therotaryrocket

My 83' RX-7 GS 12a has been bogging down. If I use all of the fuel out of the float bowls on the carburetor the gas tank is clogged so it can't keep up. I took the gas tank out about 2000 miles ago and had it flushed at a radiator shop in something like cotsqwik soda or something that was boiling overnight. after re-installation using a new fuel filter the problem was seemingly solved, after another 500 miles the fuel filter clogged up and the problem persisted, at that time I changed the fuel filter again and it was doing okay but if i would floor it from a stop by the time i got to third gear it would usually bog down. then after 700 miles later I changed the fuel filter again, now it really sucks and will bog down in normal driving. Also the car has a new fram universal electric fuel pump, and a mr.gasket fuel pressure regulator. i needed the fuel pressure regulator at first because it would cause the carburetor to flood the engine, but now i opened the fpr all the way open so it doesn't restrict fuel since something else is obviously doing so. I was wondering has anyone had any similar experiences? does anyone have an idea for me to try? I thought about putting a fuel cell in the stock location but then i have to custom mount it, run a custom filler tube, and run custom feed/return lines. my latest idea is to find a banjo bolt that would fit in the drain bolt location with a (5/16"?) fitting for the fuel supply. that would be temporary because eventually if i swap in my s4 nonturbo engine keeping fuel injection i will get the s4 fuel sending unit welded on to the top of my tank so i can use the in-tank fuel pump(unless i put in a fuel cell.) btw i did search quite a bit, didn't find what i was looking for so hopefully someone can help me here. thanks, zach

trochoid

iTrader: (6)

I had a similiar problem on one of the 7's I bought and it turned out that the fuel pickup tube in the tank was filled with rust. The car would idle, but as soon as you gave it any throttle, the engine died.

I bead blasted the the pickup tubes, problem solved. The filter sock in the tank had a split in it and that allowed the junk in the tank to get sucked up.

Lee Lyons

or you need a new fuel filter

therotaryrocket

oh yea, when i changed the fuel filter today the color of the fuel on the output side was dark brown as if maybe some rust? atleast that's what i'd imagine. i've heard of putting a sealer in the tank after flushing it, but then i heard it didn't work(and i don't see it working on bare metal that might have a rusty surface).

therotaryrocket

trochoid, did you have an s3 model (84-85), they have a removable sending unit style pick-up tubes, the ones on my tank are like welded on or something so if I bead blasted them sand would enter the tank.
Lee lyons, i replaced it like 3 or 4 times in the last like 3,000 miles.
oh, and i never mentioned, i'm kinda restoring this car as it was sitting since 99' so it wasn't driven until i got it and i've only driven it like 3,000 miles total.

Rogue_Wulff

Check to insure the fuel pump isn't getting clogged. I ran into this on a car that had been sitting for a while. The pump got so full of stuff, it totally quit pumping.

therotaryrocket

good idea, i got a couple of stock pumps, i may try it out. but if i can find out what size thread the drain bolt in the bottom of the tank is i can probably make a new fuel feed from there. using like NPT fittings or something.

Wankelguy

There's a section of the pickup tube inside the tank that runs horizontally and gets filled with rust. I took an old bass guitar string and bent a little hook on the end, then chucked the other end in my electric drill and roto-rootered the pickup tube out. It worked for a few months, but eventually got clogged again. I finally replaced the tank.

trochoid

iTrader: (6)

It was an S3 tank, but the idea is the same. Sounds to me like the tank needs to come back off and get flushed and sealed, or replaced.

therotaryrocket

wankelguy, where can I get a new tank? maybe i will flush the tank again and then get a new pick-up tube welded in or something. I haven't came to a conclusion on what to do next, tomorow i'll take the tank out.

