Starts on one rotor (sometimes) wont idle....

[wiggman2030]

Hi all,

I've got a problem with the 7 that is doing my head in. I'll start with the basics. All four plugs have spark, compression is 80psi on all faces on both rotors when cold as I can't seem to get the thing warm. I recently had the carb apart but it wasn't running before I took it off either. I can see fuel being squirted when i press the accelerator.

So, I can get it going if I hold the choke just right after a few presses of the throttle pedal. Most of the time it runs on one rotor (the front) sometimes it will run with both.

If I give it too much throttle it dies straight after, If I don't give it enough choke or too much choke it splutters and dies, Just wont stay alive in general. The closest I've got to this thing getting warm was 3 minutes of run time. It's driving me nuts.

Any ideas?

Oh the fuel mixture screw has been wound out 2 turns from the stop and the air bleed screw 3 turns. The throttle stop screw has been adjusted so the butterflies just move. I've tried running it on the main circuit but the problem stays the same.... It's so frustrating. I've done so much to this car and it still wont run. Even after an engine swap....

[TOOL]

Check the dizzy is lined up correctly for a start. At TDC you should have the rotor arm pointing at L1. Confirm this.
If you're a tooth out you'll have spark but at the wrong time.

Pull the fuel line off the carb and put the end in a bucket. Turn ignition on and check for good fuel flow.
If ok this rules out pump and filter.

On to the carb.
The accelerator circuit is working based on your description, but that only works to get you from idle circuit to main circuit.
You need to check the jets in the side of the float bowls. Chances are they're blocked or the other air jets are too.
After that I would say tune the carb. Set the idle at about 2000rpm and get it to run. Once warm, start turning it down making adjustments as you go.

TOOL

[wiggman2030]

Ok brilliant, thanks for the help. I'll post the results up soon

[wiggman2030]

OK, Rotor arm is pointing at L1, fuel flow is good. The only thing I'm unsure about it what to check on the carb. I'll disassemble it again and just make sure everything is clean/jets aren't blocked. I'll keep you posted

[wiggman2030]

Ok, I've had the carb off. All of the jets are clear. The only thing I haven't checked are the two parts with the weight and check ball. I noticed that one of the jets on the side of the float was missing a washer. Could this make a difference? If not I'm stumped as to where to go next? If it's something to do with the accelerator pump would this still stop it from idling?

Thanks

[Engrooved]

The only time I've had issues with an idle (when all else was seemingly ok) was with an elusive vacuum leak.

[wiggman2030]

I've took the inlet manifold off too, made sure the face was clean and smooth as I have a new gasket to go on anyway. Most of the emissions stuff has been removed so there isn't that much in terms of vaccuum. I can't hear anything and the strange thing is. When I do get it to idle (eventually playing about with the choke and pumping the pedal) it only idles around 500rpm. It doesn't seem to want to go any higher without stumbling and dying... I'll still have a check though just for good measure

[ian65]

these seem to be the same issues you had 3 yrs back...

http://rx7fb.com/viewtopic.php?f=7&t=676

are you sure your coils are ok?

[wiggman2030]

Haha yeah, since then it's had another engine as the other one had very low compression (hence the warm idle issue) and another carb from a donor car (only bought for the engine as it was a complete rust box). Yeah the coils are ok. I pulled leading plugs on both rotors cranked and there was a good strong spark. Same with the trailing I also have a spare set which I tried. I've never had this thing running properly since I bought it. Sad that it's never turned a wheel on the road in 3 years....

[codge]

Long shot but I'd rig up a temporary ignition circuit to bypass the wiring loom.
The common factor with 2 engines the same is the wiring harness. A fractured wire making intermittent contact and flexing under engine movement could just possibly make it die on acceleration.

I've known this previously on old cronky piston engine cars (typical 1950's to 1960's type of problem).