Vacuum Leak - Spark Plug tube seals?

[CharlieS]

Every situation is different. What worked for me may not help you.

Mine had varying degrees of idle problems from significant to minor until I fixed every vacuum leak (last one was injector seals). Confounding my results is the fact that my injectors were rebuilt at the same time, so I have good flow, pattern and volume out of all six. At the moment, it runs like a new engine.

You situation may be very different. I'm just a diy hack, not a mechanic, so just trying to help.

 

[banjo1981]

When I hook the vacuum gauge up and hit the throttle, vacuum drops to ZERO! Some internet reading says potential plugged exhaust/cats???

 

[banjo1981]

Ok, so I went down a rabbit hole. But before I did, I did a proper vacuum test by blocking off the intake manifold with a rubber glove and a layer of plastic wrap with a tight rubber band. Nothing was escaping the intake. I hooked up a hose to the brake booster inlet on the intake and blew into it. It would pressure up and hold pressure until I could hear a little bit of air escaping the vent hole on the EGR vacuum modulator. That was the only place air was escaping, and I think it’s supposed to do that.

So this morning I had the bright idea to cut the cats off of the exhaust system to see if they’re clogged. Both were clean as a whistle and now the cruiser sounds like a jalopy stock car. BUT… I could tell which bank was having the misfire issue. Bank 2 (cylinders 4-6) were puffing irregularly compared to the smooth purr of bank 1 (cylinders 1-3).

Hypothesis: bank 2 has a misfire because of fuel injectors, injector seals, or possibly injector wiring. Not likely the intake manifold gaskets since the vacuum tests were pretty definitive.

What do the gurus say to my hypothesis?
Thanks in advance

 

[DIRTBIKEUSA]

If it is a fuel delivery lean misfire get a stethoscope from HF and check the injectors for plunger clicking. If not clicking check that injector wire end for 12v and ground with a meter/non contact voltage tester/ noid light/ test light. Figure out if it’s mechanical or electrical and go from there.

Maybe bad connector, or melted/pinched wire.

Maybe clogged/dead coil injector.

Maybe clogging fuel filter

Maybe but not likely clogged fuel rail or failing/clogging fuel pump.

I just did my injectors because of a misfire in cyl 6. Did them all, fuel filter upper, manifold gaskets, ext.

Fun stuff! Good learning experience and not too difficult for a motivated mechanic.

 

[banjo1981]

Actually in the middle of that diagnosis as I type: started about an hour ago.

 

[banjo1981]

All six injectors have power to the connector when checked with a test light.

Man it feels good to be a gangster:

That’s the #6 injector directly under the spot where the hvac control was leaking down onto it. After I changed the hvac control valve, it never ran the same again. Makes sense now, because it was full of coolant. Guess I’ll go ahead and replace it . What’s one more part thrown at this thing.

 

[ZackR]

Open up the loom here and see how the wiring harness looks:

Also put some wadded up paper towels in the open intake to keep the dirt out.

 

[DIRTBIKEUSA]

That EGR pipe gets HOT.

If the law permits..get rid of it.

 

[banjo1981]

Open up the loom here and see how the wiring harness looks:

View attachment 3602003

Also put some wadded up paper towels in the open intake to keep the dirt out.

I did put some paper towels in there after this picture. Good suggestion!

 

[banjo1981]

New belts, distributor o-ring and injectors have arrived. Will get those installed after lunch. Cross your fingers.

 

[mudgudgeon]

New belts, distributor o-ring and injectors have arrived. Will get those installed after lunch. Cross your fingers.

Also consider changing the harness connectors for all your injectors.
I see three different colour connectors. They would have all been the same colour originally.
They get brittle and break. New ones cost less than $10 ea. Ballenger Motorsport are a good source

 

[CharlieS]

Also consider changing the harness connectors for all your injectors.
I see three different colour connectors. They would have all been the same colour originally.
They get brittle and break. New ones cost less than $10 ea. Ballenger Motorsport are a good source

In case it is helpful, here are the part numbers I used at Ballenger.

Pigtail with connector:

CONN-85971

Sumitomo 2 Way TS Plug Pigtail for Denso Injectors, (Toyota # 90980-11153)

Plastic connector alone:

CONN-75971

Sumitomo 2 Way TS Plug Kit for Denso Injectors, (Toyota # 90980-11153)

For whatever it is worth, my 1994 had two different color injector connectors (I am pretty sure they were original equipment), alternating between brown and grey. The replacements from Ballenger are all brown.

 

[ZackR]

In case it is helpful, here are the part numbers I used at Ballenger.

Pigtail with connector:

ONN-85971

Sumitomo 2 Way TS Plug Pigtail for Denso Injectors, (Toyota # 90980-11153)

Plastic connector alone:

CONN-75971

Sumitomo 2 Way TS Plug Kit for Denso Injectors, (Toyota # 90980-11153)

For whatever it is worth, my 1994 had two different color injector connectors (I am pretty sure they were original equipment), alternating between brown and grey. The replacements from Ballenger are all brown.

Correct, the injector connectors on the 94' harness alternate between grey and brown.

 

[banjo1981]

Buttoned it all back up and it’s running like a champ. Only one small drip of fuel from the filter. I’ll replace that tomorrow. Huge win so far. Thanks everyone for the help and knowledge and experience on this one.

I found a website from a fellow cruiser-head who documented the same experience: dead #6 injector. So I would say this isn’t too uncommon.

Injector Service

 

[banjo1981]

So I thought I was done, but it had a slow start/long crank situation. I read a bunch on here and google searching my symptoms. Had a strong gas smell from the exhaust after the long crank startup. I guess one of the inexpensive Amazon injectors was bad internally. They have OEM part numbers on them but don’t say Denso. They are also an exact match for color to the original ones.

I had to pull the upper plenum to replace the injectors the first time, so I knew what to do. So I pulled the upper plenum again to replace the first 5 injectors with the original ones since five of them were good. Buttoned it back up and it cranked perfectly right away, but started to smell gas. Shut it down and saw where it was leaking from and it wasn’t the fuel filter this time. #4 injector o-ring was damaged and fuel was gushing out of it.

So I bit the bullet and pulled the dang upper plenum a third time! I took the fuel rail and injectors out AGAIN, and found #4 o-ring tore when I installed it the last time. Put a new o-ring on and made sure all 6 felt the same when twisted. I installed everything and buttoned it back up about 15mins before my daughter’s birthday party started. Cranked it and it fired up with no hesitation and NO leaks. So this problem is officially fixed. No leaks, no vacuum leaks, running great again. Sure it has a bunch of new “potentially unnecessary” parts, but that’s part of the Land Cruiser game right?

 

[DIRTBIKEUSA]

Good job! Thanks for the update.