I have a lawnmower that will only start with starter fluid. Once it gets started it runs fine both on high speed and idle. I cleaned the carb and the carb seems to be working fine. When I try to start it it seems that the spark plug is not getting enough fuel ( I pulled it out after about 10 pulls and it was barely wet). I am thinking that it could be the fuel tank filter screen, because the carb seems to be functioning right, so I am not sure. Sometimes it starts without starter fluid when the engine is warm. I checked the fuel cap to make sure that it is vented properly. What do you think it is. Thanks for any suggestions. Bob

Please post the engine model and type but it sounds as though the gasket between the carb and air filter housing is leaking and which would keep the primer from working. Have a good one. Geo

Briggs and Stratton engine 6HP Quantum
12H802-1929-B1

This model has a standard round circular gasket (looks like a gummy ring) at the end of the intake manifold that the carb seats against. I sprayed gas on the carb while it was running and found no surging. Also, the air cleaner cover is missing along with the air cleaner would this cause the problem? Thanks

You need the aircleaner since it contains the primer circuit, see the IPL in the link below, page 4. Have a good one. Geo
http://www.briggsandstratton.com/pdf/illustrated_parts_list/100/MS0990.pdf

Geo,

Thanks for the info and link. I have the side of the air cleaner that has the primer, I am just missing the cover and the paper filter. The compression is 80PSI could this be what is only allowing it to start when primed with starter fluid? Does anyone know what the compression should be and the valve clearance gap for this engine? Thanks for any help. Bob

Maybe a little weak on compression, but I don't think this is whats causing your issue. Like geo said in his post, it's probably the seal between the air filter base and the carburetor leaking and not letting the primer work properly. You might try doubling up on the gaskets between the air filter base and carburetor, sometimes this works.

Valve clearance for your engine is .005" - .007" intake and .007" - .009" exhaust.

Thanks for the advice 30yr and Geo. I am going to finish the valve lapping that I started and then I will take a look at the gasket between the carb and the air cleaner and primer. I will let you know what happens, as soon as I get the work done, hopefully later today. Bob

Update

I found out the the lawnmower will not start unless the air filter cover is on the mower. I put a rag over the carb opening and the mower started right up, so now I need to buy the carb cover and get a filter. Thanks for the help. I was able to get the compression from 80psi up to 120PSI what would a good range be for this mower?

what you can also do to save you a couple bucks, get 2 or 3 of those gaskets first and put them on and try it, thats what I do with a lot of briggs with those style of air filters and it works out fairly well and save the customer $20

FYI, this is a common problem with these style of air filters on briggs motors

EASIEST way to make sure it working properly, is when you put it back together, before you put the air filter on, look in the throat of that carb, and hit the primer, if you see a stream of gas shoot up, you are in the clear :thumbsup:

Once the mower cooled down overnight, I found that it was still hard to start. Geo and 30 year were right it was a small leak between the air filter and the carb. I doubled up the gasket and that solved the problem. I also was able to see into the throat of the carb to make sure fuel was forced into the carb when it was primed. Thanks for your help once again. Bob:)

Nothing sounds better than success. Have a good one. Geo