nitro engine starts fine but dies after a few seconds of running

[jayb6550]

I have just gotten into the nitro rc hobby and was needing some help on this issue. Every time i start up the engine, it stalls shortly after starting. I constantly have to prime it and sometimes go as far as taking off the filter and putting fuel directly into the carburetor. the longest i’ve had it run was around 10 seconds and it ran hot the whole time. I thought tuning was the issue so i set the carb to factory settings and tried to tune from there and it helped a little but still did the same thing. my guess is there could be an air leak somewhere that i’m not seeing or it’s not pulling enough fuel. not sure if this will help but the engine is a dynamite mach .15r.

 

[BarnFabRC]

Do you have a line from the silencer to the fuel tank installed? I’m not a nitro guy but I had one years ago and that was basically the fuel pump.

 

[jayb6550]

Do you have a line from the silencer to the fuel tank installed? I’m not a nitro guy but I had one years ago and that was basically the fuel pump.

yep. that was actually the first thing i checked to see if something was wrong with the line.

 

[alicankeser]

I have just gotten into the nitro rc hobby and was needing some help on this issue. Every time i start up the engine, it stalls shortly after starting. I constantly have to prime it and sometimes go as far as taking off the filter and putting fuel directly into the carburetor. the longest i’ve had it run was around 10 seconds and it ran hot the whole time. I thought tuning was the issue so i set the carb to factory settings and tried to tune from there and it helped a little but still did the same thing. my guess is there could be an air leak somewhere that i’m not seeing or it’s not pulling enough fuel. not sure if this will help but the engine is a dynamite mach .15r.

you may be right check the fuel pip for a leak or change it and if it still doesn't work turn the HSN by 15-30 mins
what model do you have?

 

[jayb6550]

you may be right check the fuel pip for a leak or change it and if it still doesn't work turn the HSN by 15-30 mins
what model do you have?

I forget to mention yesterday that i tuned it some more and now it stays running and idles great and accelerates fine, my only problem is the engine is running extremely hot. the tuning used to be perfect but ever since i messed with it everything went down the drain. the model is a Team Losi XXXNT rtr. I don’t why i decided to get a vintage nitro for my first one. the car is in great condition for its age though and all think it needs is a tune up and it will be running great again.

 

[jayb6550]

could the engine be running so rich to the point it’s getting hot?

 

[tudordewolf]

could the engine be running so rich to the point it’s getting hot?

Overly rich will run the engine cool, it won't overheat from too rich a tune, only too lean.

 

[jayb6550]

Overly rich will run the engine cool, it won't overheat from too rich a tune, only too lean.

i don’t understand though because both the needles are almost flush with the housing meaning it should run rich
but when the needles are lean it also runs pretty hot

 

[johnnydmd]

i don’t understand though because both the needles are almost flush with the housing meaning it should run rich
but when the needles are lean it also runs pretty hot

That would strongly suggest an air leak if it's not running rich at those settings.

 

[jayb6550]

That would strongly suggest an air leak if it's not running rich at those settings.

ok i got the engine running rich with lots of blue smoke and unburied fuel leaving the exhaust but what stopped me from running it any longer was the temps. they were exceeding 285 degrees and the engine itself was struggling to stay running and it was smoking. it is possible there is an air leak somewhere but i’ve checked the tank, exhaust, fuel lines and exhaust line and they have absolutely no leaks. maybe too hot of a glow plug? i know it’s not the fuel either because i’m running 20% and that engine can go as far as 30 %.

ok i got the engine running rich with lots of blue smoke and unburied fuel leaving the exhaust but what stopped me from running it any longer was the temps. they were exceeding 285 degrees and the engine itself was struggling to stay running and it was smoking. it is possible there is an air leak somewhere but i’ve checked the tank, exhaust, fuel lines and exhaust line and they have absolutely no leaks. maybe too hot of a glow plug? i know it’s not the fuel either because i’m running 20% and that engine can go as far as 30 %.

i’m running a medium plug

 

[Roog]

I have just gotten into the nitro rc hobby and was needing some help on this issue. Every time i start up the engine, it stalls shortly after starting. I constantly have to prime it and sometimes go as far as taking off the filter and putting fuel directly into the carburetor. the longest i’ve had it run was around 10 seconds and it ran hot the whole time. I thought tuning was the issue so i set the carb to factory settings and tried to tune from there and it helped a little but still did the same thing. my guess is there could be an air leak somewhere that i’m not seeing or it’s not pulling enough fuel. not sure if this will help but the engine is a dynamite mach .15r.

I had this problem, I didn't notice that my makeshift tank didn't have a vent in it! Duh!
Might not be that same issue for you but I thought I'd mention it.

 

[jayb6550]

I had this problem, I didn't notice that my makeshift tank didn't have a vent in it! Duh!
Might not be that same issue for you but I thought I'd mention it.

A fuel tank or at least my fuel tank completely relies on pressure since there is no fuel pump. if I were to make a vent it wouldn’t receive the pressure it needs to pull fuel through the line. causing it to either run extremely lean or not even run at all. if you don’t have a line coming from the exhaust pipe to the fuel tank it will run just how I said it would. obviously I don’t know how your tank works because it is a makeshift tank but all i’m saying is if I were to put a vent in my tank it would make problems worse.

 

[DeathMetal Junkie]

You might start with replacing all the fuel lines. And at every connection point wrap a small zip tie around the hose. Then seal the engine at the back plate and carb where it slides into the engine with a small,(emphasize small!) bead of silicon. Then reset to factory settings and see how that works.

