Water / Electrical issues under the hood

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Reaching out to those of you that have done, or have experience with, troubleshooting/refreshing the wiring harnesses in our 80 Series. I am not an electrical-savvy guy, but trying to expand my knowledge and reliabilty of this 30 year old rig.

This weekend necessitated getting out the pressure washer to clean the mag-chloride stuck under the rig that gets applied to our dusty county road every so often. I did NOT spray directly into the engine compartment from the top, but did spray from the bottom sides (obviously, to get rid of the mag). I have water entering the electrical system SOMEWHERE and cannot track it down thus far. I had a similar issue that stranded me at a car wash not too long ago after the undercarriage spray hit it, causing the engine to sputter and die until it had time to dry out, about 5 hours later.

Yesterday I spent time on the passenger side looking at possible connector issues and of course the distributor cap and connections. I spent time adding dielectric grease where I could, in hopes this might supply some extra protection for water seepage. Distrib., o-rings, wires, etc. should be replaced with OEM- it is on the short list now; however, I found no evidence of water inside, either yesterday or today. BUT this morning I wanted to give a light rinse to the engine bay, as a check of my efforts (spraying thru the pressure washer with just hose pressure, not high pressure) and the water did its deed again. Checked the distributor cap, no apparent water inside, but occasional air blown into the cap allowed the rig to start for a little bit before sputtering out again. I'm not sure if water is just getting into the 30-year old harness and finding a bare wire and causing the issue... seems to be my best guess. Or maybe the O-ring under the distrib. cap is really that worn out, even with dielectric grease...(?) Tried to check other connectors tying into the harness, as well as blasting air around and into various connections and harness splits resulted in no help.

I am leaning toward purchasing a used wiring harness to check/rebuild and replace when complete. Maybe this is secondary to replacing the distributor components first. I do have the FSM EWD book to reference, but having a tough time trying to trace what harness connections would be most susceptible to water interfering with engine running (obviously, water and electrical don't mix, but how to trace?) I guess I am trying not to just fire the parts cannon and keep guessing about what is going on.

EDIT: 5+ hours in, and something is still wet- won't start.
2nd EDIT: 8 hours in- got it started, needed 2000 RPM to keep going, not wanting to idle.

Please give me some feedback if I am making this more complicated/expensive/time consuming than necessary; or have some good feedback on quality harness materials to utilize.

Thanks, and Cheers!

Sheila Wiring Harness.JPG
 
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OK, so as the day goes on, I notice that when it does finally start, it does not want to idle; stumbles and wants to stop, but when revved up, runs OK. This leads me back to thinking water interfering with the distributor again. I'm really not sure how, after popping the cap and drying with compressed air. If anyone can point out what I'm missing, I would certainly appreciate it. Also, still wanting to refurbish the wiring harnesses, so any input on quality products to investigate/use is also appreciated.
Hope you all had a great weekend!

Cheers-
Brian
 

DSRTRDR

I can mangle anything ...
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most important thing is to inspect your wire harness by the EGR tube (assuming '91s have those; calling @jonheld for expert input)- and if intact, pull it away from this hot tube towards the driver side by a long zip tie and, for more protection, also wrap it in heat resistant wrap - if not intact, repair the melted wires
 
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The 3FE harness doesn't run by the EGR pipe.
@ColoradoBoy I'm assuming that when this issue occurs, you have verified that the CEL is illuminated with the key in the ON/RUN position before cranking the starter.
Assuming everything else is working properly, only 2 sensors will stall a running 3FE. The AFM and the TPS, so I would start there.
 
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The 3FE harness doesn't run by the EGR pipe.
@ColoradoBoy I'm assuming that when this issue occurs, you have verified that the CEL is illuminated with the key in the ON/RUN position before cranking the starter.
Assuming everything else is working properly, only 2 sensors will stall a running 3FE. The AFM and the TPS, so I would start there.
Hi, Jon-
Yes, CEL is good. Thank you for the info- I will begin in those locations.

