I'm new but have been reading the threads a while and looking for answers to a starting problem on my 83 RX-7 with no solution. I try to start it after sitting overnight and it isnt getting fuel in the carb. After months of messing with different tricks found a 3 second spurt of starter spray into the carb/intake and it fires right up, then runs like a champ. Start it during the day after that and it usually does fine. Occasionally I have to choke it out as with any RX-7 starting cold but usually it starts up well after the fuel gets going in the morning. Its the extended sitting that seems to cause a backflow out the carb and it wont refill when I try to start after a sit overnight or especially longer. Sometimes even just sitting a couple of hours is long enough to cause a need to use the starter spray now. I'm not much of a mechanic on these rotaries, and carbs are not my specialty either, so any advice is much appreciated. I'm thinking of getting a rebuilt carb put on it to just stop this mess altogether, but dont want to waste my money or time (I dont have much to blow!) if there are better answers. Help!

 

1st question.
Are you using the choke after it sits overnight when starting?

 

Q. My RX-7 won't start, where do I begin?
A. Pele has written a "book" entitled: End all for no start threads.

And to me, that sounds like your Accelerator Pump might not be working properly. If you take the airbox off and look down the primary (smaller) barrels of your carburetor while working the linkage with your hand, you should see gas squirting into your carb. If you don't, then you should pick up a carburetor rebuild kit and have at it.

When I start it in the morning, there's still enough fuel in the bowls that I can just do 3 taps of the gas, pull the choke, and crank it. If it's been sitting for a week or two, I have to crank it for a few seconds to fill the float bowls, then do 3 taps of the gas, pull the choke and crank it. ('84-85 fuel pump doesn't come on unless you're cranking. '79-83 the fuel pump is on when your key is in the position just before cranking)

Jon

 

When I try to start it after it has sit overnight (or it doesnt crank right away) I use the choke and might give it 3 pumps of the accelerator to see if I can get fuel flowing. It just doesnt seem to be getting fuel into the carb. But after it starts (using the starter spray method) it does just fine. It IS NOT flooding, EVER. There just isnt any fuel retained in the carb. I've thought about putting a shut off valve on the fuel line below the carb but thats a half *** fix. And when I (we) work the linkage my bud (who does know this stuff better than I) said he did see fuel hit the carb. We dont suspect the pump.

 

Correction on the accelerator pump info, tells you how long I've been dealing with this... my bud reminded me we recently replaced the diaphram and the pump works great. The pump is sending it fuel as it should. It aint the pump. Its definitelly coming from a carb issue itself it seems. I've been battling this so long I am about ready to purchase a rebuilt carb and put it on and be done with it... but worry THAT might not solve my problem in the end. Any words of wisdom?

 

Sounds to me like the classic coolant leak problem. Sometime in it's life this motor was overheated and the coolant seals were ruined. When it sits overnight coolant leaks into the combustion chamber so the engine fouls when you try to start it. That's happened to me 3-4 times.

The temporary temporary solution is to remove plugs, crank engine to expel coolant, clean plugs with Brake cleaner, reinsert plugs, start car and drive off.

The longterm 'temporary' solution is to use CRC Block Seal, appropriately applied per Rotary Club veterans, and drive off for the next 1-2 years.

 

Thanks for your suggestions folks. I'll start with the simple stuff and hit the plugs and try out the CRC block seal as suggested it may be on the coolant leak problem. WAY BACK WHEN I was going to buy an 87 RX-7 and on the way to the shop to get it checked out it had the coolant system blow out on it. I'm kind of gun shy on those now. From there I'll follow up with the carburator issues and may end up getting a rebuild or a rebuilt one to to stick on. Any other ideas to help throw 'em my way because I could sure use them. Sure dont want to blow this car up.

 

Another fix is to pull the intake manifold and discover the deteriorated neoprene ORings therein. Replace the old ORings either with new ones, or (and some say this is the best and the most final solution) replace them with solid disks, like quarters or 20mm freeze plugs, JB Welded into place. That cuts off water to the manifold, but who cares? I guess it doesn't adversely effect the rest of the coolant flow. I guess. But I don't know: I've never done it.

 

Freeze plugs are the best bet for plugging those passages, and it doesn't affect the flow of coolant through the engine at all. If you pick up a rotor housing and look at the cooling jacket, you'll understand why it doesn't adversely affect coolant flow.

So starting with the simple stuff first, pull the manifold, get some freeze plugs in there, top up the coolant and reinstall the manifold with a new gasket.

Do you notice a loss of coolant at all?

Jon

 

Never noticed ANY loss of coolant. I watch the coolant systems/levels .. and all fluids to be honest, religiously and it never has dropped. Check them daily pretty much. Have to add about 1/4 qt of oil every month and thats it, and that seems to be mostly leaking around my oilpan seal VERY slowly from an underbody wash and inspection.

 

Changed out the plugs (had Denso, replaced with Denso) and found no water/coolant on them whatsoever. However, did find them to be extremely fouled. Primarily light brown coloring, some dark brown and some black discoloration. Dont see how this thing was getting ay spark at all because it was so caked up to be honest. Bad thing is that I let it go a about 16 months or so between changes. For a guy who is really trying to learn about these cars (crash course here), I couldnt really imagine getting lucky enough that the fouled plugs could be my one and only starting problem... could I? Or should I still be prepared for for woes tomorrow?

