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tm454 10-20-2003 06:29 PM

Mustang guys Help!
A buddy put a 2000 cobra 5.0 in his 86 stang. The 86 was 5.0 but the problem arises when the fuel rail for the Cobra and the 86 5.0 don't interchange. The 86 fuel rail has a fuel return line and the cobra 5.0 fuel rail dosn't and the Cobra runs RICH as HELL on the 86 fuel rail. What is the fix? Don't know if they have the same fuel pressure needs and don't know about adding a 2000 fuel rail and stuff in the 86? If this isn't confusing you maybe you can help, I couldn't help him. Thanks guys.


Rat Rods Rule!

dmorris1200 10-20-2003 06:43 PM

Well unfortunately I have no manuals to check but I thought that after 1996 the Mustangs all had 4.6 modular engines in them. I didn't think Ford used a returnless fuel system in the newer Mustangs so there should be a return fitting. If it is a returnless system rail it will not work with the old pump and pressure rail. I would think you would need to modify the rail with a pressure regulator and a return line. The returnless systems are regulated by the PCM which drives the pump.

mstngjoe 10-21-2003 05:10 AM

DMorris is 5.0 in year 2000. The Cobra had a 4.6 in it (the Corbra "R" had a 351W) and I would assume a Cobra specific fuel setup. I could be wrong on that though.

woodz428 10-21-2003 06:59 AM

I believe by 2000 that the Cobra "R" was using the 5.4 mod motor. So no Windsor there either.

klassik100 10-21-2003 07:32 AM

Ask around at some of the mustang forums like or some of these guys do some weird stuff retro fitting late model motors into earlier cars.

Good luck


Kaylah 10-21-2003 07:49 AM

You could do an HO "conversion" and go with a 4bbl, if all else fails and things get too expensive. Now this is based on the assumption that you are using a 5.0.

mstngjoe 10-21-2003 07:54 AM


Originally posted by woodz428
I believe by 2000 that the Cobra "R" was using the 5.4 mod motor. So no Windsor there either.
I stand corrected. :)

It was the '95 R with the 351W. The 2000 did indeed have the 5.4 with 32 valves.

87442lover 10-21-2003 01:40 PM

All cobras 96(maybe 94-95) and newer use the 4.6 281 V-8. There is no ford 5.0 anymore. Even the concept cobra uses the 4.6 with a blower on it. My friend has a 98 Cobra with a 144 and the 4.6 in it and the figures look almost the same on a dyno to the new cobras.

I dont believe there is a 5.4 in the 2000 cobras, at least not from the factory. But I'm not a ford guy, I just know my friend loves his cobra and thats how I found out the info.

Try using smaller injectors if your running so rich.

tm454 10-22-2003 05:40 PM

it is a 2000 Cobra
I called it a 5. 0 not knowing any better. I told him to CK this site for himself, maybe he will post.


Rat Rods Rule!

2wld4u 10-22-2003 08:09 PM

there wasnt a 5.4 in a cobra, its too tall, it would have to have a 3" cowl from factory N/a and a 4" cowl wouldnt clear the supercharged version, there was however a 5.4 lightning and it was supercharged...

mstngjoe 10-22-2003 08:39 PM


Originally posted by 2wld4u
there wasnt a 5.4 in a cobra, its too tall, it would have to have a 3" cowl from factory N/a and a 4" cowl wouldnt clear the supercharged version, there was however a 5.4 lightning and it was supercharged...
The 1995 Cobra "R" along with the 2000 Cobra "R" had larger displacement engines than the standard Cobra.

The 351W (5.8) in '95 and the 5.4 (330 cid) in '00.

Check out the info here:

2wld4u 10-22-2003 08:54 PM

I stand corrected, I have delt with the 5.4's and they seem to be a little to tall for a mustang, but thats what the site said, Hmm, Id like to try that swap...

