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: 71.244.230.46
Old 08-10-2018, 09:36 PM
sdemore sdemore is offline
Senior Member
 
Join Date: Nov 2016
Location: Pasadena, MD
Posts: 230
Thanks: 84
Thanked 43 Times in 33 Posts
Fuel Pump Troubleshooting Question

All right guys, I'm having a problem and looking for any secret tips for the mechanical fuel pump.

Engine wouldn't start and I got it down to a fuel issue. Started looking and it wasn't moving any fuel from the tank to the carb. The lever on the fuel pump feels "funny." I can't really describe it, but it doesn't feel like it is moving as far as it should be.

I pulled the pump off, disassembled it and all looks good. I just rebuilt it about this time last year and it has less than 10 hours since then. I reassembled the pump and it felt better in my hand. Reinstalled it then tried to refill the bowl with no luck. I put a vacuum pump on the fuel line and it seems to be allowing the fuel to flow, so I am really thinking it is in the pump. I didn't have a fitting to go straight from the pump to a gas can, but will tomorrow.

Everything looks good, seals are in good shape, springs and caps look good, diaphragm is moving freely. There doesn't seem to be any warping above the bowl either. Are there any secret things that I may not know about?

I'll be back there in the morning to do some more work on it.

Thanks,
Steve
__________________
Steve Demore
S/V Doin' It Right
Pasadena, MD
Reply With Quote
  #2   IP: 138.207.175.58
Old 08-11-2018, 08:41 AM
Administrator's Avatar
Administrator Administrator is offline
MMI Webmaster
 
Join Date: Oct 2004
Location: Chestertown, MD (Langford Creek)
Posts: 2,198
Thanks: 1,335
Thanked 365 Times in 182 Posts
Hi, Steve:

I know next to nothing about these pumps, but is this the kind of behavior you might expect if the pump were starving for fuel from the tank side? Clogged tank vent, clogged tank pick-up tube, shut-off valve issues, etc.?

HTH.

Bill
Reply With Quote
  #3   IP: 155.186.126.158
Old 08-11-2018, 10:15 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
Steve, to add to Bill's statement it could be a very minor air leak upstream too.

About the only thing that will keep a mechanical pump from pumping is lack of motion IE the plunger that actuates the pump is missing or worn out or the check valves are in backwards.

If you can actuate the bail and get no pumping it could be either scenario.

Dave Neptune
Reply With Quote
The Following User Says Thank You to Dave Neptune For This Useful Post:
Administrator (08-11-2018)
  #4   IP: 137.103.82.194
Old 08-11-2018, 11:00 AM
joe_db's Avatar
joe_db joe_db is online now
Afourian MVP
 
Join Date: May 2009
Posts: 4,474
Thanks: 49
Thanked 1,026 Times in 721 Posts
Easy to check - hook it up to another tank like an outboard tank.
Reply With Quote
  #5   IP: 199.87.176.245
Old 08-11-2018, 11:02 AM
zellerj zellerj is offline
Afourian MVP
 
Join Date: May 2005
Posts: 304
Thanks: 5
Thanked 115 Times in 69 Posts
could also be a pin hole leak in the pick up tube, or some air leak in the supply side.

Jim
__________________
Jim Zeller
1982 Catalina 30
Kelleys Island, Ohio
Reply With Quote
  #6   IP: 71.244.230.46
Old 08-11-2018, 12:26 PM
sdemore sdemore is offline
Senior Member
 
Join Date: Nov 2016
Location: Pasadena, MD
Posts: 230
Thanks: 84
Thanked 43 Times in 33 Posts
Thanks for all the suggestions. My first thought was that it was a plugged screen in the fuel tank, but sort of ruled that out. I tried to hook it up to a gas can last night, but didn't have a fitting for the fuel pump inlet. I did connect it at the filter and couldn't get flow there. Went back this morning with a fitting, a piece of tubing, and the gas can. Hooked it up and the pump wouldn't pull fuel from the can.

Disassembled the pump again and everything looked good. Cleaned it up and tried blowing through the inlet, but nothing. Pulled the two little rubber valves and found them both stuck closed. A little PB Blaster and a gentle prod with a small screwdriver and they were functioning perfectly. Reassembled and tested it, and found it to be working. Reinstalled it, hooked everything up, and it is working as good as new.
__________________
Steve Demore
S/V Doin' It Right
Pasadena, MD
Reply With Quote
The Following 2 Users Say Thank You to sdemore For This Useful Post:
Administrator (08-11-2018), Dave Neptune (08-11-2018)
  #7   IP: 207.118.20.35
Old 08-12-2018, 07:06 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
Glad you found the problem. As another mechanical fuel pump owner, I noticed your statement that the two little rubber valves were stuck. My question is why did that happen? In 2500 hours, that has never happened to me, and I use MMO in non-ethanol fuel. My opinion (I like to call it a theory, but others might call it a superstition) is that ethanol degrades the rubber in the valves and diaphragm of a mechanical pump, which makes the valves sticky. MMO keeps them lubricated. If you are not using MMO in your fuel, I recommend that you do, especially if you are using 10% ethanol.
Reply With Quote
  #8   IP: 71.244.230.46
Old 08-13-2018, 07:39 AM
sdemore sdemore is offline
Senior Member
 
Join Date: Nov 2016
Location: Pasadena, MD
Posts: 230
Thanks: 84
Thanked 43 Times in 33 Posts
I do use MMO in the fuel (and oil), but haven't been able to find non-ethanol fuel locally yet. I've been working on the boat and wound up going for about 2 months without starting it. Not sure if that was the whole problem or not.
__________________
Steve Demore
S/V Doin' It Right
Pasadena, MD
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
Mechanical fuel pump rebuild services Don Moyer Fuel System 40 01-14-2013 11:17 AM
Fuel Line From Pump to Carb Question bpowdrell Fuel System 7 09-21-2012 03:16 PM
Fuel Pump Question Nick duBois Fuel System 7 08-22-2010 12:02 AM
Fuel Pump ID? '79 Catalina 30 NorfolkRagbagger Fuel System 5 08-24-2009 03:41 PM
Mechanical Fuel Pump Rebuild Question Kaiser Fuel System 1 05-31-2005 09:41 AM


All times are GMT -4. The time now is 01:20 PM.


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