Poulan 3700 no rev

[Ginger15]

I have a poulan 3700 that when cold runs great but once warmed up it sounds like the ignition coil is failing. It wont take full theottle. It keeps bumping. Its not hitting rev limit because its low revs. And when you let off the gas it dies. It will run fine for 10 minutes and then start acting up. It has a clean carb, tuned, and new fuel lines. Whats the consensus here? The spark plug gap is correct, and the flywheel gap is as well. Ill try and post video later.

 

[adamrjones77]

I have a poulan 3700 that when cold runs great but once warmed up it sounds like the ignition coil is failing. It wont take full theottle. It keeps bumping. Its not hitting rev limit because its low revs. And when you let off the gas it dies. It will run fine for 10 minutes and then start acting up. It has a clean carb, tuned, and new fuel lines. Whats the consensus here? The spark plug gap is correct, and the flywheel gap is as well. Ill try and post video later.

How old is the plug? I've seen a bad plug give symptoms of a bad coil. Most especially when warm. Plus, it's the cheapest fix.


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[hotshot]

Install an in-line spark tester & go cut wood. If the spark dies off in the indicator window when the saw won't rev, you need a new coil.

Those saws never used a limited coil.

 

[Ginger15]

Interesting. It acts like its hitting a limiter and bumps when you WOT with no load. Ill try a new plug and if that doesnt help i try the in line tester if i can find one. Where would i get it? Auto parts store?

 

[adamrjones77]

Interesting. It acts like its hitting a limiter and bumps when you WOT with no load. Ill try a new plug and if that doesnt help i try the in line tester if i can find one. Where would i get it? Auto parts store?

Harbor Freight or any auto parts store will have and in line tester


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[Ozhoo]

I'd be raising her skirt and taking a peak at that piston.

 

[Ginger15]

I'd be raising her skirt and taking a peak at that piston.

I had the muffler off when replacing the fuel line to check for any damage. It's pristine. No scoring, nothing. No lean marks, no sign of an air leak either. Loved the way you phrased that message though.

Harbor Freight or any auto parts store will have and in line tester


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Thank you, I'll place an order, looks like a handy tool to have on hand.

 

[Ginger15]

So I pulled the plug, its a BPM7A(cross to champ 858), looks like the manual calls for a BPM4A(champ 848). Is the wrong plug causing this issue?

 

[adamrjones77]

So I pulled the plug, its a BPM7A(cross to champ 858), looks like the manual calls for a BPM4A(champ 848). Is the wrong plug causing this issue?

I'd certainly replace with the correct plug. Rules out the plug issue all together.


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[Ozhoo]

When you did the fuel lines, did you do the vent line? Have you tested the vent?

 

[Ginger15]

When you did the fuel lines, did you do the vent line? Have you tested the vent?

Yes, i did the vent line and it works.

 

[Ginger15]

Well its not the plug or the kill switch. Now the saw wont run at all. Inspected the coil and it looks fine. But I don't have a spark tester yet.

 

[Acornhill]

You flooded it

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[Ginger15]

It was hardly running even when I had it running. It popped first pull, started up, would only sputter, let go of the throttle and it dies. Its gotten progressively worse over time. The carb screws have not changed.

 

[adamrjones77]

After all that,did you pull the plug and see if it's wet? Did you replace pump and metering diaphragms when cleaning the carb? Sounds like a fuel issue now. Also, didn't happen to use high pressure air to clean the carb, did you?


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[Ginger15]

After all that,did you pull the plug and see if it's wet? Did you replace pump and metering diaphragms when cleaning the carb? Sounds like a fuel issue now. Also, didn't happen to use high pressure air to clean the carb, did you?


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No high pressure. Just carb cleaner. I put it all back together and it fired up today, it screamed. Then died. It stopped getting spark. Took it apart again, cleaned everything again, and now its screaming. So in a sense it was flooding due to no spark. It will hiccup at start up for a moment now, and then start screaming. Before it acted like there was a rev limiter and the revs would bump, go up and then down.

 

[Acornhill]

Air leak or still carburetor issues

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[Acornhill]

Switch carburetor if you have another

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