JYD

i just picked up a clean little '85 RX7.

for some reason, it only runs until the float bowls run dry, then it dies. if i let it sit with the key on, the pump fills the bowls back up, and it will start right back up, and run for about 15 seconds. it runs great for the short time it actually runs. the pump and carb are new.

any ideas? thanks in advance!

mazdaverx713b

iTrader: (91)

it sounds like you are having a problem with the fuel pump not functioning when the engine is running. sounds like the pump is functioning only when the key is in the accessory position.

JYD

it works when the key is in the run/on position but yes, for some reason its not running when the motor is actually running....

or, is there a regulator somewhere that is maybe letting all the fuel bypass the carb too quickly?

mazdaverx713b

iTrader: (91)

no regulator. the floats shut fuel flow off to the carburetor. can you confirm that they are raising properly and that the carb is in fact running dry?

Jeezus

iTrader: (4)

I am going to insert the usual "change your fuel filter?" question.

Those will clog up, and not supply enough fuel to the carb when running.

JYD

this part is also new...

possible sediment in the tank....clogging the new filter?

mazdaverx713b

iTrader: (91)

very possible. i had this happen recently. the tank was ruined with rust anyways. i replaced it, the filter, and pump. the sediment will be present in the filter and you should be able to see it easialy.

JYD

whats a car like this worth in good running shape, all original, and pretty clean?

Jeezus

iTrader: (4)

I went through 4 of them in a week when I first got mine back on the road.

axle

there is a screen on the inside of the gas tank on your fuel line I just had to clean mine my fuel filter was fine just that screen clogged up because of unstabilized fuel (turned to lacquer in the tank) was a pain to have to drop the tank but now the car runs fine how long was the car sitting if this is the problem you can diagnose this by removing you fuel filter and blow into your fuel line back into your gas tank that temporarily cleared mine so I could figure out the problem for estimates of value we need pics

JYD

dammit. ive just discovered the car has a brand new gas tank, and clear fuel filter, and its completely clean! dang. this thing should only need what, 5 psi of fuel pressure to run?

DivinDriver

iTrader: (15)

Carb screens plugged?

JYD

where are those? the carb is also brand new. the only thing not new in the fuel system, are the lines from the tank maybe thats what ill have to do. or get an inline electric pump and regulator of some sort....

Rx-7Doctor

iTrader: (13)

You need to verify that you are getting power to the fuel pump after you start the car.

If so then I recommend that you perform a fuel pressure/quantity test per the Factory service manual. Also download a copy of the Carburetor manual.

That information can be found via the link in my signature.

DivinDriver

iTrader: (15)

Carb screens are located under the bolts that hold the ends of the fuel inlet spider to the top of the carb. Small, fine brass circular screens; fragile.

JYD

so i did the fuel volume test, because i dont have a pressure guage, and i came up just barely short on the minimum volume. with the aftermarket filter, i removed the line from the carb, and performed the test. i was supposed to get 1100cc of fuel into the container in exactly one minute. well i only got about 900cc. i removed the filter completely, just to re-test, and this time i got just a hair under the 1100cc minimum. now the car runs fr a little longer before it turns off, and requires slightly less wait time before it starts again...it eventually backfires a little through the carb and dies. are these things that sensitive to fuel volume? im thinking the next step is to just buy something like a holley red fuel pump, and regulator, and install that so that i know exactly what im getting. the pump that is on the car is a little chrome cube shaped thing...i think may have come from ebay or something....


any more ideas....


and always. thanks for the help

trochoid

iTrader: (6)

Sounds like you've eliminated the usual parts that cause restrictions. A new fuel tank and carb are a big plus. Since the carb is fresh, there's a good chance the screens are clean too. That leaves the fuel lines, supply line in particular, and the fuel pump. Since the tank was replaced, experience tells me the entire fuel system had corrosion problems. Disconnect the supply line at the carb and at the output side of the fuel pump, then blow compressed air through it and see what comes out. If it blows clean, then it's time for a new pump.

JYD

FIXED!!!

i installed a holley red pump, and inline 4.5 psi regulator, right before the carb. runs great now!!

thanks for the help!

Rx-7Doctor

iTrader: (13)

Glad to hear you got her back on the road and thanks for following up and letting us know what it took to fix her.

bliffle

Need pictures, mileage, model , etc.

Where's "ATX"?

JYD

ATX is Austin, TX

its an '85 GS, 144k miles

bliffle

$500-$800 depending on how much you like it.

Rogue_Wulff

The niceness of the interior is lost to the crappy condition of the paint. The paint is typical of most all mid 80's clear coat paint, in that the clear is totally gone on most of the hood, roof, and likely around the hatch.
It's very hard to get much money for a car with bad paint, regardless of how clean the rest of the car is.

JYD

cool. ill just paint it then.

bliffle

FBs are surprisingly low priced considering their driving value and potential.