85 12a ran fine yesterday. Now it won't run.
 

Hi guys, new to the forums and still trying to figure rotaries out. It ran fine yesterday and I filled it up and added 8oz of MMO to the fuel tank per your guy's recommendation. Ran fine after that. Also saw oil was lower than half way so I got it to 3/4. Walked out this morning to start it. It's a bit chilly here so I gave the Weber the usual 3 pumps and it fired right up. Idled at 1000rpms and I said: alright, it's just cold. So I gave it ten minutes to warm up. Engine temp was perfect and smelled more like oil than usual, still idling at 1000rpms, normally idles at 1500rpms. So I gave it some gas to see if that would do the trick, nothing. The car died. Started it back up and Idled at 800rpms, gave it some gas and then it died again. So I checked the oil, it was a touch higher than full so I drained just a hair. Pure gold came out. I have no idea what to to.
Please help.
The only other thing I did was tighten the omp bolt on THE carb. It was loose.

I don't know the background of the car but I would do the usual. Check the plugs, check for good spark and fuel. When you revved it and it died, what did it sound like? No fuel or something else?

It's possible that carburetors arent for you.

How many carb'd cars have you owned/operated before taking on a "weber" for a daily driver?

It takes a lot of experience and know-how to make a carb run every day. You have to bathe yourself in their inner workings and get good at self diagnostic to make everyting work properly.

Like the above posted, I have no idea any other details of the car. I can assume that the engine has no cold start mechanisms, being a weber.

Having said that, its not going to start up and run like a 2015 car. It may feel like everything is tuned in proper at running temperature but when the engine/carb/oil/parts/etc are all cold you have a ton of variables bringing on the need for a richer mixture. Knowing how to start a cold rotary with no choke isnt for those who havent been around them for some time.

How are you starting it?

I recommend a few strokes of the accelerator BEFORE even turning the key. This will load the engine with fuel while minimizing the risk of totally flooding it.

Once it starts, it could take 10-15 minutes of running for it to go to your "normal" idle setting, which is absurdly high for what I can only assume is a stockport 12A@1500 RPM.

Further, ignition plays a huge role in cold starts. I had one this winter that ran totally fine always except the first start of the day, where it had the weakest spark I have ever seen in an HEI system. Turned out to be battery cables and a weakening battery.

What is the setup you are running exactly? Weber 48 IDA? Is the engine ported? Ignition setup?

It's also possible you have a junk accel pump, seeing as the engine was dying when you stabbed the pedal@running temperature. It could also be a dirty or sticking weight or check ball...

I pump the accelerator 3 times before starting in the cold weather, the engine fires right up.

The engine will idle fine, albeit low rpms, and keeps idling @1000rpms until warm(20 minutes of sitting at idle) and stays there. The problem arises when I press on the gas and let my foot off. I'm not stabbing the pedal, just gently giving it gas and as soon as I let off, it putters down to 800rpms, then 6, then 5, then it dies. I do believe i might have a bad accelerator pump, car would stumble when I stabbed the gas(when it was running normally of course)
I realize now my initial post wasn't too clear.

P/O says engine is streetported, sounds and eats fuel like a streetport.
Dual MSD 6AL for the ignition.
Fuel is good, spark is good.

Now that I think about it, it could 100% be the MMO dislodging stuff in the fuel tank and clogging the filter. I have a racing filter from the P/O installed. Would that be the only one?

In my experience tuning my own weber 48, and a couple motorcycle carbs, a tendency to idle lower than usual, or stalling at idle indicates a rich condition.

So something happened that caused the weber to not get as much air, or something was dislodged allowing it to meter more gas. Before you go and start arranging sacrificial circles to the carb gods, go over the basics please.

See if it runs like that in the middle of the day, there could be enough of a difference in temperature. Just in case you didn't know, carbs will run differently at different temperatures. I'm not assuming you don't know anything about carburetors, I just want to make sure we're on the same page. So it could just be attributed to a real cold day.

Check for vacuum leaks. I know I said that your problem may be an indication of a rich condition, but I may be wrong. That was the number one source of all my woes tuning my own weber! You never know what happens to your car when you aren't watching it. Maybe a hose finally decided to make your day and develop a crack, or something has backed it self out from driving (carburetor to manifold bolts). There are numerous ways to hunt for vacuum leaks. I won't go over all of them, but one that hasn't let me down is spraying wd-40 or carb cleaner around suspected vacuum leaks and having another car friend watch the tach for anything irregular.

