poulan chainsaw issue

[corvairbob]

my neighbor brought me a poulan chainsaw to try and get running. it is model p4018wt and he said it ran until he put in a new primer bulb. well i clamped it in the vice and pushed the primer and i can see it put gas in the bottom part of the carb. but it will not start. so tell me i tried pulling the handle on the safety back to the holding handle as when i used to mess with them that had to be back and if your hand slipped off the grab handle and hit that it braked the chain. it has spark i put starting fluid in the spark plug hole and in both parts of the carb and i put the filter back on and spraed that just in case.
i did the same with gas and it will not start. it has compression. so before i start taking it apart i figure i will give yo guys her a shout and see if i'm doing it all wrong. i tried another spark plug. and the samething. i gapped the original plug all the way from .015 up to .050 and stil the same. plus i put one of those spark testers and i can see spark. but i still may be missing something. i did not use a lawn mower plug but a car plug as that was all i had. but for all my small engine work they always did the job for testing. tomorrow i will take my snowblower plug and try that for testing. but in the meantime maybe some can lend some troubleshooting ideas. i can see the primer doing something and it seems squirting gas and starting fluid inthe carb and plug should have given me some signs of starting.

thanks for any ideas. bp

 

[ILENGINE]

Make sure the fuel lines are installed correctly. The line with the filter should connect to the carb. Then a line goes from the carb to the short connector on the primer, and then a line from the long connector on the primer back into the tank. If those lines are reversed will pump fuel into the carb and cause flooding. Something else to check is remove the spark plug and with the piston down look through the spark plug hole and check the cylinder wall for scoring.

 

[corvairbob]

ok i will double check. it did run before he changed out the primer bulb so maybe he got them installed wrong. however it does have good compression, or at least from my past experiences with chain saws. i did put in a known good plug and still will not rum.

another thing that i do not understand is i put starter fluid and even a squirt of gas and nothing. now i have worked on enough small engines and cars to know that a squirt of gas will cause at least a sputter. but i just may be that the small chainsaws do not like it. but snow blower 2 cycle engines don't seem to mind a squirt of gas to get past the choke or even starting fluid.

but tomorrow i will check the items you talk about here to make sure they are installed correctly. now this carb is way different than i have seen before having 2 bores. one that is connected to the trigger for speed is on the top and looks to go directly into he side of the engine, the other is connected to the choke and when i prime it i do see gas squirting into that bore behind the choke butterfly.

thanks for the pointers so far when i get back to it tomorrow i will let you all know what i find then. thanks bp.

 

[ILENGINE]

another thing that i do not understand is i put starter fluid and even a squirt of gas and nothing. now i have worked on enough small engines and cars to know that a squirt of gas will cause at least a sputter. but i just may be that the small chainsaws do not like it. but snow blower 2 cycle engines don't seem to mind a squirt of gas to get past the choke or even starting fluid.

but tomorrow i will check the items you talk about here to make sure they are installed correctly. now this carb is way different than i have seen before having 2 bores. one that is connected to the trigger for speed is on the top and looks to go directly into he side of the engine, the other is connected to the choke and when i prime it i do see gas squirting into that bore behind the choke butterfly.

There should not be fuel squirting into the carb bore at all. Will happen if the primer bulb lines are not installed correctly because it pressurizes the main jet side of the carb, and pushes large amounts of fuel into the carb throat. I would say the engine is badly flooded, and the extra fuel or starting fluid can't over come the flooding. The primer doesn't inject fuel into the carb. The primer pulls the fuel into the carb by vacuum not push fuel into the carb by pressure.

That style of carb is a strata charge type system. The lower unit with the carb is the fuel inlet for the engine. the top butterfly without the carb is air only, and helps to reduce the emissions by putting a cushion of plain air in front of the incoming fuel air mix from the lower crankcase to reduce the unburnt fuel from going into the muffler.

 

[bertsmobile1]

A bit confused
1) did it fire with the carb cleaner down the plug hole ?
Remember you only need a tiny shot & you can flood it so much the plug gets wet & the spak tracks down the side of the plug.
2) is the primer on the carb or remote on the saw ?
You should see the fuel flowing back into the fuel tank
Fuel goes tank, carb then purge vale then tank .

