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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 26054
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Dear Mr I have a Tecumseh Power Sport 6HP OHH60 engine on my

Customer Question

Dear Mr Bennett
I have a Tecumseh Power Sport 6HP OHH60 engine on my daughter's go kart. I have just restored the cart having bought it 2nd hand. All works fine until power fades out after short distances ( 50 -200 feet) on full power.
If I suspend back wheels off ground and run engine at high rev range for several minutes by manually manipulating the carb all runs fine - however if I then fully press the accelerator peddle (with rear wheels still off ground) the revs barely increase from low rev/idle range. I have a feeling the governor linkage may be wrongly set up (I did not alter the linkage's arrangement from previous owner's settings which could have been incorrect as kart was not working when I bought it due to broken clutch). I cannot find a diagram showing correct linkage connections - can you tell/show me please ?
I'd really appreciate a diagram and any advice.
By the way, the carb is non-adjustable and mixture seems to be running rich as spark plug has a black soot deposit - but I can't see that this can be causing the main problem of failing power delivery to the wheels.
Thank you, Guy (UK)
Submitted: 11 months ago.
Category: Small Engine
Expert:  Curtis B. replied 11 months ago.

Here is link to manual, showing the linkage. You say plug is showing black carbon? Too much fuel or too little air. Or the exhaust can be restricted. Check the exhaust system!

Customer: replied 11 months ago.
Thanks, ***** ***** is a good start though it is not clear if my engine is "late" or "early" version and the linkages of each are differently set up.
Do you think that I am correct in thinking the fault ( lack of power after short bursts of good power) is a governor linkage issue ?
Regarding carbon deposit on plug : the exhaust box seems OK though I am not sure how to verify that - there is no black smoke emitting. The carb has no mixture adjusting screws so I do not know how to balance fuel / air - can you advise me ?
I am waiting for an air filter to arrive, in mean time I have fabricated a simple cloth and gauze screen to prevent particles entering carb chamber - I can't see that air supply is being reduced.
Guy
Expert:  Curtis B. replied 11 months ago.

Remove the exhaust and make a test run, with exhaust off! I have to assume your choke is wide open. I really doubt it is the governor linkage. Your engine should be (late) model.

Customer: replied 11 months ago.
thanks, ***** ***** saying that if the choke is wide open then that could be the cause of the lack of full revs after short bursts of full revs and power being available ? Is a wide open choke consistent with the full depression of the throttle pedal not activating high revs ?
Please tell me :
1) how do I tell if "choke is wide open" ?
2) if it is how do I correct that ?
3) what am I looking for in doing a test run with the exhaust box removed ?
Expert:  Curtis B. replied 11 months ago.

Choke flap would be open and not restricting air flow into the throat of the carb. Do you have choke cable or just lever? Choke being partially closed, restrict air, and will make mixture rich.

Expert:  Curtis B. replied 11 months ago.

Test run with exhaust off, would show if exhaust is causing the low power.

Expert:  Curtis B. replied 11 months ago.

If choke is not fully open, adjust the cable or lever till it is wide open

Customer: replied 11 months ago.
Thanks Curtis. It is evening in UK. I will have to check all this tomorrow.
How do I tell visually if choke is fully open or not ?
Expert:  Curtis B. replied 11 months ago.

Just look at the choke while manually working it, it should go to the fully closed when pulled, fully open position, when released.

Customer: replied 11 months ago.
Hi CurtisExhaust box is not the problem – removing it does not alter the performance.Choke seems to open as close as you suggest it should – but the carb is a completely non-adjustable model so I cannot alter mixtures. The carb is brand new (although a cheap Chinese one) – I fitted it without taking it apart to check needle etc.The symptom seems consistent with an intermittent fuel supply but the fuel hose flow to the carb seems fine.The rain has been bad for 2 days so have not had much opportunity to test.The air filter arrived today from USA (it was previously missing a filter so I fabricated a j cloth screen) and fitting the proper filter seems to have helped performance somewhat but not cured the problem.If it is not all running smoothly by this w/e I will have a mechanic come over to look at it.I want to give you a 5* review so will wait till I have had a chance to completely solve the problem so I can do so. Please bear with me.Can you think what else could be the problem?
Expert:  Curtis B. replied 11 months ago.

Is it fouling the spark plug? Will it run any better if you try to choke it when it dies down? Is fule ap open, and venting the fuel tank? Not causing the tank to draw a vacuum?

Customer: replied 11 months ago.
Spark plug is still getting a little black, exhaust gas (when box was off) was a bit black, leaving a black deposit on carb/air filter housing adjacent.,
I do not understand what you mean by "choke it down when it dies down". Trouble is - the engine runs fine when kart is static and wheels suspended. problem occurs when kart is driven - hence I can't jump out to manipulate choke / throttle plate.
And sorry again, I do not follow what you mean by "fuel ap open and venting the fuel tank?". Did you mean "tap" ? There is no valve/tap on the fuel hose. I have tried replacing fuel tank cap with tape with a hole cut in to ensure no vacuum in fuel tank is preventing fuel exiting from tank into outflow hose. There was no difference in performance when I did that. I replaced the old fuel hose with new when I restored the kart - so no blockage in the hose is likely - I have checked that fuel flows to carb.
The fact is that after a short distance of good performance the drive to the rear wheels fades, I can blip the throttle but the revs do not translate to power coming through sufficiently to drive the wheels. After a few seconds, power resumes but then fades off again shortly after. The more aggressive the throttle use the quicker the problem of power fade occurs ie if I drive a little softer the problem takes longer to occur.
Expert:  Curtis B. replied 11 months ago.

Fuel filler Cap! I thought it had a choke cable, sorry. Everything point to a lack of fuel as you drive .If I had it , I would try a pulse fuel pump in the line from tank to carburetor. Which is powered by the pulses of the piston moving in the crankcase. You would have to add a line from the engine to power it. From crankcase or rocker cover.