Intermittent stall-out issue

ClaireDanas

New Member
Original poster
Joined
Jun 6, 2021
Messages
8
Location
New Orleans, LA
Hey y'all, recently bought a 2000 Sahara 4.0, 184k, for a bit of a song; practically all stock. It's been having a truly weird stall-out issue I can't seem to nail down. Half the time it's right after starting up, half the time it's after ten-fifteen minutes driving. She'll start up fine (or glide to a stop fine), stall out, and not crank over immediately. I give her a thirty second break, try again, and she fires back up, no problem. If I had to guess this happens every twenty-five to thirty starts. It's always just the one stall. Just cleaned the battery terminals, and all the grounds I can find. Only other electrical hiccups are the aftermarket radio isn't working, and the fan/ac only blowing on highest setting (I have a new blower motor resistor ready to install but want to chase this first). Spark plugs are 10k old, though looking through the service records they've been chasing a misfire on cylinder 1 for about 100k. Alternator was replaced at the same time. The only thing I can think of is that the fuel pump might be starting to go but I'm truly stumped because of how consistent the gap is with the issue popping up.

Sorry if this is confusing; trust me, I'm even more lost. Thanks for any help, thanks more for even reading.
 
Could be any number of things that is causing your problem. You need to determine what you are losing to cause the engine to stall; whether it's ignition spark, fuel pressure, voltage to a sensor or even vehicle operating voltage.
Enlist the help of a friend and test for fuel pressure problems in your driveway. Attach a pressure gauge to the fuel rail schraeder valve; operate the throttle and increase the engine speed to 1500 rpms and see what the pressure is; should be 49 psi (preferably about 52 psi or more).
With the engine running test alternator voltage on the back of the alternator at the charging stud; should be at least 13.3V or more; rev engine to 1500 rpms and voltage should increase. Turn on headlights and other electrical to see if the voltage stays steady or drop dramatically indicating alternator or voltage regulator (inside ECM) problem.
 
Battery age is?

Got in touch with the person I bought her from and she said about 6 months. Apparently she's also been doing this for a few years, but since it always fires up on the second try, didn't think it was worth mentioning.

I have an OBD scanner on the way, but I guess I better get some more diagnostic equipment as well.

Thanks for giving me a place to start!
 
Got in touch with the person I bought her from and she said about 6 months. Apparently she's also been doing this for a few years, but since it always fires up on the second try, didn't think it was worth mentioning.

I have an OBD scanner on the way, but I guess I better get some more diagnostic equipment as well.

Thanks for giving me a place to start!
There are batteries out there with a 90 day warranty.

I seriously would get it tested. The cranking amps of it.

Do NOT test it immediately after running. There will be a superficial spike in your readings