Return to the home page...

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

Reply
 
Thread Tools Display Modes
  #1   IP: 108.185.116.22
Old 04-14-2023, 01:41 AM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
Carburetor Blues

So I removed my carb and took it apart to figure out if there was a problem with the float system that was allowing too much fuel. The floats, needle and seat looked great, which is not surprising because mine is a 2020 built carburetor.

I put the carb back in place and the motor ran great! I tuned the idle to a smooth 800 rpm and I was really in a happy place. The engine started and restarted like a champ.

A few hours later, I went to start it again and the same problem raised its ugly head. No ignition due to pooling of fuel in the carb, which I can see when I take off the flame arrestor. So I must have either a fuel pump problem or a carburetor float problem, because fuel is overloading the floats and spilling into the throat somehow. Any sage advice?

EJ
1978 Cat 30
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #2   IP: 76.176.224.167
Old 04-14-2023, 10:37 AM
ndutton's Avatar
ndutton ndutton is offline
Afourian MVP
 
Join Date: May 2009
Location: Torrance, CA
Posts: 9,619
Thanks: 198
Thanked 2,208 Times in 1,425 Posts
What fuel pump do you have?
__________________
Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
Reply With Quote
The Following User Says Thank You to ndutton For This Useful Post:
capn ken (04-15-2023)
  #3   IP: 162.245.50.247
Old 04-14-2023, 11:24 AM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Is the scavenge tube clear and in place?

How many "turns" is the idle air screw out off the seat?

Did you set the float level and if so to what clearance?

An "easy quick starting A-4" is usually indicative of an over rich condition. An "updraft intake system" requires choking and more than a few seconds to start. Sounds counterintuitive but true.

Dave Neptune
Reply With Quote
The Following User Says Thank You to Dave Neptune For This Useful Post:
capn ken (04-15-2023)
  #4   IP: 108.185.116.22
Old 04-14-2023, 12:00 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
I have a facet electric fuel pump which clicks nicely when the ignition is on. I spent some time with the idle so that the engine runs well at 800 RPM, but perhaps I need to tighten the idle screw?
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #5   IP: 108.185.116.22
Old 04-14-2023, 12:04 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
Quote:
Originally Posted by Dave Neptune View Post
Is the scavenge tube clear and in place?

How many "turns" is the idle air screw out off the seat?

Did you set the float level and if so to what clearance?

An "easy quick starting A-4" is usually indicative of an over rich condition. An "updraft intake system" requires choking and more than a few seconds to start. Sounds counterintuitive but true.

Dave Neptune
I did not check the scavenge tube patency when I had the carb off, unfortunately.

I dont know about the idle screw, but I guess I could tighten it

The floats and needle looked great with the float parrallel to the body. I did not remove the seat however because it requires a large slotted screwdriver which I did not have on hand.
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #6   IP: 76.176.224.167
Old 04-14-2023, 12:18 PM
ndutton's Avatar
ndutton ndutton is offline
Afourian MVP
 
Join Date: May 2009
Location: Torrance, CA
Posts: 9,619
Thanks: 198
Thanked 2,208 Times in 1,425 Posts
What model # Facet do you have? Looking to cross reference the # to psi output.
__________________
Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
Reply With Quote
The Following User Says Thank You to ndutton For This Useful Post:
capn ken (04-15-2023)
  #7   IP: 162.245.50.247
Old 04-14-2023, 03:19 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
My reference to the idle screw is for info only. The screw "averages about 1 1/2 turns off of the seat. Some engines like a bit more fuel and run about a quarter turn further in and some at a quarter turn further out or leaner. The screw adjusts air into the idle stream not fuel.

Is the scavenge tube "clear and installed"?

Did you check or set the float level to be sure it is in the stock position?

Dave Neptune
Reply With Quote
The Following User Says Thank You to Dave Neptune For This Useful Post:
capn ken (04-15-2023)
  #8   IP: 107.77.230.233
Old 04-14-2023, 05:42 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
I spoke with MMI today and the PO bought and likely installed a Catalina specific facet pump which has a higher PSI. Why would my Cat 30 need a higher PSI, and could that be the problem? Could the higher PSI be forcing fuel past the float needle?

