Multiple cylinders not working

[Banana]

I'm in Hawaii and all mechanics are backed up for over 2 weeks, so I'm trying to fix this truck myself.

1984 Toyota Land Cruiser

After noticing terrible idling and weak driving I changed all 6 spark plugs (even though I just did this about 3 months ago). The old ones were a little charred but looked workabl to me. This did not fix the problem.

Here's what I tested:

1. Spark plug wires and distributer are all fairly new, replaced about 9 months ago. (And I hardly drive the truck).
2. With the truck running I disconnected the first 4 plug wires. None of these affected the idling. Only the last 2 caused the truck to die when pulled.
3. Knowing that the last two spark plug wires are good, to be certain, I switched with a bad one. Same results. Spark plug wires are good. I can also hear the sparks from all the wires (and shocked myself a couple of times actually).

I'm fairly confident the problem isn't with the spark or plugs.

My only guess is that these cylinders aren't getting any fuel. What could be wrong when only 2 get fuel consistently and the others don't? Thanks!

Other things may worth noting:

1. I get black stuff shooting out of my tailpipe pretty often. It's like black water.
2. Truck often gives off a strong smell of gasoline when idling
3. My battery probably finally went bad, now it can't keep a charge and I have to jump it every time as I try to fix the above issue.

 

[Wile E Coyote]

60 or 62?

 

[Banana]

60 or 62?

It's an 84 land cruiser

 

[Wile E Coyote]

Has the carb been rebuilt? How old is the fuel filter? How about the fuel pump?

 

[Banana]

Has the carb been rebuilt? How old is the fuel filter? How about the fuel pump?

No, a few years old, I've never replaced it.

 

[Banana]

No suggestions??

 

[tmxmotorsports]

Do a compression test. Its not fuel injected so fuel should be going to all cylinders you said you smell a strong odor of gas then its probably not getting used. I would say a blown head gasket don't hold me to it. Like I said do a compression test and go from there.

 

[60 toy ota]

x2

 

[Matty f]

And u will need a strong battery to do compression test.
So u will have to think about getting or borrowing a charger to get some decent charge in your battery first

 

[SPANNERSPINNER]

> 1984 Toyota Land Cruiser
> all 8 spark plugs



Also... do a compression test.

 

[mongoose2231]

Compression test right away, since u smell gas, seems as though u have fuel as well as spark based on the above. Have u attempted a valve adjustment lately??

 

[gregnash]

Yup just like everyone is saying do a compression test, note that your numbers may be slight off due to the fact that some camps of thought believe that you should only do a compression test when the engine has come up to temp.

Other thoughts are to get a spark tester tool.. this is the adapter that goes between the spark plug and the end of the wire, has a small section in the middle kinda like a bulb that shows you that you are definitely getting spark to that cylinder.

Pull the valve cover, pull the plugs and shift into neutral and turn the engine over by hand watching the valve train to ensure that there are no stuck valves.

If the carb hasnt been rebuilt then time to look at @Pin_Heads videos on Youtube on rebuilding the carb and give her a good go. Also, download the FSMs from my sig line and start going through the troubleshooting to see what you come up with. The black liquid coming out of the tailpipe could be a couple things. More than likely it is unburnt fuel that is passing through the entire exhaust system but it could also be some condensation that is collecting in the cat or in the pipe and getting pushed out which would give it a black, sootie look and smell slightly like gas.

 

[vipergrhd]

Leak down test will never lie to you unlike a compression test.

 

[Speen Shaytan]

To back up a little and keep things simple, what is the gap set on your plugs for the affected cylinders?

That stuff coming out the pipe may very well be unburnt fuel, condensation, coolant, or a mix of all three, coupled with blow by. It sounds like you're not getting ignition on 4 of the cylinders so you would need to check for the basics: air, fuel and spark. Since two cylinders are working on this carbureted setup, spark would be the suspect. It could be something as simple as worn out boots which provide inconsistent contact with the plug.

If you verify you're getting spark and still nothing, this is where compression/leakdown comes into play. If the valves are stuck, or adjusted too tight, it can cause the cylinder to not hold pressure, and vent the combustion instead of harnessing it. The same would go for bad rings, or a bad head gasket.

A few things you can easily check are the oil, coolant, and crank case blow by. If the oil comes out looking like chocolate shake, that indicates coolant leaking at the head gasket and getting in the block. This would cause the venting of cylinder pressure. If it's not full of chocolaty goodness, how is the pressure coming out of the crank case?

You should see an increase in turbulence with excessive blow by at the piston rings (especially with 4 potentially defunct cylinders) which would cause things like any breathers or vents (could look in the PCV area, or pop off any lines coming out of the valve cover) to go nuts.

When cold and the coolant system not pressurized, you may see pressurization from a bad head gasket, or oil in the coolant system. When it heats up, it pressurizes and could cause a flame out in a cylinder. You would see coolant dropping though, so if you're not having to top off your radiator, that may not be the issue.

Then again, if you have crappy friends like me, check for chewed up straw wrappers shoved into the posts on the distributor...

 

[18Doc]

I know this is the first thing a crazy person would say.....but, I'm not crazy. I had the exact same symptoms: cylinders 5 and 6 not firing, smell of unburnt fuel, etc. I checked plugs, wires, compression, distributer until I was blue in the face. I ended up finding the problem purely by accident. On your intake manifold where the ports for the 5 and 6 cylinders are, there is a vacuum port that services the brake booster and something else that is slipping my mind at the moment. Regardless, it is a decent size, two outlet port and if there is a vacuum leak at this port or anywhere leading from it, it is enough to starve those last two cylinders of fuel/air. Pull the lines off the port and plug the holes while the engine is running and see if it fixes the problem. If so, track down the leak and make a permanent and hopefully cheap repair. See attached picture for clarification.

 

[18Doc]

The smaller port goes to the AC idle up circuit. It was killing me, so I looked it up.

 

[Cgbeachbum]

Where in Hawaii are you? I'm on Big Island near Hilo. If you need a compression tester I can lend you mine? I've got an 84 as well that likes to throw me fits ever so often!