Engine will only run above 4000 RPM. Carbs or timing?

[madkaw]

He stated earlier he had 3 psi - so it was good.

Not sure about the spark tester- what does the results mean?

I would think you want a strong blue spark and you could have done that against a bolt.

[grannyknot]

It could be the carbs... to much fuel or not enough fuel ( dirty carb from sitting to long ). Have you checked the plugs when the engine has been running for like 20 seconds at 4k rpm?

Compression test was okay, so it's either spark or fuel problem...

Bart, every time I have removed the plugs, the old ones or the new ones I just put in they were black and sooty. As well, there is some fuel dripping out of the carbs after every secession.

Just noticed the "new RX7 fuel pump". Maybe you're getting too much fuel pressure to the carbs. I don't know anything about SK/OER carbs. Maybe a defective/sunk float or bad needle valve. Most of your signs point to flooding.

I agree Zed, but the RX7 fuel pump is suppose to be a low pressure pump (which is why it's so quiet) but I have a regulator on the fuel line set at 3.5 psi. Float level might be out and I don't have the SK/OER float tool to measure it properly BUT all floats are at the exact same height so... hard to imagine all of them being wrong.

He stated earlier he had 3 psi - so it was good.

Not sure about the spark tester- what does the results mean?

I would think you want a strong blue spark and you could have done that against a bolt.

Steve, I don't know man, multiple gremlins. I guess since no one mentioned the ohm readings that they are okay?

Thanks,

Chris

Edited April 30, 2013 by grannyknot

[beermanpete]

Your resistance readings for the coil are typical and suggest it is good. If you know the model of your coil you should be able to get specs from the manufacturer for comparison.

Don't use an ohmmeter on circuits that have power, it can throw off the reading or damage the meter. In the case of your coil measurement, don't turn on the ignition while taking the readings.

A blue spark is good. A yellow spark is weak. When checking while cranking a yellow spark is not uncommon beacuse the battery/system voltage is lower than when the engine is running.

All that you have said so far suggests you are way too rich. If your float height is ok perhaps the floats have become sinks. If the floats are the brass type shake each one to see if there is fuel sloshing inside. If they are plastic it is harder to tell. Try floating all of them at the same time in a bucket of water or gasoline (carefully) to see if they all have the same bouyancy. Or if you have a sensitive scale weight each one and compare their weights.

[bartsscooterservice]

Bart, every time I have removed the plugs, the old ones or the new ones I just put in they were black and sooty. As well, there is some fuel dripping out of the carbs after every secession.

If your bowls are full it doesn't mean it's functioning good. What I read from your answer, sound alot like it's flooding the engine, to much fuel.. flooring the pedal will give just enough air to let it run. Clean the carbs !

[grannyknot]

Okay so 'm cleaning the carbs, got them done this after noon, all jets out, carb cleaner, methel hydrate and compressed air. There was some varnish that came off easily, and one of the float levels was set way too high.

All the floats are black plastic and in good condition and all seemed to float at the same height in water.

I set them all exactly the same so the fuel level will be 1mm less than the base setting, I can always raise it later externally if I have too. I'll re-install tomorrow afternoon and let you guys know what happens.

Thank you,

Chris

[madkaw]

Chris,

Did you find the specs for your coil ?

After some research, I found the normal reading from + to - posts should be .5-.9 ohms.

My coil reads .9 and from center output to post is 6k

Not sure if this relevant it not, but you need to verify yours .

[SteveJ]

Chris,

Did you find the specs for your coil ?

After some research, I found the normal reading from + to - posts should be .5-.9 ohms.

My coil reads .9 and from center output to post is 6k

Not sure if this relevant it not, but you need to verify yours .

A coil designed for a ballast resistor should be in the .5 to .9 Ohm range. The coil Chris has is designed to operate without a ballast resistor, aka a 3 Ohm coil.

[madkaw]

My car has the ballast deleted and reads .9

I run a 81 dizzy.

I came up with those numbers by googling typical resistance readings.

I'm not an expert spark chaser, but this is what I found

[madkaw]

Steve j ,

Sure you dont have it backwards as far as resistance readings?

Chris,

You are running a ballast resistor?

Which coil are you running?

[grannyknot]

No ballast resistor here. Pertronix flame thrower, 3.0 ohms.

Madkaw, remember the scale I used for those readings, the scales I used brought the decimal point as far left as possible

so as to give as much detail as possible.

[madkaw]

Was that Pertronix matched for your HEI module? What application was the HEI from?

Is this EXACTLY the way it came off the running engine?

[bartsscooterservice]

Okay so 'm cleaning the carbs, got them done this after noon, all jets out, carb cleaner, methel hydrate and compressed air. There was some varnish that came off easily, and one of the float levels was set way too high.

All the floats are black plastic and in good condition and all seemed to float at the same height in water.

I set them all exactly the same so the fuel level will be 1mm less than the base setting, I can always raise it later externally if I have too. I'll re-install tomorrow afternoon and let you guys know what happens.

Thank you,

Chris

Chris, any results with cleaned carbs?

Bart