tmking66

Ok, I am still having the same problem. The engine will not go from an idle to anything above 1200 rpms. When I step on the gas the car dies as quick as if I turned off the key. No sputters, coughs, wheezes, just stone cold dead. Turn the key and it starts right back up. However, if I cover the primary barrels on the carb. with my hand and try to rev the engine it revs right up. Once it gets above 2000 rpms it revs fine and strong right up to redline. If I let it drop back to idle (idling at 800 rpms) it will not rev back up unless I restrict the air flow into the primary barrels.

What I have done. Rats nest removed. It was doing the same thing before emissions were removed. This had no effect on it. Rebuilt carb. (TWICE). The first time no fuel was getting through the carb. Took it apart again and now fuel flows fine but guess what. It IS STILL DOING THE SAME DIEING CRAP IT WAS DOING BEFORE THE REBUILD. NOTHING CHANGED AT ALL. I have checked the accell pump. It works. Not sure if it is adjusted exactly right or if there is much of an adjustment that can be made on it. But it squirts fuel into the carb as it is supposed to. Checked timing (leading and trailing are right on). I have adjusted air fuel mix (no effect on problem at all) Tried a different carb.. Same problems. Checked engine compression (not great but acceptable: around 93 on both rotors).

I do not know what else to do. This problem almost seems electrical because of how quickly the car dies when the accel. is opened (pressed) and the fact that it has done this with more than one carb. But, I don't see how that could be possible. Would any of the electrical components on the carb. possibly cause these symptoms if they were not working correctly or if no current were activating them at the correct time? I am at a total loss as to what to do next. I have taken the carb. off so many times I can do it blindfolded now.

PLEEEEEEESE HELP!!!!!!!!!!!!!!!!!!!!!!!!!!

christaylor

Sounds more like a vacuum problem. Do you have all the holes on the deck spacer plugged? How about the holes in the carb after you stripped the rats nest out... did you plug those?

tmking66

I have not found any vac. leaks. The car idles fine at 800 rpms. Only dies when accellerator is pressed.

Is the butterfly valve on the primary carb. barrels supposed to close when the throttle is opened? If I close the butterfly valve while opening the throttle the car revs. fine. once rpms build up I can release the valve to open position and the car rev. and runs fine. Makes me think something on the carb. is not hooked up right and maybe the butterfly valve is supposed to close as the throttle is opened.

What do you think?

blwfly

iTrader: (4)

wish i could idel at 800

christaylor

The primaries are the smaller diameter holes... if the bigger (secondary) butterflies are opening at low throttle settings I could see it flooding the thing down and killing it immediately.

Can you take some pictures of this beast? I don't know much about carbs but I've rebuilt enough of these damn things I should be able to spot something out of place...

tmking66

I should have been a little more specific about the butterfly valve. The valve I am talking about is the one on top of the carb. that closes when the choke is pulled. With the engine idling, if I close this valve, I can open the throttle quickly and the car revs up normally. Once it is at rpms above 2000 I can release (allow the valve to open) and the car continues to rev normally. However, if I leave this top butterfly valve open the engine dies as soon as I touch the throttle. Seems like the carb. is getting too much air for the fuel. Limiting the air intake keeps the engine running and allows the engine to rev. up. Engine only dies when going from 800 rpms to 1500 rpms. If I get the engine reved above that I can keep reving it all day as long as I don't let it drop back down to an idle.

Any clues here????

tmking66

I know you are not supposed to bump threads to the top here but this is getting buried and I still need some suggestions here.

Pleeeeeease, anyone with any other ideas.

I would hate to part this car out but I have been working on it for months now and it is still not much better than when I started. So, if I don't get it going before long, it is coming apart and another 1st gen will bite the dust.

trochoid

iTrader: (6)

Are you getting a squirt of fuel from the AP when the throttle is pressed?

nick1

he said the accelerator pump is working

are you doing all of this when the engine is cold (not up to operating temp)??? i do't know how cold it is in your area, but here you have to keep the choke on (valve on top of carb closed) until the engine reaches operating temp. you say it runs fine when the choke is on....how about keeping it on until operating temp has been reached.

if that's not it...i would suspect possibly an air leak. have you replaced your intake gasket and o rings? what about the gasket between the carb and the intake?

these carbs can be a bitch. i know what you're going through...i finally just got my car running fine, but when i shut it down everytime, the secondaries fill up with gas and i have toi de-=flood the engine. what i've done is run a switch for the fuel pump, and then every time i shut down, i hit the fuel pump switch, and let it die....that way there is no pressure to fill the secondaries. but ya its a pain in the *** (if anyone an help ME with that problem i'd appreciate it....don't mean to hijack the thread)

slashdawg00110

tmking66 - sounds like a vacuum leak somewhere. Rats nest removed? Sorry, can't recall if you mentioned this in your post somewhere.

nick - 1) fuel pressure too high? 2) fuel vent solenoid disconnected or failed 3) float level set incorrectly or 4) needles sticking.

tmking66

Yes, rats nest is removed. I have checked for vac. leaks with the car at idle. None found. If it is a vac. leak it must only happen when the throttle is opened. What vac. lines would be pulling vac. only when the throttle begins to open?

