What was the outcome to your problem CMB?

I'll know this week, finally got a little time to dig into it.

Going to see what happens with the deck off, and try the old carb spray around the base of the carb to see if it picks up RPM's.

Being spring, I plan on giving it a new plug and wire, fuel filter and see where that gets me.

With the short and mild winter, I am already looking at needing to mow, quite a few weeks earlier than usual...

I'll be posting back the results.

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On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

I really know nothing about mowers so this might be totally worthless but would dull blades contribute to this problem?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Might exacerbate the situation, but the bogging down happens even when I am not in the grass.

That and I tend to keep the blades sharp as a knife

__________________
On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

Don't worry about air leaks, if you had one the engine wouldn't idle. If you can, observe the throttle lever on the carburetor and make sure it goes to wide open as the mower requires more power. If it doesn't, you have a governor problem. If it does, you have an engine problem, either fuel or mechanically related. That engine (1983) has lasted far beyond its expected life. It could be suffering from worn valve guides and a dirty cooling system, which will cause a loss of valve clearance as the engine gets hot. While you're at it, R&R the blower housing and make sure the cooling system is clean.

Finally got the mower dug out.

It has a Briggs 400 IC engine.

Doing the same thing as at the end of last year, runs great for about 15 minutes, then tries to die under load. During the 15 minutes, it went up hill, blades engaged, through thick grass with no problem. Once the problems started, it will go uphill without blades, or run with blades, but not through thick grass.
Was able to verify that it is not the gas cap, as I was able to remove the cap during the sputter with no change.
Would a governor issue kick in after the 15 minute period, or would it be constant?
Could a partial blockage either in the main jet or elsewhere in the carb only show up after the engine gets warm?

Attached Thumbnails

         

__________________
On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

Oh yeah, what the heck is that little silver doohickey that has the fuel lines going in and out of it?
It doesn't have power going to it...

__________________
On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

looks like some sort of pressure regulator or metering type thing

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

The device with the lines is the fuel pump. It is operated by crank case pulse. That vintage engine probably came with a breaker point system when it was made. Briggs ignition systems either work or they don't- there's no in between. Point gap will not affect timing, it will affect whether or not the ignition system works at all. You can update it to Magnetron ignition if it hasn't already been done.

If the butterfly on the carb. is going to wide open, you could very well have a compression problem, most likely a tight exhaust valve as I mentioned before.

Valve clearances will change as the engine gets hot. Perhaps one is not quite seating properly after it does. This may be a high hour older lawn motor that has never been checked.

I do not know if this is even possible with an air cooled engine of that design. But problem seems to be present after temperature builds up.

Agree with other's comments -- all solutions are possible to one degree or another -- esp fuel - ethanol is crap. But if bogging under load maybe the governor is full of grass and weeds causing it to move/react slowly and not fully? Back to ethanol - it seems to damage the needle & seats causing frequent replacement. It also seems to attack certain kinds of rubber/rubber substitute. Ethanol is a political solution which means it's a compromise. The BTU content is lower and the cost is higher so naturally the govt mandates it. The Corn Lobby is pretty powerful also. Also make sure the intake filter is clean - if not getting enough air it will lose power.

Seems that after the intial run this season, the mower bogs/dies when engaging the blades, even when just started.

Looking through the service history (pretty cool that a mower came with a service history) this seems to be a fairly regularly occurring issue which has been solved with carb rebuilds. Probably should have dug through all those receipts earlier. Tomorrow is get the kit day and hopefully by midweek I will have it done.

rscurtis, thanks for identifying the pump as such, that's what I imagined, but was a little mystified by it's operation.

barry, the mower was purchased new by a small (3~5 employees) landscape company in 1983 and was their small mower. I suspect that it saw a lot of hours, but also got regular maintenance. Not all of the service records are entirely legible, but there is one which mentions engine rebuild, but the parts list is virtually illegible, so I am not entirely sure what was done. According to the date, 2007, and the PO, the machine did not see regular use after the rebuild, as they purchased a new mower out of necessity while this one was being fixed.

__________________
On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

Now that the poster has gotten somewhere hopefully. I hope this year backs off a little moisture wise as already I have to cut the lawns almost twice a week. Usually the wife cuts one lawn but is too busy recienly. It was kind of hilarious what she managed to break and her experiences that occured during her first year of doing it long ago. We should have had a sale on twisted blades alone.

To top it off both our lawn tractors are about the same age and one was a little more dicey than usual to get running this spring.

Also needs a battery and the charging circuit is too active. The rear tires are seeping air at an unaceptable rate.

On the the other one all is well except the deck and drive belts need replacement. On the first one it is probably getting close to replacement time.

One change I had to make this year was using straight 30 grade base oil. I could not buy 40 grade oil anywhere locally. They no longer stock it but I seem to have good luck with air cooled engines using 40-50 weight base oils. Both these lawn tractors are more than fifteen years old now and the lawns are hilly.

My lawn tractors engines seem to last well and I really do not know if the thicker oils are really helping but suspect so. Could as easily be my imagination though.

Still not as comforatable using 30 weight. If I source some 40 weight soon will probably change oil again. Any thoughts? Neither engine burns any more oil than when new. Both seem to still have excellent compression.

Have not priced lawn tractors reciently. They used to be substantially cheaper in the USA than Canada. About half price.

I though I saw chinese engines in one mall display of lawn tractors but not certain. Some with a briggs and stratton label maybe. Personally I would not want one but feel there may be no choice a few years down the road. Of course by then they may be good. Curently to me just an unknown.

I really am starting to be concerned by all the stuff in the marketplace that is of chinese origin. It seems to be rapidly accelerating into areas they were not particularily active in before. Last week is a good example of my concern. Everything we purchased except food and gas and a few yard sale items I got to was made in china.

This to me is a serious disaster still underway if it continues. You can no longer buy many things of an equivelant nature made in north america. There is no choice left.

As we are due for a larger canadian incoming duty excemption. We may slip south of the border and buy from an american vendor making a weekend of it at the same time.

Re-Engine your tractor/mower if you need to. It's cheaper then buying new... new ranges 600.00 on up as high as you wanna go... new engine costs 2-400 bucks.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

That could be an issue. "L" head engines of that design are NLA. Retrofitting a slant-cylinder OHV engine from any manufacturer could be an engineering nightmare. The best bet is to repair that engine. If it had enough power when new, it should have enough power when running right again. And forget the 40 and 50W oil. That engine should run fine on 10/30 synthetic oil.