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Old 04-05-2003, 03:26 PM   #1
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Default fuel comming out of exhaust

I have broken in my engine and I am trying to tune it out for the past week. I have noticed that fuel still comes out of the exhuast. Even after it goes through a tank of fuel if i flip the car on its side, fuel spills out. Also i have noticed that after a run, the gas tank is moist (i'm guessing from fuel). Could this be from the exhuast? I checked the car out and i see no other leaks.

also, I noticed that my fuel lines are dirty, on the outside. I have cleaned them, but should i disonnect them from the exhaust and the engine and clean them more thoroughly?

one last thing, i have alot of road grime on my chassis in hard to clean places. what should i use to get all that gunk, sand, dirt, fuel out?
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Old 04-05-2003, 03:36 PM   #2
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Default Re: fuel comming out of exhaust

Quote:
Originally posted by alucard13
I have broken in my engine and I am trying to tune it out for the past week. I have noticed that fuel still comes out of the exhuast. Even after it goes through a tank of fuel if i flip the car on its side, fuel spills out. Also i have noticed that after a run, the gas tank is moist (i'm guessing from fuel). Could this be from the exhuast? I checked the car out and i see no other leaks.

also, I noticed that my fuel lines are dirty, on the outside. I have cleaned them, but should i disonnect them from the exhaust and the engine and clean them more thoroughly?

one last thing, i have alot of road grime on my chassis in hard to clean places. what should i use to get all that gunk, sand, dirt, fuel out?
I can't really answer your first question being as I'm also learning the ins & outs of Nitro. However, your fuel lines will always get dirty on the inside. I believe this is due to the oils and lubricants and stuff in the fuel. Someone else can probably shed more light on this if I'm incorrect.

One thing you can do to help keep your car clean in those hard to reach spots (aside from stripping it down and cleaning it) is to buy a can of Pro Shot or other safe cleaning spray. Most of the time you can use the little straw that comes with it and blow pretty much everything out of there. I know that some racers have started to use rubbing alcohol in a spray bottle since this is cheaper.

Bottom line is, your car is always going to get grimey and nasty when you run/race it. a good rule of thumb to remember is 'a clean car is a happy car'. If you have time, depending on how much you run it I would recommend a good tear down cleaning every two weeks. Every week would keep it nice and clean and allows you to keep a good eye on loose screws, worn parts etc. before they become a problem.

Last edited by RedScorp; 04-05-2003 at 03:41 PM.
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Old 04-05-2003, 04:15 PM   #3
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As long as the dirt is not on the inside of the fuel lines your ok. Now the question is, is what coming out of your pipe fuel or oil. If it is fuel, somehow you are sucking it through the exhaust pressure line into the pipe, if its oil your engine is probably still rich.
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Old 04-05-2003, 04:21 PM   #4
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Quote:
Originally posted by Distroey
As long as the dirt is not on the inside of the fuel lines your ok. Now the question is, is what coming out of your pipe fuel or oil. If it is fuel, somehow you are sucking it through the exhaust pressure line into the pipe, if its oil your engine is probably still rich.
Should the engine always leak a bit of oil or as long as its throwing exhaust it's fine?
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Old 04-05-2003, 04:34 PM   #5
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Yes, but it shouldn't pour out when you lay the car on its pipe side. My guess is, when he puts the car on its side the fuel is just running out of the tank down the pressure line and out the pipe.
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Old 04-05-2003, 04:44 PM   #6
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Quote:
Originally posted by Distroey
Yes, but it shouldn't pour out when you lay the car on its pipe side. My guess is, when he puts the car on its side the fuel is just running out of the tank down the pressure line and out the pipe.
Nope. It's unburned fuel leaving the engine. I had this same problem when I started out with nitro. I couldn't get the engine setup for the life of me. After tuning and more tuning, I finally was able to figure it out. All it is, is a matter of getting the engine tuned right. Make sure there aren't ANY air leaks in your engine and then keep tuning it till you get it right. If you have fuel coming out your exhaust, that mean's you might be running an incorrect glow plug (too cool) or you engine is extremely rich. Residue in your fuel return/pressure line will always be there. I see it on all nitro cars, and seems to be the worst on the Nitro TC3. After a racing day, my fuel return line is already showing signs of residue.
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Old 04-05-2003, 05:20 PM   #7
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Learned something with my NTC3 a 10 minutes ago...lean it out with LITTLE adjustments!!! Smokey motors aren't a good thing...luckily everything is fine...even the glow plug.

