Stall upon applying brake

raymond

Member
Messages
21
This 4.6 is honestly driving me crazy.

Whenever I brake it keeps stalling no matter the settings.
The idle gap is ok, I have checked it. When I apply the brake, the carb is closing. Is this normal?
The engine was broken in not long ago. It's barely seen any use.
I have tried so many different tuning settings but nothing seems to be working.
 

olds97_lss

Well-Known Member
Messages
2,067
Location
Dekalb, IL 60115
When you move the throttle on the remote from idle to brake, the carb shouldn't move. The idle set screw should be adjust to hold it in that spot. The split servo saver thing is what gives to allow the servo to pull the brake lever while the throttle arm isn't allowed to move due to the carb stopping it.

So, either your idle set screw is set wrong or your clutch springs are bad and the clutch is dragging/killing the engine when you get that low of RPM or the clutch bearings are seizing and killing the engine when it gets that low of RPM.

I'd start by checking the idle set screw.
 

raymond

Member
Messages
21
Thanks for your reply bud. I think the clutch is fine since it's new but I cannot be too sure. I will check the idle screw and write back.
Thanks again
 

raymond

Member
Messages
21
When you move the throttle on the remote from idle to brake, the carb shouldn't move. The idle set screw should be adjust to hold it in that spot. The split servo saver thing is what gives to allow the servo to pull the brake lever while the throttle arm isn't allowed to move due to the carb stopping it.

So, either your idle set screw is set wrong or your clutch springs are bad and the clutch is dragging/killing the engine when you get that low of RPM or the clutch bearings are seizing and killing the engine when it gets that low of RPM.

I'd start by checking the idle set screw.
Seems to have worked although I cannot try it as it is late at night. The carb is not closing when I brake.
I will try it first thing in the morning and let you know :)
I didn't really know that the idle screw holds it in that spot. I probably gotta play with the LSN and HSN now.
Thanks man.
 

olds97_lss

Well-Known Member
Messages
2,067
Location
Dekalb, IL 60115
Yep. That's the idle screws job. What you want is to have the throttle/brake servo so that when it's at home/idle, it has bumped the throttle slide up against the idle set screw and is applying a bit of pressure. When you apply brake, the engine note/rpm shouldn't change at all from "idle" on the transmitter to full brake as the idle set screw is doing it's job.
 

raymond

Member
Messages
21
Yep. That's the idle screws job. What you want is to have the throttle/brake servo so that when it's at home/idle, it has bumped the throttle slide up against the idle set screw and is applying a bit of pressure. When you apply brake, the engine note/rpm shouldn't change at all from "idle" on the transmitter to full brake as the idle set screw is doing it's job.
I have finally got it running, although I think it's a little too rich as it sometimes stalls when given gas at a slope.
Thanks again.
 

InTheZone

Active Member
Messages
75
1. Set needles to factory settings
2. With a good glow plug installed, start the engine
3. Get the engine up to temps
4. Tune HSN, do not proceed until this is spot on
5. Tune LSN, do not proceed until this is spot on.
6. Adjust idle

Follow the tuning order and you'll be good to go. At no point should the carb close completely and when you're done tuning it should never close any amount from idle to brake.
 

raymond

Member
Messages
21
1. Set needles to factory settings
2. With a good glow plug installed, start the engine
3. Get the engine up to temps
4. Tune HSN, do not proceed until this is spot on
5. Tune LSN, do not proceed until this is spot on.
6. Adjust idle

Follow the tuning order and you'll be good to go. At no point should the carb close completely and when you're done tuning it should never close any amount from idle to brake.
Hello :)

Good thing you replied because this thing has been giving me problems non-stop and it's driving me crazy.
It's always too rich, no matter what I do.
If I set the LSN, it's too rich and it stalls when I give it gas.
If I set the idle, nothing much seems to be happening, or maybe I'm imagining things.
If I set the HSN, nothing much seems to happen as well.

I'll try what you told me to and I'll let you know.

Another question. After using the truck I keep seeing dust buildup from the clutch. Is this normal?
How much does the clutch usually last on these things?
 

raymond

Member
Messages
21
After I would say like 1 million tries, I got this thing running. Made sure to read almost every article and watch many videos. It seems to be keeping the settings just fine but needs a new glow plug because it sometimes turns off upon removing the igniter. I was able to counter this by giving it a little gas when starting it (off the ground, I always start it off the ground no matter what). I am going to be honest, I did check the glow plug I used for the break in and it did seem fine and glows as it should too.

Thank you.
 

olds97_lss

Well-Known Member
Messages
2,067
Location
Dekalb, IL 60115
I pretty much always give a bit of throttle when starting any nitro. You could be a bit on the rich side which is why it's flaming out when you remove the heater. I usually leave mine on the engine for a bit after it's running until I blip the throttle a couple times.
 

Savagebeast93

Member
Messages
33
This 4.6 is honestly driving me crazy.

Whenever I brake it keeps stalling no matter the settings.
The idle gap is ok, I have checked it. When I apply the brake, the carb is closing. Is this normal?
The engine was broken in not long ago. It's barely seen any use.
I have tried so many different tuning settings but nothing seems to be working.

I had this exact problem. If the idle set screw isn’t helping it’s because the throttle linkage isn’t set up right to the servo. In order to fix this, unscrew the nut that holds the linkage/servo horn on the top of the servo. Once it is off, set the throttle trim on your remote for dead centre. Now put the servo horn/linkage back onto the the top of the servo but MAKE SURE that it slots in in a position where the carb slide is completely closed to the idle gap. In other words. The whole horn has to be rotated by a few teeth so it isn’t opening the carb up when in a central or reversed position (ie, taking your finger off the throttle or braking) .....

After you’ve positioned it correctly, screw the whole thing back on, this should solve your problem. Nothing to do with the clutch as mentioned above. If your clutch was the problem the car would take a lot of throttle to even get it to move, or it would be doing the opposite and running without you even touching the throttle and even after adjusting the idle screw.

If it is the throttle linkage that’s the problem you can screw the idle screw in all day long and as far as it can go in and out and it will not fix the problem. Also make sure that you don’t have the idle screw backed out so far that it isn’t even catching the carb slide because this will cause problems once the linkage is set back probably in place.

Hope this help!
 
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