Author Topic: Poulan 2550--what's wrong with this dang thing?? (Read 5304 times)

piedmont · « **on:** January 26, 2008, 06:43:09 pm »

Hi y'all,
My dad recently gave me a chainsaw that's been sitting in his barn for a couple of years. It wouldn't prime, and he had got it to start using starting fluid and it would run great for a couple of seconds until the fluid was gone. So we figured it probably had bad fuel lines.
Sure enough, when I took off the carb I could see the lines were hardened and cracked, including the one going to the fuel filter in the tank. I replaced all of them, and it primes perfectly, only now it won't crank, even with starting fluid. The spark plug is reasonably clean and makes a great spark, so that's not it. The muffler's also clean, and not obstructing air flow. When I had the carb off I also (unnecessarily) took out the four bolts on the bottom of the saw and took the cylinder/head section loose from the crankshaft/piston section. The piston and ring looked ok.
So why the heck am I not getting an explosion in the combustion chamber at all? Is it possible I messed something up when I took the engine apart?

peter nap · « **Reply #1 on:** January 26, 2008, 06:53:25 pm »

My first guess is that it was left with gas in it.

Carb clean or more likely, rebuild time. Get out the Varsol!

Nate Surveyor · « **Reply #2 on:** January 26, 2008, 06:55:01 pm »

Have you tried cussing?

Or Poulling on it?

Another trick is to place it under a cardboard box, in your street, and blame somebody else.

This is the best I can to to help.

Or place a cherry bomb under it, and go fishing!

N

piedmont · « **Reply #3 on:** January 26, 2008, 07:01:54 pm »

Quote from: peter nap on January 26, 2008, 06:53:25 pm

My first guess is that it was left with gas in it.

Carb clean or more likely, rebuild time. Get out the Varsol!

peter nap,
It was left with gas in it, but I replaced the gas even before replacing the fuel lines. The carb appears clean, and even if it weren't clean it shouldn't affect starting with starting fluid. And it did crank that way, before I started working on it.

Nate Surveyor, I'll keep those in mind as my last options. Thanks for the "help."

peter nap · « **Reply #4 on:** January 26, 2008, 07:32:42 pm »

Replacing gas doesn't help if it's really clogged. It gets in the circuits.

There isn't much left except valves and I doubt that's the problem unless it's spitting gas back out.

I also wouldn't use starting fluid anymore. It van ruin a salvageable saw. See if you can find a rebuild kit.

Nate Surveyor · « **Reply #5 on:** January 26, 2008, 08:30:40 pm »

OK, I'll try to help.

DON'T use starting fluid in it! That stuff is BAD for 2 strokes. I'd Use WD-40, or Silicone spray. I have used that stuff successfully in situations like this.

2 strokes like a little lubrication on the cylinder. So, I'd try the lubricating spray.

That will probably lead to getting it going.

Sorry about the earlier "help". It was the best I could find at the moment!

N

piedmont · « **Reply #6 on:** January 26, 2008, 08:49:44 pm »

Thanks guys. The only reason I was using starting fluid was to try to duplicate my dad's results, and determine if the saw is salvageable. What's frustrating is that it won't come anywhere close to cranking. No combustion at all. I'll try WD-40. I just can't understand why bad fuel clogging up in the carb would have anything to do not starting on ether (or WD-40). The airway is fine.

p.s.: Nate, I think I'm fixin' to use your cussin' at it suggestion!

beenthere · « **Reply #7 on:** January 26, 2008, 10:39:44 pm »

piedmont
When you say it won't come close to "cranking", that to me means it will not turn over when you pull the starter cord.

Or do you mean it won't come close to "firing" or "turning over under it's own power" ??

Old cars and tractors that had a crank, one could crank all day and not get the engine to fire and run.

Is the engine siezed tight, so it won't crank?

piedmont · « **Reply #8 on:** January 26, 2008, 10:48:29 pm »

Quote from: beenthere on January 26, 2008, 10:39:44 pm

piedmont
When you say it won't come close to "cranking", that to me means it will not turn over when you pull the starter cord.

