Engine barely runs when warm

[zavikan]

Car hasn’t gone even 1000 miles in the last 8 years, but has been periodically started and driven around town. Around 8 months ago I locked the keys in it and didn’t get around to getting back in until today.

Charged the battery and the car came to life no issues. As it warmed up it began to misfire and sputter. Barely made it home. No check engine light. Restarted the car a few hours later and same thing. Restarted next day and same issue.

Thoughts?

[Noriyasu]

If you leave it for 8 months, the battery may not recover even if you recharge it.

It is recommended to replace the batteries. SVX tends to consume more power than a typical car. Misfires can be closely related to battery deterioration.

I always use batteries which uses calcium alloy electrodes because it has low internal resistance.　FYI.

[Blacky]

Get the battery load tested. I leave mine months at a time and it usually starts. It has been deeply discharged many times and has recovered. If it's the same battery that has been sitting in the car for 8 years then yes, it likely needs replacing.
Very old fuel could be an issue. A plugged fuel filter, cheap to replace.

[Noriyasu]

Yes, it could be bad gasoline. In that case, when you remove the fuel filler cap, it smells different than usual. Japanese high-octane gasoline usually does not cause problems for about half a year.

If you have a problem with gasoline, I recommend draining the old gasoline from the tank before you replace the fuel filter.

The filter is placed in two place. One is in engine room. and other is attached on fuel pump in fuel tank. The genuine fuel pump and packing are discontinued. I do not recommend removing this. You will need to access from fuel filler port to remove old gasoline because there seems no drain bolt at bottom of tank.

The filter in engine room can replace easily. But, usually fuel hose will deteriorate and become stiff. If you haven't replaced it recently, it's a good idea to prepare up on fuel hoses.