Assuming you don't have the rats nest (and please excuse me if I'm wrong about it starting without a rats nest, I have never worked on an RX-7 with a rats nest) take off all the hose connections going to the manifold and plug them and see if it still idles like that. What this is doing is isolating the manifold from the rest of the engine components that require vacuum. We need to see if the engine can idle on it's own not hooked up to a brake booster or vacuum advance. If you have an air filter, remove that as well. A big enough clog in the air filter could be affecting it as well. If it runs perfectly, then it's another component that is affecting it.

Make sure your fuel delivery is good, change your filters. There should be one in the bay before the carb, and one under the tank. After that, check for adequate fuel flow, and pressure. I'm not sure what the specified liters per hour is, but I'll try and look that up.

Check all your ignition components, make sure your dizzy cap and rotor aren't corroded to hell. Make sure there's no cuts or kinks in your wires. Make sure your spark plugs aren't so fouled, and in good condition. When you play around with your ignition components, remember where the spark plugs go. L means lower, T means top. 1 is the rotor in the front closest to the radiator and 2 is the rotor closest to the firewall.

Start with the basics and report back. If any part of this post doesn't make sense, please don't be afraid to ask!

Alright, day two.
I took the carb apart anyway to fix my accelerator pump, lubed it all up and it feels much smoother, but I figured that wasn't the problem so I checked the rest of the bits. The check ball is sticking ever so slightly, so that might be my problem. I'll clean that up tonight and take a look tomorrow night after my rugby game if I'm not too tired. I visually checked all of the ignition components, going to double check spark too.
Now, when it drove, I noticed that if I held it at 3500 or 4000rpms, it would spit a little bit when driving, i.e. little pops every now and then, but if I jumped on the throttle, it would have no problems whatsoever.

• Checked air filter, no clogs
• No rats nest
• No difference depending on temperature
• Fuel pressure regulator is set for 3.5psi, the specified psi
• Will try searching more thoroughly for vaccum leaks when I have the carb back together, thinking its the check ball.

Okay sounds like good progress. While you're at it, make sure the float levels are set to spec on the carb. What kind of weber do you have? IDA, or DCO?

Float levels are important, I remember there was a point where I switched out the floats from my 45 DCOE into my 48 DCO just because they looked nicer. :lol:

Anyway, I assumed the levels were the same but they were not. The droop allowed for the needle valve to hang open and the brass was rougher so it would get hung up and either allow fuel to keep flowing, or not at all. Of course, this brought along running issues like stalling at idle, hard to drive, etc. Once I swapped back to the old float, it ran normal.

Okay, got it fixed. It was that sticky check valve, also replaced spark plugs. Now its overheating.
When I was replacing the spark plugs I knocked a loom. No biggie. Started right up and everything seems to be okay but within one minute the temperature gauge had shot up to hot, and past it. I immediately shut it off. Opened the hood to let some heat out, except there was no heat. None of the hoses were hot and the beehive was cold too. I let it rest for a minute while I took the sunroof out and looked at that loom. There was an exposed wire, but the p/o gutted most of the systems so I figured it was left over. I shut the hood and started it back up. No problems starting, Idling around 1000 rpms, and it sounded great, no lumps or burbles.

So I took it around the block. Now this is where things get interesting. It seemed to be stuck on cold, but after a bit it moved to the second thick mark in from cold. Sat there for a bit, then shot up, almost hitting hot. Let off the throttle and it dropped back down to what it would look like when cold, got back on the throttle, and it didn't move. Took it up to 6000 rpms, no problem. Got to a stop sign and while it was idling, the temp shot back up, so I decided to turn it around and head home. Temp kept rising, then dropped some and then rose past H, luckily I was only 50 feet from my driveway. Shut it off and opened the hood. Hoses seemed warm, but not warmer than normal. Beehive was warm, but not as hot as it normally gets after a drive to the market. Checked that wire and looked to see if there was any place where it might go. Attachment 754042 This is where the wire seems to go. I looked in the FSM and couldnt figure out what this part is. The wire is yellow with a redish purple stripe going around it. Any ideas???? This part is right below the bee hive

Thats your engine temp sensor so no wondering you have temp issues . Put the wire back on and you are good to go

This thread might help.
Details on checking the sensor and verifying the dash gauge.

https://www.rx7club.com/1st-generati...gauge-1074146/

Cool, I'll take a look!
Question. Could I just pull this out and replace it with a mechanical gauge? If the probe and the nut size was the same?

Absolutely. The OEM sensor is engineered at that spot for a good reason....so what are you going to do with the dead gauge in the dash at that point?

:cool:

Just ignore it:lol2: