Bought a '92 4runner 3.0 with 44k miles about two weeks ago. This week, it has struggled to start. Turns over all day but won't start every time.
Filled up with gas yesterday, and it wouldn't start for about 30-40 minutes. Once I got it going again it stalled out on me at a red light and wouldn't start up again for about 20 minutes, after I fooled with the EFI relay. I changed the EFI relay, but that didn't improve anything.

This morning it started right up, idling at about 1500rpm. Turned it off and restarted it, and now it wont idle above 400rpm when it does decide to start.

Any ideas? What should I be looking for?

 

I’d had some similar issues with a 22re, ended up being the fuel pump for me. It would work, sorta, which was what confused me.
might be worth checking the filter and the sending unit pressure though.

Best of luck!

 

I second this, sound like an issue with your pump. Either the pump motor itself is wearing out, or you’re filter/pickup screen is clogging up. I’d start with the fuel filter, if that does not clear things up then replace the pump.

 

Fuel pump or filter issues can be diagnosed typically with fuel pressure and volume returned to tank tests.

 

Today my dad and cleaned the throttle body, reassembled and threw some starter fluid into the intake - still wouldn't start.

We then changed the fuel filter - now it starts, but runs very rough, pops/backfires when I give it gas. Also get that catalytic converter smell and black smoke now coming out of exhaust. Wants to die when i let off gas. Also sounds like there may be a vac leak somewhere but can't find exactly where.

 

Black smoke is a sign of to much fuel. "Popping" is a sign of no spark. No spark = fuel combusting in the exhaust, more specifically your CAT. Starting fluid not burning in the engine (not starting) = no spark.

Check your ignition system. Plugs, wires, cap, rotor, coil. My money is on the coil as it generates spark for all six cylinders, and it sounds like that is your issue.

What most likely happened here is your engine had spark issues to begin with. Changing the fuel filter helped the pump deliver more fuel to the engine, resulting in your engine being able to run on what little spark you had.

When's the last time you did a tune-up? I.e. spark plugs, wires, cap & rotor?


Edit: I'm sorry, I might of rushed this response a bit. If it were my truck, what I would do next is test for spark. First at the coil wire and then each cylinder.

The best way to do this is with a spark tester. You can pick one up at any parts store for around $20.

This is my preferred style and the easiest to use (you can always YouTube "how to use an on-line spark tester"):
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Hook this up in-line between each of the six wires. My money is on the coil. If the spark checks out ok, pull the plugs and inspect.

Here is a photo I took of a good plug vs. a bad one:



Notice the gap on the left plug due to the electrode worn away. This engine had very similar symptoms to what you are describing.

Anyways, my 2¢. Take it with a grain of salt lol. Good luck and post back!