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Thunder91 02-13-14 09:47 PM

1991 Ford Thunderbird 5.0 HO questions?
Hello! Very new to this site, I've been doing some searching and can't seem to find what I'm looking for so I wanted to post a few questions.
I just bought my first thunderbird a month ago and things seem strange.

1. I have a 5.0 HO motor in my car. Do 1991 thunderbirds come factory with this? I can't find anything on it considering it is the HO.

2. How to find out what year my motor is, for parts or general fixes, I can't do anything until I find out what year the motor is, considering there is a difference in parts and power throughout the years of the HO.

3. Horrible gas mileage.... Like went from getting 15mpg to 8 in a matter of weeks. No check engine lights or performance issues just bad gas mileage. Also a faint smell of gas in the morning when I go out to start it. Also the exhaust is supposed to be side pipped but it was cut aparently.

Anything you guys can help me with would be great. It's said to say but I'm more of a Honda guy than a muscle guy, but I'm up for the challenge!

Thunder91 02-13-14 09:51 PM

Re: 1991 Ford Thunderbird 5.0 HO questions?
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This is my carAttachment 39369

Thunder91 02-13-14 09:53 PM

Re: 1991 Ford Thunderbird 5.0 HO questions?
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DaveFordMan93 02-14-14 02:29 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
Ah yes, the 1991 Ford Thunderbird... wish I owned one of these. I know I am an avid fan of the Super Coupe and the previous gen's Turbo Coupe. But enough of my personal preferences. Let's get to business!

1. Yes! In fact, the 5.0 was used in these car from 1991 up until 1993. However, I remember the H.O. version being in bigger cars such as Lincoln Town Cars (1980's), Ford Thunderbirds of the previous gen (1983-1988) and the Mercury Cougar that is similar to the previous gen Thunderbird. So in short, it's possible but not for certain.

2. As stated above, the H.O. typically means 80's Personal Luxury Cars Such as the Thundebird, Cougar, Town Car, Mark VII, and some of the 80's Fox Body Mustangs. So in short, mainly 80's Ford. After all me and my dad took an H.O. and cured a 1972 Chevrolet Vega with it!

3. Oh my, now if you're smelling gas at all means you got a leak! Check the entire fuel line system and filters. Check the fuel pumps if those are external. And having the exhaust cut, while does add performance, could mess things up if you're not careful. Check anything and everything and never lose a part!

I don't know much about Hondas other than there's a particular year of Accord I'd love to cure like that Vega, but like with any car, once you get to know it and all of its secrets not to mention treat anything with the utmost care you'll get to have a long time of enjoyment and fun with your car. Be it Ford, GM, Honda, etc.

If you have any more questions, don't be afraid to ask. Oh, and welcome to the forums BTW.

Thunder91 02-14-14 02:59 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
I was thinking since it has a MAF and fuel injected it would be a newer motor than an 80s motor, there are more wires in this thing than I have ever seen, everything had a sensor and all the wires for the most part are tucked pretty good, I was thinking aside from a gas leak, that there would be performance issues, the only thing I can think of is the car stalled out after taking the cold air intake off while it was running, I figured it would breath better or I would short ram it, but it's not very responsive with a short ram, so I've gotta keep it where it's at. Aside from that no missing, no hesitation in get up and go, it must be something with the fuel line that is causing bad gas and the smell, it's only on cold mornings. Living in South Dakota that's everyday but you get what I mean. So for now I think I can rule out spark plugs, coil, and so on. The ignition works perfect so I don't think it's that. Maybe an injector is clogged but wouldn't that cause missing or lack of power?

Even if there was an issue like a bad pump wouldn't power be affected? So as I'm writing this I'm kindof thinking there has to be a leak somewhere. Unless anyo else has any other ideas as well!

DaveFordMan93 02-14-14 03:43 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
Not so much as a bad pump but one that seeps and leaks slightly even though it's extremely rare. Check the fuel hoses if you can. I know those for a fact go bad with the modern fuels that are in our gas stations today. Modern fuel isn't kind to rubber. Don't know how many times I had a fuel hose go bad and a mechanical fuel pump that squirted fuel on the block almost cost my dad his 69 Galaxie and it was amazing the fuel didn't combust.

