Rotax engine starting problems, diagnosing hard starting problems on your Rotax and other aircraft engines.

Light Sport & Ultralight Aircraft Information.
.....
Airfield
(by appointment ONLY)
EMAIL
Click here for more
HOME PAGE

Hear what our customers have to say!

BRS parachutes - save lives! Tips for proper BRS parachute installation. Click here for more information!

*What do I do when the &^%$#@, Rotax, Hirth, Cuyuna, Kawasaki aircraft engine won't start?**
As human's we need certain things to operate efficiently - we need food, crisp clean air, a healthy working body with no damaged parts - and an exhaust. A two stroke engine needs these to. And if one or a combination of these things aren't right then the engine doesn't run properly. In some cases it won't even start.

While the human body has amazing recuperative properties (don't I know it - 12 broken ribs, two punctured lungs, broken back, broken leg, broken ankle, fractured pelvis) - a two stroke engine "can not heal itself!"

Now most of the pilots I run into on a weekly basis are good at what they do in the real world, but when it comes to engines, especially two strokes, they are like 12 years olds out on the first date. They don't have a clue what to do, and are as nervous as hell about doing something wrong! And they should be, their lives depend on doing things right!

But when an engine won't start there is always a reason or reasons. A two stroke engine needs fuel, air, ignition, and compression to work. That's not to say you just add fuel and it will work, nor can you have ignition unless it is at the right time, and how much compression is compression? Let's go through a step by step procedure to help someone out "on their first date" or engine troubleshooting adventure remembering that the information obtained here can be used in future encounters.

The first thing is - Is there fuel in the tank and is the valve turned on! If the answer is YES then proceed to the next step. If not then put fuel in the tank and turn the valve on - it is as simple as that!

