Hi guys,
I hope someone here can enlighten me on this problem. The car is a 1985 RX7, 1.1 eng., automatic transmission, a/c, 140+ on the miles but in good shape. A friend of mine brought this car to me with the problem of it stalling when you accelerate normally or fast. It wouldn't stall if you feathered the throttle. It also would stall, say going around a corner where you slowed down and then hit the gas again. He had replaced the plugs, cap, wires and rotor and adjusted timing. I checked the car over and repaired one vacuum leak on the large hose running to the carb from the lower intake. I also rebuilt the carb and replaced the accelerator pump, the floats and replaced the base plate gasket. The carb is back on and it idles good(within specs) starts fine and runs fine...again...but with the same problem. Now I'm a little confused and would appreciate ANY suggestions or help...please. We really want to cure this problem. I've worked on quite a few RX7s but most were fuel injected and I own an 88 RX7 so I'm a little rusty on the earlier models so I'm thinking maybe I'm totally off base on this one. Also I did a compression bump test and checked fuel pressure before rebuilding the carb. Thanks in advance guys.

 

Have you changed the fuel filter? That's a prime cause of symptoms like yours on these cars.

 

Did you check for proper float adjustment? The reason I ask is because stalling going around corners is typical with these cars when the floats are out of adjustment. Oh yeah, and ditto on the fuel filter too.

 

Yes..sorry, that was one of the first things I did, replace the fuel filter. The float level is within specs. Thanks for the replies though...any other suggestions???

 

Sure sounds like a lack of fuel though. Have you checked the pump output to make sure it's within spec? Could also be a kinked fuel line, clogged fuel pickup or something like that.

 

I've kind of run into the same problem. Replaced everything but the fuel pump and went and had the tank cleaned since it was rusted up inside and kept clogging the fuel filters before I could leave the driveway! Anyways, long story short, do a flow test. Not only was my fuel pressure just below the minimum (3.7psi) required (mine was 3.1psi) but the flow rate only came out to ~28 fluid ounces and it should be a minimum of around 37.6 fluid ounces. Blah

 

Have you checked to see that the accel pump is working? I adjust mine so that it starts to squirt the moment the throttle starts to open. Maybe try backing off the nut 3-4 turns, make sure you count them so you can put it back if it doesnt help.

 

sounds like a vaccume leak. chek over the rats nest and all the other emmissions systems. easyest way to do this is with a can of carb cleaner or spray gun with water

peace

 

he said it was idling fine so i'd throw a vacuum leak out. have you rechecked pressure? another problem could be the pump is not flowing enough. is it the factory pump? i would also suspect the tank. if you haven't already, put on a clear fuel filter to check for rust problems. they're relatively cheap.

 

Thanks guys...I checked the accel pump even though it's a new one, it squirts fuel as soon as you move the throttle. I rechecked fuel pressure and here I'm a little confused also...in a Haynes manual the minimum fuel pressure is 3.7, now if you look at Alldata or Mitchell the fuel pressure range is 2.8 to 3.7, this one stays just below 3psi. I even ran the gauge into the car so I could moniter pressure while driving and when the car actually stalls. It stays about 3 psi or a hair lower, even when it stalls. Now is the fuel pressure too low or is it within specs? The pump appears to be probably original or very old from all outward appearences and I've already changed the filter. As far as vacuum leaks there was only the one I found early on which I told about in the earlier post and repairing it helped to stabilize the idle but had no effect on the stalling problem. I have yet to do a flow test...what would you say it should be for say 1 minute? Also, with the key on-engine off should the pump pressurize or not, it only pressurizes once you crank the engine? Thanks once again I appreciate the help.

 

84-85 rx-7s turn the fuel pump on only when your cranking.

 

3 psi is plenty for the carb. Maybe your secondaries are opening too soon?

 

I recently bought an 84 w/automatic that has the same problem, but have not yet tackled it.
Does the automatic use engine vacume for a modulator valve? If so, perhaps the modulator valve is leaking?

 

Hey guys,
Here's an update on this car. We rechecked timing and found that secondary wasn't firing, which we traced down to a bad ign. module for the secondary, replacing that improved it a bunch, but...there's always a but...every once in awhile it'll still stall, sometimes from a dead start or sometimes when your like coming out of a turn and you give it gas to accelerate. Not very often, it's improved like 90%, but it still has a problem. Any thoughts, it's got me, I'm running out of ideas. Thanks in advance.

 

If its out of a left hander, thats common with a Nikki. Fuel sloshes away from the primary jets and causes a stumble. Try upping the fuel level in the bowl a little, also you may be running the bowl down while driving due to lack of fuel delivery. Check filters, pump output, fuel lines. Is this a stock system? no deadheaded carb? stock pump? no regulator? Whats your fuel pressure?

 

Yes it's all stock. The fuel pressure ranges from 2.8 to 3 psi. Any thoughts? Thanks for the help.

 

I just bought my very own 85 rx7 as a project (with only 57k miles!) and I've come across this issue. I knew it was going to have a fuel management issue but I was thinking vapor locking which seemed like a quick fix but the fuel line setup couldn't cause vapor locking at all. I've noticed that my car also has either an idling issue or a/f ratio issue considering it seems to require choke. I'm really beaten up from what this issue could be and how to fix it. I don't suppose you would have any clue what the problem could be 16 years later? I have good fuel flow, the carburetor has been cleaned and the jets have been replaced, however the larger jets appear to be not working, but I have been told that it could be a timing issue. Ive got it down to 3 possible issues, poor timing, major vacuum leak (likely involving the air pump), or fuel delivery issue. If you have any idea I would greatly appreciate it

 

wow, 16 yr bump. sure hope the issue ur having is the same as what the subject of this thread is about. otherwise should have started ur own thread. i can only guess the carb is stock? i suggest cleaning the stock jets and putting them back in the holes from which they came, and start there. why did u feel the need to replace the jets? and with larger ones?

 

So when I bought the car the previous owner said that they were having an issue where the car would run for about 5 min and then shut off... I had decided to buy it cuz I had assumed that what he was describing was it vapor locking and that I could easily fix that by moving the fuel filter closer to the tank... They had found another 85 fb with a manual transmission in a junkyard and he pulled the stock carb off that one in hopes that he could swap it and be good but he never got around to it ig. I picked up the car and it didn't start at first but halfway back from the trip we started it up and drive it solidly for ab 2 hours the rest of the way home. Then the next day it started to have these exact symptoms. I noticed the secondary jets (the larger ones used when on the throttle) weren't flowing any fuel at all so I opened up that stare carb and compared the air flow on then and determined that I should swap them. The engine seemed happier during free revs and idling in neutral but as soon as it was in gear the power fell on its face and died. I don't know much ab carbs but I did also notice one float was significantly lower than the other so I adjusted the idling mixture screw till it sounded happy and healthy, and then turned the other a/f ratio screw more to the richer side but have seen no improvements. I'm down to thinking it's a vacuum issue.

 

How did you determine that the secondary jets weren't flowing any fuel? How did you compare the flow rates of the jets from the two carbs? When you noticed one float was signifigantly lower than the other why didn't you correct them? Do you mean the floats hung differently when not running, or that one bowl was getting fuel and one wasn't? My 85 Nikki carb had a single idle mix screw - is this a stock carb you're working on? Some pictures would help.