When I hit the emergency stop on the platform control panel, the motor dies but then will rev up . It never dies it will keep doing this. Is the emerg . stop circuit supposed to ground the coil or does it cut fuel. I need to correct this as it doesn't allow me to shut down the motor if I'm going to be stationary , like painting.
Welcome to the forum mark3885. :usa Gasoline engine 40H?
yes , LSG 423
Yep, what I thought. The reason your engine doesn't shut down is because of a problem with the anti dieseling solenoid on the carburetor. The anti diesel solenoid stops fuel flowing through main jet of carb and kills engine. When you hit E stop button, it takes away power from choke heater and anti diesel solenoid. The E stop kills power to ignition coil pack as well, but it will continue to run from voltage input from alternator on ignition circuit. The anti diesel solenoid has to work proper to kill the engine or it will continue run when E stop is pushed in. You can remove the solenoid from the carb and test its operation using jumper leads to a battery. It may be stuck from varnish build up. Use some carb cleaner on plunger pin as you work it in and out of solenoid body if it's stuck, then test it again with jumper leads. You need to get the plunger pin to where it will pop in and out when power is applied then taken away. And the rubber seat at the tip of the plunger pin needs to be in good shape as well.
I just rebuilt the carb, so the inside and out are clean as a whistle. I'll have to check the solenoid. So I would assume that shutting off the master switch , will kill all power to the engine, this is the only way I can shut it down.
I'd have to look over schematics to see exactly how the master switch works. All I know is, on the Ford VSG411 and LRG423, when you hit the E stop, it takes power away from the anti diesel solenoid on the carb. The engine will run for a short moment, then die because the fuel flow through the main jet of carb is cut off. If that solenoid isn't working properly, the engine will continue to run, or, "diesel".
any conclusion? mine is doing the same thing.. was it the solenoid? thanks any conclusion? mine is doing the same thing.. was it the solenoid? thanks
Welcome to the forum cnckieth. :usa It's pretty easy to check the operation of the anti-dieseling solenoid. It's a round cartridge looking gizmo located at the base of the float bowl on the carb, has a single wire going to it. With the engine running, connect a test light or a volt meter to the wire connection terminal on the solenoid, it should have power. Then shut of ignition, power should go off. If it doesn't, you have some form of wiring problem. If power does go off, and engine continues running, the pintle of the solenoid is likely stuck. I see it quite often with the alcohol gas we have now days.
thanks for the fast reply.. i'll check it tonight and report back thanks for the fast reply.. i'll check it tonight and report back is there a jlg 40h dedicated forum? or am i in the right place? i've fixed my own cars all my life, but being new to the JLG, i've got a few questions and a few mysteries to solve about the machine.
Well, there's no particular forum thread dedicated to a 40H, no harm in posting your questions here. There's a JLG 40F thread that has grown huge and has become a single information resource for the 40F. It's your choice, you can either continue posting here, or you can start your own thread when you become a Junior Member.
new test data for the 40h not shutting off.. Ok.. here is what i found out.... While the engine is running there is 13.5 volts on the fuel cut off solenoid. when the ignition on the ground controls is switched off.. the voltage drops to 12.75 (note: which perfectly matches the battery voltage while the engine is NOT running) this is also repeated when using the platform controls, while running 13.5, and press the E stop button and it drops to 12.75. so apparently the battery voltage is not being cut off from the solenoid when the estop on the platform or ignition on the ground control is in the OFF position. and the engine continues to run.... the only way i can turn it off is the switch from the Gasoline to LP setting on the fuel select switch.. and the volt meter shows 0 volts when this is done and the engine shuts off.. fine for ground controls.. but no way to shut off when you are in the air:-( does anyone have a starting place for me to look for this wiring problem? does this sound like a relay related issue to you'all? and is there anywhere on line to download a 1998 40H wiring diagram? thanks in advance for any input!
I guess I should have asked, does your 40H have the Ford LRG423 four cyl dual fuel engine? You can download operators, parts, and service manuals at JLG website, although the service manuals aren't very informative. The wiring and hyd diagrams are in both the parts and service manuals. Go to www.jlg.com When the home page opens, click "Services" in the left column. When that link opens a new page, click on "Parts, Operators, and Service Manuals" in the left column. That will take you to a PDF download page, simply select JLG and you machine model.
40h not shutting off yes.. its a ford lrg dual fuel. thanks for the tip on the jlg site, that's cool they still have that stuff up there. without seeing the wiring diagram it sounds like a relay related issue since it exhibits the same problem from both the ground and platform controls, does that makes sense you'all? has anyone else seen and solved this one? thanks.
