Chuckydaphish

So, bought this mazda RX-7 1984 with a 12a. Changed oil, put in new fuel pump, new spark plugs ,fixed parking brake, changed transmission fluid. Car ran great in driveway. Made an appointment for inspection, pulled out of driveway and headed up the road, made it about a 1/3 of the way up the hill and the rpms dropped. Car stalled and would not restart, finally got it started and it barely runs, extremely ruff, will not increase rpms. Checked for spark and it’s good, also getting plenty of fuel, any suggestions would help.

Toruki

Was it a stock fuel pump? Read the forums here for a while and you eventually see plenty of posts where people replace the fuel pump with an aftermarket one that runs at a much higher pressure than the three to four PSI that the stock pump provides and that the Nikki carb likes.

You can get a stock pump new from Mazda.

The other really common problem with cars that have sat around for a while is that the gas tank is full of crud and the filter gets clogged. There's maybe enough fuel supply for idle but not for driving.

Chuckydaphish

Forgot to mention, dropped fuel tank, coated it. Put a new gauge in it as well, and yes stock fuel pump, also a new filter. and as I mention plenty of fuel. It’s definitely something other than a fuel issue, I also tried dumping some fuel in the carb while the engine is doing the ruff idle, nothing changes, no rpm increase.

Chuckydaphish

Also, drove car around I driveway and yard before hitting the road, everything was running great, also pulled fuel line off where it hook to t the carb and turn the key, plenty of fuel.

mazdaverx713b

iTrader: (91)

Running issues such as this are commonly traced back to fuel issues. Seems you have done a lot of preventative maintenance already. Have you gone through the carb yet? Its common that they need thoroughly cleaned and reassembled with new gaskets. Sediment in the float bowls can rise under increased need for fuel and can clog the jets. Once at idle the sediment will settle again and the jets will be free. Its a nasty cycle that can have you chasing your tail. If you have not rebuilt the carb, I would suggest that as the next step in diagnosing the running issue.

speedracer_not

had the same problem going up hills, car would sputter and die.......new fuel filter fixed it.

if you changed the fuel pump, I hazard a guess that you changed the fuel filter, although you didn't mention it.

red spark plugs insulator screams lacking fuel. insulator is supposed to be tan or light brown

Chuckydaphish

Yes changed fuel filter as well

Chuckydaphish

How about a clogged catalytic coverter? Would that cause this?

impulsive-rx7

iTrader: (2)

Haven't seen a catalytic converter on an RX7 in a long time. I've had a leading spark plug wire work itself off the distributor just enough to lose conductivity and cause rough running condition. Hopefully you still have all your apex seals.

mazdaverx713b

iTrader: (91)

A clogged cat would yield extremely higher than normal exhaust temps, excessive backpressure, and little exhaust output from the muffler. Even at idle you'll have a strong exhaust output at the muffler. A clogged cat would cause running issues at all rpm ranges.

MM54

You replaced the fuel filter, but did you clean the carb bowl inlet screens? There are small screens on the banjo bolts where the fuel lines enter the carb bowls which could clog up, and you'd still get plenty of fuel from the return (since a clogged inlet screen would look the same to the incoming fuel as a closed needle).