when i barely touch the gas it revs up to 4k then i push down a little more and it cuts out and sputters

 

Need a little more information.

What year is your rx7?

You say when you barely touch the throttle it revs up to 4000rpm, do you have to press the throttle more and more untill it reaches 4000 or with a light light touch of your foot on the throttle does it jump to 4000 from idle?

 

running out of gas will kill older fuel pumps, either that or you've got debris clogging the filter or the filter screen in the tank.

 

yea i have to keep pushin slightly up on the throttle and it will go up to 4k then i give it more and it will sputter,
its a 1986

 

Seems to happen a lot when people run out of gas. I think it's from the crud floating on top of the gas in the fuel tank. Try replacing the fuel filter. Besides that it might be the fuel sock (a little plastic net around the fuel pump intake). You could also try some Techron concentrate cleaner, though the gasoline additives you get from filling up at the pump will do the same thing. It'll just take a few fill-ups to get the same amount.

Oh, and 3800rpm is when the secondary injectors kick it. Hopefully those aren't clogged.

 

That's very unlikely, because running out of gas causes the engine to stall, which immediately turns off the fuel pump.

 

true, but they are also cooled by the fuel, which is why everyone and the manual says "do not run the tank empty"

i've had this problem twice.... once it was my PD going bad.... then it was the pump itself. after many times of literally running out of gas, using my GSL-SE as my long distance car for a year for my job, i burned the pump out running it dry

 

I know that, but you don't seem to have understood what I said. If the engine stops, the fuel pump's power is cut straight away. If there's no fuel, the engine can't run, so the pump won't run either.

 

Yeah but trying to start the engine after the fuel has been depleted causes the pump to heat up, thus burning out.

 

Do you really think a fuel pump is going to burn out from such a short time running dry? That would have to be a very poorly engineered pump, not one that's proven to last for well over 15 years or normal use.

 

the fuel pump should cut out. This is because its circuit is ran through the AFM so there has to be some air coming in for the pump to run. BUT if your lucky like me and the spring the AFM is bad and doesnt push the door back all the way, your AFM thinks some air is coming on and your fuel pump is running anytime the key is in run or even accesories. yup it sucks, might be rare but it can happen.

 

island-fc... when you ran it dry all the garbage thats been collecting in your tank for who knows how long probably clogged the sock. or/and filter. When you refilled the tank you also stirred all this garbage up. This is why they say dont get gas at a gas station when they are filling there tanks. Well anyway that probably clogged something. at lower rpm you dont need as much fuel when you get to the hirer rpm you engine cant get enough fuel. Just a guess hope it helps

 

When it gets near to the last of the gas the dirt collected in the 20 years of life the car has had becomes more concentrated, and it sends all the crap into the fuel filter.

Not only that, but as long as air is still being sucked through the afm the fuel pump will stay running, at least on an S4, sometimes the car bucks and tries to go just as you run out. Running dry hurts the pump. Unless you always decelerate in neutral or you have an automatic car, you will still be sucking air through the afm if you run out of gas.

That with the increased back pressure from the excess debris now stuck in the fuel filter, will make the car run like crap, and the fuel pump will crap out soon. It's happened to alot of people, not just with RX-7s.

If the fuel pump was new, this wouldn't be so much a problem, as well as if you had a fuel tank cleaning done every few years.

It's happened to me, it's happened to people i know, my dad has work in service as a manager or shop foreman for almost 20 years, it's happened to plenty of people who've come in to where he works. The first thing he said to me when i told him my pump went out was had i run out of gas recently.

If you still want to argue it we can start a poll.