit malfunction. I replaced my camshaft sensor and synchronizer about 6 months ago with OEM equipment. Do you guys think this could be the reason for my long cranking?
 

Gollywomper

TJ Addict
Supporting Member
Joined
Feb 9, 2019
Messages
2,754
Location
Corning CA
Update: Had a very hard time starting this morning in the cold and a new code popped up. P0340, which i read is a camshaft sensor circuit malfunction. I replaced my camshaft sensor and synchronizer about 6 months ago with OEM equipment. Do you guys think this could be the reason for my long cranking?
OEM from auto parts store or a mopar packaged unit?
 
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DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
Is it cranking over slow or normal and no start?
It will crank normally but sometimes it will then randomly stop and try to start again but it seems like it can’t. At this point I just put the key back in off and try again and it’ll start up after cranking for a little bit and run perfectly fine. If it’s been turned on within the last 3 hours or so it’ll turn on just fine with no problems.
 

Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
23,754
Location
Fleming Island Florida
To test your battery, hold the meter probes on the battery posts while the engine is cranking... have a friend work the ignition switch for you. You want to see what the battery voltage is doing while the ignition switch is in the Start position. It should not drop below 9 volts after being cranked several seconds.

Without the engine running a fully charged conventional battery should measure 12.6 volts, a fully charged AGM battery will measure 12.8 volts.

And place the meter's probes on the battery posts themselves, not the connectors. If you get good voltage on the battery posts while the engine is cranking, move the meter's probes over to the connectors on the battery. If the voltage on the battery post is ok but not on the connectors, remove both connectors and wire brush the inside of them and the battery posts. Securely reinstall them so they are tight enough that they can't be moved around on the battery posts even with considerable hand pressure.

The very best way to test a battery is with a "load test" device which places a heavy load on the battery for 15 seconds while it measures the voltage. The voltage should not drop below 9 or so volts at the end of the 15 second test. Not all auto parts store sales people know how to properly conduct a load test, many don't know they need to hold the load on the battery for 15 seconds. Many will just hold the load on for a couple seconds which can give an erroneous good battery indication.
 
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DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
410
Location
Roanoke, Va
To test your battery, hold the meter probes on the battery posts while the engine is cranking... have a friend work the ignition switch for you. You want to see what the battery voltage is doing while the ignition switch is in the Start position. It should not drop below 10 volts after being cranked several seconds.

Without the engine running a fully charged conventional battery should measure 12.6 volts, a fully charged AGM battery will measure 12.8 volts.

And place the meter's probes on the battery posts themselves, not the connectors. If you get good voltage on the battery posts while the engine is cranking, move the meter's probes over to the connectors on the battery. If the voltage on the battery post is ok but not on the connectors, remove both connectors and wire brush the inside of them and the battery posts. Securely reinstall them so they are tight enough that they can't be moved around on the battery posts even with considerable hand pressure.

The very best way to test a battery is with a "load test" device which places a heavy load on the battery for 15 seconds while it measures the voltage. The voltage should not drop below 10 or so volts at the end of the 15 second test. Not all auto parts store sales people know how to properly conduct a load test, many don't know they need to hold the load on the battery for 15 seconds. Many will just hold the load on for a couple seconds which can give an erroneous good battery indication.
Will try testing again, I bought a new battery just to see if it would remedy my issue but I still had the same issue. Since then I returned the new battery since it did the same thing