MAC 2816 Won't stay running ?

Wheel Rush · #1 07-21-2008, 01:34 PM

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 · #2 07-21-2008, 01:49 PM

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 ?

**Dave31** · #3 07-21-2008, 03:13 PM

I have two of those motors. Remove the Mac 2816 cover to access the air filter.

**Dave31** · #4 07-21-2008, 03:16 PM

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.

eDJ · #5 07-21-2008, 05:34 PM

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.

**Dave31** · #6 07-21-2008, 06:12 PM

Owners manual.......http://manuals.mtdproducts.com/mtd/D...=211662-03.pdf

Parts list....http://motorbicycling.com/newreply.p...uote=1&p=21350

enginemaster31 · #7 08-16-2009, 12:52 AM

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 · #8 08-16-2009, 05:19 AM

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 · #9 05-21-2010, 06:36 PM

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.

GearNut · #10 05-21-2010, 08:29 PM

$50 a carb! Dude, the rebuild kits are $20 or less the last time I bought a few.