Blind Dr

I have been working on this project for most of the spring and summer with some really goood results. The car has been sitting for a long time, (see my other thread) and I did get it up and running. It was running great and I started to develop a carb issue with it. It was having a tough time starting, but once it started it would run smoooth without any issues, a little hesitation but not much.

So I decided to remove the carb again, and rebuild it. After putting it back on the darn car runs rough, there is no gas in the front sight glass, I don't see any fuel being squirted into the primary when the pedal is pressed and when it does run at idle if I give it any gas it dies, right now. I am leaning toward a float issue? Not sure though. I have replaced the duel filter already before it was started.

Any ideas????

74RX4

iTrader: (10)

Did you replace the needle valves? New ones often stick open or closed after a rebuild. Sometimes a couple well placed taps on the top of the carb with a mallet or the handle of a screw driver will un-stick them. A drop of light oil on the tip of each one while you have the carb open can help. Did you clean and replace the 2 weights and *****? If the rear bowl is empty the accelerator pump will have no fuel to squirt into the primaries. It's inlet is in the rear float bowl.

Kentetsu

^^^ what he said.

Blind Dr

I did replace the needle valves, the car does run. It seems like it is running out of gas. So it is getting some gas, so I think the valves are working. I am thinking float adjustments?

Auto Tech

I would go with the float adjustment. What sort of fuel pressure do you have at the carb? Have you also checked the volume of fuel flow?

Blind Dr

I haven't checked the fuel pressure. It did run just fine until some sediment made its way into the carb from somewhere in the system. It does have great volume though. I never had any fuel shooting into the primaries before the rebuild when it was running. Odd....

74RX4

iTrader: (10)

The fuel level should be 1/2 way full in the site glass on the front and rear of the carb. A small mirror can help you see the rear one. The needle valves are opened and closed by the action of the floats. They open and close frequently as the fuel level in the bowls change. If they are sticking, some fuel may get through at first then not enough as you press the accelerator. I would recommend adjusting the floats only if you are very sure they are not correct. Unless you bent them during the rebuild they probably are OK. Look through this. Troubleshooting is down a couple pages.

http://sterlingmetalworks.com/the_nikki_carburetor.htm

Kentetsu

DON'T MESS WITH YOUR FLOATS!!!

If one of the bowls is empty, then the needle is stuck. Just bang on the darned thing with something non-damaging until you shake it loose. You should be fine after that. Trust me, this is not a new issue.

DivinDriver

iTrader: (15)

^^ yep. It's virtually impossible for a float to accidentally be so far out of adjustment that the bowl would be empty.

Stuck needle, or perhaps the float got hung up on the side of the bowl during reassembly. Or a really, REALLY clogged inlet screen or debris above the needle seat.

Blind Dr

If the needle is stuck will it still get enough fuel to start? The car will start but runs terrible and then out of gas...

DivinDriver

iTrader: (15)

If one needle is stuck but not the other, you're only feeding fuel to (mostly) one rotor, plus a little through the crossover slot to the other. Fuel feed is way out of balance and 1/2 the normal amount.

Blind Dr

Well I have had the carb off 2 more times and I can honestly say it has me beat. I have gone thru everything and I am unable to find a cure. I have the fuel bowls looking great yet it still floods the carb. I have not checked the pressure of the fuel pump yet, but I am coming down to having to much pressure from the fuel pump. I purchased it from O'reilys and i don't know what the output is. So I am towing it to a friends garage and have him look it all over.

If this doesn't work, it is going up for sale.

Kentetsu

I know this stuff can get frustrating, but try to hand in there.

There may be info in this thread that can help, it covers the installation of an aftermarket fuel pump, along with a pressure regulator to tone it down to what the carb can handle: https://www.rx7club.com//showthread.php?t=529605

Not knowing the specs on the pump you have, I could easily believe that it is too high psi. The Nikki only needs about 2psi, which is very rare.

But since earlier you mentioned that you had one float bowl that was empty, you also have either a float that is hanging up (this can happen during installation, if they don't hang just right then they can get stuck), or the needle is sticking.

I think I would just bang on the carb until that float or needle starts behaving, then throw a Holley fpr on it to control the pressure. They're only like 25 bucks or so.

I think you're getting close.

Blind Dr

Thanks for the responses. I finally looked up the specs on the aftermarket fuel pump. It shows 2.8-4.5 psi range. Looks like the pump is a little to much. I will have to get another one, just not sure where to look this time, any suggestions?

