Ok '00GS2 had a radiator leak down low that emptied the coolant and caused an overheat issue, sigh. Got it towed home, etc. Now I've been troubleshooting it for a few months off and on since I mostly work from home.
Thermostat was stuck, replaced that with new radiator, hoses, temp sensor.
After I got it refilled with red coolant... had light smoke/liquid coming out of tailpipes, sigh. Checked that out... sooty and wet at the tips but not oily, suspected head gasket was busted on the coolant side? Unsure. Had bubbling/boiling while filling/burping coolant. Also had some P302/303 codes. Figured it was those cylinders with the issue.

Started shopping for motors but a mechanic friend of mine said I should give the liquid gasket sealer crap a try first. Didn't feel like removing the head at this point so I removed thermostat and ran the Blue Devil sealer fix. The smoke went away pretty quick, no throttle lag, idles ok. Engine codes cleared on their own.
Took it for some test drives, seemed fine, slow to heat up as expected but no exhaust smoke, even on start. Wary of the thermostat not being in, but wanted to make sure the devil crap had some time in the system before I bled some/half of it out and replaced with fresh coolant and put the new failsafe thermostat back in.

2 days after the last drive after the Blue Devil was added, the car starts reeeally rough, almost coughing for air/gas? Tank is 3/4 full, premium. Apply a little throttle, and it dies. Restart and floor it, and it slowly coughs its RPM up to an idle and then maintains fine without shutting off. MAF? clean. Cleaned it anyways. Air filter? not too bad, banged it out a bit. Even tried to start it without the filter. Chanced a drive to lunch locally, same start issue. On the way home, started the same way but held and got home. Did it again the following night, same starting issue, thought it was the battery perhaps since it was toast and I had been trickle charging it over the course of troubleshooting. New battery! Same problem.

1 day after the new battery, now I can't get it to start at all. It's all aggressive starter on new battery and won't light. It sounds like.. lets see... Whiz-iz-ika! whiz-iz-ika! whiz-iz-ika!... but there aren't any codes. sounds the same every start attempt.
Listened for the pump... but no wizzing/priming sound I'm used to. Yanked the rear seat out and tried that again a few times, no sound, put hand on top quick, no vibrations. Pump is gone? It just seems like it is being electronically cut-off... Or did it simply finally die? Likely OE.
Ok ordered new pump and relay. Just today replaced relay, no change.
Found the fuel pump controller in the trunk but it looks pristine, no idea how to test that guy. Do they go bad? Is there a fuel pump fuse elsewhere or a reset button?

Checked all the fuses I could find, unsure about relays. Interestingly.. radiator fans turn on when key is in ON position. Figure there's a busted relay but it looks like there is 3 of them in the fuse box? I'm unsure which one controls those or what to troubleshoot to get the fans to run like normal.

Next steps! Rebuild the fuel pump with new motor? Or how can I save some time on that?
Saw a forum post where a member had similar trouble but got it to start when unpluging the MAF, but that didn't work, only produced the codes related to it being disconnected/busted. Cleared the codes.

Another thought that crossed my mind is that my O2 sensors got fouled from when the smoke was present? I could MAF/carb clean them a bit and see? I have not removed one yet but I will, just to check the state of it. They are not OE I had replaced all four a few years ago as well.

Any other thoughts on this? I don't have any starter fluid atm. I have replaced the fuel filter on the pump unit in the past so I'm good to go back in and swap the motor out. I'm not great with electrical but I'm wondering if I should try to send power to it to verify that it is not dead? I'm thinking I need to finally buy myself a multimeter I'm just not sure how to test with it.

Could it be the igniter? Replaced valve cover gaskets few years back and replaced all the spark wiring so I don't think the cables are bad yet.

Appreciate any knowledge to help me get this thing running. Even if it starts rough again I can at least drive it to the local shop where I have a good referral.

o7
Jon

 

First thing you need to do a compression check those head gasket fixes in a can best case don't do any harm. The fuel pump only runs when the engine is being cranked or actually running. The starter problem is probably bad battery terminal to post connection (don't assume it is good). Of course the starter could be going bad.

 

Thanks.
It will take me a while to get a compression test going... strip the top, rent a kit, etc. At this point I need to get it to a shop or start removing the head myself.
Pretty sure the pump primes the line/rail when key is turned to ON, and I've heard it before, but can't now.
There is no problem I can tell with the starter. Placing a white dot on the aux belt, I can tell its turning over.
Never heard of a starter going bad failing to start the engine when its turning over.
In researching this issue, I can't find a good list of things to check that would cut off the fuel. Not looking forward to replacing the pump just to see if that's all it is.