MAC 2816 Won't stay running ?

Wheel Rush

New Member
Jun 21, 2008
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I just got interested in weed eater engines, so I broke out a MAC 2816, I got it started on a little gas and oil mixture I have here, it was a 20:1 marine mix, so it started up, and it started a couple of times, but when I release the throttle it quits now I can't get it started again ?

I am going to check filter if I can find it and if it's flooded.

Any ideas on what to check ?
 

Wheel Rush

New Member
Jun 21, 2008
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I don't see a filter on this, and there is a special mix using MAC oil, will it be ok to use the mix just to start it ?
 
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Dave31

Moderator
Staff member
Mar 1, 2008
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Aztlán, Arizona
Your marine mix should be just fine just to get it running. If you got a extra plug swap it out.....On two-stroke the air filter needs to be clean for it to run. Any blockage in the filter will not allow it to run. Try to start it with the filter off.
:ride2:
 

eDJ

Member
Jul 8, 2008
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Wayne National Forest
I just went out to the shed and looked. I have a 2816 and a FR 45 ? (reconditioned) I think they put another number on it when it's reconditioned. But it's just expactly like the 2816. The engine set up looks just like the Vacuum blower Windstream IV.

My biggest problem over the years with all the Mac's I've had was the unitized mag with the Hall Effect switch potted in them. I've got about 5 of those ignitions sitting on the shelf dead. One of my neighbors has a lawnmower repair shop/junk yard and his buddy a few doors down from me is a flea market junkie who's always hauling in string trimmers, brush hogs, blowers etc. Anything I can fix we use between us and if it's just dead it goes to our buddy's shop as a gift. (for this I get to ravage his junk yard for spare mags)

Also check to see the carb is good and tight. Some times they get loose and need to be tightened down. When air starts getting in they won't run well.

Even when I find one that starts up and runs awhile, it may start stalling when it gets warm and crap out. That's what my vacuum blower is doing now.

I run 40:1 mix in my Mac's by the way. I've always been told when you get a Mac....get a can of spray start too. Most of my Mac's start better cold than hot and still they are ornery as blazes about starting.

Our friend with the lawn mower shop has an egg beater with a magnet epoxied to one of the beaters. He hooks his VOM meter up to the mag and places the eggbeater under it and chanks it while watching the needle of the VOM. I need to get him to tell me exactly how he does this. But he cranks the thing for awhile to see if the Hall Effect starts crapping out. (the hall effect which replaces the points is basically a reed switch) But if the coil craps out it still doesn't matter cause it's all molded in epoxy.

My friends started suggesting I leave Mac's behind for Homelite products and
the Little lite weight Homelite string trimmer I have is the sweetest running
weed whacker I've ever owned. Don't even need to shoot it with spray start.

I've been using and working on Mac's since the mid eighties now. They run good once you get them running. But woe be to those who don't run them dry at the end of the season to put them up for the winter. There are two cleaners I use in my Mac's. Sea Foam which is sold in cans at Advanced Auto and other places or Marvel Mystery Oil. Just a cap full will clean one up in some FRESH 40:1 mix. Once you get it started run it up for a few minutes before cutting it off.

Fresh mixed fuel in a 2 stroke is always the best. I make my mix in a 2 liter plastic bottle for my neighbor and myself. So every couple weeks I'm making new fuel and my stuff runs dependably.

So, I hope those thoughts help. Just keep starting it up and see if it will run longer and longer. If it will you could rule out the magnito. If you run it up and it sounds like it's got static electric in the sound it may be the ignition distorting. I'd have to look up my owners manual for the 2816 to get the adjustment screw settings for you. There are three. One positions the throttle valve and the other two the low and high rpm adjustment. But if the carb is gunked up it will need to be torn down and cleaned out with carb cleaner and blown out.
 
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enginemaster31

New Member
Aug 16, 2009
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lower nicola
well i just fixed one of these. first take apart and clean the carb then the air filter and check if the gas cap vents and if that does not work take the kill switch off and change it to a one wire switch if this does'nt work tune it till it runs
 

Wheel Rush

New Member
Jun 21, 2008
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Hey !
I haven't been back here for awhile, I see I have some reading to catch up on, I still have that mac here and have to tell you, I'm giving it some thought to make-shift it into an outboard for a light weight dingy that I still have to build but have the plans drawn up,
it's about as far as I've got, There is plenty to read and keep me busy here, I just have to get up from under this pile of stuff called work I'm suppose to be doing.

But thanks much, when I brake it out, I'll give some feed back on-it, Hatty OOs Imeegoes!
 

happycheapskate

New Member
Nov 26, 2009
1,989
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Rockwall TX
If the carburetor resembles those on Kioritz/Echo engines, the diaghram is very thin and vulnerable to chemicals. I used to run Echo weeders in a lawn business. I replaced a couple carbs at about $50 each maybe 10 years ago. Probably some really stupid price now.

If you have a duplicate McC engine and carburetor, just swap carbs and see if it starts then.
 

walkinman

New Member
Jun 18, 2011
2
0
0
USA
I've got an old Mac 2816 that has no spark. Initially I tried changing the spark plug with no result. Next I disconnected the kill switch, (which had a small fray on the insulation of the wire going to it). I still got no spark when I cranked it. At this point I suspected either a worn or sheared flywheel key or a faulty ignition module. Both the key, and the keyway were in good shape, showing no wear, or deformity. Finally I was able to find a new ignition module for the machine, (no small feat in itself), but after swapping out the old one, I still have no spark. When I installed the new ignition module, I used a set of feeler guages to set the air gap between the flywheel and both legs of the module to .012" that should be well within spec.
Since I had the recoil start housing off the machine I spun the engine using an industrial electric dril at approx 175 rpm.
It's a pretty simple circuit, with no interlocks or anything that I'm aware of. As a result, I'm stumped. Does anyone out there have any new ideas I can try?
 
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zean

Active Member
Dec 5, 2010
230
49
28
california
Hi. I'm looking in a book, I don't have experience yet. It says,"Check for continuity between the spark-plug terminal and coil connection. Verify that the air gap between the coil and flywheel is within specification...Many mechanics do not bother with gap specifications, which to some extent are arbitrary. They use a playing card instead." Thankyou.
 

walkinman

New Member
Jun 18, 2011
2
0
0
USA
Re: MAC 2816 No Spark

Thanks. When I installed the new ignition module, I used a set of feeler guages to set the air gap between the flywheel and both legs of the module to .012" that should be well within spec.
 

Teresa Berend

New Member
Sep 23, 2014
1
0
0
Oklahoma
We put a new carburetor kit on and still won't stay running. I also need to replace the throttle cable.could you tell me where I can order that please. MAC 2816 Weed eater...