87442lover 10-22-2003 09:16 PM

Yeah but those cobra "R" s are cars that we will probably not see. And why is the 2000 Cobra R only putting out high 300's on HP and torque? My friends 98 cobra with a 144 on a 4.6 at 5-8psi puts out 400HP/380ft lbs. ?? With those numbers I would think the new cobra is supercharged, but they are still kinda low.

Smoked Rubber 10-23-2003 06:21 AM

Mustangs from 1979 - 1995 Used a 5.0 L block, Which was Basically a 302 Windsor Block that was available back in 1968 Mustangs.

(In 1979 They added 5.0 To make it look more appealing.)
So truthfully 1968 - 1995 Marks the Exsistance of the 5.0 (302 W) Block in publically available Mustangs.

Fuel Injection started in 1985 for The Ford Mustang. The 5.0 Does have a Fuel line that goes straight into the engine (No return lines) In 1996 Ford Switched to a Smaller 4.6 L (281 CID) Block... The 2000 COBRA "R" MODEL (Notice the R at the end) used a 333 CID 5.4 L Cast Iron Windsor Block. (This is the same block used in the Current Ford SVT F150)

And to the guy that said a 199x - 200x Mustang can't handle a 5.4, They're wrong. Theres an issure of HOTROD magazine as well as the 1994 10L Boss Produced by SVT Team *only 10 in the world exsist*, (In which theres a 429 CID Engine) in each Mustang.. Check out
go to concept cars and check out the 10L boss... They did that without cutting and it fits right in, nothing needed to be moved around...

To the guy that started this trend, from my understanding your going to have to switch fuel pumps and fuel rails, the 4.6 Block that came from the 2000 COBRA (Notice its just cobra and not COBRA R) needs a return fuel line, it wasent made to burn the Excessive fuel that the 5.0 Needed. The Injectors would also have to be switched (Use the Injectors from the 4.6 with the 4.6, Because the 5.0 Used Higher Lb/Hr. Injectors then that of the 4.6)

I personally think it would be easier to swap a fuel tank from a 4.6 onto your 80's Mustang and swap the blocks, and that should settle all the Major problems you would experience... (You will also need to get your hands on a 4.6 ECU..)

If theres anything else Just reply here and hopefully I can keep up on this thread.

Mustangs are my Favorite car, Love em to death, I currently co-own a 1997 and am looking to buy a 94 - 95 GT for myself (Last years of the 5.0) Good luck and I hope this Helped others as well.
When I re-read your post I think you got the Engines mixed up man..

The 4.6 281 CID (used in the 2000 Cobra) uses a Fuel Return Line

The 5.0 302 CID (Used in your Friends 86 Mustang GT/LX, Etc.) Uses a Straight Line that fed into the engine and had NO FUEL RETURN line

Then theres a 2000 Cobra "R" which uses a 5.4 333 CID Engine, From what I recollect this as well diden't use a Fuel Return line.

I doubt you got your hands on a 2000 Cobra "R" because theres only 300 of those in the world and the selling price on one was marked at $54,000+ The Engine could have been ordered After market but You said your friend got The block out of a 2000 Cobra...

So that leads me to beleave you have your hands on a 2000 Cobra 4.6L (281) Block, and your friends origional 5.0 (302 W) blocks.

Remember as I said earlier, the 4.6 HAS and NEEDS the fuel return line to keep it from running RICH.

The 5.0 uses a NON Return line system (The Fuel pumps into the engine and stays there).

Thats why when you put the 86 5.0 Fuel rail on the 2000 4.6 Block The Engine ran RICH as hell, because it diden't have the Return fuel line the 4.6 Block NEEDS, to bleed off the un-needed fuel it was getting.

You might also want to check your FPR (Fuel pressure regulator) and make sure its not Set at a High pressure, or else your defeating yourself there as well....

G-unit gt 10-23-2003 10:09 AM

hummm?????? the first fuel injected mustang came out in 1986,i own one,and it dose have return fuel lines,need to know if your friend is usen the 86 ecu,if so ,this is his problem you need to use the ecu for correct for that spasiffic engine..

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