Today was one of the most stressful days I've had in a long time. In the course of replacing the canister vent solenoid on an '01 4Runner, I had KOEO for bidirectional testing, and the vehicle was on a power supply.
At one point it randomly started running the fuel pump. I wasn't even doing anything with my Otofix/Autel at the time, and I certainly wasn't in the fuel pump command section.
At first I cycled the key and this remedied the problem. Later it would start running the pump again and cycling the key did nothing -- the pump would just resume at KOEO.
In hindsight I heard some clicking from the engine bay, but I was laser focused on the solenoid at the rear of the vehicle above the spare tire. I had no idea why the pump was running, but as I was on a power supply I didn't much care.
I finished up the solenoid and changed the engine oil as requested. When I went to start it it sure seemed like the starter wanted to spin the motor but simply couldn't get more than a revolution or two.
It really struck me as hydrolocking and I thought back to the weirdness earlier. Before potentially damaging something (further) I decided to pull the plugs. Sure enough, each cylinder had a lot of fuel.
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I cranked with all 6 plugs removed and a wall of fuel blew out of both valve covers.
Like an idiot I replaced all the plugs and she spun like no compression. This seemed odd because if I'd bent something in one or two cylinders, I'd hear a changing cadence.
I pulled all the plugs again and after squirting in quite a bit of motor oil was able to get all cylinders from ~60 to 135-150.
She drives great and it would seem disaster was averted
but I'm wondering if anyone else has ever seen early 2000s Toyotas run the pump continuously AND fire all injectors at KOEO? Was this my Otofix/Autel --
maybe but it wouldn't do it EVERY time the scanner was plugged in.
@Trav @14Accent @The Critic @Timmastertech -- ever seen something this bizarre?
The lesson for me is to never ignore a fuel pump that keeps running inexplicably. You could try to determine if the injectors are actually firing, but to be safe in the future I'll just find a way to disable (a runaway) fuel pump unless it's the thing being diagnosed.
I never thought a vehicle could try to commit suicide just by having the key on, but now I know better.
Oh and yeah, I changed the oil AGAIN after having JUST done it!!