I have an '81 F-150 with a 302 that the previous owner(s) converted from carb to an '85 fuel injected top end. It has no end of problems and mechanics scratch their heads anytime I take it anywhere. I'm seriously thinking of converting it back to a carb and am wondering what is involved....also curious as to the actual gains achieved by the original conversion.

any ideas?

thanks

 

Well, had the conversion been done properly, some of the gains with EFI are:

1: Better fuel mileage, appreciably so.
2: More power, assuming stock to stock.
3: Far better drivability in extreme heat or cold, or when changing altitudes.
4: More efficiency means less pollution, and that's a good thing.
5: Better starting and drivability when the engine is cold, as well as much better throttle response in all regimes (idle, midrange, WOT)

What are the major problems you are having? EFI isn't all that complex.

 

Thanks for your response....

the fuel pumps (twin tanks) were not upgraded so it would start only after considerable cranking (to build pressure) - took multiple visits and many $ to figure that one out - other small little things, but they all accumulate..... The major issue is that most mechanics would rather not deal with it.

I'm not toally conviced yet about swapping back, but I know carborated engines much better than I know EFI, so maybe the issue is really me.....

 

The main fuel pump is different for EFI. EFI works on a fuel pressure of 32-36+ psi - if you don't have at least that at the fuel rail, you're going to have problems. The low-pressure lift pumps in the tanks *may* be the same used for the carbed trucks, I don't recall; however, there is a third pump in the system after the tank selector solenoid. It is capable of producing 100psi and its output is "regulated" by the fuel pressure regulator on the rail, which is essentially a vacuum and spring actuated bleed valve which sends any excess pressurized fuel back to the tanks. If you're still running the carb pumps without the main EFI pump, that might be the source of many problems.

Most mechanics would rather not deal with "hybrid" vehicles because they don't know what all was done with it. However, if presented by a properly converted truck, there's no functional or service difference from, say, my 86 EFI truck, so there won't be any problems.

I will also note that an EFI system can go a lot longer without any significant maintenance than a carb can. I have one Bosch L-Jet system that's been running for 20 years without anything approaching an overhaul. Try that with a carb.