Stalls after a few minutes.

UPDATE! Fortunately me, unfortunately for diagnostics, the issue remedied itself. I believe this confirms my suspicion of water contamination to a circuit or component. Given the feedback from you (as well as my experience and coworkers), I think because the o-ring on the distributor cap is old (flat as a pancake), it allowed water to contact the rotor and pool at the base. A short period of sitting allows the water to drain down, off the contacts. Restarting flings the water back onto the contacts, causing the no-start conditon. Let me know what you guys think, and thank you for the input!-----

TLDR: Stalls after idling for a short time, only restarts when switching ignition from "on-off-on" and then attempting to start. Runs for a very short time, stalls again. ~15min sitting resolves the issue for a couple miles of driving, then stalls again.

1994 4Runner SR5 4wd, 5-Speed Manual, 3.0 V6 w/227,000 miles.

BACKSTORY

Purchased the vehicle 2 days ago. Aside from leaking engine oil from every possible location that is feasible, runs great!

Driven the first two days without issue, mixed city/freeway driving up to 75mph.

Pressure washed the engine bay at work(I was cautious around any electrical connections I saw) to clean up the residual oil to identify the leaks. Fired right up after pressure washing, no issues.

THE ISSUE

Decided to go home at lunch to grab food from the house about four hours later. Made it about 4 miles (city streets no faster than 45mph). While at a red light, I noticed the battery light suddenly illuminating, and saw RPM's @ 0. Vehicle was idling, in neutral previously. First time it's ever stalled out. Attempted to restart, and it did... Then stalled again immediately after. Managed to get it to the side of the road about a block further by keeping RPM's up via throttle. Couldn't keep it alive after it stalled again, even with throttle input.

After spending some time under the hood (maybe 15 minutes) and not finding any obvious culprits, I attempted to start. Started right away and held idle. 30-45 seconds later, idle got rough fo 2-3 seconds, then stalled.

Engine would crank, but would not catch- Unless I turned the key to "off" before cranking. It would fire up for a half-second, then stall. Wait another fifteen minutes or so, engine will fire right up before exhibiting the previous symptoms a few minutes later and stalling.

I'm a mechanic by trade, but I'm not familiar with 4Runners specifically and my ability to diagnose OBD1 vehicles is limited more or less to identifying common symptoms that lead to a cause, as with most vehicles.

I attempted a jumper from B+ to FP @ diagnostic port- no change. ~12 volts @ FP circuit from diagnostic port when ignition is on (not running). Ohms @ 0.8-1.0 when ignition off.

I believe this to be an electrical issue, although I'm skeptical of the fueling system since it will start (albeit briefly) when the ignition is switched from "off" to "on" (I assume because like most vehicles, the fuel pump is provided power directly when cranking, before diverting to a middleman like an inertia switch or other component after a few seconds.

Any thoughts, ideas, or diagnostic procedures you'd recommend? I'd like to think the issue will resolve itself if related to a shortage due to water, but I'd also like to find the connection/component that is not sealing well so I don't have to deal with this in the future.

Also, first post. Thanks for having me!

 

A couple of things came to mind. Did the truck sit for some time before you bought it? If so, I would be suspicious of the fuel (varnish, dirt) and put a new fuel filter on it.

I am not a fan of pressure washing of engines. The law of unintended consequences. Instead, I have used Simple Green as a degreaser - best results with a warm engine, followed by a light water rinse, and repeat until clean.

I will wait and see what others say while I think about this some more...

 

CRC-656?

 

That is a good thought - pressure washing = water in connectors. Maybe get some contact cleaner and go through the connectors.

 

It’s used to start wet outboards and coats but dries it.

 

Cap and rotor?

 

Here is an excellent guide to diagnose the fuel pump electrical system.

https://www.yotatech.com/forums/f116/my-truck-runs-few-seconds-then-quits-312747/

 

Updated the 1st post. Thanks for the responses!