DB780 Injector pump troubleshooting

R_C

New User
I started my David Brown 780 to warm up a bit then shut down and replaced both fuel filters. I bleed according to the service manual order but I get no fuel at the injectors. I have air-free fuel at all bleed points but nothing at the injectors or the injector pump outlets. The fuel cut-off lever is open and the throttle wide open but no fuel from the injector pump while cranking the engine. I've gone through all the bleed points in order three or four times while using the fuel pump lever, captured fuel in a container to verify no air bubbles but still no luck. Here are the bleed points in order:

1. Vent plug between the two filters
2. Filter outlet
3. Injector pump vent plug #1
4. Injector pump vent plug #2
5. Injector pump inlet (from filter outlet)

I'm stumped. Any ideas? Thanks.
 
How long did you crank it with the high pressure lines at the injectors/pump cracked? Can take up to 30 seconds sometimes to get fuel there.

Was there a reason that you decided to change the filters? Like it quit running?
 
It was running just fine. It had been several years since I changed the fuel filters so I figured it was due.

I cranked it many times for what I thought would be sufficient time to get fuel to the injectors but maybe only 15-20 seconds each time. So I just tried it again and you are right it took probably 30 seconds but the fuel finally got there and now it's running just fine again. Thanks for the help.
 
Glad to hear it. 780s are fun little tractors, alot of power in a tiny little package. I use mine for real farmwork, square bale, grain drill, rake hay, run auger, 16' spring tooth harrow...

Amazing what it will do on a tiny bit of fuel. I just wish it rode better in the field.
 
I bought my 780 about a dozen years ago to replace a late 50's gas International Farmall that had plenty of problems. I use my 780 primarily for snow removal with a 5-foot blower and the front loader. The Farmall didn't have enough HP at the pto to drive that blower very well but the 780 does just fine and its multiple reverse speeds are very helpful. Early on I converted the 780's electrical to an alternator and it has really been a great tractor.

I'm a bit embarrassed that I didn't crank it longer after the filter change and bleed. Since it had been so long since I'd done the filter change I just figured I did something wrong. These forums are a great resource. Thanks again for your help.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top