8 horse looses power and dies.

Hi fellows!
So the other day I got a 1987 Montgomery Ward 8/36. It hadn't been run in a while, and it was missing a few parts. I cleaned out the carb and did get it running.
Now it runs good for a few minutes, then starts to lack power. then it surges slightly and dies. After that it won't restart unless it sits for a while, and the carb goes dry (there is fuel in the tank). I originally thought it was crystalized valves (due to straight pipe) but it's got a good 115psi of compression. It only runs on choke, but I was attributing that to the straight pipe. New sparkplug. Cleaned out the cylinder. It burns a descent amount of oil. (constant smoke).
Ideas?

Thanks.

Clean your fuel lines.

It does run fine for tw first little bit. But sure I'll do that. Also it hesitates. I hit the throttle butterfly at the carb (didn't use the throttle lever), an it didn't do much. I expected the motor to fly.

It sounds like poor fuel delivery. Indeed, check the fuel lines. More likely, there's trash in the tank all collected around the debris screen at the tank outlet. Also check for crud in the petcock (if equipped) and replace the fuel filter (if equipped). Also make sure that the float is set and operating correctly, and that there isn't trash in the fuel inlet valve (that which the float actuates).

I know you said you already cleaned the carb, but you'd be amazed how many times folks have to attempt it a couple times to get it right.

You're telling me, Doc. It just seemed odd to me because it took time to build up and actually stop the motor from running. And then it goes away after a little bit of sitting. But I'll have a second look tomorrow.

To much oil will do this also if its about a 1/2 quart over filled.

I can tell you that's not it.  It's at the add line, and burning more all the time!

If you want to check fuel flow to the carb, remove the mixture screw at the bottom of the carburetor bowl, and see how much gas is flowing out.  That will tell you if the tank, lines, filter, and needle valve are letting gas through.

Ah ha. I would've just unplugged the fuel line, but this is even better! Thanks!

One other possibility that no-one else has yet proposed-

Try running it with the fuel filler cap very loose. There is a chance that the vent is clogged/defective, and a vacuum is building. That will starve even a perfect carb and fuel system.

Also- does your engine feature a fuel pump? If so, make sure it works! If not, make sure the very bottom of the fuel tank sits higher than the carb bowl...

I will put that on my list of things to check. The cap originally had a gauge, but the float part broke off.

There's no fuel pump on this motor, it's a 1983 8hp!

Doc Sprocket wrote:

It sounds like poor fuel delivery. Indeed, check the fuel lines. More likely, there's trash in the tank all collected around the debris screen at the tank outlet. Also check for crud in the petcock (if equipped) and replace the fuel filter (if equipped). Also make sure that the float is set and operating correctly, and that there isn't trash in the fuel inlet valve (that which the float actuates).

I know you said you already cleaned the carb, but you'd be amazed how many times folks have to attempt it a couple times to get it right.

Yes, what he said. Also remember that even the best gasoline starts to break down and leave deposits that plug jets after only two months.

its easy to miss a vital hole of its small. If it has sat for any time, any number of passages are plugged.

I took apart as much of the carburetor as I could, and blew it out with my compressor. Also i was runnin on fresh gas (now it's a mix).

So I cleaned the carb again. There was a decent amount of dust in the bottom of the bowl. I also cleaned the fuel line, fuel filter, and tank as best as I could. So now it only runs at 0 throttle and full choke. I thought it was just too rich, so I opened the choke a little bit, and it dies. If I open the throttle, even a crack, it dies. The fuel is slightly yellow, it could probably use fresh gas. But would that do this?

Not getting enough fuel.

There are 3 screws to adjust to tune the old briggs carbs. 

Main mixture, on bottom of carb bowl.  Turn this one in all the way, then back out 1 1/2 turns.  That will get you roughly close, once it is running you can fine tune it.

Idle fuel adjustment on top.  Screw that has a spring around it, on top, pointing down.  Turn in also all the way in, then back out 1 1/2 turns.

