I've got a 2016 farmall 70a that throws a code 3808 after you run it for a while and return to idle. Last night I took the primary fuel filter base apart and cleaned it and blew the line to the tank out and it didn't help anything. Any ideas?
There was an update to the ADIC (instrument cluster) that was supposed to help with the issue of tractor randomly reverting from operating RPM down to idle, not sure if that code relates to it or if you're describing that particular issue. Need to have your dealer run your SN to see if the update has been done. Seems like it was corrected from the factory on 2016 or 2017 models forward, can't remember for sure. Best to check it out. It is simple to fix, dealer just plugs in computer and does the update. Only takes 20 minutes or so. I did a couple of these on the New Holland Workmaster versions.
I broke down and purchased a Farmall A Service Manual. Below is information for DTC 455-03 (CASE IH 3808). Too bad I couldn't help sooner - better late than never. Be really careful with the high pressure fuel system, the pressure is extremely high. Wear eye protection and never put your skin anywhere near a suspected leak.
DTC 455-03-High pressure pump fuel delivery quantity at low idle is too high
The Engine Control Unit (ECU) monitors fuel rail pressure. If the ECU determines that the requested fuel pressure is greater than the actual fuel pressure at idle, leakage is assumed and this fault will occur. Other active faults may have caused this fault to occur. Use the Electronic Service Tool (EST) to check for other faults. Diagnose other active fuel system faults first, and then return to this fault. For information on fuel system trouble shooting, see Fuel injection system - Troubleshooting (section 10.218).
Possible failure modes:
Fault in low pressure fuel system, clogged filter or leak/blockage.
Fault in charge gear pump, low efficiency or line clogged/damaged.
Faulty fuel metering unit, unable to open fully.
Faulty high pressure pump, low efficiency.
Faulty fuel injectors, stuck open or internal leakage.
Faulty Pressure Relief Valve, leakage.
Faulty fuel rail pressure sensor, drifted or leakage.