I have a 92 F150 (Supercab, 5.0, Auto, 4WD) with 42,000 (yes, you read it right!) miles. It does not seem to have enough power when pulling up hills. Kind of like it's not getting enough fuel. Can a bad cat converter cause this condition? Also the gas mileage is terrible.

 

Absolutly!!! A plugged up catalytic converter or one that has melted down due to raw fuel getting inside will kill an engine. Since an engine is essentially a big air pump, if it cannot get the air out again, it will not be very efficient.

A CAT went on my old man when he was driving a freinds 460 powered motorhome through Nevada. The mixture was running rich, they had an intermittent MIL on from D.C. all the way across the country. The CAT finally plugged and the engine quit.

Is your check engine light on? Also, what do you consider terrible gas mileage and what are you pulling. I know my 5.0 has never pulled like a champ.

Hope this helps.

42K!!! dang, that's sweet! how did that happen? I know my 93 only had 75k on it when I got it in 2002.

 

I haven't actually done the math on the fuel mileage, but it's a seat of the pants feeling that it's bad. My 1975 F250 4WD (Only had 75K on it when I sold it 3 years ago) got better mileage moving a load. I know that the 5.0 isn't a powerhouse, but the it has to run better than it does now. It motors down the flat highway fine, but when I have to go uphill it drags down. Maybe a new cat and aftermarket muffler will do the trick. I've cleaned everything else and put on a new pressure regulator.

As for how I got this gem, I needed a truck that was easier to drive than the F250 since my kids were getting to that age that all parents dread. I sold the F250 for only $1500 less than I paid for it 25 years earlier and went looking for a 1/2 tone 4WD. Bought it in the rain from an older guy who never drove it. The original bed liner did not have a scratch in it. It's my extra vehicle so it will probably never hit 75K miles!

Thanks for the help.

 

It's a baby BRT. Fix the cat and let us know when you catch up to my 350K+ miles

 

My 92 F150 5.8L had two plugged cats when I got it and taking them off made a huge difference in both performance and mileage. I also replaced the pipe with 2.5" and the muffler at the same time. I ran it for about a year like that with no cats and now it has a single high-flo Catco on it and still runs great.

What kind of hills are you talking about here? You're in CA so are you talking mountains? And what did your F250 have in it? I went from a F350 PSD to a F150 5.8L towing horses in the mountains of BC and I thought it really sucked. But fact is, it was my expectations, not the truck.

 

You can check your cats with a vacum guage, Hook it on, and start the truck, give it some throttle and hold it there, the vacum should decrease, then slowy come back up to a little less than when idleing , if it just stays decreased, it has a plugged cat, im pretty sure thats how it works, Some one correct me if im wrong.

 

Sounds about right for the vacum check. Since the air can't get out, it won't be getting pulled in very vigorously.

 

There's another way to check for a plugged cat. Drive it for a while and look under the truck. If it's glowing red then it's plugged.

I have a buddy that has a Toyota truck. All he had ever done is drive it and put gas in it. He works out of town so he puts 100 mi/day minimum on it. About a year ago he mentions that it isn't running real good and that it is getting poor gas mileage. I drive around with him and sure enough it's not running too good and it sounds like it has an exhaust leak but I can't see anything wrong so I tell him to do a tune up first thing since he's never done one. Of course he does nothing but put gas in it and drive. Then about 6 mos later his girlfriend's father, who is a mechanic, looks under the truck after running it and the cat is glowing red. This is where I learned it from. And it did form an exhaust leak. So this fella pulls the pluggs on it and all four plugs are pretty much burnt away. Almost no electrode left. He does a complete tune up and removes the cat and now it runs well again.


Moral to the story: If your cat is plugged, get it fixed, but make sure to fix the problem that caused the cat to plug in the first place. In this case, shot spark plugs no longer able to burn fuel. If he'd just spent $5 on new plugs none of this would have happened and he'd have saved hundred$$ in fuel.

 

the reason it was red was because of the excess fuel in it and oxygen from a misfire, it will not always glow red when its bad, but it will while its being killed because it is burning to hot due to the extra hydrocarbons and oxygen (gas and air) then it melts and gets plugged,

 

For duc_grrl

I'm in southern California in the mountains at 6,000 feet, so the hills being driven are pretty good grades. I'll try the vacuum test. The cat is not glowing red.

 

Yeah, see that's the thing. I sometimes think we have to lower our expectations a bit when we drive 20 mile 8% grades just to commute to work . In BC there were probably 3 diesels to every gasser, and I almost never saw a gasser towing horses. When I moved back east here, I see half-tons everywhere and even towing 4+ horses.

One other thing to consider ...I might be right out in left field here, but with motorcycles, the FI can be tuned for different altitudes. If you buy it on the coast you have to recalibrate it to run better at altitude. Okay guys, don't razz me too much about my ignorance ...

 

I had the same symptoms you describe, no power and bad mileage on my 94 5.8.

It turned out to be a bad fuel pump regulator. I was getting 95 psi into the injectors instead of the 35psi the engine wanted. Changed it, power went way up and mileage improved dramatically.

 

Altitude shouldent matter The Map sensor will correct for this. and if it has a baro sensor that will correct it to, but i dont know if a 92 would have a baro. maby, defidently check fuel pressure though, never thought of that, DOHH...