Poulan P4018 (no idle)

[Okie]

Received a donor Poulan P4018 due to No idle. 40CC, 18 inch bar.
Has a Zama W26B 63A carb.
Saw looks like not very many hours of use, chain and bar good, air filter still very clean.

I seen the primer lines and fuel line was hard and could tell that someone had been flogging the carb jets and they had removed a piece of plastic from the top cover for direct jet ADJUST access with the splined carb wrench. I ordered a $18 tuneup kit consisting of carb, fuel and primer lines, fuel filter, air filter, spark plug, primer bulb.

Installed all, added FRESH 50:1 NON corn gas, no start, would just flood. Discovered someone had connected the old fuel and primer line wrong. They had been connected wrong for long time because the lines were hardened in place. (indicating that the saw had been stored for long time after the lines were connected wrong)

Connected fuel and prime line per the Poulan Zama diagram, got a start and run. Runs good a High RPMS and will idle for awhile and just all at once die. Sometimes will idle for 15 to 20 secs then just die. Piss revs good, no bogging, L jet adjusts but saw will just all at once die at idle, Will re-start at fast idle on 1st or second pull if throttle is placed on fast idle with no choke and immediately accelerates good. Low speed jet very critical to get a idle and set a 1 turn out and same with the H jet. If H jet is turned out to 2 turns saw won't start. Old carb acts same as the new carb. Compression checks at 120, piston and cylinder looks ok. The carb manifold throttle boot fits snug and has a new carb base gasket of correct type. Muffler not clogged.

The main fuel line to the carb with the fuel filter is the smaller tygon line. (I mention this because I seen some members recommend using the larger tygon hose as the fuel delivery line to the carb) I do not have any replacement tygon lines of correct size in stock now to change the lines, but doubt that using larger delivery line would cure a idle issue on a Zama Poulan????

Can anyone tell me how to Vac/pressure test the crankcase on this 4018 Poulan. (like what is required to seal off the carb intake holes???) Do I need to remove the complete intake manifold to seal this area? Appears the seal is made into the crankshaft bearings)

Anyone have idle issue tips with these disposable type Poulans? (it's not heavy enough to use as a boat anchor, Yet)

 

[s sidewall]

Piece of rubber like a bicycle inner tube or something similar, put that between carb and boot, cut two small holes for carb screws. Cranks seals part of bearings.

Steve

 

[s sidewall]

Is it 4 stroking at wot? Also, it this a strato charged model or regular, strato will have an upper and lower carb air inlet?

Steve

 

[redunshee]

Is it 4 stroking at wot? Also, it this a strato charged model or regular, strato will have an upper and lower carb air inlet?

Steve

If recollection is correct, believe its a strato saw.

 

[dougand3]

These can leak between clamshell and jug. Make sure 4 cyl bolts are tight. They are long bolts: Bolt head - plastic chassis - clamshell pan - cylinder.

 

[scottr]

If recollection is correct, believe its a strato saw.

Bob , you are correct .

 

[Okie]

It's a strato type, Zama W26B carb. Yes it will 4 stroke. I checked the 4 clamshell bolts and they a very tight and did not move any tighter.

The saw started easily cold this morning (28 F) and idled good for about first 30 seconds of engine warming up then the idle started going slightly up and down and warmer the saw got the more erratic the idle. Piss rev was good and seemed that engine was little slow coming off high rpms to slower rpms. Not fast drop in rpms from high to low after the engine got warm as compared to the cold response.

It will 4 stroke. Sounds like lots of power at mid to high rpm,s. I've tried adjusting the jets out further enriching on both carbs but it gets worse and leaning in any further makes the saw smother and die. Have to start the saw when it's warmed up at fast idle position. (with the throttle setting on the fast idle position of the choke lever but choke off)

Both carbs have same erratic idle symptoms.

To me it has symptoms of slight air/vac leak. I've never been into or around this type strato Poulan.

I'll make a full gasket maybe today for behind the carb and muffler and do a pressure test.
Two different small engine compression gauges indicate 120 compression.

Here is the ebay Poulan tune up kit I installed. If the link don't work use the 2828 number in the ebay search bar,

https://www.ebay.com/itm/Carburetor...01-PP4018-PP4218-P3314-PP3516-ZAMA-W-26C-Carb/282818497289?hash=item41d94bcb09:g:NDwAAOSwxOFaZZvV

Anyone seen problem area of crankcase leaks on these type strato clamshell Poulans/Crapsman saws?

