ray green

iTrader: (14)

Hi Folks, I have just purchased (on ebay) a real nice 85 GSL, great deal. However it has a problem with low speed acceleration - sometimes there is a slight hesitation or dead spot when you first give it gas. I've been driving the car a week now and three times I've stalled at red lights (which never happened in two years of driving my 84 GSL). It then won't immediately restart (probably flooded, I can smell some gas) but I have learned that waiting through one cycle of the light is enough time to get it restarted. Otherwise it runs pretty good, especially at high speed and/or high revs, although the gas mileage seems to be not as good as the 84 GSL it is replacing (which was rear ended). I looked at the carb this morning and it is clean, with a new air filter. However with light acceleration I couldn't see any fuel being injected into the throat of the two larger openings in the carb, which I presume are the primaries (but I don't know much about these things). On the other hand, when the accelerator was pumped harder, it was easy to see fuel being shot into the two smaller openings, which I assume are the secondaries (but still no visible fuel in the primaries). So I am wondering, are my problems because the primary ports or jets or whatever they are called aren't opening, or is it something else (float levels, stuff like that that I also don't know much about)? Any suggestions for diagnosis/repair? All help greatly appreciated!
Ray

Rx7carl

The small barrels are your primaries, thats where the accel pump shoots into.

I see 2 possibilities. Your accel pump shot needs adjusting (most likely as you gave excellent info on how its reacting), or your carb passages are blocked, specifically the transition circuts (unlikely). Adjust the nut on the end of the accel pump arm to make it squirt as soon as the throttle is opened. Start there and see how it runs.

ray green

iTrader: (14)

Thanks Carl! I knew I should have gotten out the Haines manual first, but that chapter makes my head swim. I'll check out the accelerator pump right away, and do some reading this weekend. I do have another carb from my 84 that was working nicely, is it much work to just swap them over? (Assuming a simple adjustment of the accel pump doesn't work, of course). Ah, the pleasures of having a complete and correct parts car! One other thing I forgot to mention, I got this car up in Joneboro Tennessee, which is a higher elevation than we are here in Atlanta. Could this have something to do with it? Again, thanks for your help.

Ray

AdrenalifeRX7

It's possible that the carb could have been tuned to run the motor slightly leaner to compensate for the higher altitudes.

Rx7carl

No, they all came jetted the same from the factory (manual trans), only autos were jetted one step richer.
84-85 carbs are identical. It is only a PITA if you still have the accessories (CC, hot start) and emissions.

And theres an altitude compensator on later carbs (84-84, maybe even 83) that does that function.
Now thats not to say someone didnt dick around and rejet it at some point, but I highly doubt it.

ray green

iTrader: (14)

Thanks Carl, I'm going to have a look this weekend to see if some simple adjustments will get rid of the stall. Also I can see if there are differences between the 84 and 85 set ups. I see you rebuild carbs, maybe I should send you my spare for a rebuild, set up for my exhaust changes - I am planning to put in a bonez presilencer in place of the three cats. Then when I put this in I can change out some of the unnecessary accessories, which are all still there. Would you be interested and is this a good idea?
Ray

Rx7carl

Your stil gonna be running the stock exhaust manifold right? I wouldnt get it rebuilt if its running good. I'd be happy to rebuild your spare if you want, but it sounds un-necessary at this point.

ray green

iTrader: (14)

Yes I am being conservative with time and money and trying to keep the car as stock as possible (except the cats). I hope just putting in the presilencer and getting rid of the cats will give enough extra power and gas mileage to keep me happy, if not then I'll go with the header, probably a complete RB system. I don't have enough experience with the different arrangements to make an informed choice, so I figured I'd just get started with the presilencer and see what happens. I suppose if I do go to a header that carb adjustments would be in order? Again, thanks Carl and others for your suggestions.

Ray

ray green

iTrader: (14)

OK, two new clues. I took out the plugs, they show that the engine is burning lean (I have a photo but don't seem to be able to attach it to this note). The plugs are not the NKGs everyone recommends, they are Denso's - I put in my NKGs from the other car and it seems to run better. The second thing is that the accelerator pump is leaking about a drip a second for a few minutes after the car is turned off. Do I need to rebuild the carb after all?

mar3

iTrader: (8)

No, try replacing the AP diaphragm first...somebody here has a tutorial on how to do it with the carb still on the engine.

Rx7carl

Densos suck, throw them away! Stick with the NGK's. Im testing the cheap Autolites, but no conclusions yet.