I did take the car to a friend who owns a garage and although he does not like the rotary engines he is going to look this car over for me and see if he can resolve the carb issue with it. After discussing it with him his first thought was fuel pressure and so it looks like he will be checking that for me.

It does get a little trying especially when your "skillset" is not very good. I have very little experience and have had to cram in tons of information to work on this car, which has really biten into the family time. I thought it would be a better reward than it has been and seem to have fallen short of my goals. I hope that it can be resolved soon and maybe I can move onto the next issue when it develops.

Kentetsu

Rather than getting another pump, I would just add a regulator to the system. You can find them at Summit, are simple to install, and don't cost much. This will reduce the pressure to what the carb requires.

Directions on the installation of the fuel pressure regulator can be found in the link I posted above. You could easily install the regulator yourself in just a few minutes.

Blind Dr

So is this rocket science or what? Talk about getting frustrated, damn! I took this car to a local garage who has experience with the rx7. He has 2 guys that both own them or have had them and he is from a mazda dealership. He has not been able to get this carb right. After 2 weeks he finally tells me he doesn't know what is wrong.

So...I haul it to a MAZDA dealer. I talk to the service manager and ask to speak to one of his techs who has experience with this year and model. After a conversation with him and the service manager, they assure me they can fix it correctly and have me up and running. 3 days down the road and I stop in. the service manager avoids me like the plague. The tech walks over and scratches his sack and replies; " I am not sure what is wrong with it" I threw my hands up in the air and walked out of the stealership. They called later and i told them I would come over and haul it away. So Monday morning i am picking the car up. Oh, and the funny part. The service manager told me my bill for diagnostic service was 400 bucks. I told him to try and get that out of me when I did not agree to a diagnostic fee but agreed to pay for a repair. The owner of the dealership will be there when i pick the car up and we are going to have a conversation about this one.

So any ideas? I mean seriously..I have very limited mechanical ability and I rebuilt it several times and it ran. Yet these certified mechanics can't get it to run. Hmmmm sounds fishy and stupid but oh well. Looks like it is time to park it for awhile and cool off. Maybe when the fall rolls around I will have a better attitude about it.

ray green

iTrader: (14)

$400 dollars for "diagnostics" is just plain wrong and probably illegal, especially since after whatever they did they have no idea what is wrong ie, nothing was diagnosed. You are right, it's not rocket science but there are a variety of things that could lead to the problems you are having and they need to be systematically run down.

Obviously this Mazda dealer isn't up to the job, but that isn't unusual. After all, Mazda dealers are in the business of selling new cars, not fixing really old ones. And the current generation of new car mechanics only knows how to plug things into computers, they really don't know much about carbs.

When I got my first carb fueled RX-7 I had about as much experience with them as you do. Over time and with some help from folks who know better I learned how to make it work. And if I can do it, you can too.

BeenJaminJames

Stick with it bud, we'll help 'ya. I got my start with carbs on the most wonderfull @$%#&*% nikki-carbed 12A (I wouldn't trade it for the world). You don't wanna know how much frustration I had to deal with, and the fact that because it's not either fuel injected or a edelbrocked V8 meant no help for me either. Most shops turned me away at the door because of the rotary engine, and the ones that tried to help were clueless. Forget the $400, that shop has no right to charge you for diagnostic services if nothing was diagnosed. Period. Hang in there, there's enough collective knowledge and experience here in the first gen section to solve ANY issue. I mean it, I'm a member of many auto forums, and spend way too much time studying technical theory, and I must say this is probably the most knowledgeable auto forum on the net. In short, if you can't find the answer here, engineers haven't asked the question yet. Don't give up, you're in good company.

rotornoob

iTrader: (2)

with that much psi on the fuel system, you should be flooding the carb, not starving it. i would inspect the floats and make sure they are not sticking on the slides. also the needles are a pain but with a little tinkering they should come loose. if thats not it, maybe check your fuel lines and filter to make sure there is no blockage or leaking somewhere. my first carb was like that and it took me 2 weeks and 2 rebuilds to figure out that the needles are a pain in the ***.

justinfox

iTrader: (3)

Check to make sure gas is squirting from the inlet hose. If it is just dribbling a little bit then your fuel lines/ pump may be blocked up. I had that problem recently and I had to drop the tank to get all of the crud out that was blocking my lines.

