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Hi,
Have read various postings with no success. I have a model #445677 Craftsman 24HP riding mower, about 3 years old. The engine cranks but won't run. For awhile if I took off the hose off the outlet of the fuel pump and leaked some fuel, the engine would catch and run fine without quitting. But leaking some fuel no longer works. I suspected the fuel supply as the hose from the vacuum fuel pump to the rocker cover was cracked, so I replaced the vacuum hose to the rocker cover. The replacement hose was shorter than the original so I added a length of fuel hose to make up the difference. I'm pretty sure the hose is air tight. While the engine cranks, it won't catch and run. Sometimes it comes close and it seems one spark plug might fire once but the engine won't catch. After replacing the vacuum hose, the fuel pump seems to work better, when I take the hose off the outlet (the hose that runs to the carburetor), a stream of fuel gushes out and seemed to be under pressure. Taking out a plug, the plug is mildly damp and I can smell gas but it's not soaked. I'm sitting squarely on the seat and the left pedal is pushed down when I start. But I don't know if I'm missing any other safey lock-outs. I'm not familiar with the electric ?? fuel injector, if that's what it is under the carb, and how to test. I unplugged the connector and applied dielectric grease to the contacts. I may be overlooking some other safety lock-outs. Writing this, I'll do a spark test tomorrow, will take out a plug, ground it and crank. In the meantime, what am I missing here? Pictures posted below for reference. Thanks for any suggestions.

Front view of engine


Replaced vacuum hose




Electric injection under carb??

If the mower cranks that should rule out safety switches. Does the solenoid on the carb, click when you turn the key on and off. Have you tried cleaning the carb. might be a clogged jet. Also have you checked valve clearances. Might be a compression problem.

Thanks I'll check for clicking on the solenoid. Is the solenoid like a fuel injector on a car, squirts out fuel just before the intake valve or more an on/off valve for fuel flow, off when the ignition is switched off otherwise on for the duration of the run?

When the engine does start, it runs well and for hours without any issues? Does that rule out a clogged carb jet?

Checked the mower some more:

Both plugs have spark. There is voltage at the end of the wire/plug going into the solenoid, when steady cranking the voltage held at 6v but the battery was dying from all the cranking and then the voltage started to fluctuate with peaks at 40v when the cranking started to quit but the key was held in the start position. Looks like the solenoid is the next to check, probably a replacement? Is there any diagnostics that can be done on the solenoid?

Adjust valves per B&S specs. engine cold, post model number from under seat and engine numbers: model xxxxxx, type xxxx, trim xx. Try this first, rotate top of engine clockwise with both hands just past hard spot and try cranking with key, if it starts you need to adjust valves. Compression release on camshaft will not work properly if valves are too loose.

reelmower said:

Checked the mower some more:

Both plugs have spark. There is voltage at the end of the wire/plug going into the solenoid, when steady cranking the voltage held at 6v but the battery was dying from all the cranking and then the voltage started to fluctuate with peaks at 40v when the cranking started to quit but the key was held in the start position. Looks like the solenoid is the next to check, probably a replacement? Is there any diagnostics that can be done on the solenoid?

Click to expand...

The fuel solenoid is an on the whole time they key is on. The sole purpose of the solenoid is to help prevent the bang at shutoff. Solenoid requires 9 volts to operate. so can be tested with a 9 volt battery. Run one time and not the next could be something floating around inside the carb bowl.

Hi ILENGINE
The 12 v might be the key. The battery is only about 3 years old but it's no longer holding a charge and won't crank. I need to put a battery charger on it before every use. It could be when I let some fuel leak out of the vacuum pump outlet, it was also the time I jumped using the battery from a second riding mower on the property. The good battery overcame the 9v threshold to open the solenoid. Then once running there was enough current generated to keep the valve open. I didn't check the voltage of the dying battery but may be it's not enough to open the solenoid. So maybe leaking the fuel had nothing to do with it, it was the fact that at the same time I used a good battery that could open the fuel solenoid.

