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Vince O.
Vince O., Small Engine Technician
Category: Small Engine
Satisfied Customers: 2772
Experience:  Over 30 years experience repairing lawn and garden equipment. Chainsaws, mowers,blowers and trimmers
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I got a diaphram carb on a model 30 jiffy. Why do i have to

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I got a diaphram carb on a model 30 jiffy. Why do i have to have the high end jet screwed all the way in to run properly. and then sometimes it runs out of gas half way threw the hole?

Vince O. :

Hello,is there a Tecumseh engine on it?

JACUSTOMER-tu0k5fcx- :

yea

JACUSTOMER-tu0k5fcx- :

New carb kit in it. needle and seat gasket and diaphram

Vince O. :

It sounds as if it is flooding.If the parts were not installed correctly or the needle tip bent it will flood.Here are a few pages from the service manual.Look at the diagrams and the carb body for any ID.The diaphram could be on wrong. 2cyc carb

Vince O. :

If the carb has 2 adjustment screws set them 1-1 1/2 turns open.If 1 screw set at 2 turns open to start.

JACUSTOMER-tu0k5fcx- :

The needle is not bent and the air test passes. blowing in inlet and needle seats and lets air in when pressed. The diaphram and gasket was installed corectly. the low end jet is out about 5/8 turn. and high all the way in. It will idle all day long and hit high end for as long as you want with no load on it. When under load it seems to run out of gas.. As i can hear it loose power i pump the primer and it gains its power back.. About a year ago i bought a new primer bulb cuz it didnt seem like it was priming very good. It improved a little but not much. About the only thing i didnt have apart on this engine is the check valve located behind the fuel inlet that is pressed in. I guess i didnt even know it was there. I am thinking that might be out and restricting gas flow? I have found on websites that 1/2 to 3/4 turns on low end jet and 3/4 to 1 1/2 on high end. Where would i find a replacment check valve. I dont know yet if it is teflon or brass yet.

Vince O. :

I don't think you will find a check valve,only a new carb if available.But I don't think that is your problem.Did you try re adjusting the high speed while under load? Is the gas cap vent open ? (vapor lock) Does it start easy even when warm? What happens when you open the high speed to where it belongs?

JACUSTOMER-tu0k5fcx- :

the only way it wants to run better even under load is if i could screw the jet in even farther. It always starts first pull when warm, a lot of times also when it is cold. Tank has been flushed out new gas lines vent in tank works properly. When i start at stock specs for jets it will idle but wont transfer over to high end, falls flat on its face. almost dies. A lot of times there is not any reaction when i would pull the throttle. once i turn it in all the way then game on till load put on it

Vince O. :

It still sounds like it's flooding,I'm not there to look at it so it is difficult.Did you look for an "F" stamped on the front of carb? I have already replaced the needle and seat and did not remove the old seat gasket and it caused problems. Here is a link where you can download the complete service manual.Maybe there's something we are missing and this will help. www.cpdonline.com/692508.pdf.

JACUSTOMER-tu0k5fcx- : Its stamped h. I will take a look at this manual and check it out thanks
Vince O. :

OK

Vince O. :

The "F" would be stamped right in front of the carb.

JACUSTOMER-tu0k5fcx- :

I will be able to figure it out with the manual you provided me thanks

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