Engine wont prime gas

[rigoletto]

people,

have a push mower, Troy Bilt, 6.75HP B&S engine, and red push primer button appears OK (pressed it onto my palm, and felt to create pressure), cleaned carb well, Ive cleaned many carbs before, but geez- primer does not suck in any gas. You can feel it and hear it when it sucks in, and it does NOT suck in any primer gas.

I did replace the paper gasket behind the black plastic housing too, just in case, but it was a waste of $2. Still no sucking gas. ideas appreciated.

 

[rigoletto]

Oh- forgot to mention, I sprayed some ether in carb to start it, and it ran great. Ran for a few minutes, so gas is good, not old, and all fires up well in engine. Shut it down, waited a minute, pushed the primer button , no prime action. No start. Starts only with ether. Prime still no works.

 

[ILENGINE]

Without knowing the model number I am assuming you have the flat paper filter in front of the carb, with the primer located in the front/side of the rear air filter mounting piece. That type of primer doesn't pump gas, it pushed air into the carb to force the fuel up into the venturi of the carb. It is common for the cover to warp preventing a proper air seal between the cover and the carb. I usually double gasket that area and it fixes it most of the time.

 

[rigoletto]

Without knowing the model number I am assuming you have the flat paper filter in front of the carb, with the primer located in the front/side of the rear air filter mounting piece. That type of primer doesn't pump gas, it pushed air into the carb to force the fuel up into the venturi of the carb. It is common for the cover to warp preventing a proper air seal between the cover and the carb. I usually double gasket that area and it fixes it most of the time.

thnaks. Right- I have the pleated paper filter in front, and I can ad the original gasket to make extra paddding- I will try it. But, I doubt it will work, cuz it is plastic, and warpage seems unlikely- it's not like its an aluminum head on an engine where slight warpage is a big factor(?). I cranked down on the 3 bolts to seat that plastic housing. Still, good tip, worth a try.

 

[ILENGINE]

Actually overtightening of the bolts is what causes the cover to deform preventing a proper air tight seal.

 

[Rivets]

You may want to check your float level. I have found that if the float is not adjusted properly (set in a lean running condition) the primer does not have enough push to push fuel up the nozzle. I try to set the level slightly rich.

 

[rigoletto]

Actually overtightening of the bolts is what causes the cover to deform preventing a proper air tight seal.

OK, then I should try to not overtighten. But how does one know(?)

Update: added the 2nd gasket, and no difference. I did notice that the primer bulb does "push" air into the crescent shaped "slit" molded into the housing (soap bubble test, then dry it off). Also, with paper filter removed, allowing one to see directly into the carb orfice, gas accumulates as seepage, then drips downward slopping all over the housing of course.

OH- I did thread a fine wire into the carb orfice where the priming gas is supposed to seep into- no blockage down there, I believe, since the wire inserted about a full inch -1-1/4.

 

[rigoletto]

You may want to check your float level. I have found that if the float is not adjusted properly (set in a lean running condition) the primer does not have enough push to push fuel up the nozzle. I try to set the level slightly rich.

OK, Riv, but do I simply remove gas line, gently remove carb, and remove bowl to check level? How does that work because, every time I unscrew that bowl nut underneath most the gas drips out............(scratching scalp, left elbow resting on desk........)

 

[Rivets]

First, if you see fuel in the air horn when priming, there is no need to check the float level. Try this trick. Cut a stiff piece of paper or thin cardboard to a size that you can cover the carb throat with the air filter back still in place. Prime unit three times, place paper over carb throat, have someone start the engine. If the engine starts and continues to run when you remove the paper, I'm betting you have old fuel which is not volatile enough to burn at low RPM's.

 

[bertsmobile1]

OK, Riv, but do I simply remove gas line, gently remove carb, and remove bowl to check level? How does that work because, every time I unscrew that bowl nut underneath most the gas drips out............(scratching scalp, left elbow resting on desk........)

If you do it regularly you get a second bowl nut, drill a hole in it and force some trimmer fuel line in there about 4" to 6" long.
replace the bowl hold the line up alongside the carb and you should see the level rise then stop just short of the floor of the carb throat.