Or do you mean it won't come close to "firing" or "turning over under it's own power" ??

Old cars and tractors that had a crank, one could crank all day and not get the engine to fire and run.

Is the engine siezed tight, so it won't crank?

Hey beenthere,
Yes, "firing" is the word I was looking for.

"Making the explosion that makes the piston go down" was as close as I got, but that sounded stupid so I used "crank" or "start." It turns free, isn't siezed, makes a great spark, and won't fire at all, even though it did fire and run (using starting fluid) even with basically no fuel lines, before I got a hold of it.

Cut4fun · « **Reply #9 on:** January 26, 2008, 11:03:14 pm »

Dont laugh, but is the saw ON/OFF switch in the ON position. Been there done that.

Is it a Walbro or the Zama carb? I have a extra good working order Zama laying around, I replaced it with a before epa Walbro and sold the saw.

Carb rebuilds take about 30mins to a hour to due, carb kits are $3 Dia kit -$10 complete kit for the carbs for that saw.

piedmont · « **Reply #10 on:** January 26, 2008, 11:19:20 pm »

Quote from: Cut4fun on January 26, 2008, 11:03:14 pm

Dont laugh, but is the saw ON/OFF switch in the ON position. Been there done that.

Is it a Walbro or the Zama carb? I have a extra good working order Zama laying around, I replaced it with a before epa Walbro and sold the saw.

Carb rebuilds take about 30mins to a hour to due, carb kits are $3 Dia kit -$10 complete kit for the carbs for that saw.

Haha! No, it's in the "on" position!

That was one reason I took the spark plug out and gave a pull on the cord (with the plug still attached to the wire)-- to make sure I was getting a spark and didn't have a bad on/off switch.

It's a Walbro carb. I may rebuild it but I just don't know if the problem is in the carb. I'm wondering if the problem is compression. Maybe I messed up the ring?

Cut4fun · « **Reply #11 on:** January 26, 2008, 11:31:10 pm »

Compression tester can be had for $20. Pull till the psi reading stops.

Piston shows no signs of scoring? How about a stuck ring in the groove?

Coil come loose? Check with index card between contacts and tighten down or a business card or a piece of paper folded to make 3 layers. Place between contacts, Loosen coil, index card etc between contacts, then tighten back for correct gap. Check for spark. Spark testers I use cost $3, go to plug and then to wire with a little light inside, pull over and can see light flickering.

piedmont · « **Reply #12 on:** January 27, 2008, 12:31:04 am »

Quote from: Cut4fun on January 26, 2008, 11:31:10 pm

Compression tester can be had for $20. Pull till the psi reading stops.

Piston shows no signs of scoring? How about a stuck ring in the groove?

Coil come loose? Check with index card between contacts and tighten down or a business card or a piece of paper folded to make 3 layers. Place between contacts, Loosen coil, index card etc between contacts, then tighten back for correct gap. Check for spark. Spark testers I use cost $3, go to plug and then to wire with a little light inside, pull over and can see light flickering.

Piston looked ok from what I remember-- I'll check the compression and if that's it I'll take it apart again. Spark is definitely not the problem. It sparks great. Just no "boom."

scottr · « **Reply #13 on:** January 27, 2008, 10:57:41 am »

When you took the piston out of the cylinder did the ring expand or was it stuck in the piston groove? Did you have to compress the ring to reinstall the piston in the cylinder?

Nate Surveyor · « **Reply #14 on:** January 27, 2008, 01:14:31 pm »

A friend has a worn out Ford Diesel. You have to coast start it. Because compression is so bad. Now I know that a diesel is a compression engine. But, a DRY 2 stroke will do something similar. I did some study on BEST oil/fuel ratios. Turns out that something like 22:1 works best, but fouls the plug bad. So, 32:1 allows the plug to work better. This is an OLD study, made during the air cooled motorcycle era. (1978 RM 80, & RM 125).

So, if this were my engine, I'd add some oil to the cylinder, and circulate the oil well, and prime it with fresh gas, with a NEW spark plug, and see what happens.

Just giving ideas.

