What Did I Do To My 3FE? Runs Then Stalls. (1 Viewer)

[jomichael]

Looking for some ideas from the hive mind.

Spent my 4th giving my 91 a tune up, new plugs, cap and rotor. Gapped the plugs at .032. Started and idled fine so I decided to clean the throttle body before it warmed all the way up. Jacked up the driver side to get as much spray out into a drip catch. Started and ran beautifully, until I drove it. Heading down the road under heavy gas and the rpms started jumping wildly and no power. Came to a stop and it died. I waited a bit and it started up and barely got home. Today on the 5th I started it and it ran fine so I pulled it out of the garage and it sounded great, no check engine light, once it warmed up it died and will not start.
Hoping for some diagnostic tips.
1. Did I spray some gunk into the engine? Then why does it run fine for awhile?
2. Filled up the tank the day before, bad gas? Then why did it run fine?
3. Did I spray some electrical item and now it's not functioning?
4. Just a coincidence and the fuel filter needs replacing? 153K on engine. Looks like the filter is original.
5. Noticed there is a big escape of air when removing gas cap when refueling, charcoal/evaporator canister?
6. Coil? No, it ran fine for awhile.

I normally figure stuff out by process of elimination but this one has me stumped. On both videos below, the engine dies right at the end while idling.

 

[jonheld]

Did you unscrew the Phillips screws on the AFM connector?
Did you tear the intake plenum when you lifted the air cleaner cover?
Sounds like a severe air leak to me. Very few things will stall a 3FE.

 

[jomichael]

Did you unscrew the Phillips screws on the AFM connector?
Did you tear the intake plenum when you lifted the air cleaner cover?
Sounds like a severe air leak to me. Very few things will stall a 3FE.

No to both. The plenum is new OEM and I just double-checked them by completely removing. To add more to this saga, yesterday after it started and died I started looking at some of the wires around the coil and noticed some sort of resistor and unplugged the wire and found that it was pretty burnt up. See video. Not sure what that is but when it was running yesterday I had lifted the wires gently and that is the moment when the engine died. I thought it was a coincidence but finding that burnt wire made me want to mention it to you.


I have also read some mud articles on the AFM 93 Camary replacement. There was a comment from you stating the AFM has a intake temp sensor. Was wondering if that has anything to do with it because it only died once warmed completely up.

Feeling kinda lost here and shooting in the dark. I guess I should at least check fuel pressure and spark this evening. Luckily, I work from home and have a backup 55 Chevy to go get parts in.

 

[jonheld]

Looking for some ideas from the hive mind.

Spent my 4th giving my 91 a tune up, new plugs, cap and rotor. Gapped the plugs at .032.

I would start with the correct plug gap for your engine.
Correct electrode gap: 1.1 mm (0.043 in.)
Recommended spark plugs: ND W 16EXR–U11 or NGK BPR5EY 11.
Wherever you read . 032 is very wrong. It is. 031 for the 3FE in an FJ62, which uses a different coil and igniter.

 

[jomichael]

I would start with the correct plug gap for your engine.
Correct electrode gap: 1.1 mm (0.043 in.)
Recommended spark plugs: ND W 16EXR–U11 or NGK BPR5EY 11.
Wherever you read . 032 is very wrong. It is. 031 for the 3FE in an FJ62, which uses a different coil and igniter.

I first used .043 and it would not start at all, then re gapped and it started. Could be a coincidence. I will go back to the .043 and see what happens. BTW, they are OEM from Toyota.

 

[jonheld]

I first used .043 and it would not start at all, then re gapped and it started. Could be a coincidence. I will go back to the .043 and see what happens. BTW, they are OEM from Toyota.

If the plugs were OEM then they should have been pre-gapped at 1.1mm. That is what the "11" stands for in the part numbers.

 

[jomichael]

If the plugs were OEM then they should have been pre-gapped at 1.1mm. That is what the "11" stands for in the part numbers.

So, I regapped the plugs to 1.1 mm like you said and added new Denso wires. Pulled the cap and there was a bunch of carbon on the inside of the cap which I cleaned up. Started right up and ran great.

Went for a drive. 6 miles no problems. Stopped and was heading home, started shuddering again. Somehow managed to get home with all green lights and everything seemed normal...until...I lifted the wiring harness next to the ignition control module. See video. Something is up with the wires...

 

[jomichael]

Well, I just keep finding more issues from the previous owner. It looks like the ignition control module wires melted at some point in the past and they just taped the exposed copper wire. One of the wires just fell out of the connector so may not have been connected securely to begin with. Also, there was only one bolt holding the coil and ICM housing on to the fender. I can see the vibrations causing issues as well. Going to cut the bad section of the wire and put 'em back together correctly with solder and shrink tubing. Hoping that will solve my issue.

 

[jonheld]

Nice. Fix it all. The coil/igniter assembly has to be bolted securely as that's what supplies the ground path.

 

[jomichael]

Nice. Fix it all. The coil/igniter assembly has to be bolted securely as that's what supplies the ground path.

All repaired and no issues driving around on a 100+ degree day. Thanks for all your input Jon!