 

[dougand3]

I've noticed the crank seals don't go bad on strato Polulans - other crap fails long before that. IIRC, there is only gasket goo between cyl base and clamshell. I think a formed rubber gasket is only in Husky clamshells. I'd just pull engine and re-goo the junction with Motoseal or similar and see what happens.

 

[s sidewall]

Have you tried 1 1/2 turns on low mix needle? These saws adjust a little different than a non-strato engine.

Steve

 

[Okie]

I lost the little darling. DNR Do Not Resuscitate

I was really surprise when the pressure/Vac test did not indicate any sign of a leak even while rotating the engine and the blocking off the strato carb intake area was easier that I has presumed.

I decided to do a hot engine compression test.(was little concerned when I seen the cold engine compression at 120 area after several cranks. (seen where others normally test at 150-165 area)
I re-installed all and cranked up the engine and kept it running for quite awhile by operating the throttle at mid to high rpms and warmed up the engine then killed engine and immediately hooked up the compression gauge while engine was hot. Compression was really low like 40-50 lbs and squirting little bit of ATF fluid in the spark plug hole did not increase the compression very little. Ring is not stuck. Cannot see any major scoring when looking into the muffler port or the spark plug hole but something is causing very low compression when the engine gets hot or warmed. Could not believe compression went so low????
Do not know history of the saw, Bubba may have already been inside doing piston cylinder swapping.

Another Poulan in the spare parts bin.

 

[s sidewall]

Sounds like weak ring.

Steve

 

[Okie]

Sounds like weak ring.

Steve

Never thought of that one but the ATF oil not raising the compression would also indicate weak ring. Just one ring on the piston on this one and I checked thru the exhaust port that the ring not stuck.
I might open up the clamshell sometime just too see. It's already in the Poulan/Crapsman spare parts salvage now.
I'm curious as to why the compression dropped so much when the engine warmed.

Noticed that the clamshell engine is a easy take down for inspection.

Also noticed this helpful info when I was looking for a primer bulb fuel line diagram for this strato Zama and determined that Bubba had the carb fuel lines connected bassackards.


How to determine proper fuel line routing on a primer bulb carb system.

https://www.youtube.com/watch?v=uCC1qO75zDk

 

[s sidewall]

Those saws are easy to work on. As the engine gets hot, a weak ring has lost tension, I've seen that on auto engines, have so so compression cold and lower as it gets hot. Rings for those saws are cheap, even a piston kit is cheap.

Steve

 

[s sidewall]

Primer lines are easy to remember how to run, fuel tank to carb, carb to primer, primer to tank. If primer is hard to push, lines on carb swapped or on primer.

Steve

 

[s sidewall]

Fuel won't flow but one way on a carb if carb is in good shape, needle prevents from flowing in wrong direction.

Steve

 

[Okie]

Those saws are easy to work on. As the engine gets hot, a weak ring has lost tension, I've seen that on auto engines, have so so compression cold and lower as it gets hot. Rings for those saws are cheap, even a piston kit is cheap.

Steve

Compression was close to 100 this morning cold with little bit of oil still in the cylinder after several cranks.

 

[s sidewall]

Don't see how it ran.

Steve

 

[scottr]

Don't see how it ran.

Steve

Sounds like the compression was just enough to run that last time. I've seen a B&S mower do the same thing .

 

[s sidewall]

Those thangs can run blowing black smoke all day. We've got an old one I pulled off the log splitter made in the late 70's to early 80's, had to pure trans fluid in carb to try and get compression up to start it. Once she starts she'll run, just low on power. Splitter is running a Honda now.

Steve

 

[Okie]

Don't see how it ran.

Steve

Compression must have been right at the failure point of even running, but it sounded strong as it was warming up. I did not even attempt a re-start this morning with the compression at close to 100 and oil in the cylinder from yesterday, knowing it was a lost cause. I just checked the compression to see if how much it would indicate when cold vs warm engine. (40 -50 difference)

Has good 18 inch bar and chain/sprocket which I can use.

More Poulan/Crapsman experience's.