Just want to throw this out there. I installed a new aluminum radiator and 3300 cfm flex a lite fan setup on my 1990 gt and was having trouble with the idle when the fan engaged. The car wanted to shut down. The cause was a basic problem I had overlooked. A faulty ground strap connection at the rear of the engine block. Replaced the old strap and problem solved. Made a distinct improvement in total performance of the car also. So if your having odd performance problems check that old lame ground connection first. Might save you a lot of frustration.

 

Thats the secondary ground for the interior/exterior lights,ac clutch,alternator and the gauges.There are 3 main grounds present that are necessary to complete the ground loop.
(Primary)
Neg battery post to engine block.
(Secondary)
Cylinder head (rear) to firewall.
(EEC)
Driver fender apron to neg battery post.

If one is loose,corroded or missing,the ground circuit will be weak.
Adding a couple additional grounds and/or increasing gauge or strand count also helps.

http://sbftech.com/index.php/topic,5....html#msg48818

 

I have taken the heads off my 95gt. There was no ground strap. I'm 99.999% sure. Could it be someplace else? (People had done some work on the car a long time ago and If there's no alternative, I wouldn't be surprised if they didn't replace it...)

 

My '95 doesn't have one there either. IIRC, the only stock engine ground is on the front, at the timing cover.

 

Years back, all Ford products had an engine to body ground strap, separate from the battery ground cable, or anything else. It was often located at the right rear of the top of the eng. My '55 Merc had one made of that very old, braided, flat copper multiple zillion wires strap, about an inch wide!

Reason for that grounding was that the eng. mounts in those days had a chunk of rubber molded in between the metal part which contacted the frame, and the metal part bolted to the block. That rubber insulated the engine from the body/frame electrically. Ditto for the rear transmission mount. So, the juice from the power source (battery/generator/alternator) could not find a complete path (circuit) from source to load (lights, blower, etc.) and back to source. ALL the return ground current passed through that ground strap. I believe later engine mounts effectively ground the eng. to the frame, eliminating the need for that strap. So, whether or not one is there depends on the design of the eng. mount. Whew!

 

One from the timing cover stud and one from the driver side motor mount bolt to a bolt on the frame.The eec ground runs to the location shown in the pic below.Its also a good idea to add a ground strap or short 4ga cable from the head or lower intake to the firewall. Any additional grounds added will help. EEC Ground
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primo232, everyone here is right on the money. On my full competition cars, I have the welder weld "ground tabs" onto the frame rails. Each electrical item receives its own ground tab. This is overkill for most of our applications, but the point here is that the importance of proper grounding can't be overstressed. P.S. I always double ground the engine block. Yup, old habits are hard dying.