Hello, I have a 1985 Mazda RX7 12a. It misfires at idle but stays alive but when I drive it down the road it makes it 1 or 2 miles then sputters out and dies. it also misfires bad when going down hills or off the throttle. It’s a new oem fuel pump and floats bowl are always halfway full. Please help here’s a video at idle.

 

you forgot to post the video.

you can get a copy of the FSM here: Foxed.ca

how long have you had the car? if you recently got it, was it sitting for a while (years) before you got it?

did you change the filter when you did the pump?

 

Sorry here you go it wont let me upload it so heres a link, I bought the car and have been fixing it up it was previous sitting for a couple years with nothing but the block in the car. I changed the filter and put an oem pump and restored the tank. I have also done almost everything to the car including ultra sonic cleaning the carb, new plugs(they might be bad now since the car flooded so many times when I had carb issues) and wires, check compression, and base timing marks were lined up, what’s the fsm also. file:///C:/Users/macph/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/5EYHN67O/ATT00002.htm

 

The factory 1985 fuel pump has not been available for a long time. What part number/brand did you install.

 

i bought the 79-82 one from atkins rotary, its supposed to be the same pressure etc but just looks different.

 

FSM - factory service manual

so, i'm guessing ultrasonic cleaning means that the carb was rebuilt as well? if so, did you use the needles and seats that came with your kit? more importantly, did you throw away the originals?

 

i have the haynes manual, i completely took apart the carb cleaned it and reused all the gaskets and everything else, i also reused the needles and measured it when assembling back together

 

Cool - I did the same but got it from the dealership.

 

Is it possible it’s running too rich? I adjusted the mixture screw to 3.5 turns out. 3, 360 degree turns, 1 180 degree turn. I also can’t get it under 1 k or it will eventually sputter and die. Should I get new spark plugs? Any other electrical issue i could check? I also am just running a muffler so the cats can’t be clogged. Any help or suggestions would mean a lot.

 

Anyone have any suggestions please I have been working on this car for over a year and really need some help. Heres another link to a video. file:///C:/Users/macph/Downloads/ATT00002.htm

 

Your adding link wrong. Try clicking on the Manage Attachments button and add the files as attachments.

 

It only lets me send videos up to 5 seconds long and won’t show anything, does my link not work?

 

Your linking to your hard drive and nobody can access it. You'll need to place thet file on a web site that is public like YouTube.

 

Sorry he’s a link to my YouTube with a couple videos of it. https://www.youtube.com/@JasonPurdy-sy3mo

Also when I adjust the Mixture screw it does not change the rpm’s even when it’s all the way in and out. I also cant get it under 1k rpm’s with the idle screw.

 

are you sure you don't have a small vacuum leak somewhere? it might not explain the stalling you described, but it could explain the high idle and carb not reacting to you trying to tune it.

 

I don’t think so, I sprayed everywhere with carb cleaner and couldn’t get a blimp in response. It also backfires loudly almost every time I shut it off. The battery is also at 13.5V when idling so the alternator looks like it’s working so I don’t think it’s running out of battery.

 

what about timing? have you confirmed that timing is where it's supposed to be?

 

Yup I put on a timing light(it was a little off) and adjusted the dizzy to line up the leading(the groove on the right of the pulley if looking towards the car/engine) to the needle. When I did a vaccum delete I plugged the dash pots so not sure I can adjust the trailing? Is this even the right way to adjust timing? Long story short it didn’t fix it but maybe runs a little bit smoother. I have noticed that the car runs way smoother and better when it’s colder and has been sitting for between 3+ days or even a week. It seems to also get hot pretty fast but my coolant gauge says it’s in normal temp unless it wrong. Also it only backfires when it gets hot.

 

BTW, spark plugs? insulator tan =good black=too rich or oil is burning red=fuel starvation

maybe you have the leading and trailing spark plug wires mixed up ? ( I did that before )

 

My spark plugs were black and I think they are also just too fouled out from all the flooding issues I had previously so I did buy some ngk br8eq-14 so hopefully that fixes the idling issue but now I still need to fix why it’s running so rich and eventually dies(also backfiring after shutoff). The wires should be all good with it hooked up this way if you are looking at the engine. Also the coils go Trailing, leading. Left to right
T1, T2
L1, L2

 

I had the 1 and 2 leading plugs mixed up...not the t and l mixed up.....amazing the motor ran with my dumb *** mistake.

And when installing the rebuilt engine, I used AUTOLITE plugs because that's all they had on hand.....engine ran like crap. Checked to see if they were even firing, they were, but the engine ran like crap. Using NKG plugs fixed everything.

 

I'm no help, but I'm having similar problems with my '79. I'll follow this thread to see which one of us comes up with a solution first. I'm working hard on mine because I'd like to drive it before it gets cold. you can read the thread and see everything I've done so far. good luck