Service & Maintenance Question
I have a 235 that will not start. It has spark, compression,...
Service & Maintenance Question posted April 8, 2015 by Gary Holmes
5881 Views, 15 Comments
Question:
I have a 235 that will not start. It has spark, compression, and new Husqvarna premixed fuel in the tank. A local, reputable small engine shop could not get it started either. He thinks it is an electrical issue. The saw has less than 15 hours of use on it. What do you suggest I do next?
Answer
Most good small two cycle shop should be at least find what is causing the problem but it takes someone experience in 2 cycle to do so.
When you say you have compression what is it in PSI. Most 2 cycles need at least 100 psi to start.
Have you checked the spark arrestor in the muffler?
Have you tried starting with 2 cycle place in the cylinder via the spark hole?
Have check the flywheel to ignition coil timing?
Be the first to rate this
|
Gary,
As Eugene stated it could be a number of things, I always use the following acroynm, "FACTS"
Fuel, Air, Compression, Timing, Spark - You need to work on each one of those items and try to eliminate each possibility during the troubleshooting process, and Not necessarily in any specific order, like making sure you are truly getting fuel into the engine, any of the "FACTS" will stop an engine from starting. An often missed problem is an engine air leak, If you have bad engine seals, or cylinder gasket/ sealant leak, or carburetor mounting leak, or de-compression valve leak. This is an often missed problem, and will even stump the pro's. The engine has to be completely air tight with good compression when you have that condition, the engine will pull air thru the carburetors venturi, pick up the fuel on its way thru, and then the proper air and fuel will result in combustion of the fuel when the spark fires. Without the correct amount of air, you may either get very little fuel into the engine, and it won't start, or too much fuel into the engine, and the engine will flood, and it won't start. All of those symptoms will almost certainly seem like you don't have enough ignition, and that it must be an electrical problem but that is not the case.
Please list, what you have tried, and also try the suggestions of Eugenes', and then re-post your findings. There are several of us on this site, who have done complete engine rebuilds, so I know we can help.
Don't give up, It definitely can be fixed, I have Not had an engine yet that could not be fixed but you must check all the "FACTS". I will also be glad to try and help you fix the problem too.
I hope this helps,
Karla
PS. I am Not a Husqvarna Representative or Repair Service, just an experimental chainsaw person.
Be the first to rate this
|
Gary,
Also its surprizing the engine shop could not diagnose, and find your problem. I would probably suggest going to a second engine shop, only to get a second opinion sometimes easy stuff is often missed, and its like going to a Doctor. Sometimes its good to get a second opinion! But, If you stick it out here, I will be glad to write some suggestions based on what you have already tried.
If we could post/ write faster back and forth, then I could probably tell you what is wrong in about 5-10 minutes, really ! I am not bragging but I really can solve problems, and diagnose fairly quickly, So just let me know when you get a chance what you have tried, and I will put together a list of questions based on your answers.
Karla
Be the first to rate this
|
Thanks for the replays. Shop told me compression tested at 60psi, and he thought that was enough to at least attempt to turnover. How do you remove the muffler and what exactly am I lookin for?
Be the first to rate this
|
Even if it was a 4 cycle 60 psi is on the low side but for a 2 cycle that is too low to even hit once.
To answer your question on the muffler removal that depends if you have a 235 Chainsaw or 235 R Brushcutter, I am assuming chainsaw so the following is based on that.
You would remove the nut and the spark arrestor cover first. Then using a Trox (Star) wrench remove the two muffler retaining screws that are deep inside two holes as picture below.
What you would looking after the spark arrestor is for either a struck ring or piston and cylinder damage. The piston and cylinder should be smooth. If it is piston or cylinder damage the replacement cylinder kit 545-050418 is about 60.00 usd plus shipping. You will also need 2 ea 530-056363 main bearings with seals which would be about another 20.00 usd.
