Need a bit more Mustang 5.0 help . . .

I was driving the car around today and it manifested a really strange symptom that repeated several times, right up until I got home with it.

It's an '85 5.0 GT auto, starts on the key and idles quietly and smoothly. HAs as much pep as you might expect, although the rear brakes might be dragging a bit, the e=brake needs adjusting.

After a few miles, it begins to become sluggish and eventually stops running. Let it sit for a while and it starts right up again, runs another couple of miles or so an repeats the symptoms exactly.

It'll do this all day long.

If it simple sits in the driveway idling, it doesn't seem to shut down, or maybe it isn't idling as long it it should to test the theory.

Sounds like a bad fuel filter or gas, but it starts easily and doesn't bog until it's been running for a while. I guess it could be the distributor or module getting hot, or both ready to fail or slowly failing already? Possibly even a bad electric choke or ignition coil? Not sure though, I know nothing about Fords, but need to learn.

Any help at all here would REALLY be appreciated. I just don't even know where to begin. Thanks ! !

TC

Ford TFI ignition on the 5.0 was notorious for doing this exact same thing. The module gets to hot and cuts out, once the car cools off it will work again. Replace the module and see what happens. I'd recommend the Performance Distributors version as the typical parts store one will work about as well as your worn stock piece.

The engine is an old '85 with one of those central fuel injection systems on it. Kinda looks like a carb but isn't.

Would you know where the module that needs replacing is located? I took off the air cleaner, to expose more of the engine, poked around a bit, but couldn't make out much that looks familiar.

I did find the distributor low and up front under some stuff, but don't know where to look for the module.

Otherwise the engine is kinda nice, oil pressure is low, but nothing sounds funny. Did the 5.0 run low oil pressure like the Buicks, or did they have weak oil pumps? Wondering if the low oil pressure is a common fault as well and what the recommended fix is for it?

As always, you folks REALLY seem to know everything . . . . seriously ! !

Thanks,

TC

Oh . . . . . I just thought of something. Since the engine DOES seem to run so well with the simple central fuel injection, I was wondering if it can be transplanted onto other small V8's with any degree of success. I know that Holley has a nice product that seems a bit similar to the stock Ford set-up, I was wondering if the central injection system might work on other cars in place of the more expensive Holley. Maybe even on something smaller like a built up Pinto engine or a turbo Escort and the like

Just wondering, Seems like a good reliable set-up.

the tbi works ok but not anything compared to multiport and really no better than a carb other than not needing constant retuning. the ingnition module is on the distributor held onto the side of it with 2 5.5 mm bolts.

Katy is right, the TFI module is on the side of the distributor. It's a rectangular hunk of plastic with a wiring connection on one end. The new module should come with new grease (TFI stands for thick film ignition, you need a special grease to sandwich between the dizzy and the module).

In reply to TeamEvil:

You do know that '85 Mustang GT's had carbs, not fuel injection, right?

bravenrace wrote: In reply to TeamEvil: You do know that '85 Mustang GT's had carbs, not fuel injection, right?

Only 5 spds had carbs. Auto's got the craptastic CFI.

Here is a picture of a TFI module on the side of a 4 cyl Ford dist... Yours is basically the same idea...

"Auto's got the craptastic CFI. "

Is it really that bad? The engine seems to run pretty well, (like I said, low oil pressure and sort of sluggish automatic gear change) no worse than a basic four barrel. The reason that I was asking about using it on a different engine is that I thought that there might be more tunability in the CFI than in a quad.

Just an idea . . .

Oh, I know that there isn't going to be much room under the hood of the MGA up front where the distributor sits. Doubt that I'll end up being able to use an aftermarket distributor at all.

Wondering . . . is there a points-style distributor from an earlier 289/302 that will fit the '85 5.0? Maybe I can get a Pertronix set-up for it, or something like that or even keep the points, my old '67 never seemed to be too fussy. The Unilite, Mallory dual point, MSD and such are just too tall, you know?

Thanks,

TC

In reply to TeamEvil:

Negatory on tuneability for the CFI unit. There isn't any unless you want to run some kind of hybrid GM TBI/Ford TFI MegaSquirt unit.

