Fuel returns to fuel tank!!

[xmontalvoa]

Excuse my poor english.....i'll try to do my best.

I have a problem with the fuel, I pump it to the carburator but the fuel refuses to reach it, it simply returns in the fuel line.

I try moving the fuel line in several positions but the fuel always returns.

Pump...return...pump again, returns. When at the end start the savage; then when I stop the motor; the fuel return again and the same problem repeats.

Even with the rotostart, I see that the fuel coming to the carburator while cranking, but when it reach the carburator, the fuel returns in the fuel line an inch or so like if something loss presure and air comes in in wrong direction..

I search for air leaks in the carburator and don't found nothing; I see if the fuel tanks was broken or something and not is in perfect condition (the o-ring in the cap is OK). I take appart the exhaust and clean it inside but all appears to be OK....

What do you think I can do?

Help me please. Thanks

 

[Çh®i§tiªñ]

Your exhaust/pressure line is either plugged or pinched.

What is happening is it is not getting air from the backpressure line at all. You can check on the lid itself as well and make sure there isnt a blockage their either.

A couple tests you can do are as follows: (use NEW line to do this)

1. Disconnect the backpressure line from the exhaust and blow through it. You should see fuel go to the carb. If so, the problem is not on the tank side.

2. Disconnect the backpressure line from the tank and blow through it. You should hear the air going through the exhaust and it should be easy.

Hope this helps!

 

[LarryA]

Or the tank is not holding the pressure due to lid not sealing or primer leaking air.

 

[xmontalvoa]

Ok, i'll do both tests.....and post the results ASAP to get your comments.

How to test the tank cap o-ring? or primer button for airl leaks?

Does anyone have a picture of the fuel lines running to the carb and exhaust?

Any other tests recommended?

Thanks Çh®i§tiªñ and LarryA

 

[Çh®i§tiªñ]

When you do the blow test to the tank (with the backpressure line disconnected from the pipe) you will see the fuel travel to the carb. When the fuel gets to the carb, pinch the backpressure line you were just blowing into. If the fuel still comes back to the tank, then you more than likely have a leaky primer or lid. The way I test the tank itself is to disconnect the fuel line at the carb and the backpressure line at the pipe. Pinch either one closed and blow into the other one. You should be able to feel and or hear the leak. If you can submerge the tank under water when doing that test, you will see the air escape from wherever the leak is.

 

[xmontalvoa]

I do the tests and everything seems ok, backpressure line is free, tank is holding pressure, i submerge the tank in water and blow over 1 line with the other pinched and there is no bubbles....

When i press the primer, the nitro goes to the carb when I release the primer nitro backs his way....

What else could be? Some ideas?

Thanks....

 

[Çh®i§tiªñ]

The Carb itself is possibly either clogged or has a severe leak.

You want to do pretty much the same test except this time with the carb. First and foremost, make sure the carb is seated properly so there are no air leaks. If it is seated properly THEN pressure test it. I'm almost wondering if your low speed needle is closed or clogged.

To pressure test the carb, remove it from the engine and remove the air filter. Then, connect a piece of fuel tubing to the carb like normal. Hold your pointer finger over the top of the carb and your thumb on the bottom. With your other hand, hold the fuel tubing and blow into it. You will hear and feel a leak if one is there. Now, remove your finger and blow into it. You should hear the air enterring the carb. If not, the needle is either clogged or closed too far.

Have you had this engine running before?

 

[xmontalvoa]

Yes the engine has been running before, I already do the break-in and run it for a while after break in.

I believe that maybe the problem is in there (carburator) because after break-in I have several issues with carburation and by mistake I move the middle speed needle (the low speed needle move it when I tight it), then I do a 'reset' procedure and works ok, but the fuel trouble are always present.

What do you recommend, another 'reset' to the carburator? please give me your advice in this procedure.

By the way, I'll check first for leaks in carburator and then maybe I'll do the reset.

Thanks in advance!!!

P.S: Which glow plugs do do recommend for the savage?

Originally posted by Çh®i§tiªñ
The Carb itself is possibly either clogged or has a severe leak.

...low speed needle is closed or clogged.

...If not, the needle is either clogged or closed too far.

The last needle that you refer is the low speed, right?

Thanks

 

[Çh®i§tiªñ]

Yes, the low speed needle is the one on the barrel itself. NOT the big gold one. Thats the mid mixture and shouldnt really be touched unless you know what you are doing.

The High speed needle is the one you can see looking at it from above.

You can do a reset, and when you are done resetting them, just turn the High Speed needle in 1/4 turn from there. That should get you where you need to be. Also, with the brake applied, you should be able to look into the carb and see a 2mm opening. Thats what controls your idle. If that is closed when you are sitting there you could prevent it from getting fuel as well.

 

[xmontalvoa]

Originally posted by Çh®i§tiªñ
Yes, the low speed needle is the one on the barrel itself. NOT the big gold one. Thats the mid mixture and shouldnt really be touched unless you know what you are doing.

The High speed needle is the one you can see looking at it from above.

You can do a reset, and when you are done resetting them, just turn the High Speed needle in 1/4 turn from there. That should get you where you need to be. Also, with the brake applied, you should be able to look into the carb and see a 2mm opening. Thats what controls your idle. If that is closed when you are sitting there you could prevent it from getting fuel as well.

1/4 turn in the high speed needle to rich or lean after resetting carburator?

In other forum, somebody has problems maintaing the fuel pressure, the issue was because he has a crack in the High Speed Neddle holder....today I'm gonna check the carburator as you told me above.....if everything seems ok i'll do a reset...

 

[Çh®i§tiªñ]

1/4 turn IN to lean the mixture once you are back to factory.

 

[xmontalvoa]

I pressure test the carburator and found that when the carb is closed it has an air leak in the low speed needle, when open no leak is vivible. I take away the purple cover and see that the barrel has a thin line than when open does not permit to pass air, but when carb is closed it connects the exterior to the interior.

I believe this is normal.

I reset carburator and willl test to see what new happens....Nothing abnormal was found neither in fuel tank (primer, cap), fuel tubes, carburator....seems realy weird....

What do you think about air leaking in the LSN when carb is closed and not when open ?????

Thanks

 

[Çh®i§tiªñ]

You can completely unscrew both the HSN and LSN and check to make sure the o-rings are seated properly. You may also want to wash everything up with some denatured alcohol to be on the safe side. If your idle is set right, you will hear some air coming in with the barrel closed.

 

[xmontalvoa]

I assemble everything again, reset carburator, install a hump pack that I have pending, put an home made central skid plate....put some nitro and start my savage....seems ok, it runs on idle a have smooth acceleration; I wait till I have no more nitro on the tank and savage turns off by it self.

When I clean and reset carburator, I put just a little grease in the bottom part of carburator to stop any air leak and in the LSD too.

Next weekend I'll do more extensive tests in low speed and high speed....and I'll do the break-in of a 'Dirt Demon' that I buy for a friend in eBay (with his money) and I will receive it this thursday.

Thanks again and i'll post my findings on my Savage and my opinions on my friend's 'Dirt Demon'.......

 

[cpunchin]

I also had the same problem. I rearranged the fuel line so that more gravity goes into the carb...