Maytag 72 Won't Run

[Bruce Wambach]

I completely disassemble my model 72 Maytag after it would not start only to find that it was missing the governor. Installed a good governor, put the engine back together and it still will not start, not event try to start. I have consistent blue spark in both plugs and have even put gas in the plug hole, just to rule out fuel problems, still no luck. Does it matter which hole you screw the governor assembly in? I did not see a difference or any marker on the crank or on in my manual. My only other thought is that even though I am seeing blue spark that the coil is not strong enough under compression. I have even used my electric drill to spin the engine faster and no luck. This has been the most frustrating engine I have worked on. I set the points at about .015 to take up any play in the bearings (there really isn't any, but I did it as a precaution). I would appreciate any suggestions or help.

Bruce in PA

[Jason N]

You might want to check your points cam and make sure it is assembled right side up. If it is upside down you might still have good spark, just not at the right time.

[maurice weiler]

Hello Bruce, Try switching the plug wires to the opposite plug.It may be firing on exhaust stroke.

[Neill]

make sure that you have the arrow on the cam facing outward.
Neill

[BobRR]

Have you tried new plugs? BobRR

[Pat Barrett]

I know this sounds dumb, but make sure the long side, or long slope on top of the piston is facing the exhaust port. If turned around, it won't run, either.

[BWegher]

Try spark tester. Or pull both plugs, hold wire ends about 1/8 inch from heads. If you get 1/8 inch long sparks outside you will have spark under compression. Make sure the plug end connectors are not corroded inside. Possible to have partially shorted coil, or poorly grounded due to corrosion. Condenser may be leaky, not properly grounded. Several improbable faults may be present. Such as magnet strength, etc

[Papa Maytag]

I had that same problem with one of my twins, Not many know, but the governor should be removed and the hole that it screws into should be cleaned. The port that allows the gas vapor to enter the crankcase thru the crankshaft maybe plugged. Clean and inspect the governor carefully . The llittle spring may have become disconnected on it. Make sure the brass governor parts are cleaned. With that being done and the crankshaft governor hole cleaned, and the governor spring checked add a drop of oil to the outside of the governor. Make sure the pistons are TDC. Screw the main portion of the governor in till it is a turn below flush. Spin the shaft over and check and clean the limit screw plug. After checking that, screw that in one turn below flush. Check the bearings for slop on the kick start end mostly, That section may have a little leak breaking the suction from the fuel jet. Listen to that area closely to hear any slop sounds.
The Maytag Twin depended on the good bearing seal to help draw the gas up the fuel tube. Then when trying to start the engine keep the air control cap closed and kick it over a few times, then open the air cap a bit more and try starting it again. Hope that may help you!! Happy Holidays!!

[Neale Behm]

The 72 fires both cylinders at the same time so changing plug wires won't help. if you're testing spark you should have both plugs out with the wires attached and the plugs grounded and watch for sparks on both plugs at the same time. Because of the way the coil is set up you can do damage to it by only having one lead able to reach ground.
I believe the proper modern plug is a Champion H10 though I've run them on CJ14's with no problem.
I'm gonna guess it's the condenser too but make sure the points are clean. I use an electronics cleaner then wipe them with a fresh piece of paper.

[Andrew Mackey]