As for the distributor, as long as it has a STEEL, not a cast iron, gear on it any distributor will be fine.

tfi = thin film ignition not thick film. just saying.

Sounds similar to what was happening with my Chevy V8 (L33) swapped RX-7. Turns out the fuel tank was rusting and clogging the sock filter on the fuel pump as a result. Car would start and idle as long as you'd like, but drive around and it would eventually die. Once cold, would start right back up and idle.

im actually more inclined to blame the tps or map on this car than the tfi. my experiences with tfi have been module goes and its gone.

Ranger50 wrote:

bravenrace wrote: In reply to TeamEvil: You do know that '85 Mustang GT's had carbs, not fuel injection, right?

Only 5 spds had carbs. Auto's got the craptastic CFI.

I didn't know that.
But then again, I don't pay much attention to autotragic-equipped vehicles.

If you're worried about the distributor taking up to much room, the Explorer's 5.0 had a distributorless ignition system. Of course you'd need all of the other parts to run it off of the factory Explorer's computer or just MegaSquirt/MegaJolt.

No electronics for this project, just simple carb and the smallest distributor that I can find. Once I get it running and sorted out in the car, maybe drive it around for a month or two, the engine will come out and be converted to a simple quad and Edelbrock, and probably a small stock distributor from the 60's.

I'll try to find a good T-5 and bellhousing assembly in the mean time (seem to be REALLY hard to find around here) and get things ready.

For right now, I need to make the engine run right without shutting down and look at the low pressure problem.

Anyone know if there is a spring in the oil pump or possibly a clogged screen or something that might cause the low pressure. The engine sounds great, but it certainly could be bearings, just checking everything before hand, you know?

There's a number of companies selling "ready to run" distributors for the Ford smallblock using HEI style terminals on the cap and the caps are not that large. Then combine with whatever canister type free standing coil you want to use and you should be done. I would only try one of these if you're also going carb at the same time since you're going to need some output from the distributor to keep factory EFI happy and these things only have a tach output. Maybe one is usable though...

I had a TFI issue that would result in all timing being pulled. New module from the parts store fixed that.... although I've still got an intermittent miss under light load that I think is an ignition problem with my later 5.0.

I've had a similar issue in the past, once with my current foxbody, and once with my old Mercury Tracer. With the Mustang it was the coil crapping out on me, a new one fixed it right up and it's never done it since. With the Tracer it was the plug wires being absolutely ancient; they'd get hot and lose all conductivity.

My suspicion on all "gets hot, starts running like crap" issues is that they're electrical.

you can swap out distributors for going carbed, but you'll need the gear off your current dist (or use an 85 5sp I think the parts places will show the right dist for an 85 gt convertible 5spd - I went through this a while back...). Me and ford coils/ignition seem to come to odds frequently.

How about something like this?

http://www.ebay.com/itm/FORD-289-302-REMAN-DISTRIBUTOR-mustang-66-67-68-69-70-/290672981065?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1985|Model%3AMustang&vxp=mtr&hash=item43ad75b449

Stock, simple, re-manufactured, and no Chinese crap to break in pieces.

I've been finding SO much chatter on line about the current crop of cheap 5.0 distributors being offered, both as electronic vac advance and HEI-style, seems that they practically snap in half after six months or so, or the modules die, or whatever.

These would be too tall anyway, but the early stocker looks promising for sure.

TeamEvil wrote: After a few miles, it begins to become sluggish and eventually stops running. Let it sit for a while and it starts right up again, runs another couple of miles or so an repeats the symptoms exactly.

Try this:
1. Take it for a drive.
2. When it stops, get out and immediately remove the gas cap.
3. Try starting car immediately after removing the gas cap.

Fuel vent . . . never thought of that.

Great idea ! ! ! ! !

Thanks,

TC

dyintorace wrote: Sounds similar to what was happening with my Chevy V8 (L33) swapped RX-7. Turns out the fuel tank was rusting and clogging the sock filter on the fuel pump as a result. Car would start and idle as long as you'd like, but drive around and it would eventually die. Once cold, would start right back up and idle.

I'm gonna throw another vote this direction.