Electronic start of 5HP petrol engine

[Zaeed]

Hey,

I'm working on a project which involves automating the start up of a 5HP water pump (setting choke, throttle etc)

I'm just wondering if anyone has any suggestions on how to convert the key start ignition to something that can be controlled by a PIC Micro controller.

Cheers for your help

 

[RadioRon]

Isn't this just a matter of connecting the PIC output through a suitable driver circuit to the starter solenoid, placed in parallel with the key switch?

 

[MikeMl]

I did this with a PIC and used large RC model servos to set the throttle and choke butterfly positions. Controlling the ignition and starter motor was easy. I incorporated speed control/pressure control of the pump the engine was driving, too.

 

[Zaeed]

Hey Mike,

would you be able to elaborate on what your ignition circuit consisted of please?

Cheers

 

[MikeMl]

Hey Mike,

would you be able to elaborate on what your ignition circuit consisted of please?

Cheers

This was in a research project. We had a piezo pressure sensor (ICP) that monitored the pressure in the cylinder during compression stroke and during combustion. The spark event was timed to the rising pressure during the compression stroke. We also had a magnet in the flywheel and used a hall-effect pick-up for that, used primarily for starting/idle. The ignition was a solid-state module out of a Honda?. It had the quirk that you had to establish a current through it long before (in engine rotation time) you wanted the spark. The spark is triggered when the module current is turned off. The PIC ran the whole shebang.

 

[tcmtech]

There either are or at least were automatic choke carburetors available with every engine manufacturer at one time or another.
Many push mowers and small riding lawn mowers had them as a standard item.

My nieces go cart has a 3.5 Hp B&S engine with automatic choke. And my dads old roto tiller has a 5 HP with automatic choke as well.

lately however I have not seen that on the smaller engine designs any more. It may be because the new emissions compliant engines need a manual choke system due to the fact that shortly after the engine gets broke in they seem to always have to run with the choke partly closed. Otherwise they always seem to develop a bogging problem or just wont run right or at all unless you take the carburetor apart and drill out the main jet larger.