My first thought was an alternator problem keeping ignition circuit powered up, but that can't be the case if you can flip the fuel switch to the center position and engine will die. What happens when you flip that switch to center position is it turns off fuel flow to fuel pump via a solenoid valve in fuel line. Engine runs until carb runs out of fuel. Alternator ign terminal, fuel pump shut off solenoid, anti diesel solenoid, and choke are kinda on the same circuit. I think the next thing I would try, with engine running, would be pull the yellow wire connected to terminal 86 on R18 and R19 ignition relays in lower control box. If engine dies, go back through the wiring to determine why that circuit remains powered when ignition switch is off. If engine continues running when you pull the wire connected to 86 on R18 and R19, you either have a stuck relay or something is wired up wrong.
Ok.. to "solve" the problem, i cut the wire going to the solenoid and ran a new wire to the "on" side of the ignition relay. (power on when ignition switch is on). I could never figure out why the solenoid had power to it when the ignition switch is in the off position. one hint may be the fact that the hour meter is also on and running while the ignition switch is in the off positions (and the master switch on). anyways its running and working now. thanks for this forum, and thanks to willie59 for the hints.
Ok, I need to ask a few questions. You cut the wire going to anti-dieseling solenoid on base of carb, and ran a new wire to "on" side of ignition relay. Take a look at this diagram, there should be 2 ignition relays (shown in red box), is one of these the relay you connected wire to? If so, which terminal did you connect to? Also, if you only ran a wire to the anti-diesel solenoid, what about the carb choke, fuel pump cutoff solenoid, and 5 degree tilt sensor, these components run off the same circuit as the anti-diesel solenoid.
Hello. I connected the fuel cut off solenoid to the bottom yellow (86) on R19. I didn't disconnect the carb choke, degree sensor or anything else.. i isolated the solenoid from the circuit that those items where on since that circuit was causing the problem. those items seem not to effect the operation of the machine if they have power to them while the ignition switch is off. i know this solution is not ideal.. really the reason why power is on in that circuit with the ignition in the ON position should be solved to get things back to 'normal'. But isolating the fuel cut off solenoid from the problem circuit seemed like an acceptable work around with no detrimental side effects. thanks.
Well, that would kill the solenoid when you turned ignition off, at least it should. The yellow wire connected to 86 on relay 18 and 19 comes from the upper and lower ignition switches depending on the position of the upper/lower select switch. If that kills the solenoid, at least you can figure that circuit is working proper. As long as you have no detrimental side effects, I would say work it that way. If you have any other questions, ask away.
yeah.. it works great.. I was using the machine today.. so happy that i can now shut the engine off from the platform. on another note.. can you tell me what the "creep" switch on the platform control panel does?
The creep switch provides very slow operation of basket functions that are controlled by PQ proportional controllers. This would include drive, boom up/dwn, swing, and telescope if telescope uses a PQ controller instead of toggle switch control.
ok..thanks.. it didn't seem to do anything today while i was testing things out ...all other functions work as they should. i'll give it a try tomorrow, got some trees to trim.
The creep function is handy when you have boom extended a good bit, it allows you to move boom functions with a long boom and not get fast movement, which can be undesirable when you're near things with the basket. With all the functions that are controlled by a PQ controller, you should be able to stroke the controller fully, giving fast movement, then flip the creep switch. You should notice a radical slow down of that function. If it's not working, that circuit is either not getting power, or the PQ controllers are not adjusted properly.
cool thanks for the info.. you made me think of one other odd thing.. the lift up down control stick on the platform works.. but i have to hold the stick just a little off it maximum travel or the movement will stop. is there an adjustment somewhere to fix that? .. i can live with it but every once and a while i move the stick to full travel and the lifting action comes to a jerky stop and will resume when i back the stick off max travel a little. I attached a few photos.. she won't win any beauty contests..
