Lawnmower Engine Starting Tips??

[sanddrag]

I took out the plug and discovered it was all black so I replaced it with a Champion EZ start plug (which didn't make it start any EZer). I also replaced most all the old gas with new gas. I still can only get it to run by putting a little gas right into the carb, and then it only runs for a few seconds until all of that gas is used up. It is like it is not taking gas from the tank.

I was going to get some carb cleaner but on the can it says in capital letters "do not spray into carb when engine is not running" and I can't get the engine to run long enough to spray anything in there while it is running.

Also, the carb makes a sucking/hissing sound if that makes any difference.

Thanks.

[NoodleKnight]

Sounds like the A/F mixtures are somewhat fubar-ed.
I think the reasoning behind why the instructions (on the carb-cleaner bottle) say not to use while not running is because the stuff is pretty flammable -- if you cranked your engine right after you sprayed a bunch there's a chance something can go bad. Additionally, the engine has to suck the stuff in, also carb-cleaner has xylene, which smells bad, and is a carcinogen. Just get a pal to crank the engine continually while you spray inside the air intake.

All carbs make a hissing noise, it's part of their design to get the air flow moving around the intake... if it's pretty loud then I'd definetaly say there's stuff in your carburetor that's probably causing your engine to choke.

[Al Skierkiewicz]

Sanddrag,
The carb has a sump tube that runs down into the gas tank and the tube has a screen filter at the bottom. If the gas had been sitting any length of time, the screen could be gummed up. As I remember the carb kit has a new screen as well. Since there is no fuel pump, the hissing sound is the carb trying to suck gas in from the tank, or bypass air around the choke or gas evaporating when it hits the hot engine parts in the intake. Since the engine runs if you squirt gas into the carb, suspect fuel delivery. You may find a manual online if you haven't looked already. B&G may group engines by family so the entire part number will not get a hit on their site. BTW, the choke (if not manual) is designed to open shortly after start. If it does not, try holding it open with a screwdriver while you start it the second time.

[sanddrag]

I referenced the B&S website and my other slightly different B&S engine and I know I've got the mixture needle in the ballpark.

For the carb cleaner, what's the worst that can happen, it flashes a little bit? Also, the carb is a manual choke.

For the engine model number, I haven't even found it on the engine.

I can't tell exactly where the fuel comes into the carb. The carb is mounted directly to the top of the tank though, so I suspect it is as Al says. I guess I'll just have to pull the thing apart and figure out how it works! (unfortunately in is like in the 90's outside today making for miserable outdoor work).

One question I had was is it possible it is the gas cap not venting properly and making a lower pressure when the engine tries to pull gas in? Maybe I can try loosening the cap to give it some more ventilation.

Once again, thanks for all the help. I'll try to figure out if there are any problems with the fuel supply.

Also I was wondering about one more thing. There is a rubber hose (maybe 3/8" diameter) that runs from the engine (upper part, but not on top) to the choke area of the carb. Any idea what it is for?

[Frank Toussaint]

Maybe this link will be helpful: Briggs & Stratton troublshooting

[sanddrag]

Originally Posted by Frank Toussaint

Maybe this link will be helpful: Briggs & Stratton troublshooting

Already saw it but thanks anyway.

I pulled the carb and gas tank off (one of those carb bolts is real tough to get to, not sure how I'm going to put it back on) and the gasket mating the two was shot. The lawnmower shop was closed so I used some red silicone rtv instead. It said not recommended for use by gasoline, probably because the gas will eat away at it, but it should work at least for a while. I'm guessing anything will be better than the rotted and split gasket that was there.

I cleaned the carb and the fuel tube screeens well with carb cleaner. Hopefully once put back together, this thing will run. I'll keep you posted!

[mtaman02]

Originally Posted by Al Skierkiewicz

Sanddrag,
The carb has a sump tube that runs down into the gas tank and the tube has a screen filter at the bottom. If the gas had been sitting any length of time, the screen could be gummed up. As I remember the carb kit has a new screen as well. Since there is no fuel pump, the hissing sound is the carb trying to suck gas in from the tank, or bypass air around the choke or gas evaporating when it hits the hot engine parts in the intake. Since the engine runs if you squirt gas into the carb, suspect fuel delivery. You may find a manual online if you haven't looked already. B&G may group engines by family so the entire part number will not get a hit on their site. BTW, the choke (if not manual) is designed to open shortly after start. If it does not, try holding it open with a screwdriver while you start it the second time.

