blizzerone

Hello everyone. I have an 84 GS that has a rough time starting up. I find myself pumping on the gas along with the engine cranking so it will start up. It sort of sounds like a helicopter starting up. Starts off really slow, the RPM gauge rises slowly too, even though im pumping away, as it rises the engine sounds better. And once it hits 3k maybe 4, it sort of sounds like it gets un-stuck or free of something holding it back and revs up. But I cant let go of the gas because as soon as I do, it begins to die out on me and turns off. Had this problem one day when i was driving. I was going maybe 30-35 on the street and suddenly I feel it loosing power and shaking and sounding crapy. Dont know what happened. I pull over and once I stoped, it died on me. Then it wouldnt start. It was working fine before this. Just had replaced the intake gasket and o-rings, due to white smoke from my tail pipe. Also had the nikki rebuilt. I drove it around a few times with no problems. And about 3weeks later, this! What the hell could it be??

FunK73

iTrader: (6)

sounds like a compression issue. Got any more info on the break down on the road? From the sounds of it, you might have blown your apexes.

The engine only really needs three things to start; fuel, compression, and spark. Verify you have all three. Also, it might be in need of a new starter but im not sure at this point from the info youve given.

When i rebuilt my 12a i put in the apex springs upside down being an idiot making it so that the triangle piece of the apex seal had no compression coming off of it. The car would start if you put oil into the carb but as soon as you stressed the motor, it would die due to lack of compression.

When you say it gets "Unstuck" at about 3k rpm, that could be a stuck seal possibly. Eventually centripetal force could win cause the engine to get enough seal to run. What happens if you try to say turn on the headlights or put it into gear when its started?

74RX4

iTrader: (10)

Was the fuel filter replaced when the cleaned carb was installed?

gsl-se addict

iTrader: (3)

Also check for spark on leading plugs. Without them sparking, it can be hard to start and run like crap.

Also, the shutter valve butterfly could be stuck closed and cutting off fuel/air to the rear rotor. This will also cause rough running and low power.

Do compression check (search for "ghetto compression test"), check leading spark and we'll go from there.

blizzerone

Well when I do manage to get it running it will only stay on if i dont let go of the gas, well at least not all the way. And if i put in drive it turns off completely.

Also, no i didnt change the fuel filter after getting the carb back.

Ill look for that ghetto compression test thread and ill check for spark comming from the plugs. Ill get to it today after work. We'll see how things go. Thanks you guys.

FunK73

iTrader: (6)

Yeah I can almost guarantee is compression

blizzerone

Alright so i finally got home to check for compression and for spark. I read up the "ghetto compression test" and i got psst after psst with no gaps or breaks. Just psst,psst,psst,psst,psst...and so on. Then I checked the spark on all plugs and they're all good. What now guys? Should I replace the fuel filter?? Is there a way to check if its any good before I replace it?? Could not replacing it after I got my carb back cause the problem im having?? Could it have damaged the carb?Let me know guys, thanks.

trochoid

iTrader: (6)

Always start with the fuel filter, cheap, easy and often the problem. After that, check the fuel pump for overheating/flow volume. If that isn't the problem, it may lie in the fuel tank and it's pickup. Rust/debris can cause similiar problems. I generally drop and refurbish the tank, inside and out, whenever it presents any type of problem.

FunK73

iTrader: (6)

I doubt its fuel since it runs after you get it started. I'd do as trochoid says and replace fuel filters and so on anyway cause he tends to be very knowledgeable. I just ramble since I had a very similar issue.

Question though. Does the engine die if you let the rpm drop below 1k(ish) and how many miles are on the engine.

The ghetto compression test just tells you if you have even compression or not, basically telling you if you blew an apex seal. You might still have even compression, just not enough to run.

When i put my apex seal springs in upside down, i had even compression on all sides of the rotor, but since the triangle piece was not being pushed on by the spring, it would not seal unless the engine was running above 1k rpm (thanks to centripetal force it could idle above 750rpm). However, the only way to start it was to pour oil into the carb to fill said gap between the triangle piece and the housing thus allowing it to start with a crap ton of pedal pumping. Once it was running, the car would stay running but as soon as you stress the motor, put it in gear or what have you, it would simply die since there was hardly any compression.

I would say try to find someone that can do a true rotary compression test for you for free or cheap (they need a special rotary compression tester) after you try replacing the fuel filter and what not. That way you can atleast try to eliminate the idea of a rebuild. If its a compression issue it doesn't always spell rebuild though, remember that.

