Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hello everybody, I have a M90 engine that I just got the other day. I can not get this engine to run for more then 5 to 10 seconds then it seems like is runs out of fuel. Engine has great spark and I’ve adjusted the plug gap between 0.15” to 0.020” makes no difference. I’ve adjusted the mixer from just barely open to 3/4 of a turn open. I’ve purged all of the air out of the fuel line, even going as far as blowing into the tank cap breather hole to make sure I’m getting fuel out of the mixer. Sometime I have to pull the starter rope 7 to 8 times before I can even get it to fire. I’m using zippo lighter fluid as fuel. I have not had a chance to try any other type of fuel yet.

Any help is greatly appreciated with this neat little fella.

Thanks

Hi, there,
I also sometimes have difficulty with first starts. I find sometimes the plug cap rubs up against the valves. I also pull the pipe off the carb and use a syringe of fuel to purge all the air in the fuel line. I am using 4 stroke Stihl fuel with a couple of drops of oil /tank.
Mine never even fires by hand i always use the rope start. After a first start of the day it is a reliable starter. I even squirt a little fuel int the carb mouth

I cut and joined the HT lead inside the box. I spliced in a lenght of green period looking cloth covered cable for the HT . I protected it with PVC sleeving where it comes through the metal. I soldered the core onto a tiny loop which goes onto the plug top. I just didn't like the slightly fat red lead.
Hope this helps, Brian

I will try some different fuel this weekend, see if that helps. This engine spins over very nice with the intake vale held open, no binding or roughness at all and when closed it has lots of compression. I did oil all the moving parts with light 3in 1 oil prior to the first start up attempt.

When it does fire it spins up fast enough for the governor weights to spread apart. I don’t know what rpm it’s running at when it does run, but it’s fast enough to where it should have no problem staying running. It just seems like it starving for fuel.

How long is the fuel line supposed to be from the tank to the mixer? The hose that’s on there is about 2.5” long and drops down below the top of the box about a 1/2”. Is that to much of a drop to allow the mixer to pull fuel into the cylinder? Seems like it wants to run the best with the mixer needle at a 1/4 open or just a little bit more

Just one other observation, and I know this is a very small engine but when I blow into the tank with no fuel in it, I can barley and I mean barely get any air to come out the mixer, but I can get a the mixer to push fuel out of it when there is fuel in the tank.

Thanks for all you’re help with this, I greatly appreciate it.

Also, make sure neither flywheel is loose on shaft & magnet timing wheel disk & sensor are secure & smallest air gap seperated. Is this the original Blue engine or upgraded all silver color engine with all Plastic sealed, Black color ignition module ??...The Negative (-) battery lead wire (or dedicated 5th wire lead on all silver engine) Must be securely attached to engine ground metal. Again, hope some of this is helpful..Regards, ..tom.