Also make sure you have clean fresh fuel, mixed at a 16:1 ratop (1/2 cup oil to 1 gallon gas. Do not flood the engine. The new unleaded fuels will short out on the spark plug insulater, under compression. The plugs will fire out of the engine, but will misfire under compression. Check the fuel pick up tube assembly = it has a small fibre disc as a check valve, and it tends to stick when old fuel gets on it. Ground 1 spark plug wire. Hold the other in your hand and turn the flywheel slowly in the proper direction. Note the exact point that spark is felt and check that it is occuring at the proper time - about 10 - 15 degrees before top center compression. There are 2 protrusions on the backing plate that must straddle a casting on the engine base, in order to time the engine correctly.
As a side note - the engine should have run all out if the governor was removed altogether Did you replace the engine crankshaft bearings? If so, did you have a hole in the outer main bearing, by the kick starter, to allow for the engine intake? When the bearing was installed, was the hole aligned with the intake port in the block? If the original bearings are still in the engine - is there any play in the crankshaft at the starter gear? Does it move up and down, or front to back? Is there end play(push and pull on the flywheel). Bearing slop will make these engines hard to start. Did you oil the bearings with a lot of oil on assembly? If there is not enough oil, the bearings won't seal the crank to create pressure differential within the crankcase! The model 72 has the intake timed thru the block by the engine crankshaft. Are all passages open? Do you hear suction at the intake when the engine is turned over? When trying to start, turn air valve closed and kick no more than 3 or 4 times. Open air valve 2 turns and try 6 times, before closing the air valve and trying to start again.
Things to check -
1) spark at proper time?
2) spark under compression?
3) fuel getting into engine?
engine flooded = Plugs wet? Short out both plug wires and open air valve 4 turns, spin over engine until excess fuel is cleared from crankcase and cylenders. Install new plugs and try starting, using above instructions.
Engine dry = no gas? check engine intake passages A) air intake pipe, B) engine intake port in block - make sure hole in bearing is aligned with block (remove brass fuel venturi by loosening allen set scrw, and look in hole. Turn crank slowly and look for intake port to align with crank opening), C check fuel intake venturi, just removed, and see that fuel can pass. Check passage in crank itself to make sure it is clear. D) fuel pick up screen and check valve clean and free? E) is the engine getting air thru it? Remove the spark plugs and kick the engine over - you should feel a little resistance as the engine is kicked over, as crankcase pressure builds and is released, and you should hear the pressure release into the cylenders when the transfer ports are uncovered. If you don't hear tansfer - check intake as above, are pistons installed correctly? F) is the block deflooder passage open to the fuel tank? Yhis passage also pressurizes the fuel tank somewhat to assist with fuel delivery, is the fuel tank filler gasket in good shape? The model 72 is not as simple as most people believe - there are a lot of interconnected operations that need to work together in order for this engine to run wellIf after all this, if it still won't go, give me an EMail, and I will try to help.
Andrew

[Kevin Weis]

Bruce, The 72 twins are a bear to get running right when everything that can go wrong is not in perfect harmony with all the other componets. If the 72 coil is the lightest bit weak it is allmost impossible to get running and running right. It is their nature, especially the 72D model. The Wico mag was supposedly somewhat more reliable. Also check oil/gas mixture if it is on the heavy side with oil it will foul the plugs quickly. Would advise to get one of the many service manual reprints out there. They show pretty much everything you need to know. If it makes you feel any better I have a similar problem with a 72 except it does fire weakly. However the cylinders are badly pitted and believe this is the problem. Replaced coils, condensors, governors, cleaned out pick up tube and everything else. Didn't make much of a difference. It runs but the slightest adjustment of the air cap one way or another and it stops runnning from starvation or being flooded. If you need more info email me. Kevin

[Tom G]

What are your plugs gapped at? I can't remember the proper plug gap for this engine offhand, but I have an engine that will not start when the plugs are set to the recommended gap. I would get a fresh plug, and gap it at about .025 Then I would ground one plug wire to the engine, pour a tiny amount of fuel mixture into the other cylinder, and screw the new plug into this cylinder, hook up the plug wire, and try to start the engine, with the air cap screwed out about a quarter turn. The coil is a weak spot on this engine. Sometimes you can ground one plug wire to the engine, and start the engine on one cylinder. After the engine starts, you can move the grounded plug wire to the spark plug. I don't claim to be an expert, but I know what has worked for me.

[Andrew Mackey]

The model 72 Maytag engines employ a pass thru type of ignition system. The high tension side of the magneto is completly independant of the engine ground. Spark originates within the coil, passes thru the high tension lead, thru one plug, thru the block, thru the second plug, thru the second high tension lead and back to the coil. THE COIL IS NOT GROUNDED! If the engine runs on one cylender when a high tension lead is pulled off a plug, then the coil is shorting to ground internally, and the coil is bad. DO NOT STOP the model 72 engines by pulling off the plug leads! This is a sure way to destroy the marginal coils these engines have in a hurry! Starting the engines on one cylender and then jumping the wire to the plug, does 2 things - 1) it creates a disasterous high voltage surge within the coil during the time the wire is not in the circut, that is sure to burn out what windings are left. It is better to close the plug gap to .020" and save what remains of coil strength. 2) You stand a good chance of getting 'bit' with a good jolt of electricity, especially if the high tension leads are not in top shape!

Maytag 72 engines are supposed to have an .037" gap for each plug - a total of .074" for the coils to make the jump under compression! If the engine magneto coils are going bad, closing the gap on the plugs may work for a while, but the coil will have to be replaced eventually. I have a 1937 72-D that had a bad coil. The engine would run on one cylender until it got nearly to governed speed, at which point the second cylender would kick in. As soon as the engine was loaded though, the second cylender would cut out. Closing the plug gap down to .020" solved the problem for a while, but eventually even that didn't work any more and I had to replace the coil. The model 72 twins will not run reliably if the plug gap is set for less than .020". On the 72-D engines, I recommend that the plug gap be set at .030", to help prevent breakdown of the internal insulation due to the hige voltage needed to fire the plugs, as these were the weakest of the twin coils.