Fuel Pump Conversion Issue

[drifter]

Fuel is spitting and oozing out of the gold center of my B & S fuel pump. Is this due to a leaky diaphragm?

Observation….Looking over the installation, I see fuel mix in the pulse line. Taking apart the pump, I see where fuel in the pulse line will exit a very tiny hole that is covered by the bronze (gold) center of the pump. So any fuel in the pulse line will ooze out the gold center.

So, what to do? Is fuel in the pulse line normal?

Is there a way to keep fuel out of the pulse line? I am getting the pulse by removing the check valve assembly and blocking off one side with a vacuum cap.

If I can’t keep fuel out of the pulse line, would the pump still operate effectively if I sealed the gold center? I can hold a finger over the gold cap and blow/suck into the pulse line and feel/hear the valves opening and closing.

Thanks for any insight on what to do next.

• This topic was modified 2 years, 3 months ago by drifter.
• This topic was modified 2 years, 3 months ago by drifter.
• This topic was modified 2 years, 3 months ago by Mumbles.

[crosbyman]

the gold screen is for equalizing the diaphragm flexing under the action of the pulses no fuel should exit the screen . Before digging in to deeply have you tried another pump ??

fuel in the pulse line may be accumulated fuel oil mix due to improprer crankcase drainage by the purge valve. if you have the manual see the section of purge valve cleaning

some engines model have a crankcase drain hole in the left channel and no drain hole in the right side channel it is possible that using the right channel is better for such a conversion . I have a feeling the upper crankcase case cavity drains internally to the left side possibly reducing chance of any fuel-oil mix exiting via the pulse line.

in any event tell us more on your exact modification procedure. all the the ones I did worked fine using B&S, Mikuni and square pumps

btw… clear tubing is great to see things but may harden up fast if not fuel resistant type

It is great for filling wine bottles but for “long term” may as well use the good stuff.

Joining AOMCI has priviledges 🙂

• This reply was modified 2 years, 3 months ago by crosbyman.
• This reply was modified 2 years, 3 months ago by crosbyman.

[drifter]

Thank you for the help. I’m going to disassemble the intake plate and go over everything again and replace the gaskets, clean the purge valve, make sure the right channel (looking from the front) is blocked using the vacuum cap (as seen in the various you tube videos).
Yes, the vinyl (clear line) is not the best but was used for ease of use to test the conversion. It did help in seeing the pulse line fill with fuel mix and watch the pump action moving fuel.
This was my first attempt at a conversion after refurbishing some 30 motors using pressure tanks. I ran out of pressure tanks so thought I’d have a go at this one.
Thanks again for you expertise and help.

[crosbyman]

Check both pulse channels for a small hole at the end. since you are not filling the channels with sealant by using caps try the alternate channel as your pulse source & reassemble .

have you seen the recent post on channelling all the crankcase residual fuel oil back to the tank ? a two line tank was used with the air line feeding the juices back to the tank instead of just air pulses

A small mod on the purge valve allows all the normally “dumped in the lake” juice to be routed back to the fuel tank.

Results seemed excellent both from an environmental perspective and I suspect fuel economy in the long run .

I have a real nice CD11 I am fixing up and time permitting I may very well go that way 🙂

these litle kickers eat up lot of fuel . my “trolling” 9.5hp 9622a eats up equal or more fuel than my 75 ETEC !

Just for nostalgia…. I may retire it and switch my rig to the “purge modified ” CD-11

Joining AOMCI has priviledges 🙂

[drifter]

The only manual I have is the Seloc manual. Can you tell me more about the purge valve cleaning? Is this the “crankcase drain leaf valve” shown in the parts manual?
Can I remove the leaf valve and simply ensure the holes are not blocked? Squirt some carb cleaner?

[crosbyman]

as a member you have access to the oldies “red bible”

go to…

MEMBERS ONLY tab click on INNERSANCTUM tab…..go down to the LIBRARY section click on GARRY SPENCER’S drop box go all the way down and find the red book logo

click and download it to a PDF on your computer for storage. I got mine printed double side printed at a local print shop in 2 binders with plastic cover shets front and back

Joining AOMCI has priviledges 🙂

• This reply was modified 2 years, 3 months ago by crosbyman.

[crosbyman]

see similar link

https://www.aomci.org/forums/topic/1954-cd-11-convert-from-2-line-to-1-line-fuel/

Joining AOMCI has priviledges 🙂

[drifter]

Well, I took everything apart and meticulously checked everything I knew to check. The drain hole is clear (I used carb cleaner and compressed air). I removed the leaf valve and cleaned it along with the seats. Blocked the right hole (looking from the front). Reassembled everything and ran the motor. No change. The pulse line quickly shows fuel mix. After a few minutes of idling, the fuel starts to ooze out of the pump.
The pump works fine and draws the fuel well. The motor runs well, starts easily and idles great.
Guess I will return the motor back to the pressure system as I simply do not know what more I can do other than blocking the left hole or maybe going to a pump that does not have a bleed hole on the pressure side of the diaphragm (if such a pump exists). I can’t see the pump itself being at fault since the pulse line does fill with fuel.
I do appreciate all of the help and I did learn a good bit.
Thanks,
Drifter

[crosbyman]

did you try running the pulse line on the other channel ?

the pump….Obviously a leaky pump is not acceptable but it seems your pump diaphragm does not mind the fuel/oil as a pulse medium versus just air pulsing .

the fuel-oil & air mix acts as a hydrolic fluid and keeps things going as it flexes the diaphragm and the engine works ok

I would try another pump before giving up on it. .

I have one or two round B S pump… tomorrow I will try pushing some water in the pulse nipple to see it the gold screen leaks . I even suspect that that part of the pump should hold a pound or two of simple air pressure !

Joining AOMCI has priviledges 🙂

• This reply was modified 2 years, 3 months ago by crosbyman.

[drifter]

I do have another pump ordered as the pump I’m working with is an older one found in my parts stash. I have one of the larger rectangular silver Mikuni pumps (won’t easily fit under the hood) and one of the very small black square pumps. Guess I’ll try those just for the fun of it.
The bigger silver Mikuni pump does not appear to have any air relief hole on the pulse side. I’ll give it a go.

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