I recently purchased a used 1989 Ford F-250 (4x4) with the huge big block 460 engine which is a 7.5 liter V-8 engine to help accomplish a full renovation of my elderly mother's house. This particular year of F250s was in the early years of fuel injection for that engine which Ford began installing there in St. Paul, Minnesota. The truck had received a mild-restoration and checked out with a reputable mechanic shop. While driving it the 700 miles home, I started to encounter engine problems. At highway speed of 65 mph, the truck appears to lose power. Specifically, while driving on Interstate 75, in middle Georgia (somewhat hilly) the truck would start to slow and lose power. An additional increase to the throttle, (additional fuel to speed-up) would cause engine knocking. When I reached the top of the incline (again, nothing severe), the truck would regain power and pick right up until I hit another hill or need any significant increase to the throttle. When the engine knocked, if I backed off the gas, the knocking would immediately stop.

I found myself in this predicament at 1:00 am so I continued to drive approx 150 miles in this reduced status. None of the dash engine gauges indicated any problems but I did notice the fuel consumption doubled. At the beginning of the trip, I was getting 11 mpg; during the last 150 miles with the power loss and knocking, the mileage dropped to 5 miles per gallon. It appears the 460 engine only consumed one quart of oil for the 700 mile trip, (although very dirty oil considering the oil change two days prior). I am assuming I likely have a ignition/spark plug problem and likely inaccuarte timing.

I would appreciate any advice anyone can offer.

 

Fuel volume...pump/filter? Timing incorrect?

 

Is the SPOUT connector plugged in? On a 5.0, it's near the distributor. When I bought my truck, my SPOUT connector was in the driver's door pocket.
The SPOUT signal is how the computer tells the Ignition Control Module to adjust timing.

 

We got it. You think the engine is big. You must be more accustomed to 4 cylinder engines. Yes. That was the second year for fuel injection on the 460. I didn’t know there was a truck assembly plant in Minnesota?

Could you have gotten bad gas at the last filling station or did that continue for several tanks? 11mpg sounds about right and would be great mileage if the truck was loaded down.

To add to this thought…..and pressure? There could be fault codes even though the check engine light did not come on.

 

No, all of my wheeled vehicles are either inline 6s (preferred) or V-8s. The 460 engine was large then and continues to be.....but I am more well versed in turbine engines. Hoping someone else will provide a better response. Just FYI, the Twin Cities Assembly Plant was a Ford Motor Company manufacturing facility in Saint Paul, Minnesota, United States, that operated from 1925 to 2011.

 

Me too since you didn’t answer any of the questions that were asked.

A quick search shows that Ford built the Ranger trucks there. Not F- Series trucks.

 

Keep searching, the NHTSA site confirms St Paul....but why is this an issue of contention for you? So you blocked me from the site because I hurt your feelings? I'm so sorry.

 

Not an issue at all. I did not know about the plant and what they built at that location.

I have no authority to do that. I don’t know what happened on your end of the computer.

 

Have you had time to check for codes, fuel pressure and volume, base timing…?