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Discussion Starter · #1 ·
It is a 1999 MTD Yard Machine. Model 13AQ670G372. It has a Briggs and Stratton 18 HP Twin 2 engine. It starts and will do up to a higher than idle speed. When I put the blades down to mow it will mow about 5 to 10 mins and start to bog and die. If I put it in slow, it will stay running and I have to keep it like this for awhile. I've cleaned the carb, tank, and fuel lines. I replaced the fuel filter also. According to the repair manual, 1 spring is missing in the fuel pump. It doesn't seem to want to stay running. Like maybe the governor is not functioning right or something. I even gapped the plugs to .030 like the manual said. I've been working on it for 4 days. Getting no where with it. Thought it had a battery charging problem but I checked it via the procedures in the manual and it's good. I really need some help with this thing. Thanks for any info or help in advance.
 

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Do you have the model# and type# and serial# off of the engine?

Should be on the engine cowl near the flywheel screen
 

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When you say its missing the carb spring do you mean part# 392A?

Product Rectangle Font Material property Parallel

If so, you need that to make the pump, pump.
It works off of engine vacuum and needs to return the diaphragm to its normal position. It goes back and forth and creates a flow for the fuel.
Use the diagram to see if anything else is missing. You can get replacement parts for the carb. I use these guys, OEM Parts Lookup System
However MLF does not endorse any particular company, its just who I use amongst other companies on line. They can be purchased locally as well just a little more pricey.
 

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Discussion Starter · #5 ·
No that is the big spring. I need the little spring # 860. The service manual shows 2 of them in the fuel pump. I only have 1. This only shows 1 also. So now I'm confused. I'm sure it needs both of the little springs.
 

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You will need to verify your Carb model, it may have been changed. The one shown represents the models prior to 98020600 which includes yours. There will be ID #s on the carb body near the flanges or on the edge of the fuel pump body.
Let me know all the info on the carb you find and I'll double check.
 
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