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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35841
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford F150 Lariat When you have a clogged fuel injector, what

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When you have a clogged fuel injector, what is the best way to detect which cylinder it is whether the motor is running or not. 05 F150 Lariat 5.4
I'm being told that all spark plugs need to be removed. Is this the case or are there better means of determining which cylinder it is?
Hello and Welcome to Justanswer,

My name is XXXXX XXXXX I am here to try and assist your with your question.

What type of problem are you having?

Is the check engine light coming on?
Customer: replied 5 years ago.
Yes the check engine light came on
Its not very likely you would have a clogged injector and the check engine light comes on when the PCM (computer) sees a system fault and when this happens the PCM will set and store a fault code and or codes. If you can give me the fault code I can direct you in the correct repair. Most part stores will retrieve the code or codes for you at no charge.

Can you tell me what type of problem your having?
Customer: replied 5 years ago.
I understand what you mentioned above. Maybe if I provide you a few more details it will help you better understand my circumstances.
Yesterday my trucks engine was running rough at low, med, high & idle (bogging). a rich oder was coming from the exhaust along with blue-ish smoke. This has never happened before. There are 114K mi. on the truck. I took the truck in and it was running.
I do not have the fault code as it is at the mechanics shop at this time. I received a call this morning telling me they couldn't start the truck. The mechanic believes the truck has a clogged injector and in order to locate the problematic injector they need to remove all spark plugs. This seems unusual. I believe the code should tell them which cylinder it is. Do you agree?
If it was running rich, it could be a stuck open injector which would cause the engine to flood with fuel and cause a no start and he is correct if this is the case, the spark plugs would have to come out to see which cylinder is flooded with fuel and the spark plug would also be fouled on the suspect cylinder.
Customer: replied 5 years ago.
Doing research via Ford F150 forums on this topic there seems to be a certain amount of concern and alarm (throwing a rod in the engine) regarding hydro-locking when a fuel injector cloggs. Is this a possibility --- and/or --- has any engine damge taken place when myself driving the truck or the mechanic shop tried to start the truck and a no-start situation occured?
Yes it is very possible as you likely know liquids do no compress, Its not likely you damaged it as long as the engine was running, usually if its hydro-locked, it will not spin over. Have him pull the plugs, if its a open injector, the cylinder will be full of fuel.
Customer: replied 5 years ago.
That's what the mechanic had to say this morning. It would not turn/spin over. They were removing the plugs to investigate the problematic cylinder.
With that being said is there a way to determine if any damage took place to the engine (signs, sounds, codes or any visuals from any engine components)? I want to make sure everything is being done to handle this properly because of the potential to have future engine problems.
It sounds like they are on the right track, as long as it was not forced to turn over you most likely ok once the injector is replaced. You should be fine.
Ron and 3 other Ford Specialists are ready to help you
Customer: replied 5 years ago.
The mechanic found the faulty cylinder to be #6 and installed a new injector. The #6 cylinder is still having fuel dump into cylinder via the injector. The mechanics are stumpped as to why this is happening. Any ideas (i.e.) faulty wire-harness, ground, fuse? Your thoughts...
You eaither have a shorted harness to that injector (very likely) or the PCM (computer) has failed.
Customer: replied 5 years ago.
What type of equipment is used to determine if it's a short in the harness or determine if the PCM failed.
In most cases it requires using a Ohm meter and a good inspection.