BTW...what glow plugs do you all use in your NTC3s? I'm running O'Donnel fuel in my AE .12. I should probably pick up a few.
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Old 04-05-2003, 05:42 PM   #8
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Quote:
Originally posted by Distroey
As long as the dirt is not on the inside of the fuel lines your ok. Now the question is, is what coming out of your pipe fuel or oil. If it is fuel, somehow you are sucking it through the exhaust pressure line into the pipe, if its oil your engine is probably still rich.
how can i tell whether its fuel or oil? I use the Team sidewinder Backyard Basher fuel. 20% Nitro 16% oil, so its all mixed together.

I have an HPI RS4 RTR3.

Another question. What does it mean when someone says "Bottom Out" when referring to your needle valve? I was reading somehwere where it said to turn your high end needle until it bottoms out. I want to start tuning my engine all over because I think I am to rich. I see smoke comming out of the pipe almost as soon as i push the throttle. At full throttle thier is a healthy trail of smoke comming from the pipe, so i know i'm not too lean.

Hey guys, thanx for all the help. I'm a newbie, as you can tell and i am learning ALOT from this site. Don't worry, gimme a few months and i'll be a pro like you all. Thanx again.
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Old 04-05-2003, 07:53 PM   #9
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I'm not sure what they mean by "bottoming out", but none the less by what you are describing you engine is entirely too rich. You should only see a little bit of smoke come from the exhaust when you are accelerating. When you first accelerate, you should see a "blip" of smoke come from the exhaust, once you start getting up to speed it should start thinning out. Going full throttle it shouldn't be very noticable. By the sound of things, you've got both your low end needle and high end needle way too rich. Start over with the factory recommended settings by HPI, and slowly work your way from there.

I would recommend you not touch the low end needle till you get the high end adjust correctly. You'll know you have the right setting when you see minimal smoke leaving the engine going full throttle, and your idling temperature vs running temperature should be almost the same. I've always known HPI to make "user friendly" cars, so if you follow their instructions you should be able to set the engine correctly. If you have any other troubles, post your problem and we'll figure it out.
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Old 04-05-2003, 09:07 PM   #10
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I am not very knowledgable in engines and tuning and types but I do know that some of the HPI's low ends come preset so there is no adjust ment to fiddle with. but who know's i'll still breaking in my first nitro.
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Old 04-05-2003, 09:20 PM   #11
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If you don't have a low end needle adjustment it's hard to avoid fuel or oil coming out of the pipe. It's ok during break in though. Just lean out you high speed needle a click and see if that helps.
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Old 04-05-2003, 09:21 PM   #12
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Default fuel comming out of exhaust

Guys;

If your lost with the High Speed needle setting, usually 2-1/2 to 3 turns out on ANY Engine should get it started. Then you can adjust from there.

alucard13:

It is normal for the excess oil to collect inside the pipe after the engine has been running. If you tip the Car on it's side with the pipe down, fuel will run into the pressure line and into the pipe, so this may be what your seeing. Use the water drop test for tuning the High speed needle. Put a drop of water on the Cooling Head after a few minutes of running/driving. It should take a few seconds for the drop(s) of water to sizzle off. The Engine may not be as fast as it can at this setting, but you need to run it rich to keep the Piton and Sleeve from wearing out prematurely.
BTW, the fuel your using is great for begiining Nitro Drivers, plenty of Oil to keep things lubed.

Good luck and Have fun,
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Old 04-06-2003, 09:10 AM   #13
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You guys are AWESOME! thanx for the tips. I do have a question into HPI on how to get back to the factory settings so i can start all over again. I only have one needle that i can adjust and my idle stop screw. All in all the car runs great. It does tend to stall out if i turn to quick and do a donut and let off the throttle. I did notice that where the fuel line connects to the tank on the bottom its very wet. I may have a leak, but i can't find any holes. Although even a little one would probably cause fuel to leak out huh? I am about to go out and run it right now and i will do the water test. I'll post back with my info. Thanx again guys.


BTW, any of you guys going to the space coast race next sunday. As long as nothing major happens in my life, i plan on being there. I will be the guy looking confused and not knowing what to do...lol
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Old 04-06-2003, 10:07 AM   #14
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Just got back from running it. And here is what i found out:

The engine seems to be ok. The water evaportated in about 4 seconds.

As the engine gets hotter if i go full throttle and let off the throttle (not braking) it dies. When i go to restart it i have to open the throttle a bit and keep it open so that it doesnt die. When the engine is cool and i start it for the first time, i see no problems. It will idle fine and not die. But as soon as i start to run it and it gets hotter and i go full throttle and then let completely off it will die. Then when i restart it it will run for a second then die, so i have to open the throttle a little to keep from stalling. Any ideas what i should do?
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Old 04-06-2003, 01:29 PM   #15
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When the engine dies if you let off the gas, it could be a few things. The idle could be to low, Your high speed could be to rich, or to lean, The RS4-3 comes with the 15fe and has no low speed, The rs4-3 ss comes with the ss engine, and has a low speed adjustment, this could be to lean.
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