Bobcat 540 no power

Help Support SkidSteer Forum:

sshev

Member
Joined
Oct 17, 2010
Messages
6
I've got a 540 Bobcat that's been re-powered with a Honda 23 hp engine. Trying to use it today, and its got zip for power. The engine runs fine with no load and it will move pretty well straight ahead or straight back, but if you try to turn or lift or tilt the bucket it really boggs down. It won't even pull itself up a minor incline without nearly killing the engine. Hydraulic fluid level is good, replaced the hydaulic filter. What are the first things I should check. Thanks in advance - Scott
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
With a Honda.... not much to check. They will burn 50% water mixed with crude oil, run with sand in the oil pan and up to four 50 cal bullet holes in the block!
Seriously, try draining the carb, look for water, or green snot if its been sitting. Does choking it seem to help or hinder the power? Muffler is not partialy plugged?
Ken
 

Dogsluvtrux

Active member
Joined
Aug 24, 2010
Messages
41
It almost sounds like you're dead-heading the hydraulic system. Does your machine have aux hydraulics? Are they stuck on? Maybe a stuck load check valve?
 

mrfixitpaul

Well-known member
Joined
Mar 28, 2009
Messages
365
It almost sounds like you're dead-heading the hydraulic system. Does your machine have aux hydraulics? Are they stuck on? Maybe a stuck load check valve?
I did one of those engine swaps and found that the honda liked much higher rpm than the original engine to provide enough power.
 
OP
OP
S

sshev

Member
Joined
Oct 17, 2010
Messages
6
I did one of those engine swaps and found that the honda liked much higher rpm than the original engine to provide enough power.
Well, tried again today...it runs great for about 5 minutes, then it starts to bog down with any load at all, smells like its running rich, and when I pull the air cleaner hose off, it looks wet and has unburned gas in the plastic air intake chamber. I pulled the carb off and made sure the needle valve wasn't hanging up, but it acts like its loading up with way to rich a mixture. There are two screws on top of the carb. that I would guess to be mixture and/or idle speed adjustments, they both have limiting tabs that keep them from turning more than about a quarter turn. The engine is a Honda GX670.
 

Jkirk3279

Member
Joined
Oct 13, 2011
Messages
5
Well, tried again today...it runs great for about 5 minutes, then it starts to bog down with any load at all, smells like its running rich, and when I pull the air cleaner hose off, it looks wet and has unburned gas in the plastic air intake chamber. I pulled the carb off and made sure the needle valve wasn't hanging up, but it acts like its loading up with way to rich a mixture. There are two screws on top of the carb. that I would guess to be mixture and/or idle speed adjustments, they both have limiting tabs that keep them from turning more than about a quarter turn. The engine is a Honda GX670.
I have this identical problem ! Did anybody find a solution? I don't have the Honda motor, though, I suspect it's the stock engine. To keep it running I have to keep the choke at least 3/4 on, but of course it's only getting 1/4 HP that way. I replaced the fuel filter, etc, and noticed that the new glass see-through filter has a large bubble of air in it. Is it necessary to bleed these filters? I know it's vital in diesels, but this is a gas engine. One theory is that the carb might be a bit gummed up. The 540 had sat for two years, and the Fuel Sender had rusted away. The guy we hired to fix it up didn't bother drying out and vacuuming the tank, he just swished some gas around and dumped it out. I must have gotten a full tablespoon of rust out by the time I was done. Clean gas, new filter, but still running poorly with the choke off.
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,829
I have this identical problem ! Did anybody find a solution? I don't have the Honda motor, though, I suspect it's the stock engine. To keep it running I have to keep the choke at least 3/4 on, but of course it's only getting 1/4 HP that way. I replaced the fuel filter, etc, and noticed that the new glass see-through filter has a large bubble of air in it. Is it necessary to bleed these filters? I know it's vital in diesels, but this is a gas engine. One theory is that the carb might be a bit gummed up. The 540 had sat for two years, and the Fuel Sender had rusted away. The guy we hired to fix it up didn't bother drying out and vacuuming the tank, he just swished some gas around and dumped it out. I must have gotten a full tablespoon of rust out by the time I was done. Clean gas, new filter, but still running poorly with the choke off.
If the choke is needed to run it, i would suspect a clogged jet in the carb. Was it ever cleaned out properly?
No matter what, you will get bubbles in the fuel filter. As the fuel warms it creates a gas/vapor bubble, it shouldn't be the cause of your poblem. In a diesel engine, as you noted, its an issue.
 

Jkirk3279

Member
Joined
Oct 13, 2011
Messages
5
If the choke is needed to run it, i would suspect a clogged jet in the carb. Was it ever cleaned out properly?
No matter what, you will get bubbles in the fuel filter. As the fuel warms it creates a gas/vapor bubble, it shouldn't be the cause of your poblem. In a diesel engine, as you noted, its an issue.
Looking for a rebuild kit. The carb # is 4847805 And the engine says Kohler.
 

Latest posts

Top