Also, do you premix or use the OMP?

blizzerone

I bought the car about a month and a half ago. The car had 176K on it. Previous owner didnt know much about the car, he had bought it at some auction. If I do manage to get it started, it will only stay on if i hold down the gas and let the RPM's rise to about 2-3K but as soon as I let off the pedal, the RPM's drop and the engine dies. Well, I bought the fuel filter yesterday, didnt get a chance to slap it on. But will do today after work. Hopefully it will be simple as that, kinda dought it. We'll see what happens. Thanks you guys.

gsl-se addict

iTrader: (3)

Also, check this hose:

https://www.rx7club.com/showthread.p...fterburn+valve

boyee

iTrader: (3)

i second this along with checking your ACV and vacuum lines. sounds like a vacuum leak to me since it stays running above 3k out of vacuum circuit

blizzerone

I use the OMP

FunK73

iTrader: (6)

After checking everything else, verify that it is working. It also sounds like you might just have a stuck seal, fixable by seafoam possibly.

blizzerone

Alright, i got the new fuel filter on. The old one was pretty clogged. It took a few tries before I could get it to run. Once it was on it stayed on without my foot on the gas. But the engine sounded a little rough. the rpm's settled around 1500. Then after a while of running it started to stumble and it turned off. I turned it on again and it stayed on. It also smelled like it was burning a lot of gas. Could it be the Fuel pump?? Maybe the carb?? What do you guys think. Oh and also, I tried putting it into gear the first time it stayed on and it died on me. But the next time I tried again and it didnt. It stayed on. I did notice though that the RPM's would drop significantly once I put it in drive, from 1500 to about 500 maybe 6 something. Whats up??

FunK73

iTrader: (6)

Its normal for the rpms to drop some, but thats pretty significant. Mine used to drop (pre-rebuild) from roughly 700 to 300-400.

Sounds like it might be getting a fluid wash now. Carburator might have been tuned to suck a lot of fuel on the old filter so now its over sucking? idk lol. Have it checked out

trochoid

iTrader: (6)

Since changing the fuel filter helped, that may simply be an indication of how much junk is in the fuel system. Has or did the car sit for an extended period of time? If so the carb and fuel system may need a thorough cleaning/flushing/rebuild. Start simple with a can of Seafoam and keep an eye on the new fuel filter. If it plugs soon then it's time to drop and refurbish the fuel tank and perhaps a carb rebuild.

74RX4

iTrader: (10)

Does your car have an automatic transmission?
Have you checked the anti-afterburn hose and the thread about it that gsl-se addict mentioned?
Who rebuilt the carb and let you put it on without a new filter?
I would put a can of Seafoam or some other fuel system cleaner in a quarter tank of gas, as already mentioned.

blizzerone

Its automatic. I did check the anti-afterburn hose and it looks good, no wear or signs of deterioration. Im gonna go get a can of seam foam and see if that helps. Thanks guys. Oh and also where should the rpm's be at idle? seems like mine cant go below 1500. Well only when i put it in drive. Sometimes i put in drive and it dies. But other times it stays on and it sounds pretty crapy.

trochoid

iTrader: (6)

Idle for autos is 800 rpm, 750 in Drive. High idle is usually caused by a vacuum leak, but they tend to cause a lean fuel mix, not a rich one like you have. The fuel mix and idle screws may have been adjusted to mask the other issues. Turn the fuel mix screw in, gently, until it seats, then back it out 3-1/2 turns. Then back out the idle screw to bring the idle back down.

As a side note, do you still have exhaust smoke and what does it smell like? Since you have an auto tranny, there's a possibility that the modulator valve is bad. When that goes, engine vacuum sucks tranny fluid into the engine.

blizzerone

Alright, i filled the car with the can of sea foam and ran it for a little while. Im still having problems during start up though. If i just turn the key it will crank and turn but will not start. But when I step on the gas a few times before cranking it, it will start up and sound kind of rough. And only after it warms up it will stay on without me steping on the gas slightly. It still idles at 1500. But this time I put it drive and it held idle at 7something. I went around the block and it was a rough drive. The reaction of the car as i steped on the gas was not great. It would surge and then drop. It would be ok for a moment and then suddenly it would die down, but did not turn off. It sort of seemed like if it wasnt getting enough gas at times. Had a question though, i dont know much about carbs but i was wondering just about how much gas should the jets be spraying in there? I was looking inside the smaller of the barrels, when it was idleing rough at around 15 maybe 1300, and i didnt see much action, maybe a little stream, hard to tell, then i went inside and stepped on the gas some and went back out to look again. This time, the smaller barell, on the right side, not the one facing the front of the car, was actually spraying something, i could see it. But the other barrel was not spraying anything. And the secondaries either, but those dont go on till higher RPMs, right? I also checked the level of gas through the little window and it was pretty low. What could this be a sign of?? Carb rebuild, again?? Maybe fuel pump?? Whats up??

74RX4

iTrader: (10)

There should be a fine mist in each of the primary barrels. It may be difficult to see at idle, but if you rev the engine a little it should be obvious. Both barrels should have a similar volume of fuel. The secondaries will not be activated until you are at speed.

I have had one 12A fuel pump go intermittent for a few weeks before dieing, but most die suddenly and never work again. The fuel pump would not cause the high idle. I'll bet you have a cracked or unplugged hose creating a vacuum leak.