9020 has no power

[Titan 0]

I have a 9020 with the Onan engine that runs fine when not under a load, but the rpm's fall off significantly when the tractor is put to work. The engine continues to run smoothly but makes no power. Where should I begin looking to correct the problem?

[midnightpumpkin 42]

Governor??

[RobertE 0]

Your symptoms sound like the same ones I had with my 4041. It turned out to be the two matched belts that connect the engine to the drive shaft. They looked tight but I replaced them and problem solved. Good luck with yours.

[D-17_Dave 11]

Your likely to find nothing physicly wrong with the govn. as they give little trouble unless someone has tinkered with it prior to you. While under load, lift the hood and varify that the throttle is opening wide open. If so then pull the choke slightly closed. If this helps then make sure you have sufficent fuel flow to the carb. so it's not starving for fuel. You also want to check the timing with a light to varify the timing's set correctly. Low timing, overheating, loss of compresion or fuel starvation. Any one or a combination of could be the problem. Step through each untill you find the answer.

[midnightpumpkin 42]

I for one tend to overlook the obvious. Take a peek at the air filter??? John U

[oli4gate 0]

Hi, I have also a powermax 9020 and experienced the same problem. The problem came from the ignition coil. One of the two exits wasn't "always" working. So the engine turned mostely on one cilinder. Or your motor is running on one cilinder too, or the coil triggering by the breaker points and condensor isn't working correctly, to my opignion. To test it, I started the motor and let it run stationary, then I pulled out the left spark plug cable. Normaly the rmp should lower, the motor should have more difficulty to turn, since it runs on one cilinder now. With my motor the rpm didn't change. So I pluged back the left spark plug cable and unpluged the right spark plug cable, now the motor stopped. This way I found out that the motor was running on one cilinder. After that I inversed the spark plug cables. The left one at the right side and the right one at the left side. Did the test again and now the motor stopped pulling the left spark plug. So I knew that one side of the coil didn't work properly. Normaly replacing the coil should have solved the problem, but since I live in Europe and it's hard to find spare parts. So,I have looked for a replacement coil. I have used a coil from a citroën 2CV with double exit. The engine was working fine now, but to my opignion the high rpm was limited. I thought that the engine could turn faster. At high rpm the timing to trigger the coil should change, this is done by the breaker points and the condenser. I removed the mecanical braker points and condenser, and developed a micro processor circuit that controls triggering of the coil. For more than one year now, my motor runs smoothly and is powerfull and runs at high rpm. I'm now to this forum, but I will post pictures and a movie soon.

[Ronald Hribar 41]

while many of us look forward to how you did it. You have to be a member to post pictures Sorry

[powermax_paul 1]

If the engine continues to run smoothly even after the rpm's fall off, I really don't think it's running on one cylinder because you would notice the tractor running rough. If it were a points/ignition problem, again the tractor would run rough. I'd look under the hood when you put the tractor under load and see if the governor is truly opening the throttle. You might have a spring missing or broken in the governor linkage.

[B10Dave 957]

dOdWelcome to the forum Olivier. Hope you pay to join so we can see pictures of your ignition modification. Sounds like an excellent mod to do on my 620.^ B10Dave.

[Cityboy 0]

I would second the points gap diagnosis. On my 720 with the same engine, the screws holding the points had worn and were not holding the setting. When the points gap narrowed, I lost power. Replaced the screws with sligthly larger ones, reset, and no problems since. Dave

[oli4gate 0]

Here are the pictures of the modifications I did: This is my powermax 9020

I removed the original coil.

I placed the citroën 2CV coil here:

I took a magnet from a defective computer hard drive and glued it at the flywheel, on the opposite side I places the hall sensor with wil detect a magnet passing by. The magnet is in front of the decector when the pistons are at the lowest point.

This is the microprocessor box I developed, I will post a picture of the printed circuit board later (I didn't take a picture yet). The µP gets its input signals from the hall sensor. Each time the magnet passes in front of the hall sensor on turn has passed, the µP times one turn. 1 turn = 360°, it will calculate the current rpm and calculate the next fire time. The µP will trigger the coil when the calculated time has been reached.

The upper view of the coil and the µProcessor box.

Here's a movie where you hear the motor turning smoothly and with lots of torque. [url]http://www.flickr.com/photos/50681398@N06/sets/72157625046316035/[/url]

[ZippoVarga 40]

It appears we have a new electrical engineer amongst our midst. Welcome to the club Oli!!!! Your experience will benefit many here.

[Roy 0]

Outstanding thinking and work to solve a difficult problem. ^ If the cost can be kept reasonable there is a market for a good Onan solid state ignition system. Carry on,

[oli4gate 0]

Here's a picture of the PCB.

I found manufacturerars of similar systems, only there's are a lot smaller. [url]http://www.shopatron.com/products/category/591.0.1.1.26484.26486.0.0.0?pp=8&pg=1[/url] Think I reïnvented the wheel :-)

[powermax_paul 1]

I'm Impressed! But then again I'm only a Mechanical Engineer. I like where you put the microprocessor....right next to the intake. Excellent thinking cuz at least on my onan's the intake stays almost ice cold even in hot weather. I've always thought about finding a small prox sensor to put in the points box but never had the smarts to build the electronics for the ignition. That's really cool!

[PGL 173]

Not too many "deux cheveaux" in North America, good solution for the ignition though.

[DMedal 0]

I'm an electrical engineer and I'm impressed. Just so everyone feels better, how much time did you invest in this system? Well designed system. what is the approximate distance from the Hall effect sensor to the magnet?

[oli4gate 0]

thanks for compliments. The distance from the Hall sensor to the magnet is about 1 to 1,5 cm There are different kind of sensors, but I chose the one with the highest distance range. It's difficult to tell exactly how much time it took to do rechearch and to develop this system, I didn't count the hours I have spent to it. But for 4 to 6 months I was working at it after a full time job.