Any intel on quality electrical wrap & materials?
Cheers!
Brian
 
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The 3FE harness doesn't run by the EGR pipe.
@ColoradoBoy I'm assuming that when this issue occurs, you have verified that the CEL is illuminated with the key in the ON/RUN position before cranking the starter.
Assuming everything else is working properly, only 2 sensors will stall a running 3FE. The AFM and the TPS, so I would start there.
Jon:
Doesn't the 3F-E have a rubber boot over the distributor cap from factory to prevent some of this?

OP:
Have you removed the D-Cap and cleaned / dried it out or sprayed the inside with WD-40?
 
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Hi, Jon-
Yes, CEL is good. Thank you for the info- I will begin in those locations.

Any intel on quality electrical wrap & materials?
Cheers!
Brian
It depends on what you're doing.
I like 3M for tape. 33+ or 88.
All the factory connectors under the hood were water resistant when they left Japan 30 years ago, so it's certainly a possibility that the rubber seals are not sealing anymore.
I like a spray grease in the connectors to help seal.
 
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Jon:
Doesn't the 3F-E have a rubber boot over the distributor cap from factory to prevent some of this?

OP:
Have you removed the D-Cap and cleaned / dried it out or sprayed the inside with WD-40?
I wish I had a rubber cap for the distributor- long gone, unfortunately. My 89 pickup still has one.
I did remove the D-cap, dried, added dielectric around the o-ring, and re-assembled.
 
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Well, once everything dried overnight, she's running again. Thank you for the input. I will get going on factory replacement style boots where I can, unwrap wiring legs and resealing them up the best I can; starting with looking at the AFM and TPS connections, and go from there. It was a frustrating weekend, but win some, lose some. Looking at it as a win for one more step to keeping a really fun rig on the (off) road.
Funny, my wife says it was running better today... All I did was replace battery cables and soak the crap out of things that aren't meant to get wet. I think she's just trying to make me feel better. I do love her!!

Cheers-
Brian
 
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Well, once everything dried overnight, she's running again. Thank you for the input. I will get going on factory replacement style boots where I can, unwrap wiring legs and resealing them up the best I can; starting with looking at the AFM and TPS connections, and go from there. It was a frustrating weekend, but win some, lose some. Looking at it as a win for one more step to keeping a really fun rig on the (off) road.
Funny, my wife says it was running better today... All I did was replace battery cables and soak the crap out of things that aren't meant to get wet. I think she's just trying to make me feel better. I do love her!!

Cheers-
Brian
OK, I'm at the WTF stage with trying to find replacement rubber boots for the 4-pin TPS and 7-pin AFM connectors... You would think Google would be more helpful. So, I am again asking the group:
WHERE THE HECK DOES ONE GO TO GET THESE TYPE OF ELECTRICAL SPECIALTY ITEMS?!?!? I really don't want to do any half-a$$ work if I'm trying to truly fix this.

I did find some over in AUS, but $45 shipping for $18 in parts just has me a bit sideways. If I gotta, I gotta, but there has to be a source closer to home.
Please help!

Cheers!
 
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The AFM connector is 90980–10071.
The TPS connector is 90980–10378.
Both of these are NON WATERPROOF according to the Toyota Wire Harness Repair Manual.

In this case, the best bet is a shot of aerosol grease.
 
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The AFM connector is 90980–10071.
The TPS connector is 90980–10378.
Both of these are NON WATERPROOF according to the Toyota Wire Harness Repair Manual.

In this case, the best bet is a shot of aerosol grease
Thank you, Jon- above and beyond service, as always. I sent a question to McGeorge as to if those parts come with the rubber boot. If so, I'll be golden. If not, the search will continue. Sorry for the meltdown... Hard to know everything, even with search engines and parts suppliers. Aerosol grease on the shopping list.
Cheers!

EDIT: No rubber boots available- apparently was installed on factory wiring harnesses, and not a replaceable part. :confused: Aftermarket boots or bust (or electrical tape...)
 
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