I too have a problem and mostly what has been said here has been done by me:

Problem - No fuel going from the circular fuel tank (located under the carb) going to the carb

What has been checked Thus Far:
1) Made sure the fuel line is clear and getting to the circular fuel tank through its provided fuel lines.
2) Checked and cleaned Carb and any methods that get fuel into the carb.
3) Fuel & Oil has been changed as well as spark plugs and air filters are concerned.

What HASN'T been checked:
1) Primer Button which just so happens to be built into the Carb Assy. thus if I have to replace one thing I would have to replace the entire Assy.

Fuel is going from the main tank into the circular tank just not going from the circular tank to the carb.

[sanddrag]

Well, the carb was cleaned and sealed back on the gas tank and reinstalled on the engine. I got it to run really good for about a minute. I took it all the way through the throttle up to WOT and it was really punchy. The only thing is that is would bog down at idle, and if I did not rev it back up, I knew it would stall. So, I ran it for about a minute then I let it stall so I could adjust the idle stop screw (screwdriver wasn't withing reach while running).

Anyway, I never could get it going again. Only a few seconds at a time by putting fuel right into the carb.

So anyway, I've given up. This week I might take it to the lawnmower shop and see what they say.

[Andy A.]

I had a similar problem with a VW beetle's carb.

It hadn't been run for a while, and there must have been years of gunk in the carb and intake track.

Since we couldn't get it to take up fuel with out just flooding the engine and/or killing the batter, we pinched the fuel line and had someone just spritz some engine starter in the carb till it caught, and again every time it started to bog down.

It ran very poorly at first, owing to all the gunk in the engine, but after about a minute of running on ether, she was doing pretty well. We hooked up the fuel line again and from then on she managed to carborize on her own. The more she ran, the better she did, and the easier she was to start afterwords.

My suggestion is to try starting it with some starter fluid, and keep it running like that for a bit. My guess is that after a little bit of running, it will manage to take up enough gas to keep running on it's own. Then, just let it heat up at about half throttle, and run most of the tank through. Keep doing it till she's begging to get started again.

Some more conservative minds don't seem to like the idea of using so much starting fluid. I've used it a bunch, and never had anything blow up or die prematurely.

-Andy A.

[mtaman02]

well as part of my ongoing tuneup continues on my 2 - 3 yrs old lawnmower continues I have done the following:


Took the carb off the mower and cleaned every hole thoroughly and re-assembled it back to the mower and badda bing the mower works as good as it did when it was first bought.

Now a new project has arised: where can I get parts for a mower that could be nearly 20 yrs old ? probably no where since I checked mostly everywhere so what I have done is match the newer mower with the older one - the engine is from the same manufacturer the parts are of different construction but can be installed and should work the same way.

I shall update you all if I am successful in rigging 2001 / 2002 mower parts with a 1987 / 1990 mower

[Mike Martus]

Your repair is easy.

There are two possible causes.
1. The ball-check valve is stuck open. This is located at the end (inside) of the tube that extends into the carb (assuming that you have the older suction feed carb).

A little carb cleaner will do the trick or replace the tube. You can test by sucking and blowing with your mouth ( boy gas tastes nasty and is poison to boot) I still use this method to test.

2. A leaking head gasket is also very common. Easy fix is to re-torque it to 150 inch lbs. You will find the bolts near the exhaust are loose and the engine is sucking in air at low conditions. Better fix is to replace the gasket.

Since this is an older engine you may want to check the level of compression - the easy test is with your baby finger. Put it in the spark plug hole (no I am not joking) and pull over the recoil. If it blows your pinkey out it has enough compression to start the compression cycle. Note: Low compression (poor) improves the faster the engine runs.