Nate

piedmont · « **Reply #15 on:** January 27, 2008, 02:55:13 pm »

Quote from: scottr on January 27, 2008, 10:57:41 am

When you took the piston out of the cylinder did the ring expand or was it stuck in the piston groove? Did you have to compress the ring to reinstall the piston in the cylinder?

I don't think it expanded, because I definitely didn't have any trouble getting the piston back in the cylinder. I even said to myself "huh, that was easy."

Nate, it looked pretty oiled up, but I'll add a little more (through the spark plug hole, perhaps?) and see what happens.

logwalker · « **Reply #16 on:** January 27, 2008, 03:11:05 pm »

Sounds to me like the ring is stuck. Whenever the piston is out I remove the ring and clean the groove carefully. Also start with a new plug. You should feel a strong compression in the pull starter. Pull it slowly and see if it holds compression for a few seconds. I think it is the plug. Even though it sparks out of the head it won't necessarily do it under compression. Joe

Al_Smith · « **Reply #17 on:** January 27, 2008, 03:20:01 pm »

Whoe ,you guys are making this way too complicated .If the little saw has spark the only thing left is fuel delivery .

If the fuel lines are ok the only thing left is a funky carb.90 percent of the time just a clean up of the stale gas gets em going.Although it could stand perhaps a carb rebuild which is relatively easy to do. All the carb makers have tutorials on their respective web sites.

stonebroke · « **Reply #18 on:** January 27, 2008, 03:37:43 pm »

In a internal combustion engine you need fuel, spark and compression. If you do not have one nothing will happen. You need the proper fuel air mixture in the cyliinder. (He should have had that with ether, but I would use a squirt bottle on gas mix). You may have a strong spark but it has to occur at the proper time, It might have gotten mistimed when you took it apart. Compression has to be high enough to turn the engine over. I have seen worn out diesels that would only start on ether but than would run. If the compression were very marginal than messing with the piston and ring might have put it below what even ether would start. Just my thoughts on the subject.

Stonebroke

piedmont · « **Reply #19 on:** January 27, 2008, 05:00:10 pm »

I haven't had a chance to work with it today, but I'm thinking the ring may be the issue. I don't think it could possibly be a timing problem on a 2-stroke, since there aren't any valves and the timing of the spark comes from when the magnet on the flywheel moves past the coil. I'll take it apart in the next couple of days and see. I don't have a compression tester, so I may go but one if they're not too pricey.
Thanks, y'all! This has been super helpful!

stonebroke · « **Reply #20 on:** January 27, 2008, 05:31:44 pm »

Sometimes on small engines the key that locates the flywheel to the crankshaft sometimes shears and that affects the timing.

Stonebroke

Nate Surveyor · « **Reply #21 on:** January 27, 2008, 06:34:20 pm »

IF the flywheel nut is loose, just a bit, and by spraying starter fluid, you get a backfire, you can shear the flywheel key, and mess up the timing of the spark. You may be able to remove the flywheel nut, and SEE if it is sheared, But, sometimes it can be partially sheared, and NOT easlily detected, without REMOVING the flywheel.

And, a puller is recommended to pull it.

Anyway, I think starting fluid is bad medicine for most motors.

Use as WEAK of a fluid as gets the job done. I personally am a fan of silicone spray. Plenty of umph, and a little lube.

Nate

logwalker · « **Reply #22 on:** January 28, 2008, 02:32:39 am »

What is complicated about swapping a plug? The plug can spark outside the cylinder and not under compression. I have seen it many times. Besides he gave you a strong clue when he said it quit firing on the ether. It was firing before he tore it down and replaced the fuel lines. The plug is cheap and easy to change. This is a process of elimination. I am still betting on stuck ring. Could put a couple tablespoons of rust reaper in the top end and let her set. Might loosen the ring.

sawguy21 · « **Reply #23 on:** January 28, 2008, 10:35:35 am »

Did you properly re seal the crankcase when you re assembled the motor? There is no gasket and you could have a serious air leak. How quickly does the saw drop when you suspend it from the starter handle? If it falls like a stone, compression is weak.

piedmont · « **Reply #24 on:** January 28, 2008, 02:51:30 pm »

Update:
I replaced the plug and although that didn't fix the problem, at least I have a new plug.

