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Plagued with Engine Starting and Tuning Issues (Seems never ending)
- Thread starter pfrederi
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as doug said mate the killswitch cannot foul a plug,,
and also as doug said, fit an 1107 and go from there
,
also as doug said, never run without a kill switch, my disconnect and check for spark was meant as a temporary fault finding solution, not a permanent run it round a field unprotected solution,
you keep saying you have a killer bee installed, can we please get it right as to what kill switch or switches you have fitted ?
killer bee is the older now obsolete and was replaced some time ago by the super bee switch,
if you are running a super bee and are using a nimh battery , have you altered the dip switches ?
if you have the dip switch set to 6volt cut off for a 7.4volt lipo then a 6 volt nimh will continually cut out all the time ,
gonna try and post a link to the FAQ section on killer rc site, it will either be direct into the dip switch settings or you may need to scroll down and find the dip settings, read that bit and double check your switch or switches,
also if you are running the super bee, please make sure you have the ferrite clip on interference reducer on the grey killswitch cable,
https://www.killerrc.com/a/faq#super-bee-dip-switch-settings
and also as doug said, fit an 1107 and go from there
,also as doug said, never run without a kill switch, my disconnect and check for spark was meant as a temporary fault finding solution, not a permanent run it round a field unprotected solution
,you keep saying you have a killer bee installed, can we please get it right as to what kill switch or switches you have fitted ?
killer bee is the older now obsolete and was replaced some time ago by the super bee switch,
if you are running a super bee and are using a nimh battery , have you altered the dip switches ?
if you have the dip switch set to 6volt cut off for a 7.4volt lipo then a 6 volt nimh will continually cut out all the time ,
gonna try and post a link to the FAQ section on killer rc site, it will either be direct into the dip switch settings or you may need to scroll down and find the dip settings, read that bit and double check your switch or switches
,also if you are running the super bee, please make sure you have the ferrite clip on interference reducer on the grey killswitch cable,
https://www.killerrc.com/a/faq#super-bee-dip-switch-settings
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Your intermittent issues are quite puzzling. You shouldn't be fouling a plug out as quick as you are. Post up some pictures of the electrode so we can get an idea of what going on. Won't be anything amazing ad a plug chop, or plug magnifier is needed to truly see tune, but we'll get an overall view of how things are running. I'll third or fourth, binning the 990 in favor of an 1107. But one issue at a time. You need it to run to tune it. If you can get it to run, spray around the engine with carb cleaner and see if the idle changes. Report back what area of it does. Also have you checked to make sure all your gaskets are good on the carb? All your fuel lines and filter in good shape? If you have a set of quick disconnect bin them as they are another area for a possible air leak.
- Thread starter
- #64
** UPDATE **
So I was writing an update last week when a new issue came up but no biggie. These things are temperamental. Anyways I changed out the carburetor on the FG and replaced it with a knockoff 990 carb i bought off ebay and had laying around. At first it was bad. the carb was doing crazy stuff, Idling wildly and when i did get it running it would bog down and cutout and this is with the correct carb settings. So i felt defeated again but i stuck with it. Next day I took it out to run again (same settings) and the thing ran like a champ!!! Matter of fact i cant remember it ever running that great!! I doubt carbs have a breakin period but thats what it seemed like happened like it needed a lil breakin because it ran like a bat outta hell after that. Im at a lost Im not quite sure what happened. i dnt know man these things i cant figure. But it does appear rhat the main issue i was having might have been the carb although i was still experiencing issues when i installed the new one. Its running great now for about a few days. yesterday though it wouldnt start. Changed out spark plug and it started. put that same plug i took out back in today and ran great. Dnt ask me to explain this crap. Im just happy ive got BOTH my FG and my Rampahge running for the most part. I cant expalin the occasional bipolar symptoms i get but im just rolling with it for now. Ive worked all my life troubleshooting and fixing electronic, electromechanical equipment and computers for the most part so I know a lil bit about troubleshooting and using the known to find out what you dnt know and might be the problem might be the most liukely culprit but these 5th scale gas just do not give a constant baseline to start and work with in my experience.
So all the questions above I appreciate
I have SuperBee Kill switch and it does not appear that was the issue. And yes I have 2 ferrite magnets installed on it now. Im using a LiPo Battery BTW.
"Your intermittent issues are quite puzzling." Yeah tell me about it, better yet don't LOL. I know man its puzzling to me to. yes all gaskets are good and filters etc. I did spray around the carb and there was no change signifying a leak. I torque t down with that in mind as i know these engines act as a pump and there should b no leaks or will mess with the fuel air mixture.
So I was writing an update last week when a new issue came up but no biggie. These things are temperamental. Anyways I changed out the carburetor on the FG and replaced it with a knockoff 990 carb i bought off ebay and had laying around. At first it was bad. the carb was doing crazy stuff, Idling wildly and when i did get it running it would bog down and cutout and this is with the correct carb settings. So i felt defeated again but i stuck with it. Next day I took it out to run again (same settings) and the thing ran like a champ!!! Matter of fact i cant remember it ever running that great!! I doubt carbs have a breakin period but thats what it seemed like happened like it needed a lil breakin because it ran like a bat outta hell after that. Im at a lost Im not quite sure what happened. i dnt know man these things i cant figure. But it does appear rhat the main issue i was having might have been the carb although i was still experiencing issues when i installed the new one. Its running great now for about a few days. yesterday though it wouldnt start. Changed out spark plug and it started. put that same plug i took out back in today and ran great. Dnt ask me to explain this crap. Im just happy ive got BOTH my FG and my Rampahge running for the most part. I cant expalin the occasional bipolar symptoms i get but im just rolling with it for now. Ive worked all my life troubleshooting and fixing electronic, electromechanical equipment and computers for the most part so I know a lil bit about troubleshooting and using the known to find out what you dnt know and might be the problem might be the most liukely culprit but these 5th scale gas just do not give a constant baseline to start and work with in my experience.
So all the questions above I appreciate
I have SuperBee Kill switch and it does not appear that was the issue. And yes I have 2 ferrite magnets installed on it now. Im using a LiPo Battery BTW.
"Your intermittent issues are quite puzzling." Yeah tell me about it, better yet don't LOL. I know man its puzzling to me to. yes all gaskets are good and filters etc. I did spray around the carb and there was no change signifying a leak. I torque t down with that in mind as i know these engines act as a pump and there should b no leaks or will mess with the fuel air mixture.
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Until you buy legit parts instead of clone stuff this will always be an issue for you
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+1 . Clone carbs are terrible
- Thread starter
- #67
This is the first CLONE carb ive ever had or bought and i bnought it by mistake thinking it was a genuine walbro. So all the carbs ive ever ran are ALL walbro so this is the first knoickoff one i have ran and it running great so far exacept for the initial hiccup. All the issues ive been having previously are all with a genuine Walbro carb installed.
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Simmer down there killer. Your first problem is your inconsistant approach to diagnostics, and having multiple erratic symptoms from 3 different cars. The point being your are the issue with your rigs. This thread had been a long story of a one man circle jerk. You've listed every major component as an issue, haven't tested jack shite properly, or in any order that makes sense. I don't give a rats hairy arse what parts you use, clone, genuine or what ever else. Learn how to run through an engine. This should be cake for someone that knows electronics in depth. There's all of 5 moving parts in these engines, the carbs are so basic it sucks, and the coils are tech from 40 years ago. Stop making excuses and learn to do it right, with the right tools in the right order. Makes your life easier and giving advise easier.
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Appreciate ur input. So what do you suggest by doing it right??
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ok you replaced the carb with a clone and it works, great, proof of concept for cheap. Now that you see its the carb, (at least that seems to be what you are saying), get a real carb, it will be more reliable and consistent. Chances are your clone carb was the reason it bogged one day and ran "like a chap" the next (inconsistency).