I did make sure the float was set correctly and the needle and seat were both clean.
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #9   IP: 162.245.50.247
Old 04-14-2023, 06:04 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
The higher pressure required for the Cat 30 is due to the longer run from the tank. The higher PSI is no where near enough to force the needle off the seat.

Check the turns off the seat for the idle adjust screw so we know where it is.

You may have a compromised float IE a pin hole allowing the float to fill and causing it to sink and the fuel level to be to high. This is a rare scenario. You can shake the float to see if there is any fuel in it.

Is the fuel leaking while running or only when shut down?

If the carb is running to rich it will allow fuel to stick to the manifold while running and the excess can run back down when the engine is shut off. I suggest you take a good look at the plugs to see that they are a "beige to brown in color" not blackened and/or wet.

Did you use a "new" gasket and NOT the old one?

Dave Neptune
Reply With Quote
The Following 2 Users Say Thank You to Dave Neptune For This Useful Post:
capn ken (04-15-2023), TimBSmith (04-16-2023)
  #10   IP: 107.77.230.233
Old 04-15-2023, 10:24 AM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
The engine runs fine, so I thought this was just a starting issue. ALthough the prior owner always complained of a gas smell after shut off.

I put new plugs in last November and they are already darkly colored.

The floats looked fine when I examined them the other day, with no apparent fluid shaking inside. The needle and seat looked great too, although I did not remove the seat.

If the pump is not the issue, then perhaps I should just replace the floats, needle and seat?

I will get a new gasket too, because I did reuse the old one.
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #11   IP: 107.77.230.233
Old 04-15-2023, 10:27 AM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
From previous posts, you might remember that I thought I had a water incursion problem because the most aft plug (#4?) was always wet. Perhaps that was excess fuel?
Reply With Quote
The Following User Says Thank You to ejay For This Useful Post:
capn ken (04-15-2023)
  #12   IP: 162.245.50.247
Old 04-15-2023, 11:34 AM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Ejay, the dark plugs mean your way to rich and perhaps a timing issue as well.

Rather than going back and forth shoot me a PM and I will give you my number or send me yours. A little conversation goes a long way.

Dave Neptune
Reply With Quote
The Following 2 Users Say Thank You to Dave Neptune For This Useful Post:
capn ken (04-15-2023), TimBSmith (05-11-2023)
  #13   IP: 162.154.106.227
Old 04-20-2023, 07:28 AM
Indy Indy is offline
Senior Member
 
Join Date: Oct 2014
Posts: 33
Thanks: 14
Thanked 3 Times in 3 Posts
Did this get resolved? Just interested in knowing what the solution was 😊.
Reply With Quote
The Following User Says Thank You to Indy For This Useful Post:
GregH (04-24-2023)
  #14   IP: 12.163.75.202
Old 05-01-2023, 03:18 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
Here is an update.

I took the carb off and cleaned thoroughly..... again. This time I used new gaskets, copious amounts of carb cleaner and compressed air and a new float needle and seat. After reinstalling, the engine still would not start, but I was able to observe the main jet with the fuel pump running, and I could not see any fuel excess, therefore I am going to conclude that the floats are good and that the fuel pump is not overpowering the needle and seat.

Any excess fuel that I noticed in the throat of the carb I believe is dripping back down into the carb after prolonged, unsuccessful cranking in an updraft carburetor. Does that make sense?

I now think the root of my problem was a water incursion into the cylinders which prevented the engine from starting suddenly after previous normal operation.
Reply With Quote
  #15   IP: 162.245.50.247
Old 05-01-2023, 05:56 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Any moisture in the cylinders will be a no start or at least a really tough one. Did you try a shot of starting fluid?

Take a look at the plugs to see if they are wet, a sniff or taste will let you know if it is water. Did you close the water valve while cranking?

And yes after prolonged cranking some fuel can run back down from the manifold.

