I bought a 89 Grand Marquis and was wanting to put it's 5.0 EFI in my 71 Comet, how much trouble will this be and what all will I need to take off the Marquis? I know I will need most of the wireing harness, sensors and ECM, will I also need the fuse box as well. Also what kind of electric fuel pump will I need? I had seen one car on here that had a 4.6 cobra in it out of a new Mustang, so I figured it must not be to hard. Any info will be greatly appreciated. Thank you, James Cooper
yeah, you'll need most of the harness and all of the engine's sensors. about the only ones you wont need will be the ones for emissions (depending on what state youre in) and a/csensors/switches (depending on whether or not ur running a/c) the ranger station (http://www.therangerstation.com) has a good wiring diagram for the 5.0 wiring. the best pump i have seen to use is one for like a 1989 Ford F150 5.0. it has an external pump that is sutable for the pressure requirements of this swap. the Advance Auto Parts part # i believe is e-2000. double check partsamerica.com or your local parts store. good luck and keep us posted
You have to remake the shock tower braces, so it fits around the upper plentum. You really dont need much of a fuse box for efi, if you get a good harness, put a fuse in the main power feed to the ecm, and thats good protection. Alot of the stuff you can eliminate,, fuel pump relay, I ran a toggle switch since I had 2 pumps, the pumps can be triggered to run off a custom oil pressure swtich, if it has no oil pressure it wont pump fuel. If you have time, make the harness if your confident in your wiring skills. Or buy one from a source. Painless wiring has em for in the 350-500$ range. Quite simple kit and its a good retro fit for the older car, new engine swaps. Will also be able to use E85 so that can bring the fuel cost to operate down. ChadS
It's not super hard, but it can be time consuming. You will need the upper and lower intake,fuel rails, injector, etc. If the throttle body intake is facing out towards the driver's side and you have power brakes (not an option in '71 unless you added them I think? ), you may have a clearance problem. I solved this by replacing the upper and lower intake with ones taken from an '88 Thunderbird, although others will work as well. I would take the entire under hood wiring harness and all sensors connected to it; you can always take out the parts you don't need later. My main harness came out of a 1986 Grand Marquis. All of the relays you need should be connected to the main harness. I can't remember if the '89 G. Marquis were mass airflow or speed density..if mass airflow, you will need the MAF sensor and the tubes that connect it to the throttle body on the intake. You will need to get the EEC (engine computer), I would get the mounting bracket that goes with it as well. When I did mine, I also grabbed the crash sensor that mounts in the trunk and will shut off the fuel pump in the event of a collision. The easiest way to do the fuel pump is to get an externally mounted high pressure pump, it needs to be capable of 38 - 45 psi. I got mine from a Mustang supply place online that sells stuff for EFI conversions (Mustangs Plus I think?). The pump needs to be mounted near the gas tank, as they like to push the fuel rather than pull it. Way up above the axle is a safe spot, although not the easiest to get to. For a return line you can use the fuel vapor line that goes from the gas tank up to the charcoal canister in the engine compartment, assuming it is not rusted out. Beware though...you will need to drop the gas tank and remove the baffle device in the top of the gas tank at the end of this line and drill out the hole. I didn't do this originally and found out the hard way that the hole was the size of a pin hole. Everything was mainly fine until this hole got plugged somehow and the fuel pressure spiked to about 100psi. First I burst a rubber, reinforced fuel line under the back of the car. Once I fixed that I ran the car and it was fine for awhile until one day it started pouring black smoke and I burned about a quarter tank of gas in about 10 miles. It was after that I found the problem, drilled out that hole and now life is good in EFI land. Those cars used dual heated oxygen sensors, so you will want to grab those, although it might be a good idea to get new ones. You will need to drill a hole and weld in an O2 sensor bung on each down pipe from the manifolds as close to the manifold as physically possible. You can get those bungs online pretty easily too. Anyway, you should also get a wiring diagram for the Grand Marquis too...and have at least some patience for dealing with lots of wires.
Wow - great info. I am also planning on doing this. I have a wrecked '87 Crown Vic that I'm going to use as a donor.