Kentetsu

Before you grab a new tank, you might want to do a volume test at the carb just to make sure that a fuel supply issue is causing your problems. Any chance that the crud has infested your carb? Maybe your tank is no longer the issue, that's why I would check fuel flow before ripping parts out. Just my .02

squagles

hey i'm having the same problem and was wondering if a gsl-se tank and just a gs one are interchangable?
my se's tank is rusty but my old gs tank should be fine.
thanks.

therotaryrocket

well, now i got the gas tank out. i rinsed it out with water, i don't know if that's such a good idea but when i first had it flushed at the radiator shop the guy there rinsed it out with water. I filled it with water then stuck the running garden hose in the filler neck opening and closed off all the holes except the fuel supply and it flows slowly. so I did as suggested before and took a guitar string(i didn't have a bass) connected it in my rotary dremel tool and cleaned out the fuel supply tube on it. but I want it to last longer than a few months. on monday i'm gonna take it to the guy who flushed it the first time and get him to weld on a new supply tube hopefully using stainless steel or something that won't rust and probably 3/8" diameter and reduce it down to 5/16" like the rubber hose that way the chance of it clogging up is slimmed down. well, couldn't i just drill a hole in the top of the tank next to the original fuel supply tube and put a tube straight down about 1/2" off the bottom of the tank(with an angle cut at the end of the tube) and weld it in place at the hole in the top? or is there some special place inside a baffle that the pickup tube must be?

therotaryrocket

squagles, it would probably work but i think the -se tank has special baffles inside for the fuel injection which means another problem may arise(no fuel in high g-force turns, or stops, or starts). maybe if you kept the tank above half full it wouldn't matter.

SparkienSuggah

or you can go completly homebrew.
If you cut the driver side frame rail and move it into the trunk, and cut out the stow-spare well (and put the stow spare in the trunk, or leave it totally behind) a Jeep YJ tank will fit.
you need to adapt (or re-make) the yj sending unit, and the diller neck needs cutting and some extra hoses to bring the sizes to spec, but the YJ tank is PLASTIC (HDPE actually) and holds up to 80 litres or fuel -- AND HAS BAFFLES!.
Furthermore the return isnt at the top of the tank, so your tank doesnt aerate the fuel like a ************.
http://sparkie.slave.ca/roxy/GASTANK/

Your car will finally be able to pass a gas station!

disclaimer: i dont reccommend doing this to anyones car as moving the rear frame rail has major structural implications during rear end collisions. Should you attempt this modification i will not be held liable for your car crumpling like a brick of butter, not will i be held liable for any passengers (like the ones hiding behind the seats) who end up looking like bricks of butter afterwards. This information is offered only for you to flame me with.

OnlyOnThurs

****Im gonna thread hijack since this does prtain to me as well*******

Im looking for my new found problem as well. Well today i went for cruise in the hill country (very hilly and very curvy...it was a blast!!). The whole time was a freakin Blast!! Just takin the fb arond sharp corners and pushing her hard. She was doing great!! UNTIL i reached a very STEEP hill (very ******* steep)...then she started bogging down in 3rd gear going uphill. I switch gears to see if that would help but it actually made it worse...so pull her over for a little bit but I do not turn her off (she is idling GREAT infact). After a quick break i am on my way again...then about 10 mins later she starts doing it agin on the smaller hills (and it only happens on the hills). So i pull over and i decide to change my fuel filter (Thank God for an extra one....). So i change it in like 3 mins tops, i start her and i am on my way...she IS GREAT NOW!!! until about 30 mins later then she did it (but not as viloently ..just smaller boggs in 4th gear) every now and then only on some hills. Now actually i do pull over again and look under where the filter is at then i see the fuel pump moving back and forth kinda violently (i dont think this is suppose to happen). Well i dont have the nessarry tools for a fuel pump removal in the middle of the texas hill country so i decided to head back home.....i fill her up with gas and i go on my way. Now on the drive back she actually was fine (though i did not push her hard like i was earlier but i was going on alot hills....she was fine. Tommorow morning i am gonna lift her up and check on that fuel pump to see if that movement it was making was the problem. BTW the fuel pump is only about 8 months old and she has a brand
new fuel filter. Any ideas guys what this could be!!!

virfighter

Your problem sounds similar to the one I've been dealing with except mine manifests itself on highway trips. I've replaced my fuel filter, pump and gas tank. The only thing it can be at this point is the carb! So its on my list to rebuild

Let me know what you find out.

Rogue_Wulff

When the car starts bogging down, pull over and release the fuel cap. If a loud whooosh is heard, you have a plugged vent. I went thru a similar issue, and finally tracked it down to the charcoal canister under the hood. I drilled out the tiny restrictor in the CC, and ended all the problems. Mine is an '83, BTW.