No start -- 7845R

[bernardcuziillo]

I have a 2016 7845R that normally starts in a fraction of a second, barely time to let the key off. Intermittently, and now always, it won't even begin to start. The cranking sounds good and strong. This last time it started instantly but then quit in about 2 seconds and will not restart. My first hunch was no 12v to the fuel cut solenoid, but it looks like it's doing what it's supposed to.

Here's what I've check so far:
1. I spun off the fuel filter and everything looks clean.
2. I opened the bleeder on the bottom of the fuel filter. No water, air, or sediment came out. It streams out faster with the electric transfer pump running.
3. The fuel cut solenoid on the injection pump looks like it's pulling correctly with the key on. The injection pump is a "Motorpal" brand made in the Czech Republic. I suspect it's a Bosch design. (It's also not the one illustrated in the service manual.)
4. There were no leaks before I checked the fuel at the filter.
5. The filter housing has what seems to be a hand pump. After a few pumps with the electric transfer pump running, the transfer pump sound changes from clicking to nearly silent.
6. Fuel tank is half full.

I have the service and owner's manual.

What's are my troubleshooting steps from here?

 

[K5lwq]

When you try to restart, are you turning the key all the way to the off position then back to on, waiting for glow plugs the to start position? That should make it run for the 2 or 3 seconds.

I think the hold part of the fuel solenoid is not getting power by your description. Things to check are fuses, relay and connectors. I would check fuses first then use a test light to check power at the connector. Should be 3 wires going to the solenoid. One is ground. One gets power when you turn the key to the on position. The last one gets power after you go to the start position and back to on position. That is the one that powers the hold side of the solenoid.

 

[bernardcuziillo]

K5lwq: Thank you! Here's the next installment of my saga:

The fuel cut solenoid is just hot and ground. The connector is taped up like someone's been in there before--I got this tractor used. I tried pushing it with the key on to see if it went full travel and yes, it seem to pull all the way to a stop. (I do know what you mean about two-coil solenoids.)

After researching the glow plugs I've come to find out that this engine has an air heater and no glow plugs. But the function is the same, and the glow plug lamp does turn on for a couple seconds. But no joy. Also, it's above 70ºF here so I wouldn't expect it to need an assist. It always started instantly--unless it wouldn't start at all. I've attached a photo of the instrument panel.

There's no smoke in the exhaust during cranking, so I'm thinking that it's not getting fuel. And the throttle position makes no difference. Maybe something stuck in the injection pump?

 

[K5lwq]

This is a different design than what I was thinking so disregard my first post.

So does the fuel shut off move when the key is turned to the on position? I would think it should not move till the key was turned off.

I may be totally wrong and we may need to wait on some of the other guys to chime in, but the way I understand it works is fuel is on in its relaxed position. When you turn key to start position engine runs. The when you turn the key to the off position it sends power to the fuel cut off solenoid and it kills the engine. Then after a few seconds power is turned off to the solenoid and it should return back. So if I am right, then fuel should be on all the time. The only time it shuts off is when you turn the key off and that should be on a timer.

But I do agree that it is not getting fuel.

 

[ptsg]

I would get those injector lines nuts loosened at the injection pump (for ease of diagnostic, ideally would be on the injector end) and then try to crank the engine and see if the injection pump is actually pumping any fuel. While it won't give us a lead if it's the solenoid or the pump, it will tell us if it's not starting because of lack of fuel and not something else.

 

[LouNY]

Or disconnect the solenoid operator from the fuel lever, then operate the lever by hand and try starting with it in both positions.

 

[bernardcuziillo]

I disconnected two high pressure fuel lines and confirmed that it's not delivering fuel. Here's a video showing what it does:

 

[K5lwq]

I would next do what Lou suggested and disconnect the linkage from the fuel shut off solenoid and see if it will start.

 

[LouNY]

Is your electric fuel pump working?
Is yours a cab or rops model tractor, the cab tractor according to the manual has a 10 amp fuse for the fuel stop and feul pump, the rops has seperate 5 amp fuses for the fuel stop and fuel pump.
If you remove the rubber line at the injection pump does your hand priming pump get fuel to through that hose?
If you turn the key on but not to start can you hear of feel the electric fuel feed pump run?
With that line disconnected you should see lots of fuel flow with the key on but not started.
If the rubber line is then connected and the banjo bolt loosened that feeds the injection pump and key on you should get fuel out at that fitting.
The electric fuel pump appears to be in the rubber line feeding the fuel filter above and just ahead of the starter.

 

[LouNY]

The supposed wiring to the stop solenoid and fuel pump;