 

[StarTech]

Have you actually checked the compression numbers? For most 2 cycles to even attempt to start they require 100 psi. And the 4018 Wild Thing usually has around 135-150 psi when in good condition.

And IL suggest it sounds like you have a primer that is connected backwards and is the pushing into the carburetor. Nearly all 2 cycle primer pull air and fuel out the carburetor and return the excess fuel back to the fuel tank. A severely flooded engine will not start. If severely flooded remove spark and cycle the engine using the pull rope at least 10x to clear the crankcase of excess fuel. Reinstall the plug and attempt to start.

Also there is a possibility that the saw has been straight gassed. A tell tale sign is a spark plug with a tip coat with aluminum. I got just in a Husqvarna 128LD that would not fire. As soon as I pull the plug to do a compression I saw the plug coated. I still did the test and it has only 95 psi compression. Pulled the muffler and sure enough the cylinder is damage. $120 repair now on a $250 brush cutter. Awaiting estimate approval.

This is only an example of proper fuel line routing but it is generally the same for the air head type carburetors too.

 

[corvairbob]

wow thanks for all this great info.
i did not test the compression but like i said the saw ran great just before he installed a new primer bulb. so today i will remove the carb and clean it and them make sure the lines are all good and then make sure they are installed to the correct ports. and yes when i push the primer it does put gas in the lower port. that is the actual carb. i found a youtube that showed taking that saw carb off cleaning it and installing it. and i will ust the above diagram to make sure the lines are correct.
A bit confused
1) did it fire with the carb cleaner down the plug hole ? no
Remember you only need a tiny shot & you can flood it so much the plug gets wet & the spak tracks down the side of the plug. i have done this lots but i may have flooded this one as you say as i did see the plug was wet. but with starting fluid i never ever flooded an engine. but this might be the first one. they are small engines
2) is the primer on the carb or remote on the saw ? remote primer
You should see the fuel flowing back into the fuel tank
Fuel goes tank, carb then purge vale then tank thanks i have the routing now another poster gave it here. i will make sure the lines are good and not cracked and that they are installed correctly and not put as much gas or fluid in it for priming. if i do manage to reflood it i will blow it out with air to dry and give it a go again.

after seeing that line routing path i'm leaning on the owner putting the lines on wrong. i have seen him do lots of mistakes on auto repairs so i will go back tot he basics and start from the beginning and follow your instructions and see how it goes. it does get good spark i see it with the spark tester. and like i said the owner said it ran good before he replaced the primer so that may be what changed. thanks bp.

i will stop back and let you know how it went.

 

[corvairbob]

ok looks like he has the line wrong. he has them from the tank lower section to the bottom part of the primer then from the top part of the primer to the top left of the carb and then from the right lower part of the carb back to the top section of the tank. see photos. also i blew out the port while cranking the engine to clear out the excess fuel. it did have a ton of fuel in the crank and that may have been flooding it as well. the cylinder is scored some so i'm going to point blank ask him if it ran before he changed the primer, he told me it did but now i wonder. i'm starting to lean on he got it from the side of the road and is now trying to get it to run after someone else tossed it. based on what i'm now seeing. but it may just be even on the side of the road a good unit that did need a bulb and he put i int wrong. anyway see the photos. i'm going to reroute them and give it another go.

 

[corvairbob]

ok rerouted the primer and now i see it pulls gas and does not flood out but i got like 2 sputters out of it and put it back together and i'm done. because i do not think he will put money into it i'm not wasting anymore time on it when it is like 100 deg out. i will take to him and if he says to put money into it i may go futher but if he says he got it off the side of the road then he can work on it as that is why it was there. thanks for all the help. i may stop back and post if he really wants to thoss good money into it. in my years of using chainsaws the poulan was thought to be a toss away item. again thanks

 

[dougand3]

I'd pull the muffler and look at piston/ring and intake cyl wall. Then pull plug and look at exh cyl wall. These strato Poulans are set REAL lean from factory and do score. The H screw may need 3-4 turns out. I won't spend $ on a piston/cyl kit for them.