12A power loss @ full throttle
 

I have a '85 with 190,000 miles. Ran great when parked in fall but was flooded this spring. Went through the unflooding steps and got her running again, but now when you floor it she just dies. I can cruise on the freeway at 80, but it takes a long time to get up there. If I give it too much gas it just dies out until I back off again. Seems like its fine as long as the secondaries don't have to open? All vacuum lines to the carb are in place, and motor sounds fine. Any ideas?

Also, after I got it running and found this problem, I replaced the plugs and gave her an oil change. Thanks for your time...

have you inspected the fuel filter. it is usually the first place to start. next, do you have an accelerator pump leak? that can cause some problems such as hesitation and at worst, stalling. when is the last time you gave her a tuneup? could just be weak on spark.....

I picked up a fuel filter today, but have not installed it yet. It only seems to happen once you hit a certain spot on the pedal. As long as you don't push the pedal down that far, she runs fine.

No visible leaks around the carb, so I don't think the accelerator pump is leaking. Besides, wouldn't that just cause a hesitation when you floored it? If I floor it when I'm going 80, she shuts right down until I back off again.

Another thought was that maybe one half of the ignition was not working (leading or trailing), like maybe one of my coils is dead or weak. Cap, rotor, and wires are all nearly new, so shouldn't be the issue.

Thanks for your thoughts on the matter, and I will keep searching for the solution.

I found my problem inside the dizzy czo, one contact was coroded away. new cap and away we go. good luck

I had a similar problem, and after asking on here, replacing the fuel filter was the resolution!

(Thread below)

https://www.rx7club.com//showthread....hreadid=315335

Fuel filter not the prob.
 

Okay, really had my hopes up, but the fuel filter has been replaced and the issue persists.

To me it feels like either the secondaries aren't doing what they're supposed to, or an ignition issue.

I'm going to take another readthrough on the procedure for mechanical secondaries and see if I'm up to taking that on. But first I'll take another look at the ignition.

Thanks for the suggestions. I will keep you posted on my findings.

Well, after I replaced the fuel filter, and that didn't alleviate the problem, I got a little desparate. I used what I would call a "shotgun" approach.

I pulled off the air filter and hosed the exterior of the carb with carb cleaner (an entire can). Then, I soaked everything in WD-40 and let it sit for about an hour. Then, I got a decent sized hammer and tapped on the carb wherever I could find a suitable surface. After rechecking all of the vacuum lines, I reassembled everything and took her out for another test run.

Although the issue is still there, it seems to have improved slightly. There is more power using moderate throttle, and when I floor it she doesn't die out on me anymore. However, when I do floor it she doesn't go any faster and just barely maintains the current speed. If I back off about 1/4 of the throttle the power returns and I can go faster.

I think I might just try driving her a bit. Maybe use her for my work commute (40 miles each way).

If I decide to investigate the possiblity of an ignition issue, any idea where I should start? I kind of doubt that that's what it is, since I did see some improvement after I beat on the carb, but I might as well check it out anyway.

Maybe just soaking in the WD-40 overnight will free something up and she'll be fine when I take her out again, who knows. Thanks again for your time.

Clean the vacuum on your secondary. If it is clogged it will take some time to build your speed up to 70 mph and usually that is the max.

Going back to the first reply you got on this thread... how aout a tune-up? Plug Wires? Plugs? (at least inspecting the plugs)

Let us know what you find out with that and with inspection of your vacuum lines/rats nest.

OH -- one more idea... try running without your air filter and see if that makes any difference (not forever, just on a test run)

Good luck!

-Jeff

mine does the same, feels like it just runs out of fuel when you try to gun it too much.

I'm having the same issue right now, following the install of a rebuilt carb with bigger fuel jets and bored out primari venturi. My first guess is ignition as well. This weekend I'm replacing spark plug wires (NGK), new spark plugs (NGK), and a Blaster 2 coil for my leading ignition. Will see if that handles it.

How are your spark plugs? black indicating running rich? Can you hear the secondaries opening? there should be a change in the exhaust sound. Also check your timing.