I would be happy to assist further if needed. Just contact me. I have been teaching Small Engine repair for 33 years. I am certifird by both Briggs & Stratton and Tecumseh.

[mtaman02]

Ok, I have an Update and a question


Do you know how a spark plug wire is constructed? (whether it has a 2 wires for + and - or just one wire)

The reason why I am asking is because on the older mower I have the following issue:

Problem: I cannot turn the mower off when I release the brake handle the mower continues to run

Cause: The Brake is worn out ( i mean after almost 15 + yrs I would be worn out to) and the Engine Zone Cable is stretched (Attaches one end at the brake and the other end to the handle)

I have bought the newer model parts and did a pre-assembly and found that the Engine Zone Cable is to long and the brake even though can be installed the same way is made for right side mounting only where as its a left mount currently installed.

What I am attempting to do is to make / attach either a dip switch or a standard house holdlight switch spliced between the starter and the spark plug - what this will do is when i flick the switch it will cut the power going to the spark plug and turn the motor off.

So if any of you happen to know alot about cars or mowers or spark plugs in general any and all help is appreciated b/c at this current moment the mower cannot be operated safely with out a way to turn it off.

[sanddrag]

I still haven't gotten my mower running for longer than just a little bit. I still have to take the carb off again and take the yellow plastic fuel tubes out/apart and see if they are clogged or anything. Or maybe see if there's that valve thing Al mentioned a while back.

mtaman02, for your mower I have some answers. A spark plug wire is only one wire that goes to the plug electrode. The body of the plug is grounded through the engine block. Some mowers have a little metal "stop" tab on top of the head right next to the spark plug. (my 2hp b&s didn't have it, my 3hp one had it). You just flip it over (it is sort of hinged) so it touches the top of the plug. This shorts the iginition and the ground so no spark is produced. If your engine doesn't have a tab, you can short the top of the plug to the head with a screwdriver (the metal shaft of) to stop the engine. You probably want to hold the insulated end of the screwdriver to prevent getting a nice shock. I don't think it would hurt you (I've gotten a spark plug shock a few times) but I'm not totally sure, besides, it doesn't feel good to get shocked.

In any case, don't wire a switch in series with your sparkplug wire/cable. It is not necessary and probably not a good idea.

Also, usually you can pull the choke out all the way out and it will die in about 5 seconds or you can try putting your hand over the carb opening if there is no air cleaner on there, although that may take longer and might not work.

Last, by Engine Zone Cable I assume you mean throttle cable?

[mtaman02]

Ok if your engine has an air cleaner assembled to the carb you would want to make sure the screws assembling the too are tight other wise for some weird reason it will not allow a little bit to no fuel to go to the carb - I found that out the hard way but yeah make sure the carb & choke is clean take it apart and just spray the appropriate cleaner into it / WD-40 =) it worked well for me and has not upset the workings of the motor.

As for the spark plug it sounds like its too much work to mess around with I was just curious if I could just hook up like a switch to cut the spark off. Shorting this that and the third is not my kind of fun.

I could try holding my hand over the carb but i really don't like the idea of having my hand next to something that gets extremely hot let alone moving.

the engine zone control cable is how the manual describes it, there is no throttle cable on it - the throttle adjustment is seperate and is actually mounted on top of the carb and choke assy. for this particular motor however i removed it since it was broken and was unable to obtain a new one due to the mowers age so what i have done is just run the mower at a high rpm to keep it from stalling out when cutting alot of greass. the engine zone control cable is basically your engine cut off / emergency brake - in case anything god forbidden happens

On the Tecumseh Motors the Brake is assembled on to a bracket which has like a bike cable attached to that end (its spring loaded or so thats what how it apears that way when you release the handle bar it shoots the brake out) the other end is attached to a handle bar which you pull back so that you can start the motor. - I'm sure you already knew that but I figured I try and explain the main function of the engine zone cable. The throttle cable on some mowers is attached either right under the handle bar or on the carb itself so that you can increase and decrease the mowers speed. which as i said before do not currently attached.

[Adam Y.]

Here is a hint. Don't start a lawnmower on any incline. The engine would always cut out when I was using my dad's lawnmower.