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Doug, ASE Certified Technician
Category: Car
Satisfied Customers: 8612
Experience:  16 years automotive and OTR repair including specialized training from Toyota and Mitsubishi
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Mazda rx7: I have a 1983 mazda rx7. It takes a long time to

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I have a 1983 mazda rx7. It takes a long time to start for the first time while pulling the choke. After the second attempt (about 6 seconds per attempt) while pumping the gas, it finally starts. At any time prior to the choke retracting by it self, the car will shut off unless I keep the throttle about 2000 RPMs. And after it warms up it will not start again until it cools. I recently purchased the car from someone who had it parked for a long time. It has 27,500 miles. I pulled out the spark plugs and they had particles of black soot on them. I also check for fuel flow from the pump and looks fine. How ever it does leak gas after it has been running for a couple of minutes from behind the center of the carburetor from a square plate being held by 4 Philip screws and I believe it has a spring inside. I has a portion in the center the moves along with the accelerator or choke. It

Thanks in advance,

Hi Moustafa,

It sounds like you are going to be in the market for a new carburetor or at the least an overhaul.

The difficulty starting as well as the black sooty plugs are both indicators of over fueling. Having to keep the throttle considerably open to avoid the engine dying also supports this. Combining this with the external fuel leakage, it is time to pull that carb and have it inspected to see if it can be overhauled or if it would make more sense to replace.
You will want to shop around for a shop for this; finding someone that still works on carburetors and is efficient with them is not as easy as it was 20 years ago. You don't want someone learning/guessing at this at the expense of your wallet. It is worth the extra money a carb-specific shop will charge.
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Customer: replied 4 years ago.

Ok great thanks. I have one more concern. Could this symptom also fall under a low compression motor? I heard that if a motor is hard to start when it's warm.


Low compression would cause difficulty starting as well as the appearance of over fueling on the plugs. Since the compression is low it would be more difficult to make combustion, so it would appear that there was too much fuel when in reality it was the right amount but just not burning. This of course would not have any impact on the external fuel leak though.

It is highly unlikely to have this issue and have it change significantly with engine temperature. Typically if your compression is low, it's low regardless of temperature.

If you wanted to test your compression first just to rule it out, you can usually rent compression testers from most parts stores or purchase one for under $50. They thread in to the spark plug holes then you just crank the engine over 4-5 times and check the gauge reading.
Minimum acceptable compression on a 2 rotor is 85 psi, but realistic compression would be more in the 100-115 range typically. 85 is just the minimum workable spec. There should not be more than 20 psi difference between any two plug holes either.