Took my 84 GSL on its first 200+ mile trip yesterday. About 40 miles in, it started sputtering like it wanted to backfire (never did) and struggled. This was at 80mph/4k RPM. I slowed it down a little to 70mph/3500ish RPM and drove it to my destination with no more problem whatsoever.

On the ride back home, it became more of a problem. I could cruise at 70-75 no problem but if I tried to give it more gas, it sputtered out.

If I put the clutch in I could rev it all day to the red and it sounded just fine. The engine seemed to like it when I clutched, revved it a little, and then let the clutch out to get back up to speed. It'd be okay for 15-20 miles and then start sputtering again.

I doctored it home using that method, and now this morning on the drive to work (~10 highway miles) I had no problems getting it up around 85. My fuel pump turns on when I click the key, but I know sometimes on RX7s it's more of a slow death.

My first thought was the pump and filters. Is there anything else I could be looking at? It runs perfectly in the city, and it idles just fine. For all I know it could be the float level on the carb (I have an OER and no idea what I'm doing with it, despite a bunch of reading). It was pretty embarrassing to have my car sputtering out on a highway cruise though.

 

Sounds like filter to start, then maybe pump.

Sure sounds like it's running out of fuel.

 

what are you using for carb and fuel pump?

 

The carb is a 45mm OER, and while I believe the fuel pump is still OEM I'm not entirely sure. 75k on the car. I haven't looked there yet. I'll do the filters tonight and take it for another spin.

I will note too that the gas mileage gets cut in half when it's going through those sputters. I was averaging ~13 mpg on the highway last night.

 

I know when I went with the 45dcoe I was told the stock pump would not be enough ....

 

Hmm, really? I would probably be inclined to agree with that based on my experiences. I should have noted before that I can't floor it. If I'm sitting in neutral and rev the engine, I have to gradually step on the pedal. If I put it straight to the metal then I stall out. It won't even try. Which pump did you decide on? I was reading in another thread that the pump for the GSL-SE was too much pressure for the 12A. But if I need more because of the carb what would you suggest?

Edit: In addition, could the use of the fuel pump with the carb have accelerated the decline of the pump? I've had the car for a month or so and the carb has been in it for ~6 months (according to the PO). It could explain why the problem is just starting to surface. I took a few other highway cruises before with zero issue other than the regular 5000+ sputter I mentioned.

 

Flat out mashing the gas and in initial stall out is a pump shot issue. If you can slowly work through the pump shot to floor it in a few seconds and it stalls out its a fuel starvation issue.