No Start Issue

Long story short, i was changing the converter in the car and i used my button connected to the relay to bump the motor over to take out the converter bolts. Pull trans, swap converter and put everything back together. Hit the button i had connected to the relay and the motor spun about a eight of a turn and that was it. I have not been able to get the motor to crank yet. I put a breaker bar on the on crank to finish getting the converter bolts in so the motor will spin. One thing i notice is the car will have power but if i try to start the car, it loses all power. None of the lights will come on or the dome light. If it sits for a minute, the lights will start to work again. I am not great with electrical. I tried checking all the grounds in the car, cleaned all the connections on the relay and the bulk head connector in the fire wall. Pulled the headlight switch to check the terminals. I need some advice. I have to be missing something.

I would start by checking the connections on the back of the ammeter gauge. All of the power goes through there except, of course, for the power that goes directly to the starter. Put the power to the ignition switch and the dome light and everything else does. Sometimes they're not loosen up on the studs on the back of the gauge and cause problems similar to what you are having.

Battery or battery connections. The cheap modern battery cables have been known to corrode where they are crimped. You need to measure voltage across the battery posts and then work your way away while trying to crank the engine. You won't get much, if any, crank below about 9.5 volts.

Not likely the cause IF using a pushbutton on the relay...

Good point. If he's using the remote button, and it is connected directly to the battery.

If that is the case, then I agree that the battery cables and battery cable connections are the best place to start.

it could also just be a dying battery or low charge.
when was the last time you charged it up?
how many bumps did you do with the starter before this?

Battery is in the trunk, thru the main disconnect at the bumper and from there to the starter. Battery is sitting at 12.6 volts. I keep the car on a trickle charger when not driving. As far as the bumps on the starter, it was enough to undo all 4 converter bolts and then get one in and it wouldn't bump to the next bolt. Ammeter has been by passed. I messed with it some last night and if i try to bump the motor over nothing happens. Once i try that i check voltage and it is at 7 volts. If i let it sit for a minute it will come back to 12.6 volts. I will pull the starter back off and redo the connections from the battery cable and the cable that runs to the relay. It almost seems to me it has to be somewhere in that area being it won't crank with a button or jumping the terminals at the relay.

if you are measuring at the battery and it reads 7, your battery is toast.
12.6 is a little low anyway, I would expect something like 13 for a fully charged battery, but meters may vary.

That 7 is only after i hit the key or try to turn the motor over.

even if it were 7 while cranking, I would call it a dead battery.
I don't mean it is necessarily "bad", I mean you need to dump it on a charger for a while before trying to start the motor again.
you will be trouble shooting without knowing if you are fixing anything with the battery that low.

First thing to do is give each cable clamp a good twist with channelocks at batt posts. Sounds llike a crappy bite on posts.

Starters draw lots of current, hundreds of amps with the initial surge. While the battery might read good with a DVM when not starting, once you put the load of the starter on a dying battery it's deficiencies come to life real quick.

When the battery went out in my MIL's car it read good with the meter connected to the battery, told her to turn on the headlights and the voltage dropped way low instantly. It was bad.

Fully charge the battery then take it to a parts store for a load test. That will tell you what's up.

Just to be clear, it doesn't have 7 volts while cranking. It never cranks. It doesn't even make a noise, not even a click. After i try to start by the key or the push button I can let off of everything and the car is reading 7 volts. I can open the door and the dome light is dim, i turn on the headlights and they barely come on. I can turn the headlights off and shut the door, then turn on the lights and open the door and everything is back to normal. I have the battery on charge and i may pull the one out of my jeep and try that one to see what happens. It's not even a year old. Everything was fine until i pulled the transmission. I will concentrate on the battery, cables and connections tomorrow and see what happens.

It looks like it may be the battery. May be a crude way to check but i took jumper cables and attached them directly to the battery and then to the starter and tried to jump the terminals and nothing. Took it over to the truck and did the same thing and the starter took right off. I never thought it would have been the battery as the car was just running and had been starting fine. I really appreciate the help you guys have given. Thanks.

I agree sounds like battery Its not a no start.Its a no carnk.Cant believe people still call no crank as no start.Drove me nuts when I was working.Rocky

as a learning moment, try the meter test on your jeep that cranked.
see the voltage at rest, try cranking it over but don't start and see what the meter reads then.
you will see the recovery of voltage is almost instant and rest voltage is much higher.

this is why I said the battery instead of the other items called out.
not that they couldn't be an issue, but once you establish battery voltage that low, you should start to verify the battery is good before moving further away.

please don't take this as me picking on you, but that is a good way to break the posts away from the internal plates, as well as possibility of cracking the case in the area the posts protrude from it.
the connections don't need to be tightened to the specs of a head bolt.
it's best to remove the cable and clean both the post and the cable end good, then re-install. tighten snug until you can't move the cable end by hand, then a tick more.
a spray of wd-40 now and then prevents the green "stuff" from growing in and around the connection.
just my experience and opinion from 55+ years of playing with cars. your mileage will vary.