How do you manage to accidently buy a clone
The walbro carb with the issues was probable because it was sitting collecting
on the inside. Also, (i haven't been following this tread super closely, so correct me if wrong) the walbro carb was considerably old. Ethanol plays a damaging role in carbs over time, especially when sitting for extended periods of time.
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Even to cover the basics in any detail would take more time then I have atm. Basically you need to take a systematic approach to the failure.
No spark.
remove high tension lead, install in line spark tester, attempt to start. If spark jumps across contacts the coil and wiring is good replace plug.
No or weak spark, remove kill wiring from coil and retest.
If spark, issue is in kill wire harness/kill switch. Both of which easy enough to isolate and test.
No spark, break out your multi meter and ohm out coil, and high tension lead. Not looking up the specs. Easy enough to find in the manual. Checking the flywheel gap is a waste imo, if it ran before the gap didn't magically change, unless something broke. At any rate you need to pull the coil to test it, so you'll have to reset the gap any way. The magnet isn't going to spontaneously loose charge, and truthfully I haven't ever seen one that would trigger the coil in one of these engines.
Flywheel key. It's either there or not. If it broke you have another issue that caused it. It's just there to make timing the engine idiot proof. The interfearance of the taper is what locks it into place. Not the key. Just get that dumb idea out of your head, and slap the fool that tried to sell you on it.
Fuel system.
This one is a bit trickier depending on symptoms, as you can think you have a fuel issue and really it's an air issue.
Basic fuel system diagnostic.
Check fuel lines/filter/tank vent. No cracks, bulges, fuel line should be flexible filter clean, vent free and clear. Note most vents are made to let air in and not out.
Check to be sure you have supply and return hooked up properly fitting next to purge button is return, lower fitting is supply.
Check purge bulb, should be free of cracks and pliable.
That covers the supply system.
Carb rebuild, refer to the carb sticky.
There is a cross over which could be placed in either fuel or air, I chose to look at it as an air issue, as really it pressure actuated. (Both positive and negative)
The pulse hole seems to give quite a few issues, and is largely overlooked. (If doing so properly) basically we need a clear path from the crankcase to the carb, to actuate both the metering and fuel pump diaphragms.
Easiest way to check is with a thin stiff wire and compressed air. (Not checking it at the carb, as you should have made sure it was clear during the rebuild)
Basically run the wire through the carb spacer, blow it out. Either clear or not.
Blow air through the hole that leads to the crankcase. Again either its clear or it's not.
I will note I think this is a poop set up on these engines, and have often contemplated converting over to a true crank case based external pulse, I have mused and recently been advised that this is a more prevalent issue then I had thought at first. Easy enough to do, but I doubt most would want to do it, but I digress.
Air. Compression tester. Self exanitory. Hook it up, make sure it's the type with the check valve built into the end of the hose and not at the Guage. Very important and I'm not explaining now. I wouldn't want to see anything bellow 100 psi, I think 90psi is the service limit. (Off the top of my head)
Next to check seals, and Intake. You need block off plates and a vac/pressure tester. I prefer to use the spark plug hole as my test port, but then you need to make an adapter, ive found its far easier just to take the carb off and use that plate as the test port for most. Engine should hold 15psi Basically indefinitely, and I normally pull them down to 10 inhg and should hold for at least 5 minuets. (The crank seals can relax and not pull great vacuum, but hold fine under pressure. It's a judgment call, when in doubt just replace them) soapy water in a spritz bottle is your friend. Don't forget about the transfer covers. They leak too.
There you have it simple engine diagnostics. I may have left a few things out, but that's it in a nut shell. There are a few symptoms that are indicative of a fuel issue that is really an air leak, and then there are the mechanical failures, but you can catch 90% of them following what I said. There are also drivetrain issues that will make you think you have an engine issue. But again. If the engine suddenly runs like crap/doesn't start, something changed or the owner screwed up. Either way, with a handful of tools youll know what's wrong in very little time.
Note, I did not cover tuning as thats not typically an engine fault, and should be needing more then an 1/8 turn to get back in peak tune from normal weather changes. Anything outside of a small adjustment means something is wrong, or it went from 100* to -50* overnight. Simply creatures. Don't over think it
No spark.
remove high tension lead, install in line spark tester, attempt to start. If spark jumps across contacts the coil and wiring is good replace plug.