Dave Neptune
Reply With Quote
  #16   IP: 12.163.75.202
Old 05-02-2023, 12:30 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
My theory is that even with the water intake shut off, over cranking the engine can create a siphon effect if there is enough water in the muffler, due to the absence of any elevated loop in the exhaust piping of the cat 30. Is that plausible?
Reply With Quote
  #17   IP: 162.245.50.247
Old 05-02-2023, 01:10 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,035
Thanks: 711
Thanked 1,289 Times in 839 Posts
Ejay, I don't see how cranking would create a syphon as cranking would be pumping air into the system creating pressure.

Check the plugs for moisture as it is something you suspect. Moisture can also encroach through a breach in the manifold, the head gasket or even a from a pinhole from a cylinder rusting through. Before searching you need to confirm if water is indeed encroaching the cylinder(s). Just look at the plugs after a bit of cranking, it is that simple.

Are you sure you did not move the plug wires since it last ran? A common mistake.

Did you try starting fluid? And are you sure you have spark to the plugs?

Dave Neptune
Reply With Quote
The Following User Says Thank You to Dave Neptune For This Useful Post:
TimBSmith (05-11-2023)
  #18   IP: 12.163.75.202
Old 05-02-2023, 06:33 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
I ordered new plugs and I will pick up some starter fluid as well. I carefully labeled the plug wires and there is a new coil in place with good spark. I will try these new maneuvers this weekend.
Reply With Quote
  #19   IP: 12.163.75.202
Old 05-08-2023, 11:24 AM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
Smile

When the definitive history of the atomic 4 is written, my name will be listed as the stupidest owner ever. I was able to get the engine running with new plugs this weekend, and my conclusion was that I had a massive water incursion that required a lot of work to dry out. The carburetor was never the problem.

The stupid part is that I put the motor at increased risk for the incursion through a certain plumbing modification, that at the time seemed like brilliance, but in retrospect, was just plain idiocy.

I am now something of a carburetor and fuel line expert, thanks to the education I received from the A fourians on this site. I really appreciate the private tutoring from Dave Neptune.
Reply With Quote
The Following 2 Users Say Thank You to ejay For This Useful Post:
Dave Neptune (05-08-2023), TimBSmith (07-11-2023)
  #20   IP: 209.6.152.28
Old 05-11-2023, 11:18 PM
TimBSmith TimBSmith is offline
Afourian MVP
 
Join Date: Aug 2020
Location: Brookline, MA USA
Posts: 162
Thanks: 2,239
Thanked 80 Times in 42 Posts
Private tutoring...

The moment Dave Neptune offers you his number is the moment thread should pause until a bracketed resolution is posted. Dude is iconic here.
__________________
Tim Smith
Oasis
Pearson 30
1974, Number 572
Boston, MA USA
Reply With Quote
  #21   IP: 12.163.75.202
Old 07-11-2023, 12:48 PM
ejay ejay is offline
Senior Member
 
Join Date: Jul 2022
Posts: 65
Thanks: 4
Thanked 18 Times in 13 Posts
Final Update

I cleaned the carb this past weekend and I was able to clear a blockage in the idle jet with a bristle. The carb worked wonderfully and I have no problems with idle now! No more stalling at inopportune moments either.

Thanks so much for all the help!
__________________
EJ
78 Catalina 30
Reply With Quote
The Following 3 Users Say Thank You to ejay For This Useful Post:
Dave Neptune (07-11-2023), edwardc (07-12-2023), W2ET (07-11-2023)
  #22   IP: 207.32.168.247
Old 07-11-2023, 02:31 PM
capnward's Avatar
capnward capnward is offline
Afourian MVP
 
Join Date: Aug 2012
Location: Deer Harbor WA
Posts: 335
Thanks: 41
Thanked 147 Times in 107 Posts
Years back I had the same experience, no idle. The idle jet was partially blocked. Couldn't see it until I removed the idle jet and held it up to the light. Ran a bristle around in it. Blowing carb cleaner through it didn't work. A carb cleaning is incomplete without that procedure, IMO. Glad you could clear up what is a common problem.
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


All times are GMT -4. The time now is 12:55 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