Try not to get frustrated, I worked for 2 months at least 3/7 days a week after work before I found and corrected the real problem. Make sure everything is very clean a little bit of dirt can cause big problems.

Blind Dr

Thanks for all of your encouragement. I have the car back home in my garage again. Long story short, I told the dealer to sue me, and I hauled the car off. I am going to wait before I tackle it anymore for the heat to die off a little bit as I don't have AC in the garage. Maybe I will start messing with it next week sometime.

It was flooding the carbs when I brought it home and looked at it. It still was having starting issues and would only run for a short period of time. I think I will start from scratch again and see what happens. But now, I am off to the lake to do some swimming and relaxing for a few days.

Blind Dr

Well how about a little update....Found someone local, from this board who has come over and is helping me with the carb. It turns out that it had springs installed in the floats which were to strong and would not allow the floats to close. So after removing them and finally getting the float level adjusted properly, we can see the gas in the glass level front and rear were it should be. Now the car itself will not idle properly. It wants to run irregular at a low rpm. Almost like a small miss???? I pulled the plugs and the L2 Plug was flooded. I put in new plugs and she started right up and ran great. After it warmed up it started to run rough again.

So, we are trying to chase down where to go. Does this carb have an air/fuel mixture screw and if so where is it located?

It also sounds like the "goose valve" if I have it correct is making some noise. Any ideas?

I am coming to the point that I am ready to sell the vehicle just due to the fact that I don't have the knowledge to work on it. So maybe soon it will be for sale. Maybe someone will have some ideas.

Kentetsu

Yes, there is a mixture screw on the driver's side of the carb. Head over to www.sterlingmetalworks.com for decent instructions on how to "Tune the Nikki" (that's the name of the section you will be lookning for).

Basically, you turn the mixture screw until it runs best. Then, adjust the idle speed. Then, go back to the mixture screw again, then back to the idle. Just keep doing that until you get to where you want to be (800 - 1000).

If the float bowls were full, then that means that the float needles aren't seating properly to shut off the flow. It's been several years since I've rebuilt one of these, but I don't remember springs on the floats. I do remember metal tabs that had to be positions exactly right in order to keep the floats from hanging up and filling the bowls.

Most likely it began to foul out when it warmed up because the idle mixture is too rich.

I can't believe that you're still chasing this dog! Talk about a string of bad luck! I think you're getting close though.

One thing to keep in mind, especially since so many others couldn't find a problem with the carb, is that a lot of times an ignition issue will look an aweful lot like a carb issue. So then you start working on the carb, screw that up, and end up with multiple issues all pointing back at each other. Even though you have an obvious carb issue (bowls full), it might still be worth while to go over the ignition wiring just to make sure that everything is plugged into the right spot.



.

Blind Dr

Thanks for the response.

Where is the idle screw located? I started the car up today and it ran really rough, like it is still flooding plugs but I was able to drive it a little bit, not far just in my neighborhood. Once I figure out where the idle screw is, i will start to adjust it as you have described. I did notice the gas level in the glass was correct, about halfway. So that looks good, or maybe...I was told that perhaps I should send the carb off to someone who rebuilds them and have it gone thru to make sure everything is correct. I was hoping to have this thing perfect by now, but as winter is setting in, I will have to put it back in storage. I am coming to the point of putting this car up for sale, as my frustration level has been exceeded. I just don't have the patience to keep messing with it with the limited knowledge I have. Sometimes it is better to just surrender and admit defeat.

As far as the ignition goes, I was going to start replacing wires, cap, etc but was hoping to get the carb issues fixed before I sink anymore cash in it.

Soooooo....any other thoughts?

kutukutu1

iTrader: (5)

Look man relax. my 7 when i bought it the guy that had it rebuilt the carb backwards, literally and the car would idle at 3k. i had to pull the carb 28 times to diagnose the issue and finally get it working, but after that it was a dream to drive. Go to sterlings webpage, the link was given by kentetsu. but its very close to the engine on the left side of the carb, if you cant see it look for a type of metal cap which is a tamper proof cap, your gonna have to saw it of to remove the cap, i doubt it still has it though. follow sterlings tuning in his website. everything will be clear. if you have the rats nest removed make sure everything is correctly connected and plugged for the vaccum lines and dont plug the boal vent in the carb. good luck and hold on man these cars are an experience not a regular daily driver of get in and drive. Best part is actually understanding your car like the back of your hand.