I wish I had a car to take over where you live and test a cold start up over there with it. My mom has a 1987 20th Anniversary Edition Cougar that has a 5.0 and I even serviced it so I know it's a fresh motor.

When you short ram something, you got to have the exhaust match. there is a balance when it comes to intake and exhaust and that balance has to be maintained for optimal performance.

All I know is that if you have seen even a small sample of what Ford was doing in the 80's, you'd find it quite the educational journey. From what I have studied, all of the cutting edge stuff goes into personal luxury cars and then trickle down to the more commonplace cars as much as it is hard to believe.

The only advice I can provide is that Ford may have added a couple more things for the H.O. 5.0 in the early 90's before the Modular became the standard V8 in 1994. Modern fuel eats rubber. Period. Yes, yes, and yes a clogged injector would cause performance issues.

Hopefully someone more educational about these 90's T-birds pick up on this. Maybe they can help you as well.

Thunder91 02-14-14 04:10 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
I appreciate your insight! Has been a good read, I was thinking about the vin and did a simple search. I officially have a 91 t-bird Lx 5.0 but it is an HO still iffy on finding actual information on that specifically, so I'm thinking if a motor swap was done it was done very well I can't tell a difference at all, although hopefully someone will recognize the motor in the pic and be able to figure out the year from there. I would be so happy to find out if I had the forged Internals motor. But one can only hope. And yes these cold starts amaze me, I was very surprised on how well this car starts on extremely cold mornings buried in snow! No rough idle or anything no hesitation at all, battery could use an upgrade but it really doesn't take much to start this car, honestly once I get this gas situation figured out I will be very happy, only other issue after that is being able to take off without breaking traction like crazy, good tires will fix that but I love how the car never needs to go over 3grand on the Tac to do anything, interstate cruising all of that it stays around 1500 so smooth.

Stud Duck 02-14-14 06:30 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
First of all welcome, and that is a NICE looking bird !!!!

We own a 1995 LX 40th Anniversary Edition, with a 4.6 V-8. A while back, I went to the station to fill it up with fuel. I got back out to the car, got and smelled gas.

Evidently, I had overfilled it. (I usually pump a tank clear full, and keep topping it off, especially if the price is "cheap" at the pump). The reason that I was smelling gas, was that the car, I am guessing has a "over full" limit, and it actually had gas running out from under the car.

My wife told me that I overfill every tank, and that I always have.

Maybe this is what you did?

{OH, I had my car looked at the FORD dealership, and there appeared to be no problems, such as leaks or anything like that} SINC doing that I quit stuffing the tank, and no more problems.

My car only has 30,000 actual miles.

WHY wouldn't that cars engine be the right one? Who says that FORD didn't "just happen to install that engine in there" ?

I belong to a forum for FORD trucks, and they have a place to check the VIN #'s, and it will even tell you options, engine, trans etc.

It is the F-150 Forum. I tried to pull up the link, so youo could use it, but it's in my favorites, and no luck. I'd look it up for you if you'd like to shoot me a PM with your VIN. :hy:

Thunder91 02-14-14 08:02 AM

Re: 1991 Ford Thunderbird 5.0 HO questions?
My car has 113xxx miles on it, I'm about to take it in for an oil change, way to cold to do it myself, and thankyou! The car is definitely growing on me.

With all that being said, I don't think it was me overflowing it will do this no matter where the gas tank is at. I think if it gets warmer ill take a look at the fuel lines if I can, but I have a feeling if the car has a leak wouldn't the gas just evaporate before I can see that it's leaking, or unless it only leaks when it car is running. Idk ill post an update after awhile, in the mean time if anyone else has some insight that would be great! Would love to hear! Also this beast could possibly be up for sale soon so any offers I might consider! Haha summers around the corner and I need a bike!

Stud Duck 02-14-14 03:55 PM

Re: 1991 Ford Thunderbird 5.0 HO questions?
Here is ALL that the site said about your car. MSRP-$17,734
Destination Charge-$485.00

5.0/302 V-8
MfR color code-P62

Built in Lorain, Ohio

Production Sequence # 117531 (Whatever this is)

Standard brakes

1991 LX Coupe

One place said if you go here: you can download the owners manuel, and other info.

I do NOT know why yoiur car didn't pull up any more info than this. ALL of my cars/trucks have a full list of options etc.

SORRY, I didn't do you any good. :BW:

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