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1989/1991? 5.0
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Discussion Starter · #1 · (Edited)
My son and I are in the process of somewhat restoring a 1989 5.0. First on the agenda is getting the engine up to cruising standards. Right now it will run to operating temp then spit, sputter, then die. It fires right back up but will not take any throttle. My research has lead me to the tfi. I've replaced it once which did not change a thing so I replaced the entire distributor that came with a tfi. Still have the same problem. No change at all.

When the car is up to running temp cruising 35 (doesn't matter what speed really) I mash the throttle to about 60%, it's like it loses fuel or air supply. I let off the pedal then it slowly dies. Gauge cluster is still lit. It will fire right back up and idle fine but will not take any throttle.

Ran codes today:
Koeo 85
Code 11 on continuous memory
Koer 94 and 44

Apparently someone was trying to convert a 1989 lx 4 cylinder to a 91 gt.
There's a bypass smog pulley. Back of the heads were plugged by cutting the pipes off at the elbow, flipping the elbow, and bolting it down. The connector from the harness is hanging there.

When we acquired the car it had a miss so we replaced parts for the fueling system. These parts where purchased from CJ pony:
Filler neck
Tank
Fuel pump
Level sender
Filter

Injectors we bought were refurbished. Originally this car had the single spray nozzles. We installed the 4 hole spray type.
Installed new battery ground and power wire to starter.
New starter and battery.
Ford racing wires
Plugs
Coil

Has the original fuel rail, pressure regulator, and hard line from the tank to rail.

Sensors we replaced:
ECT
Air charge temp
TPS

Relays replaced:
Eec
Fuel pump

Water pump is new from CJ

I'd really love to get this thing running good for my son asap. Working on cars is the only thing he really takes interest in. If he's willing to bust some knuckles I'll bust some with him. I'm new to 5.0s so forgive my ignorance pls. Any help anyone can provide would be deeply appreciated from a defeated 5.0 owner.

One other thing that I found odd, with car at running temp, if I unplug the MAF it will die.

Thanks again

Jon
 

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Take a measurement of the sweep of the TPS.

Have you smoke tested the car? Might be wise considering the plethora of vac lines that run the emissions systems. Smog system is ran using a few solenoids and vac lines. Located behind the passenger side strut tower. A crappy removal of that could cause a big leak.
781839


Unplug the MAF and adaptive fueling is disabled. To me it sounds like it immediately yanks a bunch of STFT out of the car causing it to go lean and die.
 
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Welcome Jon and thank you for joining ALLFORDMUSTANGS!
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1967 Mercury Cougar XR7
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It could also be a bad coil. Under load, it has more resistance, and if it's on the way out (or even has a bad connection?) it wouldn't fire the plugs properly, which would lead to the symptoms you're describing. Is it running well when cold, and then getting screwy, or is it stumbly at WOT no matter what? If its bad behavior only happens once it's warm, that definitely points more to computer mischief or sensor problems.

Speaking of, have you pulled a plug and looked at 'em to see what they look like? I know they're new, but at least you'd be able to see if it's doing something crazy like 'dead lean' or 'fuel fouled' and that might give you more clues.

Good luck!
 

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It should stay running with the MAF unplugged. When it’s unplugged it’ll use the TPS and the ECT to get “readings” that are good enough to at least keep it running. Since it won’t run without it something is wrong with the ecu, tps, or ect I think. Since you replaced those sensors maybe it’s in the wiring? You replaced the sensor that’s in the hard heater hose correct? Not the small one in the manifold?
 

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1989/1991? 5.0
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Discussion Starter · #6 · (Edited by Moderator)
Quick post to answer questions.

The coil is new. Car runs amazing before it hits running temperature.

The ect on the hard heater hose was replaced. To the left of the distributor facing the front of the car.

Thanks for the troubleshooting directions.

I pulled a couple of plugs after getting it up to temp.
Hand Finger Auto part Thumb Metal Wood Thumb Auto part Nail Finial

Checked the TPS voltage and it at .87**.

I don't have access to an evap smoke machine. I've heard of folks spraying starter fluid around the rear of the engine while running and listening for a spike in idle. I'll give it a try tomorrow.
Motor vehicle Automotive fuel system Automotive exterior Auto part Gas

I've tried testing the resistance between the TFI and ECU (or is it EEC) but the pinout I have are not accurate. It had me testing empty pins..... I'll have to research that more.

Have a good evening. Jon

Something is not right with this wiring crap. All the info I've gathered for a 1988 to 91 5.0 does not match what I have. The diagrams and pinouts I have do not match. What the hell is this car....... I'm trying to test resistance from point A to point B.

I'm seriously thinking of buying a new harness. Wtf
 

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I know you put new pump in, but I would still check fuel pressure @ idle (vac connected and disconnected from FPR).
You can also tape FP guage outside windshield, with longer hose (connect to schrader on fuel rail or pass front of motor on
hard fuel lines going to rail)), leave hood popped (but latched) and check it under load that way.
 

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It was originally a 4 cyl?
Don’t set it or yourself on fire with the starting fluid. You’ll probably not be able to get it to spray where you need it to go to get a very good “test.” I don’t think it’d be a vacuum leak any way really. It seems if it was a vac leak that it would run bad all the time not just at operating temp. But maybe the higher idle when it’s cold keeps it running I know.
Was that spark plug wet? Check the fuel pressure like ole boy said. It should be 32 or so psi with the vacuum line connected to the fuel regulator and 40-42 or so with it off.
 

