If you are encountering login problems please check here

Fuel Pump Conversion on 1984 Ford SVO
#1

I own a 1984 SVO that I installed a 1986 SVO engine in. After 200,000 miles on the old fuel pump finally quit. I want to upgrade to a single in tank pump and eliminate the external pump. I have been told that a 190ph pump from a 5.0L mustang will work as a single in tank pump.Is it correct that the mustang 5.0L from 1987-1993 had this type of pump? If I go to the local parts store and request a complete with the holder fuel pump assembly for a 1992 mustang with a 5.0L engine is this all I need? What changes to the wiring will I have to make? Will the fuel gauge work correctly? Any advice/suggestions will be greatly appreciated.
Thanks
Phillip
Reply
#2

I don't know, dude. I have a 93 LX 2.3 that just got converted to a turbo and I went with the 255 Walbro. I would think that if you changed the in-tank pump and deleted the external, you'd be okay. I mean, they both worked on the same relay, right? I'm not sure on the 5.0 fuel pump.

------------------
'93 Mustang LX: Precision techniques T3/T4 turbo; Richmond's professionally ported head with cheater valves; Ranger roller-cam; windage tray; Racer Walsh underdrive pulley on the crank; gutted upper with knife-edged lower; ported E6 exhaust manifold; Mac cold-air intake in the fender; large VAM and LA3 computer; Spearco front-mount intercooler; Esslinger aluminum flywheel; kevilar "puck" clutch with a Centerforce II pressure plate; Eibach lowering springs; Sacramento Mustang 3" Down-pipe through a high-flow cat, 2.5" y-pipe ala SVO to dual Flowmasters; 70mm front calipers with 13" rotars up front; 8.8 Traction- Lock rear end with 3.73 gears with God knows what size calipers and 12" rotars; '93 Cobra master cylinder... Special thanks to Chad Hayes for combining three wiring harnesses to make this beast run!
Selling for my deployed husband so he can get a brand new Shelby Cobra upon return!
Reply
#3

An 85-97 Mustang 190 lph fuel pump can be used in the tank of an 84 SVO and then you can remove the external pump. That is much cheaper than replacing both pumps. Your fuel guage is not affected.

You can get a pump and bracket from Ford if you like, or you can get the Walbro pump from http://www.autoperformanceengineering.com/ (part # FPF001) and get a bracket from a salvage yard from any late 80s or early 90s Mustang. Then you'll need to replace your fuel filter with a Ranger filter because it has longer inlet and outlet pipes. Just connect the fuel line from the tank to the Ranger filter and remove the external pump and the short fuel line that is between them. Tie up the wire harness from the external pump so it doesn't hang.

Next you need to replace the resistance wire that is inline with the fuel pump ground wire with a good wire. Look under the carpet in the hatch. The wire harness that comes up through the floor is the pump and level sensor harness. The pump ground wire is the one that changes size from a thick wire to a thin one. Cut the wire where it is thick, on the pump side of the thin wire, and solder another thick wire (like 16 guage, no thinner than 18 guage) onto it. Connect the other end of the new wire to a good chassis ground. I connected mine to the green-painted ground screws near the tail lights. You'll have to remove the rear interior panel to find them.

If you're in a rush you can install the pump and do the wiring later. But you'll want to get to it soon or you may run lean at high rpm and boost.
My totaled 84 SVO had: ported big-valve head, roller cam, front IC, BPV, E6, 3" exh; 259 rwhp, 331 rwtq at 19 psi.
Reply
#4

Whoa!!!!! Tell me about this ground thing again estell! The guy I bought my SVO from said it has a 190 in the tank. I'm not too sure though as it does knock and ping at high boost and rpm. Do you have a schematic? Can you draw one? I'm gonna have to check this out. If its just a ground problem, then I'll be set with an easy repair.... If its the pump, I'll have to swap it.