 

Well 1/4 qt of oil a month makes sense, that's what my OMP burns off roughly, so that's good.

No loss of coolant, that means that it's probably not coolant o-rings (thank God, that pretty much means a rebuild, or the crazy patch above).

So the engine itself sounds mostly solid, from a leak perspective, and you've replaced the plugs. That only leaves you with air, fuel, and compression.

Since compression tests can't be easily and reliably done on a rotary without the mazda tester (there is a way, but it only gives you a general idea), I'd say bite the bullet and rebuild the carb.


Hey, you didn't mention if your fuel filter had been changed or your tank cleaned.... Restriction in the fuel supply might do it...

Jon

 

anybody have input/advice as to whether or not you can or should put a Holley 390 on an 83 RX-7 to replace the stock carb?

 

the fuel filter is new and running clean. The filter I replaced was actually clean when it came out but I went ahead and changed it anyway since I had it down. I run regular (unleaded) fuel in it because it doesnt like the higher octane stuff, so I was told by the original owner and by other owners. Should I be running high octane fuel? I'm thinking rebuild or replace on the carb at this point. Still wondering, can a Holley 390 fit on this thing? I'm just asking!

 

Have you checked the float bowl windows when it isn't starting? The fuel level should be half way up the glass. If the fuel is at the proper level does the fuel squirt into the carb when the accelerator is pressed? If the answer to both of these questions is yes then lack of fuel in the carb may not be the problem.

How old are the battery cables? If they are original parts they probably need to be replaced. They can be clean and look fine, but be corroded inside the wire. This is not an uncommon problem. The starter does not get enough power to turn fast enough for the engine to start. It would be more apparent when trying to start a cold engine. Starter fluid is more easily burned than gas so it might be getting the engine started at the slightly slower starter speed. Just a thought in a different direction.

 

Like the post above, check the fuel level in BOTH the glass windows, front and back. Check them after the car has been sitting. Check as the car is running, after you turn it off, and then again after it sets.
Post your results.

You are getting to many ideas, and too many directions to follow. Let's start with the carb and go from there.

Also, have someone pump the gas as you look down the carb. Can you see it squirting fuel in to the carb?

 

Don't even think about a Holley at this point. You don't know what trouble is until you try that route.

 

Yeah, if you really wanted to go Holley, get a Racing Beat Holley 465 with intake. You don't want to take a Holley that hasn't been tried and tweaked for rotary application and try it out, you're asking for no end of headaches there.

Stick with a stock carb, or modified stock carb.

As for the fuel issue, the only thing octane does is resist detonation caused by compression. That's it. That's all. Since our motors are no where near high enough compression to pre-ignite the air/fuel mix from compression alone, the only way the fuel in our cars ignites is when the spark plug fires. Running higher or lower octane fuel will give no advantage, and in fact the presence of additives in the high octane fuel to resist detonation may decrease power slightly. But it probably wouldn't be measurable.

To give you an idea, when Mazda raced these in the 80s, they brought their own 83 octane fuel with them to the track because all they could get was the high-octane race gas that the high-compression piston cars were running.

Honestly, I think you should get ahold of Sterling or Rx7Carl and get those guys to rebuild your carb for you. At least then you'll *know* you've got a carb that's done right and made to run your engine.

Jon

Edit: 74Rx4 has a point... even if the carb is good, when a car is cold it takes more to get it started... Replacing battery cables costs like $20, but you have to make 'em yourself. It's worth every penny though.

 

Will change out the battery cables immediatelly no matter how they look. From there will get the carb checked out. After pulling out the old plugs and putting in new it had no water in the cylinders and when I went to start it up cold today after about a 24 hour sit it took some serious pumping of the accelerator and naturally use of the choke, and about 4 key turn tries, but no starter spray this time (first time in months). Think there may just be a carb tuning issue that I am no good at adjusting at all. I would rather spend a few dollars for someone to do it right than mess it up myself after all the work I've put into it up to this point. Thanks for the help folks. Anything you think I'm missing, yell out.

 

I'd say run a can of seafoam through the tank for gooid measures.

 

I have a 1987 RX-7. Ok so my fuel pump is whining but it wont pump any gas at all! So I went out and bought a brand new one and it is doing the exact same thing. Its almost as if it is blowing instead of pumping. This is very frustrating and if anyone knows what may be causing this please let me know right away! Thanks.

 

I NEED HELP!!!!!!!! (^ look^ at ^above ^massage ^)

 

^ try the 2nd gen section.

 

my friends car is a 83 efi turbo and they have 2 fuel pumps make sure there both working or it wont start

 

T-Rex, loosen the fuel cap before letting the car sit overnight. If the problem seems to go away, you have a fuel tank venting issue. Most likely cause, is the charcoal canister under the hood, as the tank vents thru it. The tank vent hose attaches to the smaller hose fitting of the CC, but it has a tiny orifice inside it that can easily plug up.
I had the fuel tank venting issue on my 83, and simply drilled out that orifice in the charcoal canister, problem solved.