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sprinkles08
sprinkles08, ASE Certified Technician
Category: Australia Car
Satisfied Customers: 22374
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Throwing P0300 code and i understand its a multiple random

Customer Question

throwing P0300 code and i understand its a multiple random misfire issue, I've checked for inlet manifold leak done spark plugs and leads all fine, checked injector pulse and had them cleaned. can get it to idle fine and then i'll go to drive which it will then misfire and while viewing the scan tool live data it saying the is a OL-Fault with the fuel system
JA: Have you seen the misfire code before? Has the car been stalling?
Customer: i replaced the engine as previous got flooded..no other codes show up and it was fine previously
JA: What is the model/year of your Ford?
Customer: 2011 ford fiesta 1.6litre petrol
JA: Are you fixing your Fiesta yourself? What have you tried so far?
Customer: yes have changed engine, have done plugs, leads and checked the spark which is all good, had the injectors serviced and flow matched also checked the pulse for them which is all ok...checked vaccum leaks and the manifold for cracks all seems fine. but the live data is showing OL-Fault for fuel system
JA: Anything else you want the mechanic to know before I connect you?
Customer: no thats all thanks
Submitted: 1 month ago.
Category: Australia Car
Expert:  sprinkles08 replied 1 month ago.

Hello and welcome to JustAnswer!

If most or all cylinders are missing then there is a good chance the problem is fuel related, but it could also be something such as an exhaust restriction or cam timing issue. There is a good chance it's running lean under a load.

The first thing that should be done from here is test fuel pressure under a load while the problem is happening. Have you tested fuel pressure?