Question?	If answer is NO then check for	Problem area	Suggestions
Is fuel getting to the carb? YES	If NO then check	A. for a blocked, or broken fuel line. B. for blockage in the fuel valve. C. for blockage in the needle and seat, or failure needle and seat. D. improper fuel tank ventilation E. fuel filter plugged F. failed impulse line G. incorrect fuel pump installation H. defective fuel pump	Fix repair or replace.
Is fuel reaching engine? YES	If NO then check	A. plugged main jet B. plugged low speed jet C. throttle valve not opening D. rotary valve gear not turning E. for blockage in the needle and seat, or failure needle and seat.	A. clean main jet B. clean low speed jet C. replace throttle cable free up slide D. repair rotary valve gear
Is fuel running out overflow tubes on side of carbs? NO	If YES then check	A. needle valve for sticking B.floats for damage or leaking C.float arms for proper level
Is engine flooding? NO	If YES then check	A. check to see if you have spark B. check to see if choke is on C. check to see if primer is working properly	Replace plugs Turn choke off Repair or replace primer
Is spark present at spark plug cap? YES	If NO then check	A. check coil wire connections for proper fit or damage. B. check spark plug cap for continuity and damage. C.check for faulty ignition switches D. check for faulty ignition coil. E. check for faulty ignition Pickups	First NEVER check for spark without the spark plugs installed in their caps! Start testing the easiest things first. Like a poor connection, then the spark plug leads, cap and spark plug. When checking plug USE a NEW plug not one you have had laying around!
Is spark present at the Spark Plug? YES	If NO then check	A.spark plug fouled B.spark plug flooded C.spark plug broken D.incorrect spark plug gap	Replace spark plugs in all instances.
Is engine difficult to start? NO	If YES then check	A.air cleaner blocked B.engine flooded C.throttle valve open too far D.water in the fuel E.poor ignition timing F.no compression G.enricher valve closed H.intake leak I. improper fuel mixture J.blown head gasket K. faulty spark plugs L. gear box improperly loaded	Clean filter Drain fuel, clean tank, and carb, replace with new fuel Repair engine Repair gear drive
Does engine backfire or kick back? NO	If YES then check	A. dampening box faulty or disconnected B. ignition wires reversed C. ignition timing out of adjustment D. flywheel key missing or sheared E. faulty ignition switch F. failed crankshaft bearing on PTO end. G. failed MAG seal oil has contaminated condenser/points H. gear box needs update/reconditioning
Does engine run on one cylinder despite good spark in both plugs? NO	If YES then check	A. improper plug gap B. fouled spark plugs C. spark plug cap defective D. no crankcase pressure E. blown or leaking head gasket F. cracked cylinder G. poor ignition timing H. crankcase air leak I. needle clip has failed on one carb
Does engine cranks without resistance? NO	If YES then check	A. stuck rings B. broken rings C. excessive piston to wall clearance D. burnt, broken or scored piston E. piston dome penetrated by pre-ignition F. blown head gasket G. spark plug is loose H. head bolts need torqued
Engine will not rotate- lower end frozen? NO	If YES then check	A. debris in crankcase B. crank baring frozen C. broken connecting rod D. piston seized in cylinder E. badly rusted crankshaft F. foreign material has enter intake on liquid cooled engines locking rotary valve gear
Does engine start but will not idle or misses just above idle? NO	If YES then check	A. spark plug gap incorrect B. worn piston and rings causing low compression C. Carb idle circuit plugged D. too much oil in gas E. plugged carb jets F. air regulating screw out of adjustment G. stuck rings H. poor ignition timing
Does engine die when throttle is open? NO	If YES then check	A. jet needle E clip installed above spring cup B.improper carb slide used, newer models have cutout in slide C. incorrect spark plug gap D. excessive prop load E. fuel pump defective F. float level too low G. vacuum line leak
Is engine slow to accelerate or does not reach full throttle? NO	If YES then check	A. fuel mixture to lean B. fuel mixture to rich C. poor compression due to broken, stuck or worn rings D. float level to high E. too much prop load F. too much prop mass weight inertia
Doe engine run rough, smoke or vibrate excessively? NO	If YES then check	A. enricher valve open B. water in fuel C. prop out of balance D. fuel mixture too rich E. gear box needs update and or service F. air in fuel lines G. fuel pump defective H. intake leak I. engine mount broken or loose
Does engine run poorly at higher throttle settings? NO	If YES then check	A. Engine misses at higher RPM 1. incorrect spark plug heat range 2. incorrect fuel mixture (too rich or too lean) 3. spark plug fouled or defective 4. poor ignition timing 5. ignition cables arching 6. ignition coils defective 7. dampening box defective B. Engine "loads up" 1. jet needle position to rich 2. main jet too rich 3. dirty air cleaner 4. poor ignition timing 5. too much oil in fuel 6. worn carb tuning components C. Engine emits "knocking" 1. timing too far advanced 2. piston to wall clearance excessive 3. crank bearing burned, failed or grinding 4. excessive wrist pin play 5. circlip missing from piston 6. excessive carbon deposits
Does engine overheat? NO	If YES then check	A. fuel octane too low B. fuel mixture too lean C. ignition timing too far advanced D. prop load excessive E. cooling duct blocked F. carb out of adjustment G. instruments or sender defective H. low coolant or incorrect anti-freeze to water ratio I. poor cooling system installation J. failed water pump impeller
Engine rpm surges or won't hold steady? NO	If YES then check	A. exhaust back pressure tuning incorrect B. exhaust system improperly modified C. engine requires modified jets in mid range D. needle and clip located above white plastic retainer E. on 532 Rotax ignition coils and or dampening box wired wrong F. intake socket failure
Does engine lose power after standard warm up or will not reach full throttle? NO	If YES then check	A. piston seizure B. stuck rings C. prop load excessive D. main jet to rich
Does engine show high CHT temps? NO	If YES then check	A. poor ignition timing B. loose or slipping fan belt C. prop load excessive D. fuel mixture to lean E. obstructed cooling ducts F. poor engine design installation G. defective gauge or sender H. lack of oil in fuel I. poor piston to wall clearance J. damaged fan K. failed fan bearing
Does engine show excessive EGT temps? NO	If YES then check	A. air intake leak B. air/fuel mixture to lean C. changes in density altitude D. changes in humidity E. changes in air temp F. timing too far advanced

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Index for this section.

Make yourself visible to others when your flying...... Strobe lights make you visible! Click here for more information!

Ultralight News
.....

Ultralight Aircraft News.ca Web Magazine EMAIL for l Information. No part of this publication may be copied or distributed, transmitted, transcribed, stored in a retrieval system, or translated into any human or computer language, in any form or by any means, electronic, mechanical, manual, or otherwise, without written permission of Ultralight News. By copying or paraphrasing the intellectual property on this site, you're automatically signing a binding contract and agreeing to be billed $10,000 payable immediately. Copyright Ultralight Aircraft News.ca

Rotax engine starting problems, diagnosing hard starting problems on your Rotax and other aircraft engines.

What do I do when the *&^%$#@, Rotax, Hirth, Cuyuna, Kawasaki aircraft engine won't start?

**What do I do when the *&^%$#@, Rotax, Hirth, Cuyuna, Kawasaki aircraft engine won't start?**