GuyNEEDS7help

Ive had problems with this car for quite some time now. Ive replaced the filters, rebuilt the carb, checked the fuel pump pressure, cleaned the tank. Okay so it starts up fine, not driving it doesnt have any problems revving or idleing. While driving, it will run good for about a block or so then starts acting like its starving for gas or only running on one rotor. Then it dies and if i wait about 30 seconds it will start right up, drive and then do it again. Any help or ideas that could possible point me in the right direction would be greatly appreciated.

DivinDriver

iTrader: (15)

Next time it dies, shut the key off immediately and the check the fuel levels in the float bowls.

If they (or one) are dry, it's a fuel volume (not pressure) problem that's only showing up under load (loose wire to the pump, perhaps, that stops delivering current when you're accelerating), or a float that's hanging up under acceleration.

If both levels are good right after it "starved out," then it's not a fuel problem.

Accelerating the car's weight puts very different demands on the engine than does just revving it while it stands still; that's part of what makes diagnosing vacuum secondary problems so hard; difficult to observe "in the wild."

GuyNEEDS7help

Okay just got back from the test run. Longest good drive its been on in awhile. Before test run.. Front float bowl was a little high. After it starved out it was low. Back bowl stayed on the line. Im going to check the wiring first. If that doesnt fix the problem. How would i got about fixing the float? Thanks DD

trochoid

iTrader: (6)

How did you clean the tank and what did you find? Either the tank still has debris in it, the intank pickup tube is restricted from rust buildup and it's sucking up more tank debris as fuel volume demand increases, thereby starving the engine for fuel. When you shut the engine off, the debris falls back into the tank to start the cycle over.

Other option is the thermal reactor and/or heat exchanger is failing and plugging the exhaust. This usually presents itself as a lack of power and slow acceleration.

Leave the floats alone! Run a can of Seafoam through the fuel tank. Works best if there's only 1/4 tank of fuel.

jibco

Sometimes ignition problems will only present under load, but it will rev fine in the garage.

Looked at the plugs lately? Wires? I suppose that car has the points distributor.

GuyNEEDS7help

I just used hot water and a little soap. The first time, i found quite a bit of debri. The car sat for 9 years before i got my hands on it. I put a new motor and everything in it. The two other times i cleaned it out. Nothing. But i did forget to check the intake pickup. I think ill drop the tank again when i check the wiring this evening since its pretty low on gas.

Yes it is points.

trochoid

iTrader: (6)

While the tank is out, take it to a radiator shop that boils out fuel tanks, then have it sealed. You can seal it yourself, just make sure you don't seal up the pickup tube.

kcscott11

question of curiousity, im bout to seal my tank, and i just wanted to know the best way to prevent clogging any of the lines??

jinxed4dub

iTrader: (7)

I'd just put some electrical tape over the ends. or some rubber caps.

DivinDriver

iTrader: (15)

I'd follow Trochoid's advice first, and save messing with the float until you're in "all else fails" territory; float setup is easily messed up by accident. It's kind of telling, though, that only one bowl is low after it starves.

That's probably not a float level setting issue. It might be a float that's hanging up on the pivot or a needle that's sticking, but again, that one's for after you've eliminated all other possibles. If you've not dealt with carb internals before, it is easy to make mistakes toying with them.

You want to make sure your tank and lines are clear first, as debris can cause all manner of problems.

trochoid

iTrader: (6)

The S3 tanks have a removeable pickup/return/vent assembly. Remove and tape off hole. Earlier tanks have the tubing brazed directly to the tank. For those, rod out the tubes to make sure they are clear, then push a wire through from the top until you can grab it from the fuel sender hole. Wrap the wire around a soft piece of cloth, part of a t-shirt rag perhaps, then pull the wire back blocking the opening of the tubes.

After the sealant has been swirled around inside the tank but before it sets, push the wire and plug down a bit so it doesn't bond and plug the tubing. Once the sealant has set, push the wire through and remove from the sender hole.