There's also a chance your fuel pump is starting to fail, which would be my second guess after ignition.

my cars fuel injected and if i matt it, then back off like a quarter inch it pulls more than when its to the floor. I would assume thats an air intake issue, because more throttle means more gas, but not neccisarily more air. Just a thought thou

It sounds almost like the secondary float is stuck closed... that can happen when it has sat for a while. Open the window (two screws on the back of the carb), spray an ass-load of carby cleaner in there and let it sit for a few. stick your pinky or a tiny screwdriver in there and work the float up and down a BUNCH of times. (you're trying to wear away years worth of varnish here.) then spray it with an ass-load of carby cleaner again.

You can do this on the front window as well.... it couldn't hurt.

I'm willing to bet that's your problem.

I know at least it's not mine... the mech secondaries open, and the difference in sound, with no cat and a PP muffler, is unmistakable.

Not more air? when the secondary butterflies open, there will be more air, that's fo sho!

Well, thanks again for all of your thoughts on this matter. Tuneup completed, cap/rotor, plugs, air filter, oil change. Plug wires are also in great shape.

I can't hear the secondaries opening because the engine bogs down when floored. The fuel pump seems to be putting out plenty of gas, I had the lines disconnected while trying to unflood it and it looked pretty good.

I will check out the float windows in the morning after work. That sounds like very good sense.

If I have time tomorrow, I will make the conversion to mechanical secondaries. I'm not sure if this will fix the issue, but its an improvement I wanted to make anyway so I'll give it a shot.

All vacuum lines and connections look good, and I can't hear any leaks. Also, there is no flaring of the engine if I spray starter fluid around the lines while it is running.

I checked the color of the spark plugs today, and they have a very light golden brown appearance.

I will let you guys know if I find anything that helps. And thanks again for your time! :)

OK fixed mine, Secondaries were sticking, battery terminal was loose, seems my fuel filter may be clogged too. I hope this may help you out.

Heres a cheep way to "clear your carburetor's throat":
Take off the air cleaner cap and the air filter. Fire it up, let it warm up. When its warm, let it idle. take the throttle linkage, rev it up to about 4 grand, stick your hand over the throttle plates. It will bog down quite a bit. once its about to die, take your hand off, while rapping the throttle to keep it going. repeat about 10 times.

What your essentially doing is creating a big vacuum on the fuel jets, which should pull any crud through them that is blocking them off, if a dirty carburetor is your problem. Hope it works

what shm21284 said is good. give that a shot as you may have crud in the jets. i would also check the floats as someone earlier in the thread said. now i have had this problem myself and it all came down to fuel. my exact problem was the fuel pump. you said it "seemed" to be pumping enough, but you dont know for sure. do you have a pressure gauge hooked up? you need to check for sure the fuel pump is pumping adequately. this has to have something to do with fuel.

When I get home this morning, I will try what shm21284 suggested. Next step will be to inspect the float levels front and back. I know that the front level looks good, but have not checked the back yet. If the back is hung up, then I will follow the procedure suggested by Metallic Rock. Thanks!

Try accelerating gently also. When you "floor it", you create a very lean condition, that is corrected by the accelerator pump. The shot of gas from the accelerator pump richens the mixture so you can accelerate. If there is not enough of a shot, you'll go lean and bog. If you can reach a high speed under gentle acceleration, you can rule out a lot of the potential problems.

Yes, I am able to get her going pretty fast if I accellerate slowly (80 at least).

I checked out the float levels, and they both look good. I also tried what shm21284 suggested, but there has been no change. Car won't even idle now.

I took it to work yesterday and she'll run smoothly under light accelleration, but if you are just trying to maintain a speed she starts bucking around alot. I had to accellerate/coast/accellerate all the way home.

I will try to work on her some more tomorrow. I did get the rear wing reattached, and washed/waxed her. That didn't seem to help her run any better though :0)

OK, I found a vacuum line that looked like it was attached but wasn't. Coincidentally, it seems to run to the vacuum secondary actuator thingamajiggy. Car now idles again :) and is again drivable, but still a power loss at full throttle.

Actually, the car feels stronger at about 3/4 throttle, but if you go to the floor with it it just kind of maintains but does not accelerate. I tried wiring the secondary up as instructed for mech secondaries, but that did not change anything.

I also noticed a distinct gasp when passing a certain point in the throttle travel, and now I'm wondering if my accelerator pump is working. I'm going to check that out now.

Ever done a compression test? 190k is alot of miles.....

Do you still have the cats on the car? Amazing how many times it's a restriction on the exhaust side of things that exhibit that very behavior...:cool: