|
|
Post by carefulrider on Mar 21, 2011 12:25:47 GMT -5
Greetings:
My 2007 Sunl Adventure LB150T-12 scooter with 12,616 kms (7,840 miles) on the odometer, starts normally when the engine is cold; but it won't start when the engine is hot, say, after I ride to the store & then want to re-start it to leave the store & so forth. Have to wait until the engine cools down before it will re-start.
Any suggestions as to a diagnosis? Thanks in advance.
|
|
|
|
Post by tortoise on Mar 21, 2011 13:33:13 GMT -5
Any suggestions as to a diagnosis? What maintenance procedures have you performed . . checked valve lash . . clean carb jets & passageways . . tested cylinder compression . . tested ignition components? |
|
|
|
Post by sprocket on Mar 21, 2011 14:47:42 GMT -5
Classic tight valves... you need to re-gap them...intake .004" and exhaust .005"
|
|
|
|
Post by carefulrider on Mar 23, 2011 9:54:55 GMT -5
Thanks for both your replies:
I began by draining a plastic pipe/tube suspended underneath the air filter box or container, of its liquid. It smelled like carburetor cleaner to me. What the heck is that stuff, & where does it come from?
Next, I verified, as best I could, visually, (is there a better method?) that all the fuel & vacuum hoses fit snugly.
I then opened the air filter housing to check the air filter. It is clean in appearance & the pink pleated paper appears to have no dirt in between the folds. I held it up to light & found no dark spots; just an even pink all around. The plastic base, upon which the filter sits had the equivalent of a teaspoon of what reminded me of an oil & gasoline mixture, from the smell of it (carburetor cleaner again?!), which I wiped off. Then replaced the filter & cover.
I then replaced the spark plug with a new Autolite 4194 plug, gapped to .032". Since the motor starts when it is cold, I presume there is no need to check for spark when the motor is at operating temperature & does not start. Is this a correct assumption?
Next I confirmed that there was air passage through the gas cap to ensure gasoline getting to the engine, without any vacuum forming in the gas tank.
For your information, when I start the scoot, I turn the throttle an estimated 1/4" & allow it to return to its natural stopped position. I then leave the throttle closed & untouched as I try to start the motor, either hot or cold. Sometimes starting procedure can be faulty.
Although we are under an on-going winter snow storm which the national weather svce states is expected to continue for the next 21 hrs, I hope I shall be able to adjust the valves tonight, working in the portable garage, in front of a kerosene heater.
Thanks for the help, until next time.
|
|
|
|
Post by carefulrider on Mar 25, 2011 7:24:44 GMT -5
I checked the valve lash last night. They are .004" & .005"
I checked the intake manifold for looseness & it is tightly located.
Should I clean out the carburetor, even though the engine starts & runs normally until I want to re-start it after it's at operating temp? Thanks in advance.
|
|
|
|
Post by sprocket on Mar 25, 2011 11:01:14 GMT -5
The other possibility is that the choke enricher is stuck in an extended position and is not retracting when the engine has been run. This would make it hard to start
|
|
|
|
Post by carefulrider on Mar 25, 2011 11:48:05 GMT -5
Thanks for the suggestion:
I shall start the cold engine & after twisting the throttle a couple of times, to ensure that the motor is running normally, with the enricher functioning, I shall listen carefully for the revs to reduce as the engine reaches idling operating temperature.
Shall report back next wk. Thanks again.
|
|
|
|
Post by carefulrider on Mar 28, 2011 7:55:36 GMT -5
I started the engine yesterday, & it idled at higher revs before slowing down to a lower steady rev, when it reached operating temp.
I repeated this procedure 4 times, ea time after the engine cooled, & it started with high revs that reduced when the engine got hot. Conclusion: enricher is working normally.
To re-cap:
Fuel & vacuum hoses fit snugly.
Air filter is clean.
New Autolite 4194 spark plug, gapped to .032".
Air passes through the gas tank cap.
Valve lash is .004" & .005".
Intake manifold is tightly located.
Motor does not start when hot.
One item of potential consequence: The original 3 yr old KOYO, YTX7A-BS, 12V6Ah battery needs to be re-charged to a "no-load" charge of 12.4 volts each day. In other words, the battery discharges overnight to a 'no-load' 12.3 volts & I charge it to 12.4 volts before starting it the 1st time ea day.
Any suggestions what I should do next? Thanks in advance.
|
|
|
|
Post by tortoise on Mar 28, 2011 9:57:51 GMT -5
after the engine cooled, & it started with high revs that reduced when the engine got hot. Conclusion: enricher is working normally. Since you know the enricher circuit is working, might try an in-place carb flush to try and clear any low-speed circuit obstructions. On a warmed-up engine remove the diaphragm-slide assembly, pinch the left side vent/overflow tube, and while wearing eye protection pulse spray carb cleaner down the main jet. The objective is to force some of the fluid through the low-speed jet, fuel passageway, and out the throttle bore port. If no change, the next step would be to remove and disassemble the carb for more thorough cleaning.  |
|
|
|
Post by ootscoot on Mar 28, 2011 10:07:44 GMT -5
check the pick -up coil. when engine is warm and won't start, check for spark, if none, suspect faulty pickup coil. - these can go out when hot. It is located on the outside of magneto at about the 11:o'clock position.
