Pum coil issues

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Ryan paluski

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Aug 30, 2021
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Hey guys so as you know I'm fairly new to the boating thing but my background is mechanics cars,trucks, machines but diesel is my job.

Can someone just give me an idea of what usually goes south with source and ignition coils for pump? My issue is weak spark on an engine I recently acquired and I changed the ignition coil and still very weak. The engine runs fine up high in the rpm but is very hard to hold an idle over a minute. I triple checked source coil air gap with a feeler gauge and checked all connections and plug gap...

In a nut shell I checked pop pressures on 2 carbs im using 1 is a wt 257 and the other is a wt 1048 and the issue is following the engine and not the carbs. My idle screws are wound all the way in and it only holds an idle for a minute or so and dies out.
 
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Rod Fonda

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Apr 30, 2021
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Hi Ryan ,I'm assuming the idle screw is fuel metering,rather than an air bleed screw,so if its screwed all the way in,,there's too much fuel getting in,,does it seem rich and smokey when it's dying ?,,based on my experience with brushcutters and walbros lol,maybe it's a diaphram/needle problem or isn't closing between pulses or a pressure buildup in the system,but I could be wrong,,a bad coil or ignition would probably not rev out or maybe not even start
 

Ryan paluski

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I guess to me it's an idle screw but it's just the screw on the side that keeps the butterfly from closing all the way off throttle. I spoke with a member earlier and we are both leaning towards an air leak now as I've trouble shot every external source for the issue
 

Rod Fonda

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Ahh,,ok,,so you have to keep the butterly open more to keep it running,,needing more air to burn the fuel,,have you set the idle mixture screw?maybe rich,,another thing to check is crankcase seals/compression in the engine if you can"t find the problem
 

Rod Fonda

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Another thing you can do before taking engine apart is to take the carby and spark plug out,,cover the intake hole with your hand,while slowly pulling on the starter cord,,you should feel some vacuum pulse,or maybe hear a vacuum leak and no vac pulse,just to get an idea and a feel,,,If it was a diesel,,I'd guess it's injector pump seals lol,,good luck,,let us know how you go,,cheers
 

Ryan paluski

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Thanks for that and not a bad idea. I was told to spray the case with wd-40 while its running to see if it loads up but for my sanity and a piece of mind I want to re seal the engine since I got this 2nd hand its making my question seals and gaskets
 

Daniel's Racing

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Cap off the intake and exhaust and introduce low pressure to the sparkplug hole and dunk it. No mistaking if and where the leak exists. You can pressurize and use soap/water to test instead of full dunk.

I seriously have done this and it and it is simple and will find your leak in a hurry.. I use my flow meter pump and have bolt on caps for intake and exhaust. Fast and easy. Even test the seal behind the flywheel without taking it off. Blow it off and spray down with Corrosion X and go to work fixing it.

The positive pressure doesn't allow any water in the engine just air escaping out any leaks unless maybe a four bearing engine or a inline spit out entire bearing or seal behind flywheel but you will know that leak as soon as you hook up flow meter. If leak is massive don't even bother testing it. Tear it down. Finds those hidden cylinder base cracks nicely.
 

Ron Olson

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Take the plug gap down to .016"-.018" which should give you more spark.
Carb setting on both which are actually the same one as the 1048 is a Zenoah part number for the Walbro 257, 2 turns out on the low and 1 turn out on the high-speed needle.
 

Daniel's Racing

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Take the plug gap down to .016"-.018" which should give you more spark.
Carb setting on both which are actually the same one as the 1048 is a Zenoah part number for the Walbro 257, 2 turns out on the low and 1 turn out on the high-speed needle.

A Zenoah 1048 is a entirely different carb that a 257 is and uses completely different settings.

A 1048 uses 1 3/8-1 5/8 LOW and 1 1/8-1 3/8 HIGH

The Zenoah 1027 is similar. to a 257 but not a 1048 though.

You want spark ? I have Super Coils in STOCK
 

rhomodel

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Jul 15, 2003
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I think issue with your engine is not the coils, but the mixture setting. If it runs FT then there is nothing wrong with them.. What engine do you have and what do you mean with turning the idle screw completely in?
 

rhomodel

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that screw you should remove, otherwise you can not stop the engine and it will continue running (also moving, unless you have a clutch). You need to adjust the idle with your radio... in such way that you can kill the engine in an emergency or on demand.
 

Ryan paluski

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Aug 30, 2021
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Also someone pointed out to me since I didn't get to go put the boat in the water since, that I may be cooling the engine too much with it on the garden hose. I have a valve adapter to go down to the cooling hose. I also was told to try 1 step hotter plug so a cmr6h plug and does anyone have any experience with it in a boat?
 

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