------------------
Anthony S
"Never argue with John. He just drags you down to his level and beats you with endurance."
My '85 SVO
Boycott Excessive Motorsports
AnthonyS

'85 turbo coupe engine going into
my '88 LX notch soon.
Reply
#5

Thanks a zillion Estell...you post is very well written and to the point. I was also under the impression that the fuel injected 5.0L mustangs had a 155ltr/hr pump in them from the factory.Is this correct or is the factory pump actually 190ltr/hr? If it is 155ltr/hr I guess I will have to hit the junk yards for the bracket and then get the pump from the source that you recommended. Thanks for your time and the needed information.
Reply
#6

PK.... I didn't know how to properly wire one of these in an SVO until I read estell's post. I can tell you however that factory 5.0s have 88lph pumps in them. You do not want one of those! It'll support 225 hp with no boost! With boost, it'll fall short in a hurry. That's why us turbo guys have to have 190s and 255s. Our pumps have to work against boost pressure. Make sense? I've heard the 4.6s use 110 lph pumps, but that still isn't gonna do a good job if you plan to up the boost or do any mods.

I'm gonna check out my pump wiring this week. I suspect it may very well be my problem.



------------------
Anthony S
"Never argue with John. He just drags you down to his level and beats you with endurance."
My '85 SVO
Boycott Excessive Motorsports
AnthonyS

'85 turbo coupe engine going into
my '88 LX notch soon.
Reply
#7

SVO,
The size of the pump is regulated by many things. First we are trying to make big horsepower from only 4 (usually) injectors. That is why we need VERY big injectors. In 5.0L, you can make almost 285hp from the puny 19lb/hr injectors. BUT you have twice as many injectors. The 88L/hr pump only has to supply a small pressure and a small amount of fuel to each injector. Once you make the system twice as big (ie 36lb/hr injectors now you need twice as much fuel. AND you still need more pressure/fuel requirements since turbo engines require you to run a little on the rich side. Think of it this way, either eight small hoses or 4 twice as big hoses to water the same amount. But with larger hoses you loose pressure, so now you need a bigger pump!
For me, I've been eyein' that 1000hp aeromotiv pump.....ahhh, i'll just a little bit overhead.... ha ha ha!
Gotta run now
-Jason
'84 SVO shiney with a "few" upgrades
'89 SC 347-9psi etc. Slow 500+hp.
Reply
#8

Anthony, the wiring instructions I posted are for an 84 SVO. I don't know if they apply to an 85 SVO because they don't have two pumps (right?). Check out your fuel pump wire harness and see if the ground wire goes from thick to thin as it travels away from the pump under the hatch carpet.
My totaled 84 SVO had: ported big-valve head, roller cam, front IC, BPV, E6, 3" exh; 259 rwhp, 331 rwtq at 19 psi.
Reply
#9

The early '85s like mine and Troy's have the same dual pump set up like your '84. I'm gonna yank up the carpet today and have a look see at the fuel pump wiring. I got plenty of wire to make a nice ground. I hope that is my problem. I've been having hell with this car for quite a while.



------------------
Anthony S
"Never argue with John. He just drags you down to his level and beats you with endurance."
My '85 SVO
Boycott Excessive Motorsports
AnthonyS

'85 turbo coupe engine going into
my '88 LX notch soon.
Reply
#10

Anthony, I looked up the resistance wire in my 1984 Ford car shop manual. In volume D, page 24-35-6 shows a wiring diagram of the fuel pumps. It clearly shows a "Resistant Wire" from the in-tank pump ground to chassis ground. There are no other resistors shown in the wiring diagram. On page 24-35-2 it says "The low pressure (in-tank) electric fuel pump is to provide pressurized fuel to the inlet of the high pressure pump...The low pressure pump has an external resistor in the electrical circuit to reduce the operating voltage to 11 volts." That is all I found about it.

From that statement I gather that the low-pressure pump contains an 11 volt motor. However, the modern in-tank pumps have 12 volt motors so we need to short across that resistance wire.
My totaled 84 SVO had: ported big-valve head, roller cam, front IC, BPV, E6, 3" exh; 259 rwhp, 331 rwtq at 19 psi.
Reply




Users browsing this thread: 1 Guest(s)