Truck won't start with the key but runs fine with a push start

I have a 2008 2.7l reg cab base model. The truck started fine until after work last Friday. I drove out of the parking lot, shut it off the close the parking lot gate then bam, no start.

When I turn the key the starter solenoid clicks and dash and map light get extremely dime almost out and flicker but it won't start. So I push started it and it ran fine the 25 miles home. Shut it off and when I tried starting it keeps doing the same problem. I took it to AutoZone, replaced the battery, it only had 500 cca instead of 1000 and was leaking. Removed the starter, tested it, it barely pashed. Figured when I drop it out of the truck it shook it enough to get a couple starts. Replaced it. Still won't start. Swapped the efi and start relay in the dash, and nothing but it runs fine with a push. I took it home and left it over night

Saturday it fired right up, no problems all saturday and Sunday. We didn't drive it at all Monday. Then had to push start it Tuesday. Tested the alternator after work, it puts out 12.3v and 40 amps. The only specs I could find was either 80, 120, or 160 amps. Replaced the alternator. And ohmed out the cables, both had less the 2 ohms. Voltage from the starter stud to the engine ground was 8 to 9. Remove the cable and cleaned the surface. It s 12 now. Won't start. I left it over night, I'm gonna drop the starter and clean the matting surfaces real good to see it that'll help. It acting like a bad starter or battery. I tried jump starting it with my dad's Jeep but nice dice. If cleaning the starter surface doesn't work I'm outta ideas.

 

Ignition switch.

Worn and or dirty.

Cleaning is free. Worth a shot

I've seen several fail (worn out) in various vehicles when someone has used janitor grade key rings for extended periods. So theres that possibility.

 

Make sure there isn't any wiring exposed somewhere shorting to the chassis or another ground. Check all ground wires.

 

Have you tried a remote starter? Simply jumping 12v battery power to the solenoid on the starter. This will tell you if it is the starter or the wiring. If it starts using this method it's the wiring. If not, it is the starter.

$20 Sunpro Actron CP7853 Remote Starter Switch for 6V and 12V Automotive Starting Systems, Black

https://www.amazon.com/Actron-CP7853-Remote-Starter-Switch/dp/B0009XQUKW

 

Your alternator should be putting out around 13.8 volts with engine running. Battery voltage with no load/not running should be around 12.5 volts. Voltage should not drop to less than 10 volts while cranking, if battery is good. If it still will not turn over enough to start, you might have excessive carbon buildup in the cylinders causing high compression, which makes it hard to start. I had the same problem with an old Ford; would start fine when cold, but would not crank when hot.

 

It won't even crank though, just a solenoid click

 

All my voltages are good now

 

What is the voltage at the battery vs starter lug with key in start position?

 

Those cables shouldn’t have that much resistance, they should be replaced. Jusy from reading I would say that right there is your problem. Sounds like they are oxidized or corroded. Should be less then a .05 of a ohm on those cables and you should be reading just about the full battery voltage on them. Easy way to tell if they are bad is just put the meter on the starter and crank the truck. See what the voltage is during crank. If it’s anything below 11 volts that should be a red flag, especially if the voltage at the battery directly isn’t dipping that low

 

Voltage is 12.5 with they key on, there is no voltage drop when I try to start it, but after the starter solenoid clicks there's a wineing sound almost like a fuel pump

 

Did you shim the starter? Not sure if those starters need to be shimmed but that could be your issue after replacement

 

There's no shims on it, and it started fine with the new starter for 2 days, now the starter solenoid just clicks

 

Okay I test voltage at the battery, no drop when I try to start it. Checked at the starter, it drops to 5 volts and stays there then slowly comes back up to 12v. I ran a set of jumper cables from the starter and engine ground to the battery. Same issue is still happening

 

Your alternator is only putting out 12.3 volts? It should be higher than that. Are you sure about that number? At idle the alternator should be putting out about 14.3 volts.

 

If you have no voltage drop at the battery, but the voltage at the starter lug (not the solenoid connector) drops to 5 volts then you either have a bad cable or cable connection. Might try pulling the starter motor out, but leaving it connected electrically and see if the starter motor runs. you need to jumper a ground wire to the battery for this test.

 

Did you toss the battery on a charger after the new one was dead? If it's not charging properly then the battery will never charge back up. I would suspect a partially failed alternator under charging the battery.

 

2 ohms resistance in a starter cable is way too high. That probably accounts for the voltage drop at the starter. Make sure the connections are clean. If so, swap out the cable.

 

The contacts you’re getting from the jumper cables won’t be enough for the amps the starter is gonna draw. You need to replace the wiring to the starter

 

Check the negative cable (and connections) from the battery, too.