When you say you see them lean, are they tan/light brown with whitish specks? Pic of the plug?

mar3

iTrader: (8)

From what I understand, you cannot "read" a plug pulled from a rotary in the same manner as you do a boinger. On a boinger, you're supposed to take a clean set of plugs and run around the block with one or two ringers and then pull the plugs after it cools down. FWIW...YawPower had short life and cracking problems with Autolites...

Rx7carl

Yes, and rotaries with their inherent rich idles tend to look like theyre too cold. To me, I just work around that.

Yaw was trying to work with boinger plugs. Im using side fires made for rotaries. And you wanna talk about cracking ceramics? Look at a set of Denso (nippondenso) plugs with a otoscope (or magnifying glass).

mar3

iTrader: (8)

No Densos, I agree....for me, it's either NGK or, soon, my suicide Bosch plugs!! I just know it's gonna work!!

ray green

iTrader: (14)

I'll get a photo if some one tells me how to put it in, basically they are all white. What's an AP diaphragm, is this something like my wife has?

Rx7carl

Be careful with those Mario! Dont munch a seal.

Ray, lol no, well kinda lol. Its the diaphragm for the accel pump. Drivers side, rear of carb. youll see a small square thingie (tech term). It has an arm in the middle and is held on with 4 screws. Behind that cover lurks the mysterious AP diaphragm.........Crikey! shes a beaut eh?

ray green

iTrader: (14)

OK, it's sinking in. AP = accelerator pump, right? (It's times like these my PhD comes in handy!). So my new questions are, will replacing the AP diaphragm fix the fuel leak dripping from the AP (I would think so). Also, is this leak what's causing the car to burn lean? Also, can I replace the AP diaphragm without removing the carb? The Haynes and Clymer manuals have you taking out the carb first, if I do this I would probably just switch in my 84 carb, which is in better shape and doesn't leak (yes, all the accessories are the same on my 84 and 85 GSLs). Finally, where can I get one of these AP diaphrams on a Sunday afternoon?

Thanks for the help guys!
Ray

Rx7carl

The ap diaphragm also incorporates the gasket built in, so yes it should stop the leak. It however has NOTHING to do with your running lean problem. It can be replaced without removing the carb, but its a PITA to do that way.

Victoria british carries the AP diaphragm, as does mazdatrix.

Running lean is unusual in a stock carb unless you have a vacuum leak. Is it just lean at idle? If so then adjust idle mixture.

ray green

iTrader: (14)

Thanks Carl, now that you mention it I did find a couple of problems with some of the black hoses on the left side of the carb, one broken T connector and another hose replaced with a gas line that didn't fit. I'll bet that's causing it to run lean. I got replacement parts for these yesterday and will put them in today. Maybe I should just switch carbs, would that be easier than redoing the AP? Especially since I will have to wait a few days to get the parts - I'd like to get it fixed today. I'm owing you a couple beers, Carl.

Thanks!
Ray

ray green

iTrader: (14)

OK, lesson learned - look for vacuum leaks first. I found two, both easily fixed, and this fixed all my stalling and lean running problems - the car runs great now. Of course I still have a leaking AP, so I am going to fix up my back up carb (which is in better shape) and install it next weekend. Starting to like this carb stuff! RX7 Carl, or anybody, can you tell me where to get information on "Sterlings AP mod, and mech secondaries", I snipped this from another post of yours.
Ray

Rx7carl

Cool, glad to hear things are going well. Use the search button and search for those key words. His writeups are on this board somewhere.

Sterling

I need to amend the AP mod of my write-up, guys. Don't worry, it's easy.

Remove the brass screw that holds the AP nozzel down.
Drill an .040 hole up the bottom, and .030 holes out the sides of that banjo bolt. The existing orifices are ridiculously too small.
Drill out the nozzels to .025.

This should alieviate any leaking in the AP system that is due to overpressure from the extra leverage, as well as deliver a much faster and robust pump shot. This
will make the carb more responsive, however, it may be necessary to back the shot off a bit.

I'm sorry I missed this all this time. If I had'nt had all these carbs all apart and little piles of parts everywhere, I would'nt have seen the differences in some of the AP nozzel bolt orifices.

The differences are huge, but even the larger ones are too small to handle the flow of this mod.
I hastily disassembled a bunch of carbs for cleaning without taking notes. I still do not know which years have the larger AP banjo bolt holes.]

Sterling