The mower is on a relative's property and we were just there visiting during the (Canadian) Thanksgiving weekend and have since come home. The repair will have to wait until our next visit at Christmas time. I'll try jumping using the battery on the other mower, if the mower starts, it's time to replace the battery. I'll update this thread at Christmas time.

mechanic mark: thanks for the suggestion. When the mower runs, it runs great so I think the factory setting for the valves is correct.

Back to visiting the relatives for Easter and am in the presence of the riding mower again. Today I swapped a good 12 v battery in from another mower. The engine cranks but won't fire.

To test the solenoid solenoid I disconnected the connector providing power to the solenoid, left the ignition in the run position, then touched the connector to the solenoid terminals. I could hear and feel a very quiet click noise. Not sure how loud it should be but I am getting some reaction in the solenoid. There is not much clearance to unscrew the 2 screws holding the solenoid on and I don't have my tools here so can't pull the solenoid to watch it work.

I pulled the fuel line off the outlet of the vacuum pump and cranked the engine and fuel spurted out.

I tested the ignition wires with a contact-less tester and I can confirm there is spark. I pulled the spark plugs and they are dry. Not glistening with fuel nor smelling like wet fuel. I'm thinking that narrows it down to the fuel solenoid or blockage in the fuel system?

Any suggestions? Mowing season is here! Thanks.

Pull thefloa bown off and see what is in there.
While it is off check the fuel solenoid is fully retracting.
Hold the float up with your finger and get someone to crank the engine.
Allow the float to drop and check for fuel coming out of the carb.
This will spill fuel so do it outside & don't smoke.

As stated check carb bowl solenoid needle valve. Notorious for sticking when fuel is left in bowl during storage. I have 27 hp Kohle Twin same problem. Gummed up needle. Used WD40 to dissolve gum . After you clean have someone move the switch between on and off and you can feel that needle move off its seat.

Hi, I'm back to the relative's property for the May long weekend. The mower engine is running again. I took the carb bowl off and it was full of gasoline so that confirmed that fuel was at least getting that far. The solenoid was moving freely and the bowl was clean. I next took the plastic cover off the top of the engine and took the metal plate with 3 screws and gasket off to be able to see the channels in the carburetor. I could see some very narrow orifices and sprayed carb cleaner into them and let it soak in. I used an air compressor to see if I could clean out the orifices some more. The engine started up after the cleaning with carb cleaner.

My suggestion for someone experiencing similar non-start problems, try the following sequence after checking the tank to confirm you haven't run out of fuel. The following are easy to more involved:
1. Remove and check spark plugs, if wet and smelling of gas then you have a spark issue and the following steps don't apply.
2. Touch solenoid on float bowl and have someone turn ignition on/off. You should feel the solenoid click. If not clicking, check battery voltage, need minimum of 9 volts to activate solenoid. Charge or replace battery.
3. Detach fuel line from outlet of fuel pump to confirm pump is working. Even crank the engine with the hose off, fuel should squirt out, catch in a container or cloth.
4. Remove cover and air cleaner holder to expose top of carburetor, remove metal plate and gasket to expose channels in carb. Clean orifices with carb cleaner.

At this point, the carb cleaner did the trick for me and the engine started.

5. Remove the carb bowl and check that the solenoid is moving freely and that there is fuel in the bowl. I did this step after step 3 above but I would do this later in the diagnosis now. There is a rubber o-ring that fell out when the bowl came off. I used silicone based automotive Permatex tune up grease, which does not harm rubber whereas ordinary automotive grease will affect rubber, to coat the o-ring and make it stick to the groove while I put the bowl back on.

Thanks for all the tips. Mower has been repaired just in time for the cutting season

Original poster here. It's 4 years later and the riding mower still doesn't start reliably. The fixes I describe above didn't have a lasting effect. I have posted a follow-up thread here https://www.lawnmowerforum.com/showthread.php/54378-Craftsman-24HP-riding-mower-cranks-has-fuel-flow-won-t-start-Part-2?p=330625#post330625 where I adjusted the throttle cable to get the choke to more fully close. I have been able to start the cold engine reliably.

Thanks for the update and even more so for going back to the origian thread.
Down side of posting photos is all thr family dirty laundry gets exposed.
In this case, those cylinders look like they are overdue for a clean.