lawnmower still doesn't run

[Capt. Orygun]

so remember my octane thread?

Anyways it ran fine on 87 Octane (or rather as well as it ever ran) but our "Senior Executive" didn't think it was good enough so he went and got a bottle of octane booster and added the whole thing to the Gas can.

So I fire up the mower last night and it starts knocking and belching out Blue smoke (oil). I call the "Senior Executive" and he thinks the Octane is to low, I told him that in my opinion (aerospace hydraulic craftsman) that the octane was fine and it was either a fuel feed problem or a problem with the spark (it starts to die off, then boom it's fine, then starts to die off again), and that it was definitely burning ALLOT of oil.

But he (guy who's dad owned a muffler shop 30 years ago) insisted that it was just in need of further octane, and that it was burning oil because it was low on oil! Noticing he had no inclination to hear me out I made a trip to Auto Zone.

Now with enough Octane booster to treat 40 gallons of fuel I start up the Mower. The Smoke has now turned a very pure shade of white, and I'm starting to get obscene phone calls from Al Gore. And it's still knocking.

My fearless leader begins fucking with the throttle and I get and idea. I take the spring off the throttle and shorten it. We're in business!

Have you ever heard a lawnmower rev to chainsaw levels? Normally I wouldn't think this was a great idea but by my math with the level of octane booster in the tank there isn't a chance of hell for detination. It's still dragging 70% of the time like before, but when it sparks up I think I can hear the grass actually yelling for help.

10 min later it dies

CLIFF NOTES
Piece O Shit Mower runs like ass
two bottles of octane booster make for nice color smoke
adjustable throttle tension rules
my co worker is a dumb ass
RIP lawn mower

 

[reckedracing]

adjustable throttle tension or were you forcing the govenor?
i used to hook a string to the govenor and give her a yank when i needed a little extra speed in turn 4
but its not good for the motor... at all

 

[Capt. Orygun]

it's the spring that runs between the choke and the motor. The mower is old so my intention was to make up for any wear of the spring. Needless to say I overshot my goal

 

[reckedracing]

yea, that sounds like the govenor
it was backing off when the motor was wound to top rpm right?

did you try changing the plug?

 

[Capt. Orygun]

plug is brand new, fule system recenlty cleaned

It also did all of this before we started fucking with it

the theory was it was running lean so more throttle= more fuel lol

the engine still turns over, I'm opening it up today after lunch

you think it could be a fule filter? I dare say there's no timing so it can't be that

 

[klyph]

Is it oil injected or pre-mix?

 

[reckedracing]

the engine still turns over, I'm opening it up today after lunch

compression test/leak down test FTW

you think it could be a fule filter? I dare say there's no timing so it can't be that

could be a fuel filter
i would get a pump spray bottle with gasoline and just try spraying it directly in the carb to see if it runs better
if spray gas = running then its either carb or fuel filter related
also make sure the fuel petcock is fully open and the tank not clogged, just unhook the fuel line from the carb and ful should pour out

they have a version of timing
the only timing problems i have seen are when the keyway gets fucked up
then they can get out of time
pull the plug wire and throw another plug in the wire and ground it out and see what your spark looks like

 

[EGProject]

So its a fuel problem?


I'd go standalone, personally -


But otherwise, check the lines and maybe pull the carb off.Something could be funky with the floats or something could be stuck.

 

[Capt. Orygun]

nope it's the choke

When my fearless leader put it back together is was assembled incorrectly...

There are two springs which connect to the choke, one connects to the adjustmant mechanisim and the other to essentially a "ground" the ground spring acts in opposition to the opening action of the adjustment keeping the assembly taunt.

But they way he put them back together they were working in concert. Putting a load of slack in the system, causing it to act like a screen door in a wind storm.

 

[Capt. Orygun]

that didn't work either, I even bent a paper clip to hold it in the prefered position and it still ran like shit, back to the drawing board

 

[reckedracing]

lets go back to the basics, is this 2 stroke or 4 stroke, push, self propelled, or ride on?
# of cylinders?
model?

i've seen everything from sheered keyways (push mower) to failed mechanical fuel pumps (riding mower)

 

[Capt. Orygun]

4 stroke, push 4hp motor

what's I've tried so far

Disassembly of fuel tank up to rail to clean and check for blockage
changed gas out
checked oil level
troubleshot choke system (as I said I even took out the spirngs and tried fusing it in the correct position and it still ran like shit, eliminating the choke from consideration)

 

[Capt. Orygun]

here, it kinda just half ass runs. It starts acting up around the :50 second mark, like it's going to really start running, but it never does

YouTube - lawn mower blues

 

[BigJ]

Dude. Just Rebuild it.

Doesn't take super long and will be like new, or get a new mower if your time is valuable.

 

[Capt. Orygun]

did you watch the video? Are you leaning toward failed powerplant? I'd hate to rebuild it over a fuel feed problem

 

[reckedracing]

i would pull a compression test to rule out shot motor but i'm leaning more towards the choke/govenor assembly
it sounds to me like the govenor it constantly engaged so it won't rev up

have you cleaned out the carb?
looks like its either getting restricted by the govenor or its a fuel problem
seems to run like a mower does when it just starts to run out of gas

 

[Capt. Orygun]

I dissembled the tank clear through the rail that run across the side of the mower. That tube feeds into a little fuel reservoir that's retained by a small cover plate with screws and a couple pry tabs. I haven't opened that yet

it's a Murry 4hp push 20" mower. I suppose if I have an IPB or a repair manual I could do more, but my functional knowledge of carburetors is Nada. It can't be that hard though

it should be noted that in my trouble shooting I fused the choke into a half doezen different positions (to keep the fan from acuating that air restricting arm by overcomming the spring tension) to see if I could coax it into running healthy, I couldn't.

 

[reckedracing]

take the crab apart, clean and inspect
i would guess dirt in the jet(s) or a stuck float

 

[Capt. Orygun]

I'm gonna try this again

need pictures lol

 

[Capt. Orygun]

UPDATE:

It runs! I took the carberator off and quickly realized it wasn't a stuck bowl (there aren't any). It basically has a filtered tube for fule, and another for air, which run through the orrifice of the carberator where the baffle (disc that opens and closes) is. Then it has a small rubber primer. The whole assembly is roughly not counting the mounting plate is like 90% plastic

I took it home and backwashed the filters with Carb cleaner, let it sit for an hour, then gave it a good rinse and set it to try. Came in and put it back together and VROOOOOOOM, shit runs like a mofo

but I have a new problem

it keeps bouncing off the Gov, it revs really strong, then cuts out, then revs really strong. I undid my spring advancmnet that was forcing the choke, but it yielded no change. Any idea where to go from here? It seems like if I can fix the gov this thing will run good as new...