Runs good then dies.

[Budrow]

46" Hydro, 18 horse Briggs (twin)
This was a great strong running mower last season.
It may be around eighteen years old but is in good condition (if it would just run).:wink:

This year it will start easily and will idle maybe forever.
When a load is applied (either motion or blades or both) it will run for about two minutes and then stall.
When this happens a stalling engine cannot be made to recover using the choke. However the engine will easily restart immediately and run for another two minutes before dying.

This season...
The oil is new (20/50) as well as the oil filter.
The fuel is new (probably E-10) but has been conditioned.
The plugs are new.
The fuel filter is new.
The fuel cap is also the fuel gauge, funky but vented through the sloppy gauge assembly.

Plug wires are probably original equipment as are the fuel lines.

This machine has had at least three previous owners and some of the wiring may be questionable.

The key was at one time also the starter switch but now is nothing more than an off/on device and a separate start switch has been added by someone previous but replaced by me recently due to overheating of the switch.

Okay I'm out of ideas on what else to do and would like some opinions.

Thanks to anyone that has any ideas.

 

[Lawnranger]

Could be lots of reasons. You need to find out what is missing at the time it dies - fuel, spark, air? It sort of sounds like the main jet is partially clogged or debris in the bowl plugs the jet intermittently. Remove the carburetor and do a complete cleaning.

HTH,

Lawnranger

 

[Budrow]

Remove the carburetor and do a complete cleaning.

That was done a few days ago. Internally the carb was spiffy as could be, nice and clean everywhere.

You need to find out what is missing at the time it dies - fuel, spark, air?

Has spark. At this time it is being operated without any air obstruction and still does it with or without the intake apparatus in place.

Will check for fuel shortage next.

Appreciate the help guys.:thumbsup:

 

[Rivets]

Sounds to me like it is running low on fuel under load. Check for an air leak of any kind on the pulse line to the pump. It may be pumping enough fuel under no load but can't keep up under load. Is there a clean clear fuel filter between the pump and the carb which you can monitor for fuel flow under load?

 

[Budrow]

Is there a clean clear fuel filter between the pump and the carb which you can monitor for fuel flow under load?

Yup, there is. Never thought to look at fuel movement, not sure if you could tell (movement). The filter seems to always set about half-full of fuel.

Check for an air leak of any kind on the pulse line to the pump.

Okay...is the "fuel pump" going to be the little "box" affair mounted to the front of the carb? If so...been in there and it is actually a diaphragm device I assumed was some type of fuel pump but didn't know what it was for sure. The rubber bladder seamed a little frazzled when we took it apart. I wonder if the rubber (diaphragm) would get bent out of shape or stretched over time.

 

[Rivets]

That pump will probably need to be rebuilt. Diaphragm should be smooth and clean. If there is a change in the amount of fuel in the filter means you will not get enough fuel to the carb.

 

[wcpost]

Also check out the fuel lines. If these are the original there could be blockage.

 

[Budrow]

Thanks guys....

We thought about the old fuel line so taking yet another path-of-least-resistance we replaced the entire line hoping for the best. But that didn't change anything either.

So now we have ordered a re-build kit for the fuel pump, that will take about a week to get here.

We are now more determined than ever to make this sucker work correctly.

 

[Budrow]

The re-build kit for the fuel pump arrived, was installed, and still nothing changed.

It was still apparent that the engine was starving for fuel so in a last-ditch attempt we decided to remove the fuel tank and inspect any nooks and crannies we may have overlooked in our zest to throw money at this sucker needlessly fixing the obvious.

The tank was clean and no sediment was found. Then something made me remove the tank (fuel line) fitting to see if I could blow air through it.

EUREKA!!!!!

The damned ninety degree fitting was full of iron oxidation and plugged severely. Once we re-bored and cleaned the fitting the engine runs like new. I suppose moisture over the years formed the rust in the fitting and slowly closed the hole over all these years. One would think those fittings (even back then) would have been made of something like brass or plastic or anything that wasn't suseptible to corrosion and rust.

THANKS AGAIN for your help.

 

[Budrow]

WELL CRAP!

As luck would have it I couldn't be happy with everything working just fine so I ordered and installed new key-start-switch. Now I'm dead-in-the- water, the thing won't start. Starter runs but no spark. Over the years the wiring has been changed by others a few times. I don't need lights or ammeter or PTO indicator or any of that stuff.

What I do need is for someone to tell me what basic wiring I need to have in place for the engine to start and run. Anyone that can give me some basics would be appreciated.

I have an original wiring diagram but that confused simple old me. I guess what I need to know is what wiring is necessary to include the battery, solenoid, starter, etc...just the very basic basics.

Thanks again.