There is a thread or two somewhere here about this...
|
|
|
|
Post by tortoise on Mar 28, 2011 10:19:04 GMT -5
|
|
|
|
Post by ootscoot on Mar 28, 2011 10:24:10 GMT -5
thanks tortoise
|
|
|
|
Post by busta on Mar 28, 2011 11:14:36 GMT -5
Check for a spark after the engine gets hot and it won't start(remove the spark plug place it in the ignition coil ground it to engine to see if you have a spark).if not I would bet the stater is going bad.
|
|
|
|
Post by ootscoot on Mar 28, 2011 12:04:27 GMT -5
the pickup coil can be the problem - more likely than the stator - when the stator goes out, there is no juice except whats left in the battery...pick up coils when going out, are first affected by heat...
|
|
|
|
Post by carefulrider on Mar 29, 2011 8:06:17 GMT -5
Well, people:
I started the scoot last eve, in 30° temp; it started reliably, as it usually does. I rode it around 4 blocks & returned to my apt & turned the switch off. I waited 15 mins & attempted to start the scoot. It started promptly.
I rode it around the 4 blocks & returned to the apt. I waited 10 mins & re-started the motor. Inexplicably, it started as you might expect a normally-operating engine to do.
I rode it around the 4 blocks; returned to the apt & waited 5 mins. prior to starting the engine. It started once more!
At that point I concluded that somehow, with my tooling around, I might have touched something that has caused the motor to operate 'normally'. It might reasonably be expected that the symptom will return again any time in the future. I certainly have not ridden the scoot a greater distance than the 4 block route.
I shall take it back into the 'real world' when the temp warms up, at the same time cringing at the thought that the engine will not start when I am some miles away from the apt.
All I can tell you is, at the present, as of last eve, the motor is starting normally. I can't tell you why; but I am glad it is. Thanks folks, for your suggestions, support & encouragement. Hopefully, I shan't have to re-start this thread. Thanks again.
|
|
|
|
Post by sprocket on Mar 29, 2011 13:45:21 GMT -5
Glad to hear it.. but before the weather turns nice, check all the electrical connections for tightness.
probably just an intermittent wire...
|
|
|
|
Post by carefulrider on Apr 8, 2011 7:47:34 GMT -5
Well folks:
The hard starting began again a day later &, just as an experiment, I replaced the new Chinese-made Autolite spark plug with a new Japanese-made NGK spark plug. Presto! the scooter is running normally. I can safely recommend that Autolite spark plugs should be kept at arms length, & not be used.
These scoots are unpredictable beasties.
Thanks for your help & suggestions again.
|
|
|
|
Post by carefulrider on Apr 11, 2011 9:33:25 GMT -5
I'm afraid the same thing happened with the NGK plug, after 2 days of use... the engine wont start reliably. If I let the starter turn over 15-20 times before releasing the push start lever/button, I'll get a smell of fuel. So the carb floods in all probability.
Then I turn the throttle while engaging the starter, & sometimes the engine will start & at other times it won't.
So I'm back to the drawing board. Any suggestions?
And I take back what I said in the previous post, about the Autolite spark plug; unless there is a condition which, if it exists, can spoil a or any spark plug in 2 days of use.
I hope you folks can suggest something that I should do. Should I try using an iridium plug?
|
|
|
|
Post by sprocket on Apr 11, 2011 15:09:59 GMT -5
I think things point to the spark-plug boot or the coil hi-tension wire. You changed the plug and it ran OK.
This means you removed the boot and put it back on...It may not have been the Autolite spark plug at all but a faulty boot...
Then the NGK is doing the same thing...
Check the boot, the hi-tension spark plug lead and the coil wires...
Iridium plugs are expensive and no better in these engines... the plug is not your problem, something else is at fault...
|
|
|
|
Post by carefulrider on Apr 18, 2011 15:18:58 GMT -5
Hopefully this is the last I have to write about this subject: I put Seafoam into the tank & the unreliability/hard starting/not starting when hot condition has disappeared. May the condition rest in peace in perpetuity!
|
|
|
|
Post by carefulrider on Apr 27, 2011 10:51:42 GMT -5
Well blast & double blast!
The condition is back. So I bought a can of spray starting fluid at Advance Auto . With the engine at operating temperature & idling normally, I sprayed the starting fluid over the hard black rubber intake manifold. What should I find, but the idle speed SLOWED down. I have not read about idle reducing. So I repeated the procedure with the same results. Incredulous, I repeated the procedure a third time, with once again, the idle slowing down.
Any suggestions as to what this is indicative of?
|
|
|
|
Post by sprocket on Apr 27, 2011 11:14:48 GMT -5
Starting fluid will rot your diaphragm.. use it very sparingly if at all. Better to dribble a bit of gas into vacuum hose attached to the intake elbow...replace the vacuum hose to where it was connected.
Adjust the valves...like I said before...
|
|
|
|
Post by justbuggin on Apr 27, 2011 12:02:54 GMT -5
take a look at the intake it sounds like it might have some cracks in it the spray of starter fuild is making the feul mix richer and could cause the idle to go down for being to rich
|
|
|
|
Post by justbuggin on Apr 27, 2011 12:03:23 GMT -5
take a look at the intake it sounds like it might have some cracks in it the spray of starter fuild is making the feul mix richer and could cause the idle to go down for being to rich
|
|
|
|
Post by carefulrider on Jun 2, 2011 9:40:33 GMT -5
I decided to mail order a new intake manifold, presuming there was a crack in it that was causing the revs to reduce ea time I sprayed starting fluid over the manifold.
When the new one arrived I proceeded to remove the existing manifold only to discover that the nuts holding down the manifold in place had loosened over time. So I think that is what was causing the engine not to start when hot. Why it started when cold, I do not know.
So, for 2 days now, the motor is starting as it should, when hot. That's 1 more item to add to the list of suggestions: tighten the intake manifold nuts!
Thanks again for your help.
|
|
|
|
Post by sprocket on Jun 2, 2011 11:04:15 GMT -5
>>So I think that is what was causing the engine not to start when hot. Why it started when cold, I do not know.
Expansion and contraction?
|
|