RXBeetle

Any significant vac leak would make a descent idle impossible (800rpm), that doesn't sould like it's the case. It sounds like a fuel supply problem to me, especialy if it seems do better choked. Idle and main fuel are two seperate circuits and it sounds like the main is just not getting gas. Twice rebuilt carb or not... double check your float sight glasses just the same. Pull the air horn and jets one by one and make damn sure each is perfectly clear. Pick at the schmutz with a toothpick then wash them (or not) and blow through them. When you blip the throttle from idle do you see fuel being sucked out of the main discharge nozzle? If not it's definetly a main circuit problem.
I've been there, 2 different carbs, both rebuilt top to bottom. You just can't let up. Keep testing but always have a known setting to return to.
If you think its electrical like something is killing your ignition, keep a timing light hooked up. If ignition is cut your light will stop flashing.
Just a random thought, where is your vac advance hooked to on your carb spacer plate? Is it seeing manifold vac? does your vac advance function? Not having the vacuum advance hooked up really killed my off idle drivability.

vipernicus42

iTrader: (4)

When you do find the solution to the problem, you will be your local carb expert.

I chased a problem for 2yrs where my car wouldn't run under 3krpm. Start it and it would immediately jump to 3k and wouldn't come down. Replaced the carb, then had it rebuilt.... the funny thing is that the *cause* of the problem kept changing (3 times) but the problem stayed the same. By the end, I figured out how to tear an intake apart down to the manifold, build it back up, and solve almost any carb problem.

But I must say you have me baffled. Especially the trying more than one carb thing.

Personally, I'd get a known-good carb off a well running Rx7, replace the spacer under the carb, make sure that any holes in the manifold are properly blocked off (ACV and the spot where the #2AAB hose plugged come to mind) and try it again. If those two (the known-good carb and spacer) work, then you know it's either your carb or spacer. Otherwise, you've got something crazy going on that's beyond my knowing.

It does sound like the car is getting too much air and not enough gas and dying out. So either your secondaries are opening at the same time as your primaries, or there's a fuel flow problem (either inside your carb or in your fuel system).

Jon

tmking66

Thanks for all the input so far. The thing that gets me about this is that the car runs perfect at idle. Then, if I get it up above 2000 rpms it runs perfect to redline. When I let off the gas it drops back to idle just fine. Its just getting from idle to 2000 rpms that kills it evert time unless I close the top butterfly valve over the primary carb. barrels.

Let me ask this once again. Is the butterfly valve on TOP of the primary barrels supposed to close as the throttle opens and then open up as the rpms build? If there were supposed to be vacuum that closed this valve and then let it re-open at higher rpms that may be the problem but I am guessing here.

Any ideas about this?

slashdawg00110

No, the butterfly at the top only closes with action of the choke. Without the choke, the butterfly does nothing. It's there to limit air entry into the venturis during cold operation so that the mixture is rich.

I think what you've got is either a vacuum leak that only manifests itself when you're accelerating the engine from idle to 2k rppms, or you've got a fuel delivery problem within the carb. I'd guess the latter.

Have you looked at sterling's website? Go to sterlingmetalworks.com and look at the "Racing" section, in the "Tech Articles" section. He's got descriptions of the idle, main and transition circuits. The material in there may help you.

tmking66

Thanks slashdawg. Good stuff on Sterlings web site. According to his tech pages it sounds like classic accel. pump problems but I am seeing a pretty good shot of gas injected when I open the accel. Looks like I will be taking it apart for the third time. whats the record for carb. teardowns before getting it right anyway?

MosesX605

Oh, I dunno. I probably had the carb apart on my '79 at least a dozen times before I figured out that I had the wrong jets installed. Evidently having two primary sized jets in one float bowl and two secondary sized jets in the other one isn't a good thing.

As for your problem, I don't really know what the deal is. It sure sounds like an accel pump problem but if you're seeing a good solid pump shot then I'm not sure what to say. Hows your timing? If the timing is really off it could cause all sorts of stumbles and flatspots in the powerband.

slashdawg00110

Do you have mech secondaries or vacuum secs? If mechanical, did you read through sterling's discussion of them relative to AP settings?

The record? It's a large number, even more than moses' dozen. I'm about to tear mine apart again ...

tmking66

Secondaries are vacuum. Have not had time to work on it in the last few days. Will probably be posting new questions when I take it off again.

Thanks for the help so far.