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: 66.126.90.242
Old 07-01-2008, 02:20 PM
Kurt Kurt is offline
Senior Member
 
Join Date: Jun 2007
Posts: 290
Thanks: 0
Thanked 2 Times in 2 Posts
Low RPMs - Carb Issue?

Hello folks. So, I'm having an interesting issue with my late model A4. Periodically throughout the course of the last year, I would have an issue where suddenly I could not get past about 1400 rpm while cruising. I don't sit around and idle the engine usually, so I only noticed this condition under load. No increase in throttle would do anything at all to the rpm - actually, the engine would bog a bit. After running a while, the condition would suddenly clear up and I had power and rpm again. I didn't do anything about this as it happened very irregularly. Now, it is an all the time thing. I have replaced my entire wet exhaust system, as it was original (1976!) and I thought maybe elevated backpressure was causing the problem - no change in this condition. I have also run the engine in neutral and it has the identical problem - no amount of throttle will get the rpms above about 1400 and I'll get a bit of bogging and LOTS of smoke out of the exhaust if I max the throttle out. Compression is 120-130 across all cylinders. Plugs were changed about 5 hours of operation ago. What do you all think? Has anyone had this problem? I'm guessing and hoping that it's just a dirty carb, but I would like to hear any other ideas.
Reply With Quote
  #2   IP: 98.218.25.131
Old 07-01-2008, 11:19 PM
sunnnnseeeker sunnnnseeeker is offline
Senior Member
 
Join Date: Apr 2008
Posts: 63
Thanks: 1
Thanked 2 Times in 2 Posts
I don't understand the smoke but the rest of what you describe sounds like fuel issues. Check fuel filters for dirt and water and clean the carb.
Reply With Quote
  #3   IP: 71.168.112.207
Old 07-02-2008, 11:39 AM
David Masury's Avatar
David Masury David Masury is offline
Senior Member
 
Join Date: Oct 2004
Posts: 265
Thanks: 0
Thanked 5 Times in 5 Posts
The first thing I would check is the carb adjustments, but what your symptoms sound like is old (bad) spark plug wires. When was the last time you replaced them.

David
Reply With Quote
  #4   IP: 66.126.90.242
Old 07-02-2008, 12:44 PM
Kurt Kurt is offline
Senior Member
 
Join Date: Jun 2007
Posts: 290
Thanks: 0
Thanked 2 Times in 2 Posts
Thanks for the input, guys. I have owned this boat for 1.5 years and have never changed the plug wires. They do look, well, not new. I actually just purchased a brand new set, so I'll definitely install those. So, I have the carb apart now and it looks pretty clean. I am taking out all the jets and will give it a good cleaning. Then I'll replace the plug wires and look at the filter in my racor. I think I'll do these things one at a time and fire the motor up between each action as I would like to know what exactly is causing my problems. I'll let you all know how this works out - hopefully I'll figure it out in time to go sailing on July 4th -- I'm wanting to go sailing again after a month layed up doing a retrofit to fresh water cooling in my spare time. Motor looks great, runs bad!
Reply With Quote
  #5   IP: 71.118.13.238
Old 07-02-2008, 04:54 PM
Dave Neptune Dave Neptune is offline
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Cool intermitant blockage

I have had an intermitant problem with an old ski boat that I still have. At the most inconvienient times the power would just go away and then after shutting down the power would come back for no apparent reason. After some head scratching and cursing I found the problem in the fuel tank. It was a plastic cap from an oil container or some sort of additive. If it would float by while there was a large draw on the fuel (powered up) the piece would suck up sometimes fully blocking and sometimes just partially blocking the fuel flow. I could see it with the fittings removed and removed it. No more intermittant problem. Just an idea hope it helps!

D Neptune
Reply With Quote
Reply

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
Carb and timing adjustments: at idle, or at cruising rpms? Baltimore Sailor Troubleshooting 1 09-25-2007 10:14 PM
Is this a carb issue? BobB Fuel System 4 04-07-2007 08:38 AM
Is this a carb issue? BobB Fuel System 1 04-06-2007 02:01 PM
Low RPM's Under Load Jeremy Thompson Troubleshooting 7 11-18-2005 06:10 PM
Carb Identity ScottLynds Fuel System 2 06-16-2005 11:20 AM


All times are GMT -4. The time now is 07:21 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