Pum coil issues

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Daniel's Racing

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Apr 14, 2008
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1,394
I'll label my trouble shooting
1. Rebuilt both 1048 and 257 carbs with all new internals and pop pressure checked.
2. Changed coils.
3. Went in both directions with needles.
4.re sealed the entire engine.
5. Using a known good plastic isolator.
6.new piston ring and checked scoring. Engine has only 2 hours on it but it's a 2nd hand engine
7.good clean fuel
8. Boat has a water pump and I just rebuilt the pump with a new walbro rebuild kit.

So my latest observation is when I run the engine for a few minutes I pull the plug and its soaked...I was told try one heat range hotter maybe it will help

I wonder if it was an air leak I would need more fuel to get the engine to behave better but it's acting like it wants more air
You got carb issues is my guess.

Are you sure carbs are back together correctly ? Double check them. Wet plug is a skewed carb. What were they opening at ? Did you adjust pop off on them from stock ?

The one screw fuel pump section the thin diaphragm and flapper section go on the body first then the gasket then the cover.

Not all the gaskets and diaphragms are always apples to apples in some rebuild kit. Some kits require two pieces to replace what was one originally.

On the four screw side the gasket goes on the body first then the then diaphragm on top then the cover. Opposite the way on the other side..
 

Wasted wages

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Jan 2, 2006
Messages
1,146
can someone please explain pop pressure and how you check it on a carb ?

I've only ever referred to it with fuel injection systems...

We may be taking about something with a little bit different terminology...
 

Ryan paluski

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Aug 30, 2021
Messages
82
So it's a wet test and you would use a pressure/vacuum hand pump. So you fill the line with gas that is connected to the pump then put it on the fuel inlet barb on the carb. You need to remove the diaphragm cover and diaphragm itself for this test. Then you pump the pressure till the needle lifts off the seat and pay attention to the gauge to see when it pops off. From my experience I've had 6 carbs from walbro that popped off at above 27psi and one went to 32psi before it popped off. I was told 19-22 psi is where you want to be at and the needle allows fuel to come into the carb So if it's hard to lift the needle then carb issues arise
 

Ryan paluski

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Aug 30, 2021
Messages
82
Getting the spring kit walbro sells or clipping coils on the springs and testing the pop till its where you want it to be. If the pop is too high the carb will cause lean conditions and be difficult to tune
 

Wasted wages

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Jan 2, 2006
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1,146
Good to know,,, I've never really had any major issues with these little gas engine carbs... I have a spare one new in the package from CC racing when Carlos was selling motors.. never had the need to use it.

Keep the fuel clean and motor flushed out,,, go thru it once a year throw in a new ring and gaskets, seals, bearings.... rebuild the carb...
good to go!!
 

Ryan paluski

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Aug 30, 2021
Messages
82
I've noticed lately it's been luck of the draw with carbs... since last year I've probably had 10 carbs for my land rigs and boats. Some where good right out of the box to absolute disasters
 

Wasted wages

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Jan 2, 2006
Messages
1,146
I've had pretty good luck with them lately...even when my pressure washer and generator had gotten all clogged up with hard crap from ethanol gas.

I looked on line and amazon had them so cheap it wasn't worth even trying to rebuild them. Bolted on a new one and with two pulls,, running like new again.

Even my 660 Yamaha grizzly was cutting out going uphill, so I reluctantly tried one from Amazon and it fired up and runs perfect. My original idea was to just use the new one long enough to get a Yamaha rebuild kit and jets,,, but it runs so good, I'm like "why bother" ??

And heck, 257 carbs are like 9-16 bucks online..
Why anyone would pay 49.99 for a "racing carb" online is beyond me. open up the throat on a lathe a little,, blueprint the carb.... done!!
 

Ryan paluski

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Joined
Aug 30, 2021
Messages
82
I hear you 100% but I have an extremely hard time believing anyone selling a walbro carb at low prices is legit. I just try to eliminate any variables for when something does act up I won't immediately condemn something because I have a suspension its fake.
 
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