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FR691V loses power after getting warmed up

#1

L

Lawnpear

Anytime i go to cut the grass it runs great for like 20 minutes then starts to act really weird. It looses power, surges, sometimes only runs with choke. This only happens when its running for awhile. Seems to be getting too hot. This has been an ongoing problem for 2 years now. I took it in last year, the shop did a full work up and ending up rebuilding the carb. Costed me $500. It did finish the season well though. I take it out this year running great 5 cuts into the year it starts doing the same thing. Instead of paying $500 again i took it into my own hands to buy the $225 carb and replace it myself. Cut the whole lawn (2 acres) but started acting up as i was driving it back to the shed. Started surging and died 3 times before getting into the shed. I fired it back up this morning and like clock work 20 mins in boom acting up and losing power. Any help would be much appreciated thanks!!!


#2

R

Rivets

Next time it starts to happen quickly open the gas cap and see if if goes away. If it does replace the cap. Alot cheaper than throwing a carb at it.


#3

L

Lawnpear

Thanks but that turned out not to be the problem. Yesterday after i fired it up again (all cooled down) to finish the rest of my grass and it started to do the same thing but it was running super rich. When i shut it off a siphon started and fuel came pouring out Of the exaust. Maybe a bad ignition on one of the cylinders?


#4

R

Rivets

I have no idea of what you mean by "a siphon started and fuel came pouring out of the gas tank".


#5

L

Lawnpear

Hear me out. So these engines work off of a pulse fuel pump. So when the engine was off fuel just started pouring out of the exaust. So there for it had to be siphoned. Theres no way fuel should be able to pour out of the exaust. I dont get it. I checked the valves and they seem fine.


#6

R

Rivets

If fuel is coming out of the exhaust, your problem is a bad float needle and seat in the carb. It is not controlling the amount of fuel in the float bowl, shutting off properly. Time to remove the carb and rebuild or replace. If you try to do this yourself, you will end up replacing, as these are not easy carbs to rebuild, even by a seasoned tech. By the way, it is not siphoning fuel from the tank, just allowing the overflow to exit the engine through the exhaust.


#7

7394

7394

The electric solenoid that shuts off the main jet in carb can be audibly tested, by listening at the carb (engine off) & turn key to on position (not start) you should hear a mechanical click, which would be the solenoid shut off in carb opening. Turn off key & should be able to hear that too in the carb.

PS: When is last time you removed engine cover to see if the fins etc are clean & free of debris ? Reason, it sounds like you are possibly overheating.


#8

B

bertsmobile1

7394 said:
The electric solenoid that shuts off the main jet in carb can be audibly tested, by listening at the carb (engine off) & turn key to on position (not start) you should hear a mechanical click, which would be the solenoid shut off in carb opening. Turn off key & should be able to hear that too in the carb.

PS: When is last time you removed engine cover to see if the fins etc are clean & free of debris ? Reason, it sounds like you are possibly overheating.
Click to expand...

The fuel solenoid shuts off the supply to the main jet.
IT does not stop the float chamber from overfilling and then leaking out of the bowl vent, into the carb throat then down into the engine which is what is happening.


#9

F

FLRon

Lawnpear said:
Anytime i go to cut the grass it runs great for like 20 minutes then starts to act really weird. It looses power, surges, sometimes only runs with choke. This only happens when its running for awhile. Seems to be getting too hot. This has been an ongoing problem for 2 years now. I took it in last year, the shop did a full work up and ending up rebuilding the carb. Costed me $500. It did finish the season well though. I take it out this year running great 5 cuts into the year it starts doing the same thing. Instead of paying $500 again i took it into my own hands to buy the $225 carb and replace it myself. Cut the whole lawn (2 acres) but started acting up as i was driving it back to the shed. Started surging and died 3 times before getting into the shed. I fired it back up this morning and like clock work 20 mins in boom acting up and losing power. Any help would be much appreciated thanks!!!
Click to expand...

I'm having the EXACT SAME SYMPTOMS. Just started today. Mower has 9 hours on it. Would like to chat with you via email or phone to try and help each other.


#10

B

bertsmobile1

FLRon said:
I'm having the EXACT SAME SYMPTOMS. Just started today. Mower has 9 hours on it. Would like to chat with you via email or phone to try and help each other.
Click to expand...

Please keep it on the forum.
That is why it is an open forum so people with the same or similar problems can read up on the fix and try it themselves.


#11

O

OldFart

HOLD THE TRAIN !!! if fuel is coming out the exhaust. you have a problem, I would Not run it till fixed, i am guessing if you check the crank case oil it would be Over full, with Gas in crankcase, fuel in oil Will ruin engine


Silly me, i need More coffee, Old post, both mowers should have engine ruined by now if the gas in oill has not been fixed at this point, hope both of you fixed it out before that happined


#12

J

Jhatfield

Having same issues anyone come up with a solution?? ?


#13

R

Rivets

Start by cleaning and rebuilding the carb, or have it done if not experienced with these carbs.


#14

D

dennisahiggins

Rivits, having same issues as other posters. Rebuilt carb, no sucess, installed 2 different new carbs and same issue. Each time i have got gas in oil and gas leaking out bottom of muffler. Changed oil and filter each time. Today with the second carb install, i caught this happening as it shut down. The engine spewed a gas oil mix back to the carburator through the vent tube shown in attached picture. Trying to prepare myself for bad news...Screenshot_20200913-212915_Google.jpg


#15

B

bertsmobile1

That is a blown head gasket over pressurizing the crankcase
Loosen the dip stick & it should not happen
Could also be a a blocked crank case vent valve


#16

D

dennisahiggins

bertsmobile1 said:
That is a blown head gasket over pressurizing the crankcase
Loosen the dip stick & it should not happen
Could also be a a blocked crank case vent valve
Click to expand...
This is where the gas/oil mixture is feeding back to the carburator. What is the fix, should I take it to a professianal?FR691v Crankcase vent.jpg


#17

B

bertsmobile1

Depends upon how deep your pockets are, how much free time you have & if you enjoy fixing things
I would start with a leak down test , see this thread to confirm a blown head gasket.
I would also dissassemble the breather valve and check it is working properly and not stuck
And i would also pull each plug, one at a time to see if there was a dead cylinder .
I like to diagnose before pulling engines apart.

I had a customes dead sure he had a blown gasket when all along he was overfilling the fuel tank and fuel was running back down the tank vent into the carb .


#18

B

Badboymagnum

FLRon said:
I'm having the EXACT SAME SYMPTOMS. Just started today. Mower has 9 hours on it. Would like to chat with you via email or phone to try and help each other.
Click to expand...
Did you ever figure out the problem? I have the same problem


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