RX-187

My car holds a lumpy idle. When the choke is still open or when the air conditioner is on, the RPM/idle is consistent and doesn't idle inconsistently with the distinct "brap brap". It also runs very rich. It backfires and shoots flames at idle and produces strong exhaust fumes that seep into the cabin. Gas mileage is also bad. I get 12 or 13 mpg at best. I'm unsure what to do. Should I go about on tuning or rebuild? If rebuild, where can I get a rebuild kit and what's the cost? I greatly appreciate your input.

Rx-7Doctor

iTrader: (13)

Well, it amy be that your needle seat is sticking in the carb and not shutting off fuel. Try some good carb cleaner for your fuel tank. Something like redlines fuel
system cleaner, Bg's 44k, which will take the paint off your car but is one of the best i have ever seen. Only available at dealerships or repair shops, don't know if
available in your area? Slick 50 has a synthetic one available that is also good.
If that does not work it may be rebuild time. Contact Victoria british ltd at 800-255-0088. They used to have very resonable kits for sale, also a needle seat replacement that is a roller ball style and does not stick.

RX-187

I've gone through several bottles already, and it didn't make a difference. The problems still persisted. What else can be wrong? Can it also be a vacuum leak? Sticky throttle, choke, float?

RX-187

^?

Rx7carl

Sure, a lumpy idle can be caused by a vacuum leak. What about when driving? Any noticeable problems? Whats the fuel level in the sight glasses? Stock fuel system and carb I presume. Anyone mess with the idle mixture screw? Did this happen all of a sudden?

RX-187

Okay, my car has always been like this since the day I bought it. If I rev it, I hear RPM breaking followed by some pops or backfires. When I'm driving, the RPM stutters and when I stomp on the gas it hesitates and doesn't respond very smoothly. As I take it to high RPM, I get backfires at the same time. While cruising at low RPM, the car bucks and shakes back and forth and the the RPM is lumpy. At idle, the exhaust sounds brap brap...brap brap....brap brap combined with a squeeling noise tied in with the brap brap...brap brap. I'm hoping you all can help me make this into a smooth running rotary.

Rx7carl

First thing is to do a good tuneup. New plugs, wires, cap, rotor, oil and filter, fuel filter, air filter,check ignition timing. Then go from there. If the carb needs a rebuild, get a kit from any number of sources. But the one I like best is made by Standard/Hygrade. An autoparts store should be able to get it for you.

RX-187

I did the tuneup the first day I got it and expected it to run better (without fuel filter replacement though). I even went out to buy NGK plug wires. Had to put in a new ignitor for the tach to work. Not like it would matter but I also then got a full 2.5 inch piping exhaust made with a catback muffler and Racing Beat headers . All of this followed by interior stuff he heh. I've done everything for this car and being the unappreciative car it is, the car still runs like $#it. It's draining funds from my FD!! Now how do I check the ignition timing on this thing? How do I change the fuel filter? btw, what rotor are you talking about?

The car has 93k miles.

Rx7carl

In the FAQ thread theres a link to online service manuals. Thatll tell you about the fuel filter and ignition timing check.

Dizzy cap and rotor is what I was talking about.

RX-187

What?

Rx7carl

Distributor cap and the rotor underneath it.

bbmac

It sounds like the problem I used to have with my "surge valve." Mine was way more severe but it is a vacum leak. not to sure the entire reason why when the surge valve diaphram is cause a leak it causes the carb to run rich but anyways, here are my symptoms and the way I fixed it you be the judge if that is whats wrong with it.

-floods often
-backfires and get absolutely horrible gas mileage
-when the engine is cold the thing will barely run and often will fire the cut out almost right away
- when you get it going you have to rev it up and keep it up to keep up with the fuel flow
-venturis are spitting gas( mine was almost a constant stream)
-If the engine is warmed up almost to aperating temp. it fires up great and only has minor symptoms


if this is all tru or even if it's not try this out, it will take you literally 5 minutes.

if you have your stock air cleaner there are a few 1/2" or so pipe running to the bottome of it to recieve clean air. Ther is one in particular that you need to plug with a cork or whatever you can find!

it is located on the drivers side of the air cleaner and if the hose that is the closest to the rear of your car, right above/beside your throttle linkage. plug it!!!! sorry my explanation is a little confusing but right now this is the only way I coul dthink of explaining it and I don't have a digital camera.hope thsi helps
brydon

vipernicus42

iTrader: (4)

The best way I've found so far to test for vacuum leaks is to use a propane torch. You don't light the torch, just let the propane flow, and wave it around the various places you think might have a vacuum leak. When the propane gets sucked into a vacuum leak you'll get a bit of a dip in idle. Do this in a properly ventilated area (like OUTSIDE) and don't do it for long periods.. Propane is not exactly resistant to flame.

Fuel filter replacement is bloody easy:
1. Buy Fuel Filter
2. Jack the drivers-side rear of the car up and secure with jackstands. (don't forget to secure your tires, or you could do what I did and bend a jack.. or worse!)
3. Get under there with a set of needle nosed pliars and some paper towels. The fuel filter is just forward of the rear wheel IIRC and is only held in place by a clip-on bracket and the "Fuel In" and "Fuel Out" hoses. Undo the clamps on the hoses, replace filter.

About five minutes... maybe ten if you really take your time. This is for a carbed car... if you had fuel injection it would be harder methinks.

Ignition timing is covered in the Heynes manual. Get one. NOW! It's the best damn twenty bucks you'll ever spend on your car.

If you've done dist cap, rotor, fuel filter and timing and still can't get it to work, then get the carb rebuilt by Sterling or Carl. You can do it yourself too.... but it's a bit more of a pain, and Carl/Sterling will do a better job of it.

If you've done that and it STILL doesn't work, look up your local rotary shop.. if it's only five or six hours away like it is for me, then it's worth the time and effort. I had an idle problem (different than yours) and I've just finished what I hope will be the final solution to the problem - blocking off the ACV. If that doesn't work, then I'm driving my car to CP racing in Toronto and having them figure the damn thing out!

Jon

Kentetsu

One simple thing you could check just for the sake of elimination would be the coils. If your leading coil is bad you could get similar symptoms. Just a thought.

RX-187

Nah...I think it's good. If my leading coil is bad, I WOULD get similar symptoms? Thank you all for the input, I'll try to figure it out with this heap of info. I didn't know an FB would be this hard to get running smoothly.

RX-187

I forgot to add this in my above post. How do I tune the carb to possibly eliminate the symptoms?

RX-187