HPI RS3 Revo 4 1/10 scale won't start

[hueyc586]

Hello Nitro RC'ers, I have several Nitro RC and would consider myself not a beginner but not expert at troubleshooting Nitro RC startup issues. The issue I am having is even with my idle, HSN, LSN set back to factory I still can't seem to get engine running using pull start. I've used heat gun pointed down top where glow plug located to warm up and verified glow ignitor is good but still nothing. Next, I've tried my pour some fuel down the carb which always worked for me other vehicles, not this vehicle for some reason. Also, even removed glow plug and pour couple drop fuel and reinstall glow plug. Tried again and nothing. I feel some back pressure when pulling on pull start but not kicking over. Any suggestions what I might have missed? All the tricks up my sleeve have failed and I am at a lost with this vehicle. The only thing that I don't know how to check is whether my fuel line and tank is sealed? Is there a trick to check this?

 

[CertifiedMike]

Hi @hueyc586
Welcome to RCTALK.COM!!!
Sorry about your troubles... so lets start with some basics...
Are you positive that your glow plug is the correct plug for THIS engine?
They aren't generic.
I would use a brand new plug, again, to eliminate it as a possible issue. You can hang on to this one for later.
Is your fuel brand new from a sealed bottle?
If not, go buy some new fuel. Save the old stuff for later, after this is worked out.
I will ask because its foolish not to... are you positive you've got good compression?
Have you attempted to start with the air filter completely removed? Not that I would ever recommend starting without a filter... its because you're having the issues. The air filter could be plugged up and not breathing well.
Have you verified the condition of the o-rings for your carb? Even tiny cracks cause big problems.
Fuel lines.... buy new ones and be done with it. Cheap and easy.
To verify the tank isnt plugged, blow thru the lines, thru the tank.
Hopefully these things will reveal the issue. If not, we can try more!
Let us know how it goes!
Good luck!!!

 

[tudordewolf]

You say the pull start doesn't "kick it over", like it doesn't complete a couple revolutions when you give it a short flick? It should make a kind of "Brrt" sound, otherwise the starter hex could be worn out or the starter shaft polished too smooth for it to catch.

 

[hueyc586]

Hi @hueyc586
Welcome to RCTALK.COM!!!
Sorry about your troubles... so lets start with some basics...
Are you positive that your glow plug is the correct plug for THIS engine?
They aren't generic.
I would use a brand new plug, again, to eliminate it as a possible issue. You can hang on to this one for later.
Is your fuel brand new from a sealed bottle?
If not, go buy some new fuel. Save the old stuff for later, after this is worked out.
I will ask because its foolish not to... are you positive you've got good compression?
Have you attempted to start with the air filter completely removed? Not that I would ever recommend starting without a filter... its because you're having the issues. The air filter could be plugged up and not breathing well.
Have you verified the condition of the o-rings for your carb? Even tiny cracks cause big problems.
Fuel lines.... buy new ones and be done with it. Cheap and easy.
To verify the tank isnt plugged, blow thru the lines, thru the tank.
Hopefully these things will reveal the issue. If not, we can try more!
Let us know how it goes!
Good luck!!!

Hi Mike,

Thanks for replying to my post and providing insight. Yeah, I did check everything you've pointed out above down to part you've said "Have you verified the condition of the o-rings for your carb? Even tiny cracks cause big problems" <-- I did replace the exhaust gasket but the cylinder head, it appear to be ok although I wanted to replace it but order wrong size.

I'll try blowing through the lines and maybe even spray soup while doing it.. Again, thanks for your troubleshooting steps!

 

[hueyc586]

You say the pull start doesn't "kick it over", like it doesn't complete a couple revolutions when you give it a short flick? It should make a kind of "Brrt" sound, otherwise the starter hex could be worn out or the starter shaft polished too smooth for it to catch.

Hi, the pull start does kick over.. doesn't appear to be slipping. I know what you mean about the 'Brrt" sound when it warm up and about to kick over but I am not getting that... constantly pulling start cord and nothing. I've recenty changed the exhaust gasket but do notice oil dripping out of the exhaust... tried to tilt car and drain but could it be plugged in the exhaust pipe? I am leaning towards pulling out engine, take apart and soaking everything in brake cleaner and alcohol but before do that, I might take engine out, spray soup and blow air through it with everything in tact including glow plug and see if any leaks. What u think? I don't think fix this problem without taking it apart.

 

[CertifiedMike]

Sounds like your muffler is plugged up.Check that.
Be VERY careful with brake clean. It can and absolutely does eat some plastics.
I have had good luck soaking metal parts in 99% alcohol.
What fuel are you using?
There is nothing wrong with taking everything apart for a thorough inspection.
If this is an old or unknown motor, it mighy he best.
You may need to reseal the engine with some gasket maker.

 

[CertifiedMike]

Post in thread 'Nitro Tuning Tips and Tuning Flow Chart'

Jun 14, 2009

Sealing a Nitro Engine for air leaks.

It is a well done tutorial of sealing up an engine with RTV. I'll go through the sealing process and make one of my own to replace this:

-------

Today I will take you step-by-step through the process of sealing your engine. Whether your engine is brand new, or you have been running it for a year or more, if you have never sealed it, now is the time. By sealing your engine from the beginning, you are eliminating most of the tuning problems that plague nitro engines. If you are having trouble keeping your engine tuned properly, chances are you...

• olds97_lss

• 

 

[hueyc586]

Sounds like your muffler is plugged up.Check that.
Be VERY careful with brake clean. It can and absolutely does eat some plastics.
I have had good luck soaking metal parts in 99% alcohol.
What fuel are you using?
There is nothing wrong with taking everything apart for a thorough inspection.
If this is an old or unknown motor, it mighy he best.
You may need to reseal the engine with some gasket maker.

Using S&W Fuel purchase locally from Easton, Pa. It's good fuel and $25 gal 15% Nitro for RC, use for bashing around neighborhood.

 

[CertifiedMike]

Check out that link I posted. That should help you put quite a bit.