I then took the motor apart again. The ring has some very shallow grooves worn into it, not deeper than the width of a human hair, I'd say. There are matching grooves worn into the cylinder.

There was also a silicone gasket (the kind you make yourself with the squeeze tube) that I didn't notice before where the two parts of the motor come together.

I plan to clean all the parts really well with WD-40, make a new gasket, and put it back together again. Should I worry about the grooves? Should I try to make sure they line back up again so they don't carve more grooves, or perhaps sand or file them down on the ring?

Cut4fun · « **Reply #25 on:** January 28, 2008, 03:36:40 pm »

Grooves sounds like light scoring to me, jmo though. I would clean up Cly with fine Emery cloth like doing a hand hone to clean up and knock off glaze and put a new ring in it.

Silicon on a set up like the clamshell design. I have never used anything for that (just tighten the 4 bolts to the Cly and tighten around the crank rubber seals real good., silicon sealant could be adding to your problem. Good luck.

piedmont · « **Reply #26 on:** January 28, 2008, 03:53:32 pm »

Cut4fun,
The saw has "rebuilt" where the serial # should be, so I'm guessing the rebuilder may have added the silicone. Since it was coming off in little pieces, I think you may be right about it adding to the problem.
I'll try honing the cylinder, and the ring may be salvageable with the same treatment. The scoring is really shallow.

olyman · « **Reply #27 on:** January 28, 2008, 06:22:59 pm »

when he pulled the barrel--end of crankcase seal--no compression--cause no fuel pull--------------------if you pull the jug again--go to dealer to get a new jug gasket---dont use silicone--none of it tolerates gas---------------------------itll get in places you dont want it to---

Nate Surveyor · « **Reply #28 on:** January 28, 2008, 06:55:50 pm »

Olyman is corrrect. Silicone will dissolve in gas.

ONLY use it where there is no gas.

Gotta have a better gasket.

While you are at it, are the REED valves stuck?

They are metal things that allow air to ENTER the crankcase, but NOT go backwards. One way check valves.

N

piedmont · « **Reply #29 on:** January 28, 2008, 09:32:19 pm »

I don't think there are reed valves on this engine, but I'm not sure I would recognize them.
In other news, I polished the ring and cylinder with 2000 grit sandpaper, then broke the ring while fooling around with it.

So I'll get a new one from the small engine shop and be more careful with it. On the plus side, by the time I get it fixed, I'll know this saw like the back of my hand.

sawguy21 · « **Reply #30 on:** January 28, 2008, 11:13:37 pm »

That is a piston port engine, no reeds.

logwalker · « **Reply #31 on:** January 29, 2008, 02:20:18 am »

And it will be running like new.

ladylake · « **Reply #32 on:** January 29, 2008, 06:04:09 am »

Put a new plug in first, then go over the carb again. Is the plug soaking wet or dry after trying to start it? Steve

scottr · « **Reply #33 on:** January 29, 2008, 12:57:36 pm »

Piedmont, there is a locating pin in the groove of the piston that is used to keep the ring from rotating and breaking. Were the light scratches on the intake side or the exhaust side?

piedmont · « **Reply #34 on:** January 29, 2008, 08:01:35 pm »

Quote from: scottr on January 29, 2008, 12:57:36 pm

Piedmont, there is a locating pin in the groove of the piston that is used to keep the ring from rotating and breaking. Were the light scratches on the intake side or the exhaust side?

The ring broke 'cause I was squeezing on it-- didn't have it on the piston at all. Kinda dumb, I know.

The scratches were mainly on the exhaust side. There was one light one on the intake side.

ladylake, I tried a new plug before disassembling the motor again. Good spark, as before, and fuel was getting to it, as before, but no firing. Plug was wet with fuel.