Nice machine, 4WD with articulating steer axle. Sounds like you may have a faulty PQ controller, not unusual. First thing I would do is pop the lid open at the upper controls, disconnect the boom controller from the harness plug connection, and connect the boom harness to the swing controller. You can then connect the boom controller to the swing harness. Operate those two functions and see if the boom now operates proper and the swing operates goofy. This would confirm the problem is with the PQ controller and not a wiring issue. The PQ controllers have operation adjustments. There should be 4 trim pots with adjustments screws labeled something like Lo, Hi, Mid (or Threshold), and Ramp. It takes a very small flat head screwdriver to adjust trim pots. The first thing you do is back off all trim pot screws by turning them CCW. Those are 32 turn trim screws for full adjustment range, but most likely each trim adjustment will be somewhere in between 0 and 32 turns already. You need to be in a real quite place when backing off screws. Turn each screw CCW until you hear a faint "click click" when rotating each screw. That sound is the adjustment at it's end. Don't continue turning much after hearing those clicks. Do this to each trim pot adjustment and you're ready to adjust controller. Let's start with boom up/dwn controller. Have boom fully retracted, start engine. Depress foot switch and move boom up control lever about 15 degrees, what's called "notch off center", and hold the control lever in that position. Adjust Lo trim pot CW until boom just starts to get a boom up movement, no more. Then, with boom up lever fully stroked, adjust Hi trim pot CW. At a certain point of adjustment, boom operation will speed up as screw is turned. Adjust screw CW until boom speed no longer gets faster, stop there. Now, bring the basket back near ground and extend the boom a good bit, long boom. Flip the creep switch to creep position. Fully stroke boom up control. Adjust Mid (Threshold) screw CW until you get a desired slow boom operation speed. Lastly, turn off creep switch, fully retract the boom, and turn the Ramp screw in about 10 turns for pre-adjustment. Fully stroke boom up controller to make boom move at full speed, then simply let it go so it returns to center. If boom abruptly stops, adjust Ramp screw a few more turns CW, try again. At some point of adjustment, boom up will no longer stop abruptly, but instead will drift for a moment and come to a slow stop when controller is released. Once you reach that point, adjust Ramp in or out to get desired power down that doesn't cause abrupt stop of boom movement nor does it drift excessively. This adjustment procedure applies to each function controlled by PQ controllers. If the adjustments won't work out, PQ controller is faulty and needs replacement.
awesome!!!,, thanks so much for taking the time to explain that, i've printed it out and will give it a go this evening after work.
Hello . anybody ever experience backfire problems with the ford duel fuel 40H? it has an electronic ign. once the machine is up to operating temperature it coughs and sputters and backfires through the exhaust . does it on gas and propane.
I have a JLG 40 HA also it just started to act up the other day when step on the boom control in the bucket the gas motor throttles wide open. A tech told me to replace the governor didn't so a thing. Any body have an idea where I look next?
I have a JLG 40HA, Deutz Diesel, bang bang controls. When I step on the foot pedal, mine does the same. I think that the idea is that when you need a function, you have to step on the pedal anyway, so why rev up when you're not moving? The electric actuator moving a cable to the throttle is what makes mine increase in rpm. So, maybe start by seeing if the linkage got tighter, or cable kinked, or rusted up. Sounds like it might be revving too much, which is an adjustment......but why did it change? Or, is the command to have high throttle stuck on all the time? Mine has no computer, just switches and relays, so it's possible to troubleshoot stuff like this, especially if the fault isn't intermittent. But, like I said, on mine, when HI engine speed switch is on, it revs up when you push the pedal, even if you're not actuating any controls.
Hi there I have 1989 JLG 40H that was running normal then suddenly the RPM went to maximum high. I shut if off with the master switch and the engine rattled and died. Moments later I restarted it and RPM went super high again. After that I can’t restart the engine anymore and ignition coil has no spark. Does anyone know if it’s caused by electric governor or electric spark controller or is it something else malfunctioning. I would appreciate some feedback. Thank you
This is a great thread! Thanks for all the good info here. I'm having a lot of the same problems with my JLG as well!
Hello all. I have a jlg 40h also. It's not the prettiest of machines. I was having problems with the drive. I recently got a new joystick. But now when I move a wheel goes into a small pothole the drive stops completely. Normally before I replaced the joystick when I lowered the boom it would reset and I would be able to move again. But instead now I have to mess around with the level thing lunder the boomn while getting someone to move the lever if this makes sense. I was wondering would the little screw adjustment on the pq joystick need some adjustments
Those little screws are called "Trim Pots" by the manufacturer. Trim pot #1 is marked "Low" it controls the voltage at which the controller first turns on, becomes active. Trim pot #2 is called "Ramp" is is the amount of delay or how long it takes for the controller to react to changes. Think of it as slow start/slow stop. Trim pot #3 is "Hi" and it is the hi voltage setting, maximum voltage when controller is fully on. Actually they measure it all in milliamps so it's current, not voltage.
Here's the adjustment procedure, but I'm not convinced the controller is your problem. Even what you described before replacing the controller seems odd.
I have 4 adjustments screws, I was messing around with the one furthest away as I'm standing in the basket, think it's the ramp one, and got it to work