Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Troubleshooting

Reply
 
Thread Tools Display Modes
  #1   IP: 173.179.108.226
Old 05-23-2021, 08:31 PM
BobGales BobGales is offline
Member
 
Join Date: Apr 2018
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Starting problem

An old UJ (1974) engine badly maintained. Cold compression figures low at approx. 50,60,55,90. Completed routine maintenance but engine will only ignite enough to blow a spurt of exhaust, but not start despite excellent spark. Floods quickly. Any suggestions!
Reply With Quote
  #2   IP: 100.40.58.241
Old 05-23-2021, 09:27 PM
jcwright jcwright is offline
Afourian MVP
 
Join Date: Jul 2012
Posts: 158
Thanks: 5
Thanked 99 Times in 75 Posts
Hello Bob.

You may have already done all this, but just in case, I've copied below an old post by msmith10 on checking compression that I find helpful.

"I usually test the engine while its warm, as you'll get different readings hot and cold, but you may not want to run it that long on the cart. Your readings will be higher on a hot engine, but if it passes cold it will pass hot.
1. Make sure water intake is shut off so you don't fill exhaust system with water which will then enter the cylinders. You're not actually going to run the engine during the test so it won't need cooling.
2. Remove spark plugs. Cover holes with a rag.
3. Remove coil wire, disable fuel pump if electric (remove fuse or disconnect wire)
4. Open throttle to wide open and leave it there.
5. Screw tester into spark plug hole 1 and crank engine with starter for a few seconds. You'll see the pressure on the gauge go up in steps and max out. When it tops out, that's the reading. Repeat on other cylinders.
6. If the readings are low or vary more than about 10% from one cylinder to the next, add a tablespoon of motor oil through the spark plug hole of the low cylinder(s). If this increases the pressure significantly, it indicates worn rings or valve guides (the oil acts to seal the gap somewhat). If it doesn't change it's more likely a valve that's sticking or not closing all the way.
__________________
Mark Smith
1977 c&c30 Mk1 hailing from Port Clinton, Ohio"
Reply With Quote
  #3   IP: 67.169.215.221
Old 05-23-2021, 09:34 PM
ronstory's Avatar
ronstory ronstory is offline
Afourian MVP
 
Join Date: Feb 2016
Posts: 404
Thanks: 106
Thanked 208 Times in 152 Posts
Welcome to the forum, likely the most helpful forums on the web.

You have enough compression to run, so that's a good start and I would make sure the choke is fully operational.

I would do a quick check of the disti and make sure the plug wires are correct (you can see the 360 motor on the moyermarine.com site). Then check to make sure the centrifugal advance it not stuck. Then I would do a quick static timing check make sure it's set to 0 deg BTDC on #1 (closest to the flywheel)

If that does not show improvement, I would venture into the carb. I've had plenty of carb issues over 3 motors... but would still check the spark side first before going into the fuel side.

I'm sure others will have more ideas and good luck.
__________________
Thanks,
Ron
Portland, OR

Last edited by ronstory; 05-23-2021 at 09:34 PM. Reason: grammar
Reply With Quote
  #4   IP: 47.142.130.107
Old 05-24-2021, 12:49 AM
JOHN COOKSON JOHN COOKSON is offline
Afourian MVP, Professor Emeritus
 
Join Date: Nov 2008
Posts: 3,500
Thanks: 54
Thanked 855 Times in 629 Posts
If the engine ran normally before the maintenance please detail the maintenance procedure(s) accomplished.
Also have you been keeping the raw cooling water valve closed while no start cranking, including the compression test? See item #1 post #2.
Not sure what you mean by "floods quickly". Is is almost impossible to flood* an updraft carburetor. If for some reason the mixture is to rich try starting with little or no choke.
*Flood - to much gas in the air\gas mixture.
Another welcome to the forum.

ex TRUE GRIT
Reply With Quote
  #5   IP: 173.179.108.226
Old 05-25-2021, 11:00 PM
BobGales BobGales is offline
Member
 
Join Date: Apr 2018
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Flooding

I used the term 'flooding' to describe a collection of gas, about three tablespoons worth, at the neck where the choke butterfly and the flame arrester join. And the motor simply does not fire up despite lots of spark.
Reply With Quote
  #6   IP: 47.142.135.3
Old 05-26-2021, 12:24 AM
JOHN COOKSON JOHN COOKSON is offline
Afourian MVP, Professor Emeritus
 
Join Date: Nov 2008
Posts: 3,500
Thanks: 54
Thanked 855 Times in 629 Posts
You need to rebuild the carburetor. The flooding is occurring because the needle valve that controls the amount of gas that enters the carburetor is not sealing or metering correctly. The amount of opening of this valve is determined by the position of the float.
This is a dangerous situation. Gas can escape from the carburetor and go BOOM.

ex TRUE GRIT
Reply With Quote
Reply

Tags
engine not starting

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Starting problem mlucas Introductions 10 06-05-2021 09:09 AM
Mercury 115 elpto starting problem Bbell Ignition System 4 04-23-2017 07:42 PM
starting problem gary randall Troubleshooting 4 10-26-2010 12:53 PM
Mystery Starting Problem Cave_Dog Fuel System 21 10-19-2010 10:55 PM
Starting Problem Alan C Troubleshooting 1 11-23-2007 01:43 PM


All times are GMT -4. The time now is 06:38 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved