Fuel flow issue

I have a Craftsman 4.5 HP push mower with a Tecumseh 4B 811-0356 carb that has a cracked PRIMER BULB. The mower will not run except when primed and then just until the prime is consumed. I've rebuilt the carb, removing and cleaning under the welch plugs, blew out the orifices and reinstalled but it won't run on it's own. I've discovered the PRIMER BULB is cracked, will this cause a lack of needed vacuum disabling the engine from running? Can the bulb be replaced? Any sources?

Thanks
SFE

I would really love to help you but I can not with out engine and mower model number.
And yes a cracked bulb will cause this problem.

BlazNT,

The Mower is a Craftsman 4.5 hp 4 cycle mod: 917-388040. The engine is a "Eagar-1" model 143.034504. We purchased this mower new and this is the first issue I've ever had with it in the 10+ yrs we've had it so I guess I'm "over due". In trying to find answers to your questions I have located the owners manual which includes an exploded view of the carb. and identifies the PRIMER BULB/RETAINER RING as part #640259 and CARB as part 640339. I found nothing on the engine itself other than EAGAR-1. I guess that's all I need to know to get a new primer bulb if that is truly my problem.

A brief description of my problem.

I mowed one week and all was fine put the mower away and then next week it wouldn't start. I immediately thought SPARK PLUG, but that wasn't the problem. I then pulled the float bowl and inspected and cleaned the needle/seat and main jet (high speed bowl nut) and reassembled with no luck. I then removed the carb and used spray carb cleaner to clean every orifice I found, blew them out with air and reassembled. Still same. At this point I primed the carb and it would start and run out the prime but wouldn't continue to run. I recalled that while I had the carb off there were several welch plugs on the carb and guessed there must be dirt under them that is causing my problem so I ordered a carb rebuild kit and rebuilt the carb after a through cleaning -- still will not run except for a brief run with the help of a squirt of gas as a prime. I have discovered the primer bulb is cracked along the base on one side. Thus my question, will such a condition cause the carb to loose necessary vacuum it needs to draw the fuel through the carb enabling it to run or can there be another issue I'm overlooking? Is this likely my problem?

Any leak in the system can cause this. Yes a cracked bulb will cause this problem. You can have other problems as well but no way to tell until primer is fixed.
The part numbers you posted are valid numbers.

Thanks BlazNT,

I've ordered the bulb. I'll report the results when I get it installed.

SFE said:

Thanks BlazNT,

I've ordered the bulb. I'll report the results when I get it installed.

Click to expand...

Ok, I'm back. New PRIMER BULB installed but no change, engine will only run if primed. I'm out of ideas. Again this is on a Craftsman 4.5 hp Eager-1 model 917-388040. It simply isn't getting the fuel drawn into the cylinder.

Please help the grass is getting high!

Next:
Dirty carb
Down and dirty: https://www.youtube.com/watch?v=VBL-BUj0c6E
More technical: https://www.youtube.com/watch?v=nAk_WDt3AD8

Nope, don't believe it BlazNT. My previous explanation should dispel this theory. This carb isn't complex and was thoroughly dismantled, cleaned and rebuilt. You previously stated there could be other problems as well (besides the primer bulb) I'm at a loss as to what those possibilities are and where to go from here. It ran the entire summer up until I shut it down the last time I mowed. The following week - - nothing.

Ok so this is what else can be wrong even though it is almost always dirty carb.
Broken or missing gaskets. Bowl gasket and gasket between carb and elbow and elbow and engine prime possibilities.
Foreign object in fuel line or fuel tank. Remove fuel line from carb and blow compressed air back to tank. Look in tank to see if anything is in there that is not fuel.


I have cleaned the same carb 3 or 4 times before I got it completely clean.

BlazNT,

Your not going to believe . . well, second thought you probably will believe it . . one word . . . KEROSENE ! :laughing:

Going on my own premise that the carb wasn't getting the vacuum flow of air through the carb I thought I would double check to be sure I was right. By cupping my hand over the air filter side of the carb as I got it started on a prime I found that it did have sufficient air draw thru the carb. I also found that I could get it to run beyond the previous short lived primed run by restricting the air flow. During the previous primed runs it would smoke sum but I assumed it was the 2 cycle mix I was using to prime with. (I was priming with a squirt bottle of 2 cycle fuel left over from working on my boat motor) However, during this extended run it smoked all the more? Then it hit me. Kerosene!

Following your suggestion to disconnect the tank and blow out the line /tank nipple I emptied the tank into a clear Mason Jar and confirmed I had filled the tank with K-1 KEROSENE! I have apparently lost track of which fuel containers contain what. (that will soon be rectified!)

I am pleased to report that the mower seems to be running fine. :biggrin:

Thanks for your help.