Be the first to rate this
|
Gary,
Yikes - 60 Psi compression ? The engine will never start with only 60 PSI compression, of course I'm not exactly sure how they are doing their compression test, but typically a new engine will have a compression of 140-150 PSI, and that is with 5-6 pulls turning the engine over with WOT (Wide Open Throttle). I just finished testing a 17 year old engine that had 130 psi, and rebuilt an engine with new cylinder, new piston and rings, and new seals, and it has a compression of 145 PSI.
Anyhow, It sounds like your headed down the right road, and remove the muffler, and check the piston and rings for vertical scratches or scoring, its helpful if you manually turn the engine over while looking into the exhaust port. If you have scoring then you will need to dissassemble the engine for further Inspection, and most likely replace the cylinder, piston, piston rings, and seals, and then re-build the engine. I think we already said that you don't have a de-compression valve, otherwise that could be leaking.
Please keep posting what you discover
Karla
Be the first to rate this
|
Well, I got the saw back, but I am still not sure compression was done correctly. Let's assume that I do in fact have compression. Reason I say that is I checked piston and ring and both look fine. No scratches, no carbon build up, nothing. It looks like you would expect from a saw that only has 10 hours use. So to start over, I have compression, spark, and new fuel. Pouring fuel or adding starter fluid to the carb did nothing so I doubt this is a fuel issue even though that is what the local shop thinks. He says get a new saw but I know this can be fixed for a lot less. Any thoughts on where to go from here?
Be the first to rate this
|
Gary,
Its un-usual that you don't even get a burp or hickup when put fuel directly into the engine. So lets backup a little, I know you said you have spark, so I am assuming you either have an in-line spark tester or you removed the spark plug, and plugged it into the HV boot and grounded the plug to see the spark. If you would do one more spark test, just to double/ triple check, but follow this method:
1. leave the original plug in the engine, next get a spare plug, and Un- plug the HV lead from the engine, and connect it to the spare plug (If you have an in-line plug tester you can add that as well to the spare Plug.
2. Next make sure you have a good ground, some times I use about a 1 ft piece of bare copper wire like 16 gauge, wrap it a few times around the threads of the plug and twist it tight, Then ground the other end of the wire to the engine cylinder or grounding wire at the ignition/ kill switch.
3. Now, find a dark corner of your shop or garage with no lights on, and give it a few good pulls, you should see either the test light or the arc from the spark plug. The reason for the second plug is you want to maintain compression on the engine, which slows down how easily you can pull over the engine so it will be pulling over at a normal starting RPM's supplied by the starter. If you had removed the plug for the initial testing, and with No compression the engine will turn over many times faster that normal.
If you have already tried this second spark plug method and you get a good strong spark, then lets try testing the engine for air leaks, If you have an engine air leak the fuel will not get pulled thru the venturi of the carburetor, since the air leak will provide the path of least resistance, Also, I know it doesn't exactly explain why if you put fuel directly into the spark plug hole that the engine didn't fire (burp and hiccup), but remember its not just fuel needed its atomized fuel and air which makes the engine fire, Too much fuel and not enough air will give you the same symptom as a flooded engine, which is no ignition.
Please try the spark test again to re-verify. Air leaks can also be found as fuel leaks, so have you turned the saw on its side, and then up on end. I like to put a piece of newspaper down on the ground or If you have a work table, and then turn the saw around, both sides , and up on end and look for any staining of the newspaper that looks like gasoline, If you have access to a very low pressure pump, one that pumps only about 5 PSIG, no more with an attached gauge, we can also try an air test. (Note: they do make a special tool called a Mighty-Vac, which is both a pressure/ vaccum gauge, But definitely Not worth buying for a one time air test). Just let me know, and I will describe the air test procedure.
Do You have access to an air compressor,( NOT FOR THE AiR TEST, DO NOT PRESSURIZE YOUR ENGINE WITH AN AIR COMPRESSOR) , But If you have an air compressor, we can try a couple other tests. Again, let me know and I will describe the procedure.
