Export thread

5 hp Briggs, 1302121919 01
Won’t start unless I prime it (w/carb cleaner), hot or cold.
Go cart sat for a year or two.

I cleaned the tank and carb
Rebuilt the carb
Put on a new carb
Put on new magneto (thinking spark was too weak to fire it)
The “upper” tank fuel bowel holds fuel, so it does not drain out
New spark plug

It has about 43lbs compression cold

It runs good, plenty of power, once I get it
started - it will start after 2 or two pulls AFTER priming it.

What am I missing? I am stumped - been fixing these for 60 years off and on, never ran into this

Please help me out here - thank you

Old fiddler said:

Go cart sat for a year or two.

Click to expand...

Carb is still plugged up or you have a delaminated fuel line or filthy fuel tank. Maybe a clogged fuel filter.

Old fiddler said:

Won’t start unless I prime it (w/carb cleaner), hot or cold.

Click to expand...

Choke issue, definitely a lean/lack of fuel issue while starting. Fires off with spray.

Old fiddler said:

Put on a new carb

Click to expand...

Chinese Scamazon or OEM? New carb will need testing.

Old fiddler said:

Put on new magneto

Click to expand...

Chinese or OEM? New coil will require testing.

Old fiddler said:

The “upper” tank fuel bowel holds fuel, so it does not drain out

Click to expand...

If this is a pulsa-jet type, normal ops.

Old fiddler said:

New spark plug

Click to expand...

Will require testing. New untested parts means nothing.

Old fiddler said:

It has about 43lbs compression cold

Click to expand...

Using a car comp tester? Those read low on small engines. They have a large ID hose for such a small cylinder and a long hose which in this case, doesn't help. Might have a compression release doing its job??

Speculation time about low compression. Could be stuck rings from rust while sitting for 2 years. Carbon fouling ice berg chunks behind the valves holding a valve open. Maybe a valve seat came loose out of the block, again holding a valve open. Having NEVER decarbonized the cylinder/s per everyone's small engine manual. Valves needing adjusted. I would look here as this is an easy check. Not compression related but could have a sheared flywheel key??

Make sure the choke is working first.

Compression test shows low, but I never rely on them to make good decisions. Go to your local auto parts store and see if they have a loaner program. Many of the major ones will loan you tools for a deposit and return the deposit when you return the tool. You need a cylinder leak down tester to preform a leak down test on the engine. This will give you a better picture of what is going on with the engine. Two questions I have about your engine. Did you purchase the new carb from AutoScam, FleaBay or an original OEM carb from a known good dealer? The techs on this site have found that those purchased aftermarket have a 50+% of being faulty. What was the part number of the carb you purchased? OEM part number should be 299437.
To Slomo, why don’t you look up the engine before asking question? You would have seen it is a pulsajet carb with no fuel filter because it is tank mounted.

slomo said:

Make sure the choke is working first.

Click to expand...

It’s a manual rotary choke, it is working - it acts the same with 2 different carbs

slomo said:

Carb is still plugged up or you have a delaminated fuel line or filthy fuel tank. Maybe a clogged fuel filter.

Choke issue, definitely a lean/lack of fuel issue while starting. Fires off with spray.

Chinese Scamazon or OEM? New carb will need testing.

Chinese or OEM? New coil will require testing.

If this is a pulsa-jet type, normal ops.

Will require testing. New untested parts means nothing.

Using a car comp tester? Those read low on small engines. They have a large ID hose for such a small cylinder and a long hose which in this case, doesn't help. Might have a compression release doing its job??

Speculation time about low compression. Could be stuck rings from rust while sitting for 2 years. Carbon fouling ice berg chunks behind the valves holding a valve open. Maybe a valve seat came loose out of the block, again holding a valve open. Having NEVER decarbonized the cylinder/s per everyone's small engine manual. Valves needing adjusted. I would look here as this is an easy check. Not compression related but could have a sheared flywheel key??

Click to expand...

Yes, car comp. Tester, it has not sheared the key. I will start over again with suggestions thank you

Have you check the valve clearances. I know old L-heads are hard to start when the valve clearances approach zero.

Take off the air cleaner and snap a few pics, it would give us more info. One shot with the choke open, and the other closed.

Fish said:

Take off the air cleaner and snap a few pics, it would give us more info. One shot with the choke open, and the other closed.

Click to expand...

I will have to do it later, if I can figure out how to do it

2 of new carb on motor
2 of old carb I am holding
Both acted the same -

is your spark plug working?
fuel lines too maybe?

Yes, spark is good
I changed the mag thinking that although there was spark, maybe it was too weak to fire it
Fuel lines are part of the base of the carb - both have fine screens on the bottom (both clean)
Both the old carb that I cleaned, then rebuilt, and the new carb, which is not an OEM, act the same way

Old fiddler said:

Yes, spark is good
I changed the mag thinking that although there was spark, maybe it was too weak to fire it
Fuel lines are part of the base of the carb - both have fine screens on the bottom (both clean)
Both the old carb that I cleaned, then rebuilt, and the new carb, which is not an OEM, act the same way

Click to expand...

