Cranks but won't start. Injection pump needs electrical power?

[slimcity9]

This regards a TYM 550 that was running fine, then after sitting a couple weeks would crank but not fire at all. I replaced the fuel filter and bled it. The only thing I've found so far that seems suspicious is the lack of voltage on the single wire to the injection pump when the ignition is in the On or the Start position. In the wiring schematic the single wire is labeled E/G STOP. Would this be for a fuel control solenoid? There's some added wiring complexity at the pump itself, with two wires routed around to a different connector on the back of the pump, and also two wires going to what appears to be a sensor mounted in the engine. What is this? In any case, is it reasonable to assume that the injection pump should have electrical power in normal operation?

 

[the old grind]

I had tractor electrics go haywire ('04 pre-tier NH TC33DA) to the point of no voltage to the injection pump. Until I come up with a fix or a new inst cluster I just ran a jumper to the pump and connect it before starting up. (turning the key on & the starter works w/o jumping at the start solenoid) I'm using a battery charger clamp at the battery & hear a click so I know it's working. The solenoid is a continuous duty bit and won't burn up or anything. When I shut down I turn off the key, then disconnect the jumper to stop the engine. It's been this way for a year now and there's surely a permanent fix, but I'm not in a rush and I use the tractor for flail mowing every other week or so.

 

[Williy]

I think this is for a TYM 553 but you should be
able to get an idea of what wires go where:

Drawing For Fixing Position Of The Fuse; Wiring Diagram Of The Electric Instrument - TYM T433 Operator's Manual [Page 114]

TYM T433 Manual Online: drawing for fixing position of the fuse, Wiring Diagram Of The Electric Instrument. Wiring Diagram Of The Electric Instrument 1. Panel 2. Light, Horn 3. Working Light 4. Stop Lamp 5. Turn Signal 5. Turn Signal 6. Controler 7. Engine Stop 8. Fuel Pump 9. Coupler...

www.manualslib.com

willy

 

[grsthegreat]

not sure on the tym, but most tractors ive worked on have a stop relay also. if the relay is toast, you wont get voltage to the solenoid.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjnhu6Nm4bxAhU0NX0KHa68Af8QFjAAegQIBRAD&url=https%3A%2F%2Fadam-bowker-j6je.squarespace.com%2Fs%2FT433-T503-T553-Workshop.pdf&usg=AOvVaw0TP-HBmC6bhkgDnGCwGWPO

the link above is a worksho manual for your tractor. im not sure if your safety switches inturrupt stop solenoid circuit

 

[slimcity9]

I had tractor electrics go haywire ('04 pre-tier NH TC33DA) to the point of no voltage to the injection pump. Until I come up with a fix or a new inst cluster I just ran a jumper to the pump and connect it before starting up. (turning the key on & the starter works w/o jumping at the start solenoid) I'm using a battery charger clamp at the battery & hear a click so I know it's working. The solenoid is a continuous duty bit and won't burn up or anything. When I shut down I turn off the key, then disconnect the jumper to stop the engine. It's been this way for a year now and there's surely a permanent fix, but I'm not in a rush and I use the tractor for flail mowing every other week or so.

Thanks for that. I was wondering if I could try applying—fused—power directly to the injection pump—after disconnecting the original wire—but want to be sure I won't fry anything.

 

[slimcity9]

I think this is for a TYM 553 but you should be
able to get an idea of what wires go where:

Drawing For Fixing Position Of The Fuse; Wiring Diagram Of The Electric Instrument - TYM T433 Operator's Manual [Page 114]

TYM T433 Manual Online: drawing for fixing position of the fuse, Wiring Diagram Of The Electric Instrument. Wiring Diagram Of The Electric Instrument 1. Panel 2. Light, Horn 3. Working Light 4. Stop Lamp 5. Turn Signal 5. Turn Signal 6. Controler 7. Engine Stop 8. Fuel Pump 9. Coupler...

www.manualslib.com

willy

Much appreciated. The PDF schematic is a lot more readable than my paper manual and clears up some things. Although the 550 doesn't have a separate electric fuel pump, much of the circuitry is very similar.

 

[slimcity9]

not sure on the tym, but most tractors ive worked on have a stop relay also. if the relay is toast, you wont get voltage to the solenoid.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjnhu6Nm4bxAhU0NX0KHa68Af8QFjAAegQIBRAD&url=https%3A%2F%2Fadam-bowker-j6je.squarespace.com%2Fs%2FT433-T503-T553-Workshop.pdf&usg=AOvVaw0TP-HBmC6bhkgDnGCwGWPO

the link above is a worksho manual for your tractor. im not sure if your safety switches inturrupt stop solenoid circuit

It appears that in the 550 as well as these later models there is a direct path for power through the ignition switch to the injection pump. I believe the safety interlocks prevent cranking of the engine, which is why I've been assuming they are not the issue. I've been bitten in the past when the PTO switch gets bumped into "Auto", and nothing at all happens when you try to start the engine.

In any case, I'm now sufficiently emboldened to try powering the injection pump electronics directly. I will report back when I've given this a try. Thanks to all for the guidance.

 

[the old grind]

I was wondering if I could try applying—fused—power directly to the injection pump—after disconnecting the original wire—but want to be sure I won't fry anything.

I'm sure it would be a first if anything went amiss. I put a spade connector on the jumper for the shutoff solenoid and routed it up to the battery area. When I disconnect I just move the clamp over to the hold down bracket. It's worth opening the hood at startup and shutdown to not have a hot wire dangling anywhere. btw, I'd wish someone luck in trying to steal the 33 even as it sits outdoors with the key in it. Not much different than having a remote shutoff for theft prevention.

 

[slimcity9]

I'll blame my assistant for thinking a visual inspection of the fuses was sufficient. I went back and tested them and sure enough one was blown. I replaced it and it promptly blew again. So now I've got a short to track down. Or I could opt for that bypass solution. But there is one other thing on the circuit. It's supplying power to a "Harness PTO", which seems to have wires going to the meter panel. It may be that I'll need to fix it properly if I want the PTO working.

 

[slimcity9]

I could use some more help with this. The short is not in the peripheral wiring. Instead the pump circuit itself is drawing too much power. There are two sub-circuits: one appears to be the main fuel-control solenoid, and is ok—powering this alone allows the tractor to start and run. The other circuit has power going through an engine sensor and into a component mounted on the injection pump. If I directly feed this circuit power it's already drawing 6 amps at 5 volts, so clearly it's blowing the 10 amp fuse when full battery power is used. My questions: What is this circuit? Is it a protective element to kill the engine if there's overheating? Or something to do with fuel regulation? I'd like to know if it's safe to run the tractor without this, or if I need to first identify the faulty component and replace it?

I'm attaching pictures of the possible sensor and pump control.