Nitro engine priming and starting difficulties (needs help)

[Geri]

Hello! Recently i had bought a nitro rc car (hpi savage 25) from a friend. He wasn't using it for a long time (1year) and he lost the transmitter. Thankfully i had one laying around. I've tested the servos, they are working, but... I can't start the engine no matter what i do. First i simply tried starting the engine (following tutorials) even with 2 types of fuel (20% and 25%nitro) with the stock glow plug (R5). Then after some tries the glow plug burned out. A month later i got new glow plugs (os no6 and no8) but still can't start the engine. The major problem is that the motor won't prime if i put my finger on the exhaust outlet and rotate the engine (with rotostart). If i increase the throttle i can see the fuel jumping in the fuel line but not high enough to prime the engine. I tried adjusting the needles. The only way i can get the fuel in the engine is lifting the fuel tank above the engine or blowing air in the fuel-exhaust line with my mouth. I'm out of ideas what should i do. I'm new to nitro motors. Any help is very appreciated.

 

[HPIguy]

I would start by setting the needles, and the carb opening to factory settings. You should be able to easily find and download a manual for that truck. From there, it sounds like you may possibly have an air leak. That's an older truck, so I would start by replacing the tank and fuel lines, and making sure the carb is sealed properly to the engine.

 

[tntpoof]

test compression...replace fuel lines..check top gas tank seal and you went from a #5 to #8 why the 8 is way cooler no nitro expert but know enough(thats why I went to slowly electric)

 

[Tunedfrog]

I'm not seeing the pressure hose from the exhaust to the top of the fuel tank. I assume the hose connects to the top of the tank?

 

[cbaker65]

Also from what I see from the pic ,actually how long are you letting that glow igniter sit on the plug?....

 

[Geri]

Also from what I see from the pic ,actually how long are you letting that glow igniter sit on the plug?....

I let the glow plug on for a few minutes (4-5min) It only uses a rechargeable 1,2-1,3v battery. With a multimeter i measured 1,45amperes. Is that a problem?

 

[cbaker65]

I let the glow plug on for a few minutes (4-5min) It only uses a rechargeable 1,2-1,3v battery. With a multimeter i measured 1,45amperes. Is that a problem?

Well ,it may run the battery down quicker on the igniter ,an I am not sure if it will burn out the glow plug!

I always try to pull the igniter off as soon as the engine starts or let the igniter rest if I have problems starting!...

 

[olds97_lss]

Well ,it may run the battery down quicker on the igniter ,an I am not sure if it will burn out the glow plug!

I always try to pull the igniter off as soon as the engine starts or let the igniter rest if I have problems starting!...

Yeah, I don't leave mine on there for more than a minute at a time.

Can you post a photo showing a straight down shot? Can't see what your pressure line is connected to on the tank, if anything. That's an odd arrangement. Never saw anyone setup the throttle/carb that way on a savage. Not that it won't work, it's just odd looking.

 

[Geri]

test compression...replace fuel lines..check top gas tank seal and you went from a #5 to #8 why the 8 is way cooler no nitro expert but know enough(thats why I went to slowly electric)

The first glow plug i that was already in the truck is r5 which is (as far as i know) a cold plug. The os.6 is a warm one, which should make easier to start the motor. Correct me if I'm wrong.

 

[Geri]

Yeah, I don't leave mine on there for more than a minute at a time.

Can you post a photo showing a straight down shot? Can't see what your pressure line is connected to on the tank, if anything. That's an odd arrangement. Never saw anyone setup the throttle/carb that way on a savage. Not that it won't work, it's just odd looking.

For me the fuel tank seems to be ok. With the fuel line closed i can't blow air in the exhaust-fuel line. If i prime the engine by moving the fuel tank above it the engine wont start but the fuel line comes off hard off the carburettor so i guess there aren't leaks. Could it be the connection between the engine and exhaust pipe? I attached a photo in which is visible a crack on the seal. Also i flipped the seal on the inside of the fuel tank which helped. Btw thanks for the help.