Oh, One more easy test, Not sure If you have tried this but sometimes this will work on flooded engines. Put the engine in its normal configuration for starting but do Not choke the chainsaw, just put it in its normal "Run" position. Now hold the trigger completely down, a zip tye , or some tape or a second set of helpful hands to hold the trigger wide open or "Wide Open Throttle". Now holding the saw down, give the saw 4-5 good consecutive strong pulls. Just be prepared if the saw does start it will Rev to high speed, and you will need to shut it off. Reason, for a second set of helpful hands to release the trigger, and rather difficult to hold the saw down, pull on the trigger and hold it down, and pull on the starter vigorously. It does work on occassion!
I hope the following suggestions help, and please let me know what you discover.
Karla
Be the first to rate this
|
Let me ask a question here if you don't mind. When you checkrd the piston and cylinder did you dis-assemlbe the engine or was just looking through the exhaust port?
I beginning to think you may have a broken ring, It would explain the low compression and the inability for it to try to start. Just a thought.
Be the first to rate this
|
Karla, I did the spark test as you recommended and I get spark. Yes, I have an air compressor. I also turned saw on it's side, back, etc. and no fuel leak. What next?
Eugene, I took the muffler off and checked cylinder that way. Looked very clean and smooth, and the ring was slightly potruding. I have watched a number of engine rebuilds on you-tube and the cylinder, and ring looked similar to those after a rebuild.
Be the first to rate this
|
Gary,
Remove the spark plug, and remove the air filter, Next using your air compressor blow some air thru the carburetor, and then down thru the spark plug hole, "Do Not try to seal the air compressor to the engine", just use the air hose, as if you were cleaning, also make sure the area around the carburetor and spark plug hole is thoroughly clean so you don't blow any dirt into the engine. If you have an excess of fuel in the crankcase this should atomize it a little, you may see some fuel come out thru your exhaust muffler. Also pull on the starter to just rotate the position of the piston when blowing air down thru the spark plug hole so the piston moves down into the bottom of the crankcase,
Next, re-install the spark plug and air filter, and put the engine in its normal cold start position, and try starting the chainsaw. Did you get a burp or hiccup, did you hear it fire ? If it fired, move the control to the run position, and try starting it again, If the engine runs, then nost likely you had a flooded engine, and by atomizing the air and blowing the excess fuel out cleared the problem.
I forgot to ask earlier but do you have a primer bulb on your chainsaw, and If so when you push the primer, Is the primer bulb staying full of fuel ? If you have a primer, and it only holds fuel when you pump it, and it then drains out, you have a bad primer bulb, which has a tiny check valve inside of it which has failed.
Ok, Next a fuel system test, remove the fuel filter and get a barbed fuel In line connector ( available at most automotive stores for a few cents, same size as the barb on the fuel filter), you will also Need a bicycle pump with a gauge, (Do Not use your air compressor for this Test). Connect the in-line connector to the fuel hose using the barbed connector and the other end of a piece of hose to your bicycle pump. Pump the line up to 10 Psig, First make sure the pressure holds for a while (20-30 seconds) now give your starter a pull and observe the air pressure gauge, it should drop each time you pull on the starter. This is actually testing a lot of different things, so its really a good test. If the gage does not hold pressure, and your sure the hose fittings are tight, then you have a leaking needle valve or metering diaphram problem inside the carburetor. If the pressure does not drop, when you pull on the starter then you may have a bad inpulse hose to the fuel pump of the carburetor, or a bad needle valve inside the carburetor, or a bad fuel pump diaphram. If you have a leaky impulse hose from the engine, then the engine will not fire, it is possible that it fell off from not being installed properly, its usually a little bit of a challenge to get the impulse hose connected again, but not impossible.
Ok - Let, Me know what you discover, there are still additional tests which can be performed. Just let me know the results. I am eliminating the engine air test for now, since it will take a little bit more prep to test the engine air seals which also may stop an engine from firing if its leaking air.
