I've got a really weird problem with a 2014 1 litre EcoBoost fiesta. It broke down and I found the lift pump not running with ignition on. Found the fuse blown. Replaced it and the car started. Removed key and the pump kept running, found the relay had stuck closed, managed to free it off but replaced anyway. Then it popped the fuse again. Wiring appeared ok so replaced the fuel pump. Thought everything was good. Then it came up with error P0103 which is MAF signal voltage high. Then it popped the fuse again for the fuel pump. I found the wiring diagram for the pump circuit and it turns out the maf is supplied by the same circuit. Replaced the fuse and watched on live data the signal from the maf. Appears fine until every so often theres a ***** load of interference and the engine starts stuttering before recovering. Then it blew the fuse again. I've checked all the maf wiring from the plug back to the engine loom connector and theres no damage. 

Here's the wiring diagram. I'd really appreciate any input!

Hi, did you get any further with this fault as I have the exact problem on a 2013 1.0 Ecoboost Fiesta, the problem seems to be in the loom to the ECU somewhere along the way.

John

On 4/27/2019 at 6:45 PM, fordboi said:

I've got a really weird problem with a 2014 1 litre EcoBoost fiesta. It broke down and I found the lift pump not running with ignition on. Found the fuse blown. Replaced it and the car started. Removed key and the pump kept running, found the relay had stuck closed, managed to free it off but replaced anyway. Then it popped the fuse again. Wiring appeared ok so replaced the fuel pump. Thought everything was good. Then it came up with error P0103 which is MAF signal voltage high. Then it popped the fuse again for the fuel pump. I found the wiring diagram for the pump circuit and it turns out the maf is supplied by the same circuit. Replaced the fuse and watched on live data the signal from the maf. Appears fine until every so often theres a ***** load of interference and the engine starts stuttering before recovering. Then it blew the fuse again. I've checked all the maf wiring from the plug back to the engine loom connector and theres no damage. 

Here's the wiring diagram. I'd really appreciate any input!

I would start at the fuel pump relay and make sure its not causing the issue. For how cheep it would be I would just get a new relay from Ford.

Also the MAF doesnt share its feed with the fuel pump as the ECU supplys the MAF with a 5 volt ref feed.

The fault was due to both the 12v and 5v wires rubbing on an earth connection bolt below the battery.

On 7/7/2020 at 6:43 PM, wilkwhit said:

The fault was due to both the 12v and 5v wires rubbing on an earth connection bolt below the battery.

Hi I currently have this problem at work on a 2014 1litre ecoboost changed the fuel pump changed the maf sensor and the fuel Pressure sensor and it still blows the fuze every time you start it did u manage to figure out what it was thanks