I measured the length of both pickup tubes to make sure they were not sitting flat on the bottom of the tank, and added an additional gasket to give a few thousands more.

hmmmm, i think then your carb could be out of adjustment

the setting for the mixture screw is turn in until snug, and then back out 1 and a 1/4 to 1 and a 1/2

MechanicLane said:

hmmmm, i think then your carb could be out of adjustment

Click to expand...

So what is your procedure for adjusting it, because I think it IS in adjustment, but always willing to learn something new

Old fiddler said:

So what is your procedure for adjusting it, because I think it IS in adjustment, but always willing to learn something new

Click to expand...

the setting for the mixture screw is turn in until snug, and then back out 1 and a 1/4 to 1 and a 1/2

Click to expand...

MechanicLane said:

the setting for the mixture screw is turn in until snug, and then back out 1 and a 1/4 to 1 and a 1/2

Click to expand...

That’s where I am at - I have gone leaner, and I have gone richer, same frustration

man you have quite a project

do you have choke all the way closed when starting?

MechanicLane said:

do you have choke all the way closed when starting?

Click to expand...

Of course

It used to start first pull - but used to doesn’t live here any more

heres what you can do, take a air compressor with a blower tip and fit it in the fuel line and press the handle to blow air while cranking the engine

put your hand over carb while cranking to see if that does anything also

Old fiddler said:

It used to start first pull - but used to doesn’t live here any more

Click to expand...

i have a 3HP b&s horizontal shaft on an edger that starts first pull also, i tell ya, its the seafoam i treat it with

MechanicLane said:

i have a 3HP b&s horizontal shaft on an edger that starts first pull also, i tell ya, its the seafoam i treat it with

Click to expand...

I just got some today, was planning on using it later on today

Old fiddler said:

I just got some today, was planning on using it later on today

Click to expand...

that stuff works wonders! i have like 5 cans of it in my shed

Old fiddler said:

I just got some today, was planning on using it later on today

Click to expand...

Thank you all for your input - I will be figuring out how to proceed and get it fixed
I will let you what happens

Old fiddler said:

I will have to do it later, if I can figure out how to do it

Click to expand...

If you have the pic on the computer, just do a screenshot/snip of it, it will load here easier. Just go to your "snipping tool".

Fish said:

If you have the pic on the computer, just do a screenshot/snip of it, it will load here easier. Just go to your "snipping tool".

Click to expand...

I did and posted 2

MechanicLane said:

i have a 3HP b&s horizontal shaft on an edger that starts first pull also, i tell ya, its the seafoam i treat it with

Click to expand...

Yep, Seafoam is the cure all. If it weren’t for Seafoam, I wouldn’t know what to do(sarcasm).

Tiger Small Engine said:

Yep, Seafoam is the cure all. If it weren’t for Seafoam, I wouldn’t know what to do(sarcasm).

Click to expand...

I was selling the cart, and wanted to avoid splitting it apart - I may just push it in the corner and deal with it later

MechanicLane said:

heres what you can do, take a air compressor with a blower tip and fit it in the fuel line and press the handle to blow air while cranking the engine

Click to expand...

What fuel line?? Carb mounted on tank!? Per previous posts.

slomo said:

Carb is still plugged up or you have a delaminated fuel line or filthy fuel tank. Maybe a clogged fuel filter.

Choke issue, definitely a lean/lack of fuel issue while starting. Fires off with spray.

Chinese Scamazon or OEM? New carb will need testing.

Chinese or OEM? New coil will require testing.

If this is a pulsa-jet type, normal ops.

Will require testing. New untested parts means nothing.

Using a car comp tester? Those read low on small engines. They have a large ID hose for such a small cylinder and a long hose which in this case, doesn't help. Might have a compression release doing its job??

Speculation time about low compression. Could be stuck rings from rust while sitting for 2 years. Carbon fouling ice berg chunks behind the valves holding a valve open. Maybe a valve seat came loose out of the block, again holding a valve open. Having NEVER decarbonized the cylinder/s per everyone's small engine manual. Valves needing adjusted. I would look here as this is an easy check. Not compression related but could have a sheared flywheel key??

Click to expand...

Make sure choke baffle is closed when throtle is in choke position. Your throtle cable could have slipped.

Your choke butterfly valve is not closing completely when the actuating lever is in full choke position. Needs a tweaking to be completely closed for cold start.

Fiddler, I'd bet you need to lap the valves and reset the lash. One or both valves was likely up off the seat while it sat. The valve face will rust causing it not to seal up. That's probably where your compression is going. You can do a quick check by pulling the head and placing a thumb on top of each valve when they're closed if you can spin it, it needs to be lapped and the lash set. A tablespoon or two of MMO in the cylinder overnight wouldn't hurt either.

Well, the solution was an improperly installed diaphragm in the NEW carburetor which was misaligned and had a fold in it.
I properly installed it, and after 4-5 pulls, it starts and runs strong.
Thank you for all your help on this.

StarTech said:

Have you check the valve clearances. I know old L-heads are hard to start when the valve clearances approach zero.

Click to expand...

Or in the case of a tecumseh engine several months ago, Negative clearance.