7aull

iTrader: (2)

(with apologies if this is hijacking this thread)
you'll can run a wire, like a coat hanger, up the tube into the tank to keep the tubes clear. Best time would be after sealer has sat a bit to firm up, but before it hardens so you can still free up the tube. The sealer is actually pretty thin in consistency IIRC, so it may not be an issue-

Stu Aull
80GS
Alaska

trochoid

iTrader: (6)

I've worked with a couple different brands of tank sealants, some are thin, others a little thicker. The danger is in the build up as most directions say to swirl the sealer around the inside of the tank several times. This allows each coat to begin to flash so another layer can build upon the prior one. It will plug the smaller tubing and I've seen an SE pickup tube reduced by over 20%

What I like about the sealer is it's ability to seal tanks that have pinhole rust spots that one could never braze well enough to reclaim and reuse that rusty of a tank. I also strip the outside of them down to bare metal, shoot a coat of epoxy then finish off with a couple coats of truckbed liner. Now one has a a tank good for another 25 years.

GuyNEEDS7help

is this what the intake pickup is supposed to look like? for some reason it seems like its missing something

trochoid

iTrader: (6)

The part in the pic is the fuel cut valve that comes on the 2nd gen tanks. It allows air to enter the tank as the fuel level goes down, but, more importantly, it prevents fuel spillage during a roll over crash. The pickup tube terminates near the bottom of the tank and is not removeable on the S1/2 tanks. The following link shows the difference between the carbed and FI versions of the S3 tanks. Look at the removeable pickup/supply part. That will give you an example of what the tubes look like internally, even though all of the pre-S3 ones are brazed into the tank shell.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/84-85-fuel-tanks-facts-416682/

GuyNEEDS7help

So heres how today went... Blew out the fuel lines, cleaned the tank, put it back up, changed out the filters and the fuel pump.

I made it about 5 blocks before it just died. Would not start back up without starting fluid and would barely run at all, still acting like it was running on only one rotor. I guess ill try changing the plugs again and see if that helps at all. Could it be a distributor issue possibly? I wish there was a shop that knew rotaries here. I need to pay somebody to fix this. =(

Sterling

I think the carb might be flooding before it dies.
Try driving it without the gas cap to see if it's a tank venting issue.
Fuel bowl solenoid hooked up?

GuyNEEDS7help

I checked the plugs. They were dry. I will try it tomarrow though. Is that what tells you how much fuels in the tank? if so, yes

NCross

iTrader: (18)

The part on the drive side of the carb is the bowl vent. Make sure you have the electrical connector plugged in and that there is at least a hose plugged into it dangling to vent it (emissions removal only).

Check your distributor. Could be the points going out. Mine would idle smooth and drive good with the choke on and after the choke popped out while driving down the road it would get rough. Swapped to electric ignition and it fixed everything.

GuyNEEDS7help

Well i tried to start it today. Wouldnt start, check the float bowls. They were dry. fuel volume and psi was fine. Took off the carb and it was full of crud. In the process of rebuilding it again. Hopefully it works out this time. Ill keep you guys posted. THanks for all the help

NCross

iTrader: (18)

Your bowl is empty because the vent isn't opening and your gasoline is boiling out. It won't start because the boiled gasoline drained through your throttle plates into your engine and flooded it. Double check you bowl vent. Your plugs could be fouled from this as well. FYI boiled gasoline doesn't burn very well.

If you can run the car for a bit after it de-floods, let it warm up to operating temperature. Turn it off, pop the hood, remove the carb ha and watch for boiling vapors. OR you can just pop the hood and listen for a coffee pot noise.

GuyNEEDS7help

Your talking about this right? I already have the carb out of the car and I cant finish it until tomarrow afternoon. I checked the plugin to that and it has power. Is there anyway to bypass it and have it vent all the time? Thanks

GuyNEEDS7help

Okay so thank you guys.. Its running now. I think and I hope only got to take it on a short tester with the gas cap off but it seemed fine except for its drives great till 5k and then it doesnt cut out but the power just seems to peg like its hitting a rev limiter.