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Engine/carb help requested

AGreyMan

AGreyMan

I'm gravely disappointed.
Brass Subscriber
#1
#1
Vehicle/engine: 2001 Yamaha Big Bear 400 4 wheeler.

Problem: Dies/backfires when throttle is added. Starts and idles great. Can increase RPM with choke, though it will stutter some. Before carb replacement, sometimes worked normally.

Background: Has been leaking fuel from carb for a year, I knew I needed to put a kit in it/clean it. Just shut fuel petcock off when finished using. Did have an in-line fuel filter which is/was not clogged. Bought a replacement carb from Amazon, threw it in today. If anything, symptoms are worse. Absolutely will die with more than the tiniest added throttle. With the tiniest added throttle, backfires frequently. Airbox/filter cleaned.

Any help/insight would be appreciated. Thanks.
 
HandLoad

HandLoad

Twinkle Me, LORD
Brass Subscriber
#3
#3
hmmm - Sounds like it is going lean. Checked all Vacuum Lines? New Carb would say not a Clogged Run Jet, where I would have gone if no new carb. Idles OK = Good enough Mixture at Idle. Open throttle, fusses = Going Lean...maybe Fuel Pump is Weak?

If electric Fuel Pump, Disconnect Fuel Line at carb, point in safe direction and Crank - Dribbles = bad, Shoots a stream = OK.

That's all I got from Here...
 
GOBLIN X

GOBLIN X

PUKUTSI
Brass Subscriber
#8
#8
do you have one of those piece of shit vacume petcocks coming off the tank? did you check the screen in the fuel tank? and it sounds like you main fuel jet is still clogged maybe in the passage OR your float needle is not set/operating correctly (not filling bowl)
 
240Geezer

240Geezer

Old dude with a ‘tude
Gold Subscriber
#9
#9
This is the virtual version of Saturday afternoons at any normal American's house.
Buncha guys all standing around "encouraging" a friend with their small engine wisdom.
(I'll assume we all have an appropriate libation in hand)
🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
 
AGreyMan

AGreyMan

I'm gravely disappointed.
Brass Subscriber
#11
#11
Thanks for the advice, guys. As I said, I replaced the entire carb, so I guess it's possible that the new main jet is clogged, I was pretty careful, with new fuel line and fuel filter. No electric fuel pump.

Vacuum leak is a possibility, as the hoses weren't in perfect shape.

I will check plug and wires. I am certain they are original...I know I haven't changed them in the 16 years I have owned it.
 
AGreyMan

AGreyMan

I'm gravely disappointed.
Brass Subscriber
#13
#13
Thanks for asking!

It always started and ran, just quit running well when cold. I have not spent much time on it as it’s been cold outside. Last few times I used it to pull the trailer from the woodpile to the house, I started it up (once at -10F) and let it idle and warm up for 10-15 minutes, and it ran fine.

The problem is always when it’s cold. When I can work on it without too much discomfort, I’ll get back at it.
 
Bud

Bud

New, and yet, old
Brass Subscriber
#14
#14
Problem #2 2014 Polaris Ranger 800 FI
Used it about a month ago, ran fine. Added fuel just before quitting from a new to me NATO fuel can. No ethanol gas and Stabil added when fueled.

Will fire immediately when cranked the first time and immediately stop. Won't fire after that. No inline fuel filter except one attached to fuel. Ordered new pump, got it changed out with no problem (thank you once again YouTube) and same thing. Can I blow air through the fuel line to blow the injectors clean? Or am I chasing the wrong solution?
 
GOBLIN X

GOBLIN X

PUKUTSI
Brass Subscriber
#16
#16
AGreyMan said:
Thanks for asking!

It always started and ran, just quit running well when cold. I have not spent much time on it as it’s been cold outside. Last few times I used it to pull the trailer from the woodpile to the house, I started it up (once at -10F) and let it idle and warm up for 10-15 minutes, and it ran fine.

The problem is always when it’s cold. When I can work on it without too much discomfort, I’ll get back at it.
Click to expand...
Let me know brother. piece of cake
 
AGreyMan

AGreyMan

I'm gravely disappointed.
Brass Subscriber
#17
#17
GOBLIN X said:
Let me know brother. piece of cake
Click to expand...
@GOBLIN X

Well, a year after I posted this, I have resolution.

I about pulled my hair out thinking about what could be wrong. It continued to do well after it warmed up, so I put it on the back burner. A month ago, it made a change and would ONLY idle. I needed it to do some wood hauling, so I decided to bite the bullet and take it to the dealer.

I took it to the dealer, who essentially said “2001? LOL! We don’t work on anything that old! Try the independent repair shop! Get that dinosaur out of here!”

The independent repair shop said “Sure, we can look at it. First appointment is November 13th.”

Trouble was, I really needed that thing to efficiently do some pre-winter chores around here, like hauling wood to the wood pile, pulling brush, etc. I just couldn’t escape the feeling that it was a fuel issue, so I bought ANOTHER replacement carburetor from Amazon.

I slapped the new carb it today, and it works great! I am so happy to have my workhorse back!

Thanks for the offers of help and ideas from everyone who contributed.
 
240Geezer

240Geezer

Old dude with a ‘tude
Gold Subscriber
#18
#18
So frustrating. We got a "free" golf cart at work from another group. It ran but not well. Been sitting for a long time.
Drained the gas and put new in.
Ok it runs.
A week later not so much.
No time to mess with it so off to the shop it goes for a tune up.
Get it back.
Same issue.
Duck around with it some.
No time to mess with it so off to the shop it goes.
They diagnose fuel pump.
It comes back runs ok then not so much.
Call the shop. We'll send out a tech.
Tech comes out. It's the spark plug says he and proceeds to pull out this groady piece of crap.
Changes it for a nice shiny new one. Fires right up now.
Shop bill was north of $500
 
GOBLIN X

GOBLIN X

PUKUTSI
Brass Subscriber
#19
#19
AGreyMan said:
@GOBLIN X

Well, a year after I posted this, I have resolution.

I about pulled my hair out thinking about what could be wrong. It continued to do well after it warmed up, so I put it on the back burner. A month ago, it made a change and would ONLY idle. I needed it to do some wood hauling, so I decided to bite the bullet and take it to the dealer.

I took it to the dealer, who essentially said “2001? LOL! We don’t work on anything that old! Try the independent repair shop! Get that dinosaur out of here!”

The independent repair shop said “Sure, we can look at it. First appointment is November 13th.”

Trouble was, I really needed that thing to efficiently do some pre-winter chores around here, like hauling wood to the wood pile, pulling brush, etc. I just couldn’t escape the feeling that it was a fuel issue, so I bought ANOTHER replacement carburetor from Amazon.

I slapped the new carb it today, and it works great! I am so happy to have my workhorse back!

Thanks for the offers of help and ideas from everyone who contributed.
Click to expand...
if you want send me the old one. I will clean it out and kit it and you got a spare.........
 
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