 

[cbaker65]

No pipe pressure ,No fuel ,It will never start!

 

[olds97_lss]

Ah, it's not a savage either. Doesn't really matter, but explains the odd linkage and fuel tank. You need to replace the header gasket, that's not helping you at all. You said you can blow into the pressure line and see fuel moving, can you blow into the pressure line to the pipe to make sure it's not clogged as well?

 

[Geri]

Ah, it's not a savage either. Doesn't really matter, but explains the odd linkage and fuel tank. You need to replace the header gasket, that's not helping you at all. You said you can blow into the pressure line and see fuel moving, can you blow into the pressure line to the pipe to make sure it's not clogged as well?

Thanks for the suggestion. I can blow air in the pipe through the pressure line (its a little hard). If i block the outlet of the pipe i can feel the air escaping through the cracked seal. Probably thats the reason it doesn't work at all, right?

 

[olds97_lss]

It would probably be ok if it was running, but to prime the engine, it needs to be pretty well sealed. With it leaking, it makes a mess and likely makes it run a bit lean when your running WOT, but due to the rpm/exhaust flow of the running engine, you get enough pressure to help the fuel along. Might be a good idea to replace the header->pipe coupler and zipties as well, yours don't look overly healthy anymore.

 

[D3MON]

your LSN is backed very very far out btw, should be almost flush with the housing on that engine. (3 turns out from snug/closed)
just to cover all bases, that yellow fuel line shut off between the tank and the engine, that is not pinching the line is it?
that manifold gasket can definitely be enough to not allow it to prime right.
using the priming method of blocking the exhaust and pulling the engine over a few times, the system has to be pretty sealed up to generate pressure.

 

[cbaker65]

your LSN is backed very very far out btw, should be almost flush with the housing on that engine. (3 turns out from snug/closed)
just to cover all bases, that yellow fuel line shut off between the tank and the engine, that is not pinching the line is it?
that manifold gasket can definitely be enough to not allow it to prime right.
using the priming method of blocking the exhaust and pulling the engine over a few times, the system has to be pretty sealed up to generate pressure.

I was thinking the same on the Lsn being that far out!...?

 

[Geri]

I was thinking the same on the Lsn being that far out!...?

Thanks for the suggestion. I sealed the connection between the engine and exhaust pipe, now the engine primes easily, but... I was changing the glow plugs, and the thread on the block got wiped out. So now there is no thread, and the glow plug sits there (i had tighten it as much as i could) but the fuel comes out between the glow plug and the bad thread. I tried gluing it in, resulting in a successful priming, but after half a minute of trying to start the engine, some fuel and smoke came out from under the glow plug. Should i buy a repair kit for my engine, or buy a new part (i dont know how is it called, the part from the picture). Thanks for your help.

 

[Hwrd442]

https://www.hpiracing.com/assets/documents/instruction_manuals/i_1406_2_nitro_star_s_25_engine.pdf

 

[CrucialRC]

That sucks but it's a head button.

 

[cbaker65]

Thanks for the suggestion. I sealed the connection between the engine and exhaust pipe, now the engine primes easily, but... I was changing the glow plugs, and the thread on the block got wiped out. So now there is no thread, and the glow plug sits there (i had tighten it as much as i could) but the fuel comes out between the glow plug and the bad thread. I tried gluing it in, resulting in a successful priming, but after half a minute of trying to start the engine, some fuel and smoke came out from under the glow plug. Should i buy a repair kit for my engine, or buy a new part (i dont know how is it called, the part from the picture). Thanks for your help.

If the glow plug is still good ,you can JB weld it in ,they use JB weld as a filler when modding engines ,so it
sticks real well ,it has to cure for 24 hrs ,that will get you by until you find a new one!

Your not going to damage that one anymore than what it is ,I would give it a go!...