I'd check that the choke butterfly is not stuck closed. This is what happened on mine, Sears lawn tractor 917.275371, Engine Briggs & Stratton 31C707 type 0230-E1 (31C7070230E1) I sprayed carb aerosol cleaner on it, noticed that the choke would not open, so it was running real rich. I ended up drilling a small hole in the red palstic motor housing and attaching a spring from that hole to the already-there hole in the black lever on top of the carb, the lever which actuates the carb butterfly. Pushing the throttle all the way forward closes the choke for starting, but the internal spring to open the choke is too small, or some have posted that the shaft is too large and that one should take it out and shave it a little smaller. The added spring works for me. Sorry, I don't have a photo yet, the lawn tractor is 100 miles away.I'd check that the choke butterfly is not stuck closed. This is what happened on mine, Sears lawn tractor 917.275371, Engine Briggs & Stratton 31C707 type 0230-E1 (31C7070230E1) I sprayed carb aerosol cleaner on it, noticed that the choke would not open, so it was running real rich. I ended up drilling a small hole and attaching a spring from that hole to the already-there hole in the black lever on top of the carb, the lever which actuates the carb butterfly. Pushing the throttle all the way forward closes the choke for starting, but the internal spring to open the choke is too small, or some have posted that the shaft is too large and that one should take it out and shave it a little smaller. The added spring works for me. Sorry, I don't have a photo yet, the lawn tractor is 100 miles away.

When a shop posts a help request similar to what is above, the normal reply is to tell them to substitute a known good technician. VBG... Test this and change that is not how to diagnose and repair a problem like this, well, by now you probably realize that because it simply doesn't work. Now sure there are times that this method does work, and occasionally you don't even spend a fortune doing it. But as a pro, you'd fail so often you would not last as a technician. A "noid" light is not an accurate test of the systems ability to turn the injectors on. The injectors initially start to draw current at such a level that if they were allowed to stay turned on long enough they would each draw twenty amps+ of current. To prevent overheating the injectors the computer uses what is called a peak and hold system. How it works is one transistor (also referred to as a "driver") turns on and starts to open the injector. Once a sufficient current flow is reached, a second transistor turns on that has a resistor in series with it, the first transistor turns off and that limits the current flow to around 1.8 amps. The "peak" part of the voltage waveform causes the injector to open, and the hold portion allows the injector to remain open long enough to dispense the right amount of fuel. A noid light will flash with as little as 1ma, or .001 amps. This type of testing has tricked just about everyone who relies on it at least once. The right way is to measure the current flow with a low amps probe an an oscilloscope. You can also use the scope to monitor the ground side of the injector to watch for both drivers signatures, and their inductive kick on turn off which is an indicator of the strength of the magnetic field that was created when the computer turned the injector on. Now just because current is flowing that does not mean that the injectors physically opened, nor does having fuel pressure guarantee there is fuel at the injectors under sufficient pressure to be injected into the engine. There are screens on the injectors themselves that serve as a last defense filters, as well as there is usually an inlet screen to the throttle body just inside of the fuel inlet nut. Once you prove that electrically the injectors should be opening, by measuring the current flow with them connected, and/or measuring their inductive kick. Plus you re-confirm that there is fuel pressure, AND volume. Then you have proven that problem is inside the throttle body, and you will need to take it apart to find out what is going on.

Having same engine idle problems. 92 chevy Scottsdale 5.7L, 104,800 miles.Starts and runs great but, when it warms up setting in drive with foot on brake, the engine surges. Idles down then back up (like a stuttering). Sometimes, when driving between 35 and 40mph it will do a little hesitation, but when I give it gas it smooths right out. I have replaced TPS, engine temp sensor, plugs, wires, 02 sensor. new fuel filter, disconnected the EGR vac (No difference), tested MAP it is good. So,a few months ago I had a new Distributor put in, it seems this is when my problem started. No saying this is the cause, but yesterday when when starting it for the first time and after a min or so the distributor started make that sound again (bearing) after engine warmed up it stopped making the noise. So I m thinking I have a crappy distributor. And yes I put in a Carquest dizzy. Had no choice the 3 auto stores around here all have crappy after market parts so I thought Carquest was the better choice. So it looks like I will be replacing this dizzy with a AC Delco if I can find one. Maybe you guys can check you distributor for your problem. Hope my impute helps someone. any feed back advise is welcomed. Email me jdcron@wmis.net as I may not see your response.

I've pulled distributors that were stuck like this by making a basket out of interwoven coat hangers to grab the distributor. The hangers should tighten up under the head of the distributor as they are pulled up. Attach the coat hangers to the shop crane and use that to apply the vertical pulling pressure. Do not just attempt to power it out with the crane, just put some pressure on it, and then use a twisting motion on the distributor housing. Remember, too much force with the crane will break the distributor. Try to not break it, and bring the lifting force up slowly.