No or weak spark, remove kill wiring from coil and retest.
If spark, issue is in kill wire harness/kill switch. Both of which easy enough to isolate and test.
No spark, break out your multi meter and ohm out coil, and high tension lead. Not looking up the specs. Easy enough to find in the manual. Checking the flywheel gap is a waste imo, if it ran before the gap didn't magically change, unless something broke. At any rate you need to pull the coil to test it, so you'll have to reset the gap any way. The magnet isn't going to spontaneously loose charge, and truthfully I haven't ever seen one that would trigger the coil in one of these engines.
Flywheel key. It's either there or not. If it broke you have another issue that caused it. It's just there to make timing the engine idiot proof. The interfearance of the taper is what locks it into place. Not the key. Just get that dumb idea out of your head, and slap the fool that tried to sell you on it.
Fuel system.
This one is a bit trickier depending on symptoms, as you can think you have a fuel issue and really it's an air issue.
Basic fuel system diagnostic.
Check fuel lines/filter/tank vent. No cracks, bulges, fuel line should be flexible filter clean, vent free and clear. Note most vents are made to let air in and not out.
Check to be sure you have supply and return hooked up properly fitting next to purge button is return, lower fitting is supply.
Check purge bulb, should be free of cracks and pliable.
That covers the supply system.
Carb rebuild, refer to the carb sticky.
There is a cross over which could be placed in either fuel or air, I chose to look at it as an air issue, as really it pressure actuated. (Both positive and negative)
The pulse hole seems to give quite a few issues, and is largely overlooked. (If doing so properly) basically we need a clear path from the crankcase to the carb, to actuate both the metering and fuel pump diaphragms.
Easiest way to check is with a thin stiff wire and compressed air. (Not checking it at the carb, as you should have made sure it was clear during the rebuild)
Basically run the wire through the carb spacer, blow it out. Either clear or not.
Blow air through the hole that leads to the crankcase. Again either its clear or it's not.
I will note I think this is a poop set up on these engines, and have often contemplated converting over to a true crank case based external pulse, I have mused and recently been advised that this is a more prevalent issue then I had thought at first. Easy enough to do, but I doubt most would want to do it, but I digress.
Air. Compression tester. Self exanitory. Hook it up, make sure it's the type with the check valve built into the end of the hose and not at the Guage. Very important and I'm not explaining now. I wouldn't want to see anything bellow 100 psi, I think 90psi is the service limit. (Off the top of my head)
Next to check seals, and Intake. You need block off plates and a vac/pressure tester. I prefer to use the spark plug hole as my test port, but then you need to make an adapter, ive found its far easier just to take the carb off and use that plate as the test port for most. Engine should hold 15psi Basically indefinitely, and I normally pull them down to 10 inhg and should hold for at least 5 minuets. (The crank seals can relax and not pull great vacuum, but hold fine under pressure. It's a judgment call, when in doubt just replace them) soapy water in a spritz bottle is your friend. Don't forget about the transfer covers. They leak too.
There you have it simple engine diagnostics. I may have left a few things out, but that's it in a nut shell. There are a few symptoms that are indicative of a fuel issue that is really an air leak, and then there are the mechanical failures, but you can catch 90% of them following what I said. There are also drivetrain issues that will make you think you have an engine issue. But again. If the engine suddenly runs like crap/doesn't start, something changed or the owner screwed up. Either way, with a handful of tools youll know what's wrong in very little time.
Note, I did not cover tuning as thats not typically an engine fault, and should be needing more then an 1/8 turn to get back in peak tune from normal weather changes. Anything outside of a small adjustment means something is wrong, or it went from 100* to -50* overnight. Simply creatures. Don't over think it
Stfu. Next time you open your mouth and not read the entire thread, I'm gonna drop a world of hurt on your young, arrogant arse.ok you replaced the carb with a clone and it works, great, proof of concept for cheap. Now that you see its the carb, (at least that seems to be what you are saying), get a real carb, it will be more reliable and consistent. Chances are your clone carb was the reason it bogged one day and ran "like a chap" the next (inconsistency).
