I have a thread under 6.0 full power no star. cranking then poped. That thread will explain all the events leading up to this moment. I just installed a new starter today due to the solenoid being faulty on the previous one (Brand new). Soon as i begin to crank it takes off full power and normal as can be a few revolutions later it starts acting sluggish. The previous starter (before solenoid went out) was acting sluggish as well. So i replaced the alternator (Just this past sunday) thinking maybe it was going out especially due to the fact i have two brand new batteries that have been load tested multiple times (autozone and i just bought a battery charger with a load tester equipped) and have checked out good each time. Well once i put the alternator in along with the batteries just having a fresh charge and check, truck starts right up no problem what so ever. Later that night I go to start the truck up and it cranks veryyy slowly and sluggish like. And thats when i took the starter and solenoid in (Today) and found out the solenoid was shot. So got new set and pt back in, referring back to the top of this post, sluggish. First few cranks were so crisp it just about took right off. But it didnt. In fact it kept getting slower and slower. So i decided not to crank anymore in fear of harming the brand new starter again or something else. I pulled out the tester and tested the batteries with the key on giving me 11.73 on each. Same reading as well with the positive on the alternator. Same reading as well on the positive to the starter. But when i went to read the positive on the solenoid it gave me 0.00-0.01. Im not to sure what to thank of this? My wife happens to be in town and i called in an ignition switch that shes going to pick up for me before i had done the testing. So regardless of anything beings ive already paid for it there will be a new ignition switch installed on the truck. Not really knowing if thats going to do me any good. Im a little clueless on what to proceed on to next though. I got the gumption up to try and start it after i seen that reading just to see what happens and, nothing. Just clicked at me. Same way the last starter did which was brand new as well. Im hoping i havent fried this one yet, im beginning to think i may have fried the last one due to what ever problem is present im unaware of? My main question is, directly after installing a new starter why would it take of at a good speed and then immediately being to slow down? I wish i would have tested it before i ever tried starting it to see what it would read. And another question beings it took off and then slowed down why is it now just clicking at me? This all transpired within an hours time. I would GREATLY APPRECIATE any help given i need this truck running veryyyy badly. Thanks in advance!!!!

 

11.73 volts is low battery voltage, you should have closer to 12.5 volts without cranking. The tester that is built into your battery charger most likely is little more than a gimmick, very poor at actually testing real battery condition. You most likely have either weak batteries or one or more bad connections. Could be bad positive connections and or bad grounds. You need to check volts from both battery + terminals right at the battery to engine ground, if that is good then test from battery connection at starter to ground. The voltage at the small wire on the solenoid should be about 0 volts unless you measured it while actually cranking the starter over, then it should read battery voltage. If that is good check it again while cranking, that will be lower but should not be too much lower, if it goes below about 9 volts cranking you could have another bad starter, but I would look very closely at ALL the battery cables. You can also try these tests with the battery charger on to see if that makes a difference. I still am leaning toward bad batteries.

 

11.73 volts with key on is fine, that's because of glow plug system draw. You could also get a 6.4 starter, cranks much faster and quicker to fire off.

To answer your question on the starter only cranking fast at first is your batteries are either Low/Dead or there is a bad cell in one or both giving you a false full charge and once amps start to draw it dies very quickly. This is not something to put off as draining a faulty battery multiple times trying to fix other things that aren't problems will kill your FICM in no time at all. Ask me how i know. Always start at the batteries - alternator - starter

 

FICM's are way sensitive to supply side voltage inadequacies. 11.73 volts key on engine off is on the low side, but not horrible. I'd suggest getting your batteries load tested and checking your grounds.

 

Cables and connections could be an issue also. Look it over and get familiar with positive and negative cable locations, top, bottom, driver and passenger side. Try to crank the truck for several seconds with the key off using the jumper wire by the heater box (you won't be powering FICM or fuel pump that way) and then make a quick pass over all the major connections looking for anything that gets hot. A poor connection can get very hot quickly, be careful not to burn your hand but they can cool quickly also so you have to check them all quickly.

 

x2 ^^^^^^^^^^^^

Use of the jumper wire is an incredible idea from Rusty. Keep us posted!