2004 5.4 xlt 4x4 with god awful fuel mileage
 

First post here and still getting used to where to find threads etc. so any help pointing me in the right direction would be appreciated!

So the history is this

Bought the truck in March 2018. Since then I have replaced the thermostat, spark plugs, alternator (exploded), and have cleaned the throttle body, done a Sea Foam top end clean*, have done a few Sea Foam in the gas tank/oil treatments. Anyway, just pretty basic maintenance stuff.

The current issue is that it's going through a lot of fuel. This past summer I was getting ~15L/100km (16M/Gal) (99% highway). Then I did a top end Sea Foam.. Might be a coincidence but I'm now getting a whopping 20.75L/100km (11M/Gal) which is a difference of approx 200km (124M) per tank.

Also, it does the classic ticking.

The other issues that I have noticed that might help with troubleshooting are the shudder at 60km/h and the fan is intermittent at idle.

Welcome to the forum, you might try posting in the thread for your year of truck and someone might be able to help you there.

A really big issue with the SeaFoam stuff..... REMOVE CATALYTIC CONVERTER before you use it. all the stuff it "burns" away goes straight into the converter and clogs it and from personal experience got to hot and the guts of it melted and destroyed the converter.

Welcome to the F-150 forum! Glad to have you join us.