McCulloch 7.5HP - A3EB Outboard

[wcsd106]

Hi All,

I have been toying with a Scott McCulloch 7.5HP Outboard for a week or two in an attempt to get some motors running and out of my garage so I have space for new toys.

When I put this outboard up on the stand, I found that it had no spark. That was remedied by cleaning and resetting the points and point gaps. Now I have spark and good compression.

I pulled the powerhead and removed the carburetor. I took the carburetor apart and gave it a light cleaning and then reassembled it and put the powerhead back onto the outboard.

Tonight I finally had a chance to try to fire it up. I've been able to get it running by spraying fuel into the carburetor, but I'm having fuel delivery issues:

1. When the fuel line is connected, I am unable to squeeze the primer bulb and prime the system.
2. I replaced the fuel line connector and the line running from it to the carb with clear line so that I could watch for leaks.
3. When I squeeze the bulb, I can see fuel run towards the carb, but it's like I have no airflow through the carb: It acts like the system is primed even though it's not.

If I hold the primer bulb tightly, I can see fuel go up to the input of the carb, but it won't go any further. There are three fuel lines connecting around that area. Anyone have a diagram of where each of them go to? One goes to a plate on the side of the #2 cylinder, one goes to the fuel line, the other goes back towards the front of the engine between the front panel and powerhead.. I lose track of it then.


Any ideas on where to start looking? I know I'm going to have to pull the powerhead to do any carb work, and when I do, I plan on going ahead and replacing the old gaskets with new gaskets at that time.

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

Does anyone have a diagram for this carburetor?

I got to thinking about it and can't remember ever seeing a float. I'm guessing if the needle valve was stuck closed that I would see a problem like this.

 

[tomhath]

Re: McCulloch 7.5HP - A3EB Outboard

The carb should have a small vent hole, if that's blocked the gas can't get in even if the needle is open.

It sounds like you need both a full carb kit and a fuel pump rebuild. When you have it apart soak the carb in cleaner for a couple of days and be sure every tiny hole is open.

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

Tom,

Thanks for the reply. Do you happen to know where I can find a diagram for the carb? It is a HC8A Carburetor. I found a few on eBay, and even found a carb kit on there for it with a new needle valve and seat. Just hoping to get an exploded view of the carb to get a better handle on where I should be looking.

If I'm looking at this correctly, the Carburetor actually sits on top of the fuel pump, if I am correct, then the fuel pump itself is what is not taking fuel, not the carb.

 

[tomhath]

Re: McCulloch 7.5HP - A3EB Outboard

http://www.searspartsdirect.com/partsdirect/part-model/craftsman-parts/boat-motor-parts/model-217585920/0247/1305320/00001043/00006

This might be it. The Tillotson HC8A carb was used on a lot of different outdoor equipment, any small engine shop should have the diagram and parts you need.

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

Thank You for the reply.

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

I think I located the problem. I pulled the powerhead again today and removed the carburetor. I went back through being a little more meticulous. After pulling the needle and diaphragm, I connected a small section of clear tubing onto the fuel nipple and tried to blow through it. I could get air through, but barely.. Sprayed some carb cleaner in there and let it work for a second or two and saw some thick old fuel ooze out..

Carb is now sitting in the bucket o' carb cleaner for the rest of the night and I've started hunting a rebuild kit... So far, unfortunately, the only one I've found is $40 on eBay but it comes with a new needle, seat, gaskets, etc.

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

Been awhile since I've had a chance to play with this outboard, but figured I'd make an update post this evening:

I finally got the engine to start and run under its own power. After rebuilding the carburetor, I was still having fuel delivery issues. This was due to the fact that my inlet needle lever was not set correctly. I set it this evening and was able to get everything up and running.

I do have one question though: The paperwork that came with my carburetor kit spoke of a purge valve that cleared air from the carburetor fuel line prior to attempting to start. It mentioned two different types, one activated by pushing the choke in, one by turning the throttle handle to 'vent' I don't appear to have either one.

I manually purged the line by utilizing the hole in the back of the carburetor inlet plate. I used a small rounded piece of wire to push in on the lever to allow me to get fuel into the carb and clear the line the first time. Any ideas on where/how to find my purge valve.

 

[Willyclay]

Re: McCulloch 7.5HP - A3EB Outboard

Glad to hear you got that old beauty up & running! I found the same description in the only service info I could locate. It indicates your A3EB model should have a "choke button" to depress while squeezing the primer bulb. How do you get that motor started when cold without a choke/primer? The link below will get you to the service info I found online. Good luck!

http://forums.iboats.com/boat-topic...nline-service-info-not-just-boats-393281.html

LOGIN as directed in the thread and then drill down to: Small Engines, Marine/Boat Motors, McCulloch and, finally, 7&1/2HP.

EDIT: Found this additional procedure - "On all models, maintain pressure on the primer bulb until the bleed valve is closed." More carb info at the link below.

http://www.discount-marine-parts.com/tillotson_hc.html

 

[wcsd106]

Re: McCulloch 7.5HP - A3EB Outboard

Thanks Willy for the great information.

Mine doesn't have a choke button.. Instead, mine has a choke lever that rotates to open/close the choke on the top of the carb.. I have been getting it to start fairly consistently by simply squeezing the primer, pulling the starter a couple of times, then priming again, that usually lets me get fuel to the carb..

It still needs a little tweaking done on the high/low needles, but for the most part this old beauty is running pretty well.

I did notice a problem with forward gear last night. You can hear it rattling, but it's not turning the prop. I'm hoping I simply have the linkage a little out of adjustment. Will have to pull it inside the garage and put it up on the engine stand to take a look at it.

Once I get everything up and running, I'll take a video or two of it running. It seems like a pretty nice little outboard.

 

[Willyclay]

Re: McCulloch 7.5HP - A3EB Outboard

Hang in there, I know you can whip it. Good luck!

 

[Psondervan]

I have a McCulloch 7.5. I can't pull the cord.Either the motor is seized or there is a safety somewhere that I don't know about.Can anyone help me??

 

[steelespike]

Welcome,
You should start your own thread there is a tab near the top of the forum.
I don't think there is any of these guys on here now though they may turn up For McCulloch or Scott Atwater.
See if you can move the flywheel by hand? I don't think there is a safety lock but guessing it could be related to the shift if in neutral it will pull if in gear no.
Take the plugs out a get a look inside.Take the exhaust covers off get a look.