Qualcast Classic Petrol 35s Running Problem

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FrankWielbo
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Qualcast Classic Petrol 35s Running Problem

Good Morning

New member here looking for some help and advice.  I have a Qualcast Classic 35s QX which has a running problem in that it runs perfectly for a minute or two then dies while cutting. It has been working very well since coming back from the garden machinery repairer a couple of months ago.  I am in no way a mechanical or electrical expert, but I think I can take this apart and rebuild  it with very few bits leftover!

It is mechanical so how hard can it be? I am assuming the problem is caused by a restricted fuel flow.

I have checked the Forum Archives but cannot find an earlier post that covers the issue I have.

It was fully serviced earlier this year.

A new carburettor was fitted but I can find no manufacturer markings or part numbers apart from a 1 on the bottom of the bowl.

The invoice refers to XPQA6391 Carburettor @ £29.00.

A quick Google  throws up - Tecumseh AQ148 Carburettor (Dellorto Type). It looks like one, but I am not sure if it is. Help in  identifying the carb would be great.

I now only use Aspen 4 after leaving it for a winter with unleaded petrol in it.

I removed the carb and found flecks of white waxy looking material in the bowl, I’ve cleaned it, but I’ve not done the jets as I’m not entirely sure where they are or how to do it.

I have made sure the fuel tank vent hole is not blocked.

I would be grateful for some advice on the problem and cleaning the carb and jets and identifying the carburettor.

After reassembly it stared easily ran for a couple of cuts then died, it started again but died. It seems like it used up the fuel in the carburettor then ran out of fuel despite the tank being full.

The Mower Type Number is F016 305042 and is dated 1999 and I have added some pics of the carb to aid identification.

Regards

Frank

 

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    wristpin
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    There’s a big blank space at

    There’s a big blank space at the end of your post - missing image?

    An image of both sides of the carb will be useful as the AQ148 has been fitted with a either a Dellorto , a Tillotson or Tecumseh’s own . I don’t immediately recognise the number in your post and it may just be your repairer’s in house number for one of the many Chinese pattern carbs that are on offer.

    Meanwhile, run a check on the actual fuel flow from the carb end of the the pipe from the tank. Pull it off the carb and put the end in a jam jar and observe the flow for at least half a minute. 

     

     

    FrankWielbo
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    Joined: 20/05/2021 - 10:20
    Pics attached now

    Pics attached now

    wristpin
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    UFairly certain that is a

    Fairly certain that is a Chinese pattern carburettor as it has an adjustable main jet - the one under the float bowl and also an accessible slow running / idle jet - rage small slot headed one just below the progression jet gallery welch plug.  If the fuel feed to the carb is ok you may find that the cure to your issue is as simple as unscrewing the main jet a fraction of a turn. Original carburettors of that era were built to EPA “compliance standards” and had no obvious external adjustments.

    While a fuel issue is still the most likely cause of your problem, it should be born in mind that both tight valve clearances and ignition module issues can produce time / heat related failures.

    FrankWielbo
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    Evening ... many thanks for

    Evening ... many thanks for that . I'll do  what you suggest tomorrow morning as it's blowing a gale here and I would rather play with the fuel outside.

    I will let you know how I get on 

    Regards

     F 

     

     

     

     

    DJD
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    A chap contacted me about a

    A chap contacted me about a new Masport machine he bought last year, he used Aspen since purchase, I simply put new pump fuel in and away it went, it was popping and banging on the Aspen too, plus an odd smell like calor or propane gas being burnt off? Never experienced this before. Not impressed so far! Was glad to help an old friend out though.

     

    wristpin
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    Joined: 23/05/2012 - 22:09
    A chap contacted me about a

    A chap contacted me about a new Masport machine he bought last year, he used Aspen since purchase, I simply put new pump fuel in and away it went, it was popping and banging on the Aspen too, plus an odd smell like calor or propane gas being burnt off? Never experienced this before. Not impressed so far! Was glad to help an old friend out though.

    That’s the second incident I’ve heard of a four stroke engine being “ Aspen adverse” , but I know of numerous people running two strokes on Aspen with no ill effects.  It may be totally irrelevant, but when unleaded fuel was introduced the advice from most of the small engine manufacturers was that the engine should be given a thorough de-coke before making the switch.