4 Hp won't fire up.

[mumptia]

Hey there,

I have one motor in my shop that has me stumped. Briggs 4 HP on a pressure washer mount. Found it at the dump and thinking maybe I should have left it there now haha.

Simply won't start. Will occasionally fart, but no steady running.

After you see the list you might wonder why I haven't thrown this in the lake, its because I'm high school small engines teacher and right now I have about 20 motors on the bench (and 30 students) in pieces and we try to go the extra mile to fix them. (truth be said most of engines that come in here have one foot in the grave already)

Here's what I have checked, any more ideas would be certainly welcome.

- 80 on compression
- Strong spark on plug
- Intake gasket good
- Breather gasket good
- Crankshaft and flywheel keyway tight
- Flywheel key in tact (new key)
- Timing inside on
- Both valves lapped
- Multiple carb change outs
- New diaphragm
- Air gap good (coil changed out)

Now I'm out of ideas:confused2:

Any thoughts?

Thanks

Rob

 

[Fish]

Hey there,

I have one motor in my shop that has me stumped. Briggs 4 HP on a pressure washer mount. Found it at the dump and thinking maybe I should have left it there now haha.

Simply won't start. Will occasionally fart, but no steady running.

After you see the list you might wonder why I haven't thrown this in the lake, its because I'm high school small engines teacher and right now I have about 20 motors on the bench (and 30 students) in pieces and we try to go the extra mile to fix them. (truth be said most of engines that come in here have one foot in the grave already)

Here's what I have checked, any more ideas would be certainly welcome.

- 80 on compression
- Strong spark on plug
- Intake gasket good
- Breather gasket good
- Crankshaft and flywheel keyway tight
- Flywheel key in tact (new key)
- Timing inside on
- Both valves lapped
- Multiple carb change outs
- New diaphragm
- Air gap good (coil changed out)

Now I'm out of ideas:confused2:

Any thoughts?

Thanks

Rob

Why the new flywheel key? Was it sheared? Check it again. Might be sheared again due to insufficient torque.

 

[pugaltitude]

What is the model, type, trim & code?

 

[mumptia]

What is the model, type, trim & code?

Fish,

I always put a new key in with every engine where I can. $1.50 is a cheap part and gives the kids one more operation to complete on the engine.

Pug,

Not sure why you need the mod& type for diagnosis but here she be. (on second thought maybe a particular model has some common issues)

Mod: 10J902
Typ: 0131 E1
Cod: 04032651

Thanks Fellas

 

[reynoldston]

I am a long ways from a teacher, but you are. I have been doing this work for close to 60 years and I will still get something that I have to put my thinking into it. Now you need fuel, spark, compression, and timing. With out any one of these things it isn't going to run. To do a proper trouble shoot do only one thing at a time then move on to the next thing. Start small and then work up to the bigger things. As for myself one of the first things I do is test for spark with a tester. If that is good then on to fuel then from there bigger things.

 

[Fish]

Fish,

I always put a new key in with every engine where I can. $1.50 is a cheap part and gives the kids one more operation to complete on the engine.

Pug,

Not sure why you need the mod& type for diagnosis but here she be. (on second thought maybe a particular model has some common issues)

Mod: 10J902
Typ: 0131 E1
Cod: 04032651

Thanks Fellas

How about a new plug? That has fooled many folks, even though the old one sparked.....

 

[mumptia]

How about a new plug? That has fooled many folks, even though the old one sparked.....

He,he Its a new day and frustrations were left on the trouble tree after work yesterday.

I haven't tried a spark plug yet, but it'll get a new one this morning.

Reyno,

Thanks for the thoughts. I'd expect a fella who's been pulling wrenches as long as you has forgotten more than I know :smile:

Like you, I have a trouble shooting system that I take the kids through. Spark (air gap, flywheel key, keyways, coil....) Fuel (carb, diaphragm...), torque checks etc....
I did not check timing because I found this at the dump in tact on the mount. Because it looked like it was just a frustration throw-away, I didn't open it it up to check. Hmm, gawd could it be that simple?

If that's what the problem is will I ever laugh ( at the same time shaking my head:tongue

Updates to follow.

 

[reynoldston]

The spark plug setting outside the engine may have a good spark. Now put this same plug under compression you may not have any spark. This is the reason you test for spark with a tester in the engine. In the older days when we use to clean spark plugs, the plug cleaning machine had a tester that you could test a spark plug under compression to see if it was any good. Now the real old spark plugs in the 20's and 30's the spark plugs came apart and you could rebuild them.

 

[wjjones]

Try a new gasket between the breather assembly, and carb face. Does it have a primer bulb, or none?

 

[reynoldston]

The thing I don't understand here why would the breather gasket make any difference in running. Maybe after its running and you are adjusting the carburetor. Now a carburetor intake manifold gasket would give you problems. What I have done in the pass with the intake manifolds is take the gasket surface and sand them down on a flat surface with sand paper. Vacuum leaks will give you some running problems.