How do you manage to accidently buy a clone
The walbro carb with the issues was probable because it was sitting collecting
Last edited:
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. Was just trying to emphasize the importance of a genuine carb 
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Nice write up Sean! Would make for a good troubleshooting sticky for newbs.
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No, that will come later.......
- Thread starter
- #76
Ok again I honestly started this thread to finally remedy the inconsistent starting\running issues i have sometimes and in the process someone else could benefit from the feedback here. So to not have a constant back\forth im gonna summarize basically my approach that I have been using and i will definitely be going back thru and reading thru all the valuable feedback and pick the notes i see applicable to me.
Heres my basic procedure and approach to the 5th scale GAS RC which some may already know and others may not but if im doing something wrong here please im all ears:
PLEASE KEEP IN MIND IT WOULD BE BEST TO START WITH ALL NEW PARTS TO MINIMIZE CHASING YOUR TAIL (as i have done in the past) although that does not guarantee that the new parts are good
By no means am I an expert but Ive learned over the years there a basic set of areas where the issues could be if youre having starting\running issues with 5th GAS RC :
Compression (I have compression to sapre)
- Piston Rings
- Crankshaft Bearings
Ignition (This one is iffy I cant quite lockdown if and when its a spark issue even with the spark tester)
- Bad Spark Plug or Coil
- If KillSiwtch installed could also be a point of failure and/or intermittent results
GAS (CARBs are my kryptonite; even when new you cant trust them)
- And this is a biggie and where i think most of my issues occur ; CARBURETOR
- Fuel\Air mixture
- Air Filter (Clogged or blocked)
My starting process:
- Doublecheck Carb settings and make sure settings are correct for the appropriate Carb
- Pump bulb approx. 5 times to see fuel in bulb
- If applicable turn on Choke
- Carb 1170 Pull slowly 1-1.5 times \ Carb 990 Pull slowly 5-6 times
- Turn off choke
- Pull start till she BRAAAPs to life (hopefully)
Now if im off here help me out.
Thanks Again
I was on the cheap and saw carbs going for $50-70 so i was like nah ill search ebay. Searched for 990 Carb and didnt pay attention to brand so yeah thats how i accidentally bought a knockoff carb. the cheap price shouldve alerted me but i just thought thats what the price should be so i wnet for it
Heres my basic procedure and approach to the 5th scale GAS RC which some may already know and others may not but if im doing something wrong here please im all ears:
PLEASE KEEP IN MIND IT WOULD BE BEST TO START WITH ALL NEW PARTS TO MINIMIZE CHASING YOUR TAIL (as i have done in the past) although that does not guarantee that the new parts are good
By no means am I an expert but Ive learned over the years there a basic set of areas where the issues could be if youre having starting\running issues with 5th GAS RC :
Compression (I have compression to sapre)
- Piston Rings
- Crankshaft Bearings
Ignition (This one is iffy I cant quite lockdown if and when its a spark issue even with the spark tester)
- Bad Spark Plug or Coil
- If KillSiwtch installed could also be a point of failure and/or intermittent results
GAS (CARBs are my kryptonite; even when new you cant trust them)
- And this is a biggie and where i think most of my issues occur ; CARBURETOR
- Fuel\Air mixture
- Air Filter (Clogged or blocked)
My starting process:
- Doublecheck Carb settings and make sure settings are correct for the appropriate Carb
- Pump bulb approx. 5 times to see fuel in bulb
- If applicable turn on Choke
- Carb 1170 Pull slowly 1-1.5 times \ Carb 990 Pull slowly 5-6 times
- Turn off choke
- Pull start till she BRAAAPs to life (hopefully)
Now if im off here help me out.
Thanks Again
ok you replaced the carb with a clone and it works, great, proof of concept for cheap. Now that you see its the carb, (at least that seems to be what you are saying), get a real carb, it will be more reliable and consistent. Chances are your clone carb was the reason it bogged one day and ran "like a chap" the next (inconsistency).
