B7800 will only run for a min but start back up?

[Rob 80]

My B7800 will run for a min and die and sometimes start back up leaving it sit for awhile seems to help.

Before it dies the exhaust will be darker and when i try to restart it turns over fine but it seems like the exhaust is darker.

It was working fine a week ago.

Could this be caused by water in the fuel? It has rained since i used it last but it never has been a issue in the past.

The tractor turns over fine just wont start.

Any advice?

 

[i7win7]

clogged vent in fuel cap? drain some fuel into jar, fuel floats on water

 

[Rob 80]

clogged vent in fuel cap? drain some fuel into jar, fuel floats on water

If i took off the fuel cap would it start if that was the issue?

 

[i7win7]

should. Water molecules could plug up fuel filter, thats what draining some and looking for separation is for.

 

[BigG]

Replace the fuel filter. You can’t look at it and judge it to be good or not. A water soaked one will look just like a diesel soaked one. They’re relatively inexpensive so the first thing you should do after checking for water in the diesel is to replace it.

 

[Rob 80]

Is what i am describing typical with water in the fuel? I removed the fuel cap no difference. The tractor did start but died shortly.

 

[Rob 80]

BP diesel by the way.

 

[woodman55]

Is what i am describing typical with water in the fuel? I removed the fuel cap no difference. The tractor did start but died shortly.

seeing that fuel, I would change the filter. Does it sputter, then stop, or stop like you turned off the key ? If the latter, could be a electrical issue.

 

[Dave_eng]

Assuming your B7800 has HSD.
Your engine is stopped under the control of an Operator Presence Controller and its internal timer.
Power is supplied to the stop solenoid of a running engine for just long enough to stop the engine otherwise there is no power to the stop solenoid.

Suggest you unplug the connector for the engine stop solenoid and see what happens. It may be that now you cannot stop the engine but this would be a big clue you have electrical issues not fuel issues.

This attached document has wiring diagram and OPC operating description.
Dave

 

[Rob 80]

seeing that fuel, I would change the filter. Does it sputter, then stop, or stop like you turned off the key ? If the latter, could be a electrical issue.

It sputters then stops.

 

[Rob 80]

Assuming your B7800 has HSD.
Your engine is stopped under the control of an Operator Presence Controller and its internal timer.
Power is supplied to the stop solenoid of a running engine for just long enough to stop the engine otherwise there is no power to the stop solenoid.

Suggest you unplug the connector for the engine stop solenoid and see what happens. It may be that now you cannot stop the engine but this would be a big clue you have electrical issues not fuel issues.

This attached document has wiring diagram and OPC operating description.
Dave

Thanks for that so does the fuel look ok?

 

[Henro]

My B7800 will run for a min and die and sometimes start back up leaving it sit for awhile seems to help.

Before it dies the exhaust will be darker and when i try to restart it turns over fine but it seems like the exhaust is darker.

It was working fine a week ago.

Could this be caused by water in the fuel? It has rained since i used it last but it never has been a issue in the past.

The tractor turns over fine just wont start.

Any advice?

By no means an expert in any way, shape or form...but I am wondering what the black exhaust smoke is telling us.

If I remember right, black smoke is a sign of excess fuel being burned, and white smoke is a sign of excess unburned fuel. I could be wrong. My memory is not what it used to be.

So the tractor is running, then it stops in a short amount of time, expelling black smoke from the exhaust during this moment. This does not sound like a fuel cut off issue, such as what would be caused by a improper operating fuel shutoff solenoid.

Is there any chance the air intake may be blocking somehow? Mouse nest in the air filter housing? Collapsing air filter element? Seems like if the air was cut off substantially, the control system might want to add fuel, to make up for dropping RPMs. Just a WAG to consider...

I have a B2910 that is essentially the same tractor as the B7800, so I am interested in you problem and whatever the solution turns out to be.

Edit: I guess it could also be an issue with the injector pump itself. Not sure of any other possibilities...hoping you find the solution soon...