DAintegraGSR

Sup fellas. As the tittle says. Ill try and keep this as informational and short as possible.
Okay so since iv bought the car bone stock ls any time i get around a half a tank the car will stall out right as i come to a complete stop.. Thats anytime i have a half tank and under. Right as she completly stops the rpms will just flow down and she stalls... New pump and sending unit.

Now my most recent issue.. Iv been driving fine since the swap about 4 months ago with no problems untill today. Was driving for about an hr.. Now when ever i hit the brake the temp gauge goes all the way up, fuel gauge starts to fall towards empty.. I also noticed at idle, if i turn the running lights on temp gauge jumps up, fuel gauge starts to fall and the idle drops down about 5 hnd rpm and when i turn the headlights ON the idle drop down even more and the car stalls out.
If gone thrru all the fuses looked for any wire problems finding nothing. However i did notice... If i disconnect the brake light switch there is no problem "temp gauge,fuel gauge" now if i unplug both headlight bulbs from the headlight housing harness when i turn the lights ON all is OK.
Only other issue im having which has got to be related but odd is my speedo which is mechNical reads 80mph at a standstill.. There is some function it will creep up to 140mph while doing normal highway speeds.
Any help is much appreciated. This is my dd and has to get me to work in the am

el crapitan

check your grounds. head and tail lights pull a lot of current. a bad ground could cause the issues you describe. go over all your main grounds first. remove and clean them. then, go over the tail light ground cluster and headlight ground cluster. remove and clean

el crapitan

for your speedo, i'd pull the vss out of the trans. have a close look at the gear. usually, if the speedo is working intermittently, it's gonna be a chewed up gear. or a problem in the cluster. or cable. or the ring on the diff. it's mechanical, so there's not much else it can be. easiest place to start is pull that vss

Bond

I'd be very inclined to check your battery and alternator while the system is laoded up (headlights on, blower motor maxed, etc.)

Sounds like a poor alt output and the battery can't keep up with the demand. But that being said as already stated a circuit with a poor ground will cause back feeding issues of current at high output (headlights on) and could be the source of your problem.

DAintegraGSR

Alright fellas ill start with the basics and let you know the out come.. I.was also queztioning.the alternator output myself.
Luckly i work at a shop so ill start digging in on lunch break

DAintegraGSR

Alright guys well i found the problem.. As i left the.key.on w the hazard lights.going i wiggled some ground connections looking for any change.. And Boom as soon as i touched the ground connection mounted to the body the marker lights lite up twice as bright.. So i removed the connection and cleaned it up and made sure the contact to the body was good.
Everything seems great. Now for the speedo. I was really having trouble beliving it could somehow be related so i pulled out the cluster and bing.. Some how the cable had slid out. But i still could not move the mph down to zero, id move it and itd bounce right back up.
I endimg up swapping just the mph cause i need the gsr tach .
so all is good there.. Thanks for the help guys

DAintegraGSR

Im prettt certain im still gonna have this half tank.. Stall out problem. I say this because.its.done it.with.the.old setup.. The.new.set up.. Diff.computers etc.
To be clear... Anytime i.have a half tank juat about any and every time.i.come to.a.stop just as i fully.stop.she dies right.out..
The more abruptly i stop the faster shell.die.out.
Any ideas fellas

Bond

Good find on the bad ground.

As for your stalling issue, I would really like to see the fuel pressure at the time of stalling. This would be a key step into understanding what is occuring when stalling. I have a feeling it would be fuel related due to the half tank issue.

el crapitan

yes. installing a fuel pressure gauge mounted somewhere visible while driving will help narrow it down. if fuel pressure drops just prior to stalling, it's fuel related.
i have a sneaking hunch it's the pump though. or something in the tank