Idle speed screw.  Screw on side of carb, with a spring around it.  I like to turn this one in a couple extra turns, to speed up the idle, until I get it tuned in.

Once it starts and warms up some(may have to hold the throttle open a little,  or choke it a little.) 

Rev the engine about halfway up.  Then adjust the main mixture screw on the bottom out until it starts to choke out, and run rough.  Then turn it in(count how many times) until engine is starving for fuel and running rough.  Then adjust it in the middle of these two settings.  Make sure choke is off.

To adjust the idle, first turn the idle speed screw on the side of the carb, until it is idling at the speed you want.  Then adjust the idle mixture screw on top, in and out, the engine will speed up at some point.  Adjust it until it  is running as fast as it can. Then you can adjust the idle screw on the side until the idle drops back down to where you want.  You may have to do this a couple of times. 

When done, I back out the idle mixture screw an extra 1/4 turn, to richen up the idle, and compensate when quickly revving up the engine(no accelerator pump on these motors)

Idle adjustment on many of these ends up with the idle mixture backed out like 3 turns, if the butterfly is worn where it goes through the carb.  This lets in too much air, and you have to compensate by adding idle mixture fuel.  If it's really worn, then you have to turn the idle up until the main mixture screw can help, and then the idle is really high.

Doc probably has a way of doing it also, it may be better.

I like what you said about the throttle being worn. It did stick open a few times. I know both screws are currently beyond the 1.5 turns out. The idle one is barley even in there.
Also, I don't believe I have the third one.

Thanks!

Stretch44875 wrote:

Not getting enough fuel.

There are 3 screws to adjust to tune the old briggs carbs. 

Main mixture, on bottom of carb bowl.  Turn this one in all the way, then back out 1 1/2 turns.  That will get you roughly close, once it is running you can fine tune it.

Idle fuel adjustment on top.  Screw that has a spring around it, on top, pointing down.  Turn in also all the way in, then back out 1 1/2 turns.

Idle speed screw.  Screw on side of carb, with a spring around it.  I like to turn this one in a couple extra turns, to speed up the idle, until I get it tuned in.

Once it starts and warms up some(may have to hold the throttle open a little,  or choke it a little.) 

Rev the engine about halfway up.  Then adjust the main mixture screw on the bottom out until it starts to choke out, and run rough.  Then turn it in(count how many times) until engine is starving for fuel and running rough.  Then adjust it in the middle of these two settings.  Make sure choke is off.

To adjust the idle, first turn the idle speed screw on the side of the carb, until it is idling at the speed you want.  Then adjust the idle mixture screw on top, in and out, the engine will speed up at some point.  Adjust it until it  is running as fast as it can. Then you can adjust the idle screw on the side until the idle drops back down to where you want.  You may have to do this a couple of times. 

When done, I back out the idle mixture screw an extra 1/4 turn, to richen up the idle, and compensate when quickly revving up the engine(no accelerator pump on these motors)

Idle adjustment on many of these ends up with the idle mixture backed out like 3 turns, if the butterfly is worn where it goes through the carb.  This lets in too much air, and you have to compensate by adding idle mixture fuel.  If it's really worn, then you have to turn the idle up until the main mixture screw can help, and then the idle is really high.

Doc probably has a way of doing it also, it may be better.

There's a slightly faster way. Turn the idle fuel adjustment screw all the way in, then out 2 1/4 turns, then do the same with the idle mixture screw on bottom. This should be about right for those older carbs off the bat. Once started, rev it full throttle, if it cuts out, bring the fuel mixture screw 1/4 out at a time, slowly till it smooths. If it acts flooded, turn it in 1/4 turn. Job done.

Runs like a champ! Thanks guys! I like that little 1/4 turn to give the throttle some kick, Stretch.  I'm going to go get a pic with the racing stripes I painted on it.

There she is. Lil Red. I need a name other than Montgomery Ward now that I have two.