Tecumseh mower troubleshooting

[Burnerman]

Just thought of something else - not so common on side valves but common enough on OHV Briggs motors!
Shine a torch down the plug hole and turn the engine over. Can you see the valves opening and closing?
Another way is to take off the tappet cover on the cylinder block - you can see the valve stems rising and falling from there.
(Just hoping an exhaust valve has stuck open or something!!)
John

 

[bsr]

Hi John

There is no tension on the governer arm if that answers your question. The throttle plate is held open by the throttle cable and isn't pulled back by the governer.

 

[Burnerman]

So when you are trying to start, the carb is held at full throttle?
John

 

[bsr]

IT'S WORKING

How? Well, after John's pointer I checked and realised I'd reassembled the throttle linkages incorrectly. Reassembled correctly with the new spark plug and it works fine.

That suggests to me that I disassembled the whole blinking mower for want of a new spark plug I think that's called a valuable learning experience.

Thanks for all your help.

 

[Burnerman]

Excellent and well done you
You'll be able to dismantle the thing in your sleep by now!
John

 

[Mursal]

Put it in the diary tonight, so you dont forget ..................

 

[monty9120]

hi all i know this is an old post.

brought myself a mountfield mower with prisma engine and dellorto carb

mower rang fine and throttle worked fine. noticed when tipping the mower up fuel flooded out of the carb.

stripped it down to find the seal wasnt fitted correctly

on refitted i noticed the linkages had come off. the spring looks tired too.

putting it back together i have no idea how the linkiages go together. the mower fires up fine but is either stuck on idle or with the linkage fitted it goes at full chat and with nothing happening with control of the choke

any ideas

 

[Burnerman]

Can you fix us up with some pics please? With the engine not running, the throttle should be fully open.
Depending on the age of the motor, it could have either an air vane or mechanical governor.....the latter has a metal arm coming out of the crankcase.
John

 

[Mursal]

Have a wee flutter through these ans stop when you see your carb, spring, linkage combo ..................
https://www.youtube.com/results?search_query=mountfield+prisma+carburettor+

 

[monty9120]

hi there all this is the setup





can i make up a rig to use the throttle differently. the metal bar controls the throttle but connected to the spring part the throttles wide open

 

[Burnerman]

A bit of a bodge, that one.....for sure that spring doesn't look right!
With the engine off, the carb throttle should be open, but only lightly held there.
What's happened to the left of the two rods?
John

 

[monty9120]

hi john. sorry i dont get what you mean about the 2 rods?

the spring does look tired so i will replace that

ive seen these on ebay but no idea if it will fit my mower. the engine says prisma but no model no. deck is a mountfield laser

http://www.ebay.co.uk/itm/Tecumseh-...268?pt=LH_DefaultDomain_3&hash=item5b104e94b4

does this look correct. if not is there a way to redo the throttle

 

[Mursal]

But, would you not be better to look at the videos to find what the linkage setup should look like and copy that? You will not be able to "buy" the correct linkage setup, because its to much a balance between the pull of the governor linkage coming out of the engine and the pull from the throttle cable.

 

[Burnerman]

hi john. sorry i dont get what you mean about the 2 rods?

the spring does look tired so i will replace that

ive seen these on ebay but no idea if it will fit my mower. the engine says prisma but no model no. deck is a mountfield laser

http://www.ebay.co.uk/itm/Tecumseh-...268?pt=LH_DefaultDomain_3&hash=item5b104e94b4

does this look correct. if not is there a way to redo the throttle

The left rod isn't connected at all?
John

 

[monty9120]

hi john sorry i should have made it clear. no matter how i connect the left rod i either get idle or full chat.

almost pulling my hair out. i found this on the web. noticed that someone has bent the rod on mine in the past. no wonder it had enough travel and was on full chat was probably 10mm further forward then it should be


http://www.outdoorking.com/forum/up.../full-2772-14500-tecumseh_van148_governor.jpg

bent the arm back and slotted it in the top. with no choke its at idle so result with all connected. problem is the spring is weak so throttle adjustment is pretty difficult but (it works )

just need to find the correct spring now