How do you manage to accidently buy a clone
The walbro carb with the issues was probable because it was sitting collecting
I was on the cheap and saw carbs going for $50-70 so i was like nah ill search ebay. Searched for 990 Carb and didnt pay attention to brand so yeah thats how i accidentally bought a knockoff carb. the cheap price shouldve alerted me but i just thought thats what the price should be so i wnet for it
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What type of spark tester are you using? The ones with the light bulbs are pretty much useless, as they don't load the ignition system. Same as checking for spark via the plug out of the head. This is the one I've come to prefer, but currently don't have. Used it a lot when I worked at the machine shop.
https://smile.amazon.com/dp/B00MCWRTOE/ref=cm_sw_r_cp_apa_glt_fabc_5VVX8K1MRH8WJZ6CBQP7
This model does the same thing but isn't near as nice to use. What I currently use. Not gonna lie, it does the job but totally sucks to use.
https://smile.amazon.com/dp/B0002STSBM/ref=cm_sw_r_cp_apa_glt_fabc_FZ40CXYARN0CETVHD2HJ
Crank bearings don't typically give issues, and when they do they let you know pretty fast. If and when they do go, you have more issues to worry about then just an inconsistent tune.
There is no point to double checking your carb settings, this is likely half your tuning issues. The integral seats in the carb are very sensitive to deformation, once deformed tuning is a real pain. So bad in fact it's hard to get the carb to tune right.
Starting procedure, you typically pull with choke on till you get a fart from the engine, take choke off and give a few pulls, should really fire up first or second pull.
remember its NOT a primer bulb, it's sole purpose is to purge the air out of the carb, it does not force fuel into the engine. Walbro does have primer systems, but as far as I know they do not use them on the WT series carb.
Your thought of new parts not being right, is wrong. We have seen a few carbs acting wonky, largely all bought from the same place, but typically new parts don't typically screw up. Your issue is the lack of testing your current parts.
https://smile.amazon.com/dp/B00MCWRTOE/ref=cm_sw_r_cp_apa_glt_fabc_5VVX8K1MRH8WJZ6CBQP7
This model does the same thing but isn't near as nice to use. What I currently use. Not gonna lie, it does the job but totally sucks to use.
https://smile.amazon.com/dp/B0002STSBM/ref=cm_sw_r_cp_apa_glt_fabc_FZ40CXYARN0CETVHD2HJ
Crank bearings don't typically give issues, and when they do they let you know pretty fast. If and when they do go, you have more issues to worry about then just an inconsistent tune.
There is no point to double checking your carb settings, this is likely half your tuning issues. The integral seats in the carb are very sensitive to deformation, once deformed tuning is a real pain. So bad in fact it's hard to get the carb to tune right.
Starting procedure, you typically pull with choke on till you get a fart from the engine, take choke off and give a few pulls, should really fire up first or second pull.
remember its NOT a primer bulb, it's sole purpose is to purge the air out of the carb, it does not force fuel into the engine. Walbro does have primer systems, but as far as I know they do not use them on the WT series carb.
Your thought of new parts not being right, is wrong. We have seen a few carbs acting wonky, largely all bought from the same place, but typically new parts don't typically screw up. Your issue is the lack of testing your current parts.
- Thread starter
- #78
Spark plug tester i bought off amazon:
OriGlam Spark Plug Tester, Adjustable Ignition System Coil Tester, Coil-on Plug Ignition Spark Circuit Tester, Autos Diagnostic Test Tool
Yeah i was just saying that be mindful when trying to isolate a problem its better to start off with known good parts (ie new) to help better isolate your problem.
All in all good info. Appreciate it. I might have to message you to get mor detailed on what the internals of the carbs are doing so i can get a better undersdtanding of that. It might help me in the long run. But as of right now BOTH Rampage and FG are running fine just in time for Memorial Day weekend.
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Your link doesn't work.
- Thread starter
- #80