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Discussion Starter · #9 ·
Thank you all very much. I don't mind testing at all just need to know what to test out.

We have a cervini's hood so testing pressure under load will be a bit easier.

Yes this was a 89 4 cylinder lx.

After comparing 88-91 to 94 95 wiring diagrams, it seems I have a 94 95 harness. All the sensors I've bought were for an 89 5.0. Not sure if that is a big deal or if it can be of some assistance to you all to help to help me.

People do the damndest things to vehicles. My wife gets the new cars and I usually get the 2nd hand vehicles. I don't trust mechanics so I do all the work myself, usually redoing someone jacked up crap. Here we go again.:rolleyes::p

Pulled two plugs and they were dry.
Fluid Gesture Handwriting Audio equipment Auto part

Not sure if this can help confirm with you that this is a 95 95 harness.
Electrical wiring Electronic device Wrist Nerve Wire

This happened yesterday. Son put it in gear, died, fired right back up. Died while idling today. Sounds good for a minute then misses back for a couple of rotations then fine, misses a few times possibly dying idles fine, over and over.

Fuel pressure was 35. Bounced with the tach but instead of bouncing down it bounced up

Car still has an hiccup at idle which is newly developed. We took it out for a drive watching the fuel pressure. The more throttle you give, the more the fuel pressure drops. Hit 7psi under load. 35 at idle.
 

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Car still has an hiccup at idle which is newly developed. We took it out for a drive watching the fuel pressure. The more throttle you give, the more the fuel pressure drops. Hit 7psi under load. 35 at idle.
What does the fuel pressure do when you shut the car off? Leak down slowly or drop pretty quickly?

Assuming you reused the stock rail, double check you got all the injector o rings out of it. I chased an issue with the car not holding pressure and a bank of cylinders being lean for the whole summer. Ended up being that i missed 2 o rings from the old injectors that were still in the rail. 2 O-rings are not better than one in this case.

I didnt lose full rail pressure once the car was off. it would leak down quickly to 15-20 PSI, then very slowly like it should if it was sealed correctly.
 
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Discussion Starter · #11 ·
Slowly drops when we shut it down.

We also swapped the ecm, maf, and the map for different ones. Absolutely no change.

Thank you for your thoughts, opinions, and guidance.

Today I replaced the fuel pressure regulator. Do not have the intake on yet just button down the fuel rail to check for leaks. I left the fuel pressure gauge hooked up while checking for leaks and now the pressure is barely dropping. It's been 15 minutes and still above 20 psi.
 

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We took it out for a drive watching the fuel pressure. The more throttle you give, the more the fuel pressure drops. Hit 7psi under load
That's definitely not normal there. 7psi isn't enough to get the injectors to spray.
Changing the FPR sounds like it was a smart idea. Hopefully, that fixes it.
Also, the sensors might be different for the 1994/95 and the 1989-93 5.0L so I would systematically go thru each one on a parts website to see it the same part # is listed for both. It'll take a little while but that will make sure that you have the right parts on the car.
 

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Just for the record, those plugs look pretty good from what I can see!
 

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1989/1991? 5.0
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Discussion Starter · #14 ·
Alright, seems the fpr took care of the loss of pressure when it's warm. We timed the car, took it out for a nice hard ride and fuel pressure held nicely. At wot the pressure would actually go up to 40 and hold it until we let off the go pedal. It does extremely well as far as that goes. I can stamp that fixed (knock on wood).

Now.......we're having a random violent jerk while cruising. Car sounds perfect other than the random jerk. Can feel it in the trans/rear end even.

Only code other than smog, 18. We put the old distributor in with a new TFI. Thinking I should have left the new distributor in due to the pip.
 

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Glad the fueling issue is fixed!

18 is for the spout circuit. Forget to put the jumper back in after timing the car?

Quick sanity check for that circuit is checking timing while someone revs the car. Wont advanced with the jumper pulled.
 
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I wasn't aware the spout connector should be pulled when setting the time.

Yeah, time the car with the SPOUT connector out. It locks out the distributor, prevents computer advance.

Considering the car thinks the SPOUT is still pulled i bet youre not getting any advance at all.
 

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I really should think about the terrible jokes that go through my head before I post them.

lol Glad you're figuring out the problems!
 

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Discussion Starter · #19 ·
I really should think about the terrible jokes that go through my head before I post them.

lol Glad you're figuring out the problems!
Ha! Didn't see the post on the forum but got the email.

Not the first time I've been ask that.

It's tempting to go home on my lunch break and set the timing so I can think about something else. Hopefully we'll get this done today and we can finally move on to other projects for the car. Suspension, interior, trim, and weather stripping. Tired of being under the hood.
 

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Discussion Starter · #20 ·
So, we're still getting the lack of fuel at wot after warm up. There was a change after we installed the fpv, hasn't died on us yet.

Is there a method I can try to test for fuel vaporizing in the line? We're going to check for a clog in the fuel return line also.

There was a ridiculous amount of rust in the tank when we pick the car up. I flushed the supply line and didn't think to do the return........
 
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