TimWilbers

iTrader: (1)

It started twice on the weekend, but not since.

Decided to back down and check things.

Monday
Shutter valve holding vacuum as it should.
Changed the fuel filter. Had to crank the engine to get gas into the filter, but then the level in the carb front inspection glass was at spec.

Tonight
Pulled the plugs to do a compression check.
Only pulled both leading and both were wet with gas.
Ran the compression test and even 95 PSI on all three faces both rotors. YEAH!!!

But "smoke" was being ejected from the spark plug hole of the rotor not being tested.
Then I noticed a black liquid a the spark plug holes. Oil? No, it had the smell of gas.

I do recall on Monday's test that after attempting to get her started, the carb primaries were gas coated. So I suspected flooding.

Has anyone come across something like this before?

At this point the carb seems to be the primary suspect. Rebuilding may not be the total cure, but I don't think it could hurt.

(The black liquid caused a missed heart beat. Smelling gas was more reassuring than it being oil.)

DivinDriver

iTrader: (15)

The "smoke" was probably vapor of compressed air, gas, maybe some assembly lube.

Black liquid is a new one on me. Obviously you would have used new oil (which shouldn't be black), & gas isn't black. Rad fluid isn't black. What assembly lube did you use?

Hopefully that wasn't the color of the gas coming from your carb bowls or fuel lines. Rotted fuel-line rubber mixed in the gas? Old carbon dissolving off the rotors (how clean were they?) ?

Mysterious!

I think your flooding suspicion may be right.

Jeff20B

iTrader: (13)

Maybe your rotors weren't cleaned enough to make microchips on them, which is ok, and is probably the source of the black liquid. Carbon + gas = black liquid.

Question: do you have to keep the emissions devices? Maybe it would be easier on everyone if you temporarily removed all of them during this critical time. They are all 30 years old and probably suspect.

You mentioned you needed to crank the engine to get gas into the carb. This is normal on the 84-85 model as a "safety feature" that has caused more headaches than you would know. It's never happened to me because I was aware of the relay bypass wire trick, but I was almost left stranded when a trailing ignitor kept cutting out on a friend's car I was testing. It got an ignitor swap and the bypass wire as soon as I made it back. It makes a handy fuel pump disable for carb testing or anti-theft.

I don't know how much you'd like to change (upgrade) about your car so I'll just leave you with that.

TimWilbers

iTrader: (1)

I'm going to pull the gas lines tomorrow and crank it.
See what comes out.

The gas in the new fuel filter (clear plastic case) was the right color of gas.

The rotors were fairly clean except the dimples in the combustion areas.

Used 10w-40 oil for assembly.

The black liquid was gas as far as I could tell by the smell.

If not the fuel lines then something further along.

I'll update after checking the gas condition and pulling the carb. (The spacer between the carb and intake manifold is black. Still available.)

This has been an issue which was been progressing downhill, not something sudden as far as I can tell.

Thanks for the response. I'm not giving up at this point.

Jeff20B

iTrader: (13)

It could be something easily overlooked like the anti afterburn hose down on the rear secondary runner of the intake manifold which gets hot and likes to leak. Or maybe the carb has crusty stuff in it.

All the stuff has to come off the carb during a rebuild so I mentioned just temporarily leaving it off (simplified) while you diagnose everything.

TimWilbers

iTrader: (1)

And I have a bag of golf tees useful for plugging vacuum lines.
Thanks. Excellent advise.

j9fd3s

iTrader: (3)

both are "normal" the black goop is some oil/gas/carbon mixture. there are a number of causes, its either too rich, too much premix/oil/assembly lube, or something like that.

the "spray" when cranking is also normal, if there is fuel in the carb, the spray is uncombusted gas/oil... i've seen some cases where the plugs left in the engine can cause enough combustion for smoke.

i might try a deflood, clean the spark plugs, and then see what happens.

TimWilbers

iTrader: (1)

I'll try that as well.
Thanks much.

TimWilbers

iTrader: (1)

Pulled the plugs and cleaned.
Disconnected the fuel lines, stuck them in a qt. measuring cup, cranked for 5 seconds. Gas looked just like clean gas. I was surprised by the volume in 5 seconds.
Removed the 20A engine fuse, cranked maybe 30-45 seconds until the vapor cloud coming from the spark plug holes dissipated.
Replaced the plugs and wires.
Replaced the fuse.
Cranked and cranked and cranked. Stopped for a moment then tried it again and the thing started.

Ran it for about 25 minutes around 1500-2000 with an occasional bump to 3000.
The longer it ran the smoother it got. Well hot-damn!!

Still have to adjust the idle as when I took my foot off the gas it almost bottomed out, but a tap on the peddle brought it right back up.

One think I suspected last November when preparing to pull the engine was that the radiator might be leaking. That was confirmed tonight. After shutting it off and pushing it back into the garage, I checked for leaks and there is was on the right side. Not a flood, but about 8-10 drops of green. Not something I want to ignore.

I'm 99.97% of the way there.

She needs a bath to get off the dust and cobwebs.


Thanks everyone for helping.

I would not have started this, and definitely could hove have gotten this far without the help I received. That includes you too Ray Green.

TimWilbers

iTrader: (1)

Yes indeed it is running but needs some tweaks.

Radiator is leaking, slow, but leaking.

Mazdatrix has an 83-85 all aluminum for $187.
https://www.mazdatrix.com/b8.htm

Atkins has an 83-85 for $275.
83-85 12A & 13B Rx7 Manual Radiator (N304-15-310)

That's a big price spread.

Opinions/suggestion, previous experiences, would be most welcomed.

TimWilbers

iTrader: (1)

Please respond to new thread. I did not realize this was tagged inside here.

Cookboy

iTrader: (10)

Www.rockauto.com

TimWilbers

iTrader: (1)

Thank you.

ray green

iTrader: (14)

"Yes indeed it is running but needs some tweaks."

Man, I'd sure like to see a utube of that freshly rebuilt 12A.

Tim, you got any grandchildren that might know how to operate a video recorder?

Before and after the mtrix installation, if possible.

TimWilbers

iTrader: (1)

I checked out a video camera from work. But have not been able to locate a tape for it. A Utube historical marker would be very nice.

DivinDriver

iTrader: (15)

A video camera that uses tape? Where do you work, 1995?