Oil & Fuel JD 790 cranking but not starting

[fl790deere]

All, I have a JD 790 4WD with 225 hours that has just developed a starting problem. Engine cranks, but does not start. I have checked a few things already, all the fuses look good, fuel filter is reasonably clean. Battery posts have some minor corrosion, but not bad at all. I will clean those tomorrow just in case, but the engine seems to be getting plenty of juice from the battery. Before I start messing with the fuel solenoid/relay is there anything else I should check out? Thanks!

 

[Muxster]

With the "ignition" on you should be able to hear the fuel pump chattering.

 

[fl790deere]

I think I can hear it about 2 sec after key is on. I should mention that the tractor has not been started for maybe six months. Definitely acts like it is not getting fuel, no smoke etc.. Engine turns over very easily.

 

[Tx Jim]

Fuel inj pump has a solenoid that must get elect. to open to allow fuel to pump to injectors. Do you have good fuel flow to inj pump?

 

[fl790deere]

Hi Jim, At this point I dont know. Does the solenoid have its own fuse not in the fusebox? Have owners manual, service manual on the way. I believe I see a cable running to it, does not look like there is an easy way to check and see if it has voltage.

 

[Flywheel]

Sounds like a fuel problem - as mentioned

In my experience - it is rare for many of these components to go out - but the main one would be the pump.

If you turn on the ignition - you should be able to hear and feel the pump working as well as fuel recycling back to the tank.

Try opening the the fuel bowl drain with the pump on. It should be pumping out.

if it just drains or nothing comes out - then you need to inspect a couple of areas:

1) fuses
2) Pump
3) solenoid
4) fuel supply


I had a similar issue due to a piece of plastic bag getting into the fuel tank from a can (bag was used to plug the spout - but fell in)

May want to get a strong flashlight and look in the tank for obstruction - the fuel tank outlet is on the driver's right rear of the tank.

Post update - it is likely something simple

 

[Soundguy]

if no smoke, and turgning over good.. then no fuel.. I think I'd pull the key-off/fuel solenoid and look for a stuck plunger or similar.. or even bad wireing to the thing.

soundguy

 

[RoyJackson]

if no smoke, and turgning over good.. then no fuel.. I think I'd pull the key-off/fuel solenoid and look for a stuck plunger or similar.. or even bad wireing to the thing.

soundguy

Bad or corroded ground is always a possibility.

However, I had a similar situation on a 790 a few years ago...cranked fine, but no start.
Fuel system was fine and, in the case it was a bad ground or terminal end (can't recall which). I messed around with the tractor for a couple weeks (and I'm the first to admit I am not an Electrical Wizard!!). Took a Deere tech a few days to find that solution.

 

[Wayne_H]

If it sat for six months, what are the chances are your battery is down a bit? Diesels need to crank over enthusiastically to start.... If the battery is a bit low it will still crank but never start. Does smoke come out of the exhaust when you crank it? Another indication it is trying to fire but not spinning fast enough.

Wayne

 

[guillory]

I have the same problem with a Ztrac 797. I can pour gas where the the breather is and it will run a little. If i hook the fuel pump staight to the battery the fuel pump will work but engine will not run still. Fuel pump will not work hooked to the wires that are for it.