Karla
Ps. Just let me know the results!
Be the first to rate this
|
Karla, Here are the results. After using compressed air in carb and plug I did not get any results. No hiccup, burp, etc. Primer bulb stays full of fuel. I did the test with the pump and it held pressure a 10 psi. There was no pressure drop at all when pulling on the starter. Should I check impulse hose? Do you have a diagram, or any tips? Thanks
Be the first to rate this
|
Gary,
I am not sure of your particular year for your Model 235, but here is a link to a similar diagram:
/images/ddoc/HUSI/HUSI2010_AAaa/HUSI2010_AAaa_29_.pdf
From the diagram, it appears that the impulse from the engine goes thru the carburetor mounting block, and there is no separate impulse line. So you would have to remove several parts, including the carburetor to get to this block. There is also an induction manifold seal which connects the air from the cylinder to the carburetor, these seals can be a problem but typically on older chainsaws.
From your description of pressurizing the fuel system, it tells you that the carburetor is not working, however If you have no Impulse coming from the engine that could still be due to an engine air leak, which would disrupt the air flow thru the carburetor, and the engine won't run. So in my opinion we are back to an engine air leak and doing an engine air leak test by both pressurizing and pulling a vacuum on the engine.
The engine air leak test is very simple but will need some items to do the test. You need to be able to remove the muffler and then block off the exhaust port, I use a piece of rubber inner tube material cut a little bigger than the exhaust port, then reinstall the muffler and bolts to clamp and hold the rubber in place blocking the exhaust. You will have to do the same thing to the carb intake, a piece of rubber between the carb and carb mounting block sealing the holes between the carb and mounting block. Finally, remove the spark plug, and If your spark plug is 14 mm, then you will need a 14 mm adapter that will threat into the spark plug hole, Not sure If you will find this fitting at an Auto store or possible a small engine repair shop, I purchased mine on-line.
Now using the same low pressure pump you used to do the fuel test apply about 7 psig to the cylinder also using the pull starter gradually move the piston to the bottom of its travel, and watch the gauge for 20-30 seconds, If the cylinder gasket is good, and the crankshaft seals are good on both sides of the engine, you should have no leaks. If you do get a leak, double check all of your connections, and where the rubber is sealing the muffler, and carburetor first, before assuming an engine seal leak. If you have a cylinder gasket leak or crankshaft seal leaks, then you will need to completely disassemble the engine to replace the gasket and crank seals. If you have No engine leaks and it passes the air test you should theoretically due a vacuum test the same way but only pull about 3-4 psi of vaccum.
I am still concerned with the compression test, and that your rings are good, I had an engine one time where the rings were stuck in the groove, and they looked good when peering thru the exhaust port but they were not moving outward from the piston, and the engine would not fire. Unfortunately the only way I could fix the engine was to disasssemble it, and replace the rings.
Ok, Let me know if your able to do the engine leak test, there still may be some other checks we can perform.
Karla
Be the first to rate this
|
Gary,
Another quick thought, and also an easy test. Remove the spark plug, and purchase a spray can of "LMT" (Lawn Mower Tune-up) spray, available at most lawnmower stores and big box stores for aprox. $3 - $5.00. Follow the directions on the can but don't use as much as you would for a Lawnmower, maybe about a good 2 second squirt. The stuff contains oil, starting fluid, and a product that helps with carbon and loosening piston rings, after putting it into the cylinder, give the starter just a half a pull, but Not to start it, just to move the piston and rings, then let it sit over night. Next day, try starting it, If it does try to start, and fires but won't run you may have located the problem.
I have had this work for me on a couple of occassions.
Please let me know what you discover,
Karla
Be the first to rate this
|
Success. With a friends help he stripped it down. Emptied all fluids, cleaned and refilled. Started up on about the 3 or 4th pull. Strong smoke at first but quickly started running as before. Apparently it was badly flooded. Thanks for the help and hopefully someone got something out of this thread.
Be the first to rate this
|