 

[EJMOPAR70]

You said its an older model. I had a Ofna Twin Titan. It was a shelf Queen when I bought it. I decided to run it cause I dont see the point in having an RC and not running it. But to get to the point the gaskets on the needles had corroded. When I backed them out it just fell apart. I was able to EBay and get new engines with good needles. I would not recommend putting silicone on backplate or carb as someone recommended. Check your high speed and low speed needles.

 

[DeathMetal Junkie]

You said its an older model. I had a Ofna Twin Titan. It was a shelf Queen when I bought it. I decided to run it cause I dont see the point in having an RC and not running it. But to get to the point the gaskets on the needles had corroded. When I backed them out it just fell apart. I was able to EBay and get new engines with good needles. I would not recommend putting silicone on backplate or carb as someone recommended. Check your high speed and low speed needles.

Actually putting silicon on the back plate and carb is a common practise to seal all areas of possible air in filtration. I've done it for years on my nitro engines. You don't hammer it on but small bead of gasket material is all you need. Pros do that all the time.

 

[jayb6550]

i just replaced the fuel line but it’s a little smaller than the older line but it’s a tight fit. will the engine get less fuel because of this?

 

[easy rider]

My guess is it’s your tune. As things age, things change. So, it might have an air leak. But, Not idling is often a sign of too rich lsn with what you described. Smoking like that is too. When you are too rich on both ends, they’ll be oil all over the back of the motor, chassis, and body.

Tune your motor methodically. Return them to factory settings and get it running. Then get the high speed setting decent. Then the low speed mixture right. Than the idle. If it runs inconsistent making this process hard, you need to start considering you’ve got a motor problem. Something that’s causing compression lose.

An air leak will often show surging rpms and a lean condition. So, without the obvious leaning out signs, it’s hard to say that your problem is an air leak.

I’m quite new at this concerning RC motors. But, I’ve built and tuned a lot of two stroke motors. And, the tuning is everything.

There are signs of an air leak. Smoking isn’t one of them for the most part. Inconsistent and surging rpms is. Excessive smoking and not idling is a sign of a rich tune. And, my guess is your tune is off.

Fix that by resetting to factory and get the top right. Then the low speed mixture. Than the idle.

Watch you tube. There are some excellent videos showing how to tune your vehicles motor. If you follow their guidelines, you’ll fix your problem if tuning is your issue. And, I’m pretty certain it is.

 

[jayb6550]

My guess is it’s your tune. As things age, things change. So, it might have an air leak. But, Not idling is often a sign of too rich lsn with what you described. Smoking like that is too. When you are too rich on both ends, they’ll be oil all over the back of the motor, chassis, and body.

Tune your motor methodically. Return them to factory settings and get it running. Then get the high speed setting decent. Then the low speed mixture right. Than the idle. If it runs inconsistent making this process hard, you need to start considering you’ve got a motor problem. Something that’s causing compression lose.

An air leak will often show surging rpms and a lean condition. So, without the obvious leaning out signs, it’s hard to say that your problem is an air leak.

I’m quite new at this concerning RC motors. But, I’ve built and tuned a lot of two stroke motors. And, the tuning is everything.

There are signs of an air leak. Smoking isn’t one of them for the most part. Inconsistent and surging rpms is. Excessive smoking and not idling is a sign of a rich tune. And, my guess is your tune is off.

Fix that by resetting to factory and get the top right. Then the low speed mixture. Than the idle.

Watch you tube. There are some excellent videos showing how to tune your vehicles motor. If you follow their guidelines, you’ll fix your problem if tuning is your issue. And, I’m pretty certain it is.

Thank you for the advice, I really appreciate it. I have already tried returning it to factory settings and it didn’t run. So I may start by leaning the lsn because you mentioned it being too rich on the bottom end. tomorrow i’ll go try it out and see how it does! once again thank you.

 

[jayb6550]

My guess is it’s your tune. As things age, things change. So, it might have an air leak. But, Not idling is often a sign of too rich lsn with what you described. Smoking like that is too. When you are too rich on both ends, they’ll be oil all over the back of the motor, chassis, and body.

Tune your motor methodically. Return them to factory settings and get it running. Then get the high speed setting decent. Then the low speed mixture right. Than the idle. If it runs inconsistent making this process hard, you need to start considering you’ve got a motor problem. Something that’s causing compression lose.

An air leak will often show surging rpms and a lean condition. So, without the obvious leaning out signs, it’s hard to say that your problem is an air leak.

I’m quite new at this concerning RC motors. But, I’ve built and tuned a lot of two stroke motors. And, the tuning is everything.

There are signs of an air leak. Smoking isn’t one of them for the most part. Inconsistent and surging rpms is. Excessive smoking and not idling is a sign of a rich tune. And, my guess is your tune is off.

Fix that by resetting to factory and get the top right. Then the low speed mixture. Than the idle.

Watch you tube. There are some excellent videos showing how to tune your vehicles motor. If you follow their guidelines, you’ll fix your problem if tuning is your issue. And, I’m pretty certain it is.

your tips worked and it runs! now the only troubles are it stalls and bogs down when i give it throttle too fast, and when It goes back to idle after high rpm’s it idles extremely high even though the idle gap is good. I can’t figure out what this could mean.

 

[easy rider]

Riches the lsn.