[77vintage]

Dies under Load?????

Anyone know what could make my surburban 16/6 die under a load. runs fine when driving, but dies when I run the mower. Keep in mind I have a new fuel pump on it. ????

 

[GT_80]

does the mower turn freely? Maybe something is siezed and making the motor "brake"

 

[Bill Kapaun]

A restricted fuel filter could cause that.

When under load, the engine requires more fuel. A restricted filter could allow enough fuel through when under light/no load conditions, but as the load increases, the carb bowl slowly runs out of fuel.

 

[77vintage]

There is a little trash in the filter, but I wouldnt think its a nuff to stop it up like that. I will change it tho and see if that works. cause it will sit there and run, but dies shorty after I engage the mower

 

[scipper77]

Could be a lack of compression due to worn rings, head gasket leak, or valve seating issues. If this was the case I would expect it to be hard to start due to the low compression as well.

 

[GT_80]

is the float adjusted correctly? If it doesn't flow enough fuel into the carb, it would do that too

 

[searstractorfan]

If you installed an electric pump id advise to check the float...Ive NEVER had luck with electric pumps...

 

[Dude11]

Without engaging mower--throw it to wot and watch the governor-is it working?

 

[TAHOE99]

Without engaging mower--throw it to wot and watch the governor-is it working?

That's kind of what I was thinking, is governor keeping up with load.

 

[ss12]

check the gas cap. their vented caps and if they get plugged it'll do exactly that. gas cant get out of the tank if air cant get in. you should be able to blow through the cap. with it removed lol

 

[Sears_ST]

I own a commercial lawn care business and without fail whenever our zero turn mowers or tractors start losing power it's always because the air filter needs cleaning/replacement.

Rod
Oriental, NC

 

[77vintage]

I havent watched it with the mower going, but I was messing with it one day, doing some adjustments and it would rev high and low it that tells you anything?

 

[Bill Kapaun]

There is a little trash in the filter, but I wouldnt think its a nuff to stop it up like that. I will change it tho and see if that works. cause it will sit there and run, but dies shorty after I engage the mower

Can you blow through the filter? It's the stuff you can't see that clogs filters.

You haven't said what engine or what the Sears 917.xxxxxxumber is.
That might be helpful!!

IF you ave a pulse operated fuel pump, make sure the "pulse hose" from the crankcase is in good shape with no leaks.

 

[TAHOE99]

He's got a 1977 Tecumseh OH160. Since you can rev it up OK if sounds like a fuel starvation issue. I've had cars do this under load. Revved fine but cut out when pulling or getting on it. Everytime was clogged fuel filter.

 

[Dude11]

I havent watched it with the mower going, but I was messing with it one day, doing some adjustments and it would rev high and low it that tells you anything?

Did you loosen the screw holding the gov.in adjustment?When I suggested wot & ck gov.What you do is to move the throddle cable to high and watch gov.if it lets engine scream or does it pull it down as it should?3200 to 3600 is about right for wot.There are steps to set gov.correctly,if your not sure,please ask.:trink40:

 

[scipper77]

I had a snowblower that blew a HG last year. At first it was just a little hard to start but after the leak got worse it would die under load.

When you engage the blades the motor sees a heavy load for that first moment while the stationary blades begin to move. This could very well be a compression or a fuel related problem as something can't keep up with the load. Because fuel problems can be a little harder to track down I highly recommend starting with a compression check on your motor so you can rule out head gaskets and other compression related issues (I know, a leak down test is needed to rule out valve issues). If there is a compression issue and you are trying to fix the fuel system you are in for a lot of wasted time.

I am not saying that I think the problem is with compression. There is a certain methodology to diagnosing motor problems. Motors need air, fuel, spark, timing, and compression to run. Compression and timing are the easiest to rule out if you have a compression gauge and timing light. Spark is a little complicated. Having spark and having good spark are two different things. Air fuel issues are pretty tricky to diagnose. That's why you will see that many of us back yard mechanics will just go ahead and rebuild a carb just to see if it helps.