Cut4fun · « **Reply #35 on:** February 01, 2008, 01:16:48 pm »

IPL for your saw http://www.odref.com/poulan/pdf/poulan/gas-saws/2550-TYPE1.PDF

Also dont forget to line ring ends up right on the piston with the pin in the ring groove to keep the ring in place.

logwalker · « **Reply #36 on:** February 06, 2008, 12:54:12 pm »

What is the update on the saw?

clousert · « **Reply #37 on:** February 10, 2008, 02:32:03 pm »

Wow - is a Poulan worth all of this effort?

Cut4fun · « **Reply #38 on:** February 10, 2008, 06:44:23 pm »

Quote from: clousert on February 10, 2008, 02:32:03 pm

Wow - is a Poulan worth all of this effort?

IMO, YES!
That Poulan is built just like the Stihl 290,250,310, etc. and the Husky 455 etc that have the Plastic crank cases with the clam shell design. Just the Poulans cost 1/3 less.
Todays poulans are crappola (yes I agree), but they were pretty good saws at one time IMO. Plus the cost less to buy back then and cost A LOT less to repair. I cut my teeth on the magnesium cased Poulans and I loved them. I bought one plastic cased poulan to just find out how they were and it passed the test with flying colors for a homeowner saw too or to cut firewood. Now a pro logger is a whole different story.
I owned Poulans 3750, 330, 3300, 305, 2000, 1800, XX, plastic cased 220, 2250 (built from 2 basket cased).

A few that was in a group pic once.

XJ99 · « **Reply #39 on:** January 22, 2010, 06:15:57 pm »

Quote from: Cut4fun on January 28, 2008, 03:36:40 pm

Silicon on a set up like the clamshell design. I have never used anything for that (just tighten the 4 bolts to the Cly and tighten around the crank rubber seals real good., silicon sealant could be adding to your problem. Good luck.

I'm working on the same saw, and found
this thread. So from what I've read, do not
use any RTV when I assemble the jug, and
make sure to keep the ring lined up with the
groove. I also found some silicone on my saw,
and it was bought new in 2000. (was not rebuilt)
I still need to order ther ring, so it'll be a few days
before I finish working on the 2550.

BTW, the reason why I'm rebuilding it is because
it was ran with out oil in the gas. I used the same
gas can, and have it marked "mixed" but I think my
wife filled it up with regular gas for the lawn mower.

Anyway, it ran great for about 20 minutes, then the
idle started to pick up really high, and it started to bog
down. It still had 1/2 tank of gas, and that's when I
check the gas in the can and found out it wasn't mixed.

Thanks for any tips on this rebuild..

boobap · « **Reply #40 on:** January 23, 2010, 04:03:10 pm »

yikes...sounds like that was a "hot seize"...not good. if it is all torn down check everything to include main seals/bearings. look for any "transfer" of metal between the piston and sleeve. you may even notice some pitting on the piston. in a hot seize, the piston expands more then the cylinder will allow, which is why it seems to run "ok" and then bog down. this is where you get the transfer normaly, because there is no lube. this happened to me once also. i was cutting a buddy's lawn (with his equipment) and come to find out that he used motor oil and not 2-stroke oil in his poulan weed whacker!!! it sucked because he was gonna give me that whacker when he moved out of town. now it is living in a dump.

John Woodworth · « **Reply #41 on:** January 25, 2010, 12:00:50 am »

Have you checked the pulse hose and pump diaphram?

XJ99 · « **Reply #42 on:** January 25, 2010, 07:07:11 pm »

Thanks for the replies..

I have not check the diaphram,
I assume it's in the carb.

Also, I'll post up some pictures of
the jug, but it doesn't look like there
was any transfer of metal.. Once it
started acting up, I shut it down pretty
quick to avoid too much damage.

XJ99 · « **Reply #43 on:** February 13, 2010, 11:59:54 am »

Well, I got the new ring in about a week ago,
and got it back together. I installed a new plug,
some fresh gas, and it runs like new! I did what the
previous guy said, and didn't add any silicone to the
jug when I was bolting it back up.

News:

Author Topic: Poulan 2550--what's wrong with this dang thing?? (Read 5304 times)