Hi everybody!
I'll try to condense this without leaving anything out.
'89 F150, 300 straight 6, EFI. A couple of weeks ago started with hard starting and idle surging from 300-100 rpm, Smoking like a fog machine, no power under load and gas mileage fell through the floor. Started trying work on it a couple of days ago. So far the EGR valve has been cleaned and checked, the ECM checked out with the same readings as a new replacement unit. The computer has been replaced, same with the throttle air bypass valve and throttle position sensor. Finally check the fuel pressure regulator and found gas in the vacuum line. After I replaced the fuel regulator the truck starts like new! Just one problem Still No Power! Under any acceleration or load (just a rise in the road) It almost comes to a crawl. Don't ask to accelerate up a hill! If you can go up hill (1/8 mile) and still be over 30 mph your doing better than this truck!

Help!
JD

 

Hi crystaldragon and welcome to FTE

With it dumping in fuel you might have burned up the catalytic convertor. Try unbolting the exhaust pipes at the maifolds and let them drop down an inch or so and take it for a spin to see if it's any better.
Let us know what you find.

 

I was hoping that someone would come up with something nice and simple.
You know? Like " you left the blue wire off the watchamacallit"

I'll let you know what happens when I loosen the exhaust pipes. Thanks

 

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Sorry to be so long getting back.
Thanks for the tip Racerguy
Both cats were in sad shape and no 1 spark plug was dead !

Now it is "cutting out " under load. Runs better seems to have a little more power. But at approx 2000 rpm under load it's like it "cuts out" or "stumbles". and feels like it is trying to stall. Changing to the next gear helps but it acts like it is "lugging" (like it is in too high a gear for the speed it is moving)

Now what? Timing? Oxygen sensor? It isn't giving me any trouble codes.
The only thing on the exhaust that wasn't changed was the muffler and it seems to be in pretty good shape

 

Put a vacuum gauge on it - preferrably one you can see while test-driving it, but do most of your checking at idle.

 

How old is your fuel filter?

 

The fuel filter is about 3 or 4 days old.

 

We found it!
I finally got a chance to get this truck on a computer and it gave a "lean" trouble code. So we checked the pump pressure. sure enough it was dropping under acceleration. The mechanic and I talked about it for a minute and he remembered that some of the '89s had a filter "before" the high pressure pump. That was it!!
It was in a canister marked "do not open"
When we got it open it looked like someone had dipped it in clay colored dirt.
Then the fun started. It isn't listed in the parts books. it took almost an hour worth of phone calls (including 2 to the dealership) to find the numbers for it. But talk about a difference! This truck runs better now than it has since I got it.