Need help troubleshooting a possible EEC startup problem

JohnW63

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Jan 9, 2022
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My Dad has a 1965 Mustang but years ago, he put a more modern 5.0 in it. The EEC unit is a version IV. Based on the engine wiring harness, I think the loom is from a 1994 Mustang. It took me quite some time to find a diagram that the color codes mostly matched and the relays matched. ( One is the the fuel system relay and the other is the A/C wide open throttle relay ) . Some months back we changed his fuel system to a tank with a built in fuel pump from the original 65 tank and an external fuel pump. After installing the tank and hooking up the wiring, I wasn't getting power to the fuel pump and I had to trace all the wires and spend lots of time reading forum posts and looking for the right wiring diagrams. Then is started working with the wiring back the way it was after I installed the tank.

Here is the problem we have now. If the car sits for a few days, the startup is really poor. It backfires a few times, the RPM is really slow and it might die. If you keep working the pedal or try again, it will finally clean up and run. Once it runs a bit and you shut if off, it starts up like it always used to.

I don't know if the EEC is not getting good constant power and eventually forgets all the sensor values it "learned" if a sensor is bad or has a loose connector, or, if a cylinder is getting flooded when sitting, due to a leaking injector. It could be the EEC is going bad.

Using a code reader isn't too helpful because the engine does not use all the plugs from the wiring harness and the EEC records things like a purge canister error since there is no canister.

On a side note, " Starting like it used to " is a little odd because ever since he's had this engine in, with the newer electronics, he would fire it up right off, it would die, and then a second attempt would fire up fine and stay running. It wouldn't die in an ugly way, it would just shut off, like it ran out of fuel. That's why we changed the fuel tank setup. To try and solve this.

I hope there are some EEC experts in the forum still.
 
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manicmechanic007

5 Year Member
Sep 26, 2017
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The fuel pressure is your concern
Are you saying you have no self test connector or otherwise cannot check the codes?
Sometimes the aftermarket tank fuel pumps leave a lot to be desired
You may want to switch back to a new factory style tank and have a fuel pump ring off a 94 Ford welded into it
Thunderchicken or crown vic should work
 

JohnW63

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Jan 9, 2022
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General,

I'll go hook a fuel pressure gauge to the rail ( I assume there is a rail. ) and report back. I can read the codes, but I did not write them down. As I recall, they were for devices, like the canister that did not exist on this engine.

ManicMechanic,

My big concern is the really crappy first startup! I don't like a stumbling and backfire situation. My Dad is considering selling it because he no longer trusts it. I won't let him do that. I would think a bit of time , learning and not too much money would be worth it for a restored 65 convertible. I hope I didn't damage the EEC with all the wire tracing with a tone generator and ohm meter.

As far as the tank and pump goes, that was a $500 "upgrade". Previously, he had the stock 65 tank and a external fuel pump with the return line threaded into the hole for the drain plug. It worked, except for the start 2 times issue, but it didn't have the bad start and backfire issue.
 
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manicmechanic007

5 Year Member
Sep 26, 2017
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General,

I'll go hook a fuel pressure gauge to the rail ( I assume there is a rail. ) and report back. I can read the codes, but I did not write them down. As I recall, they were for devices, like the canister that did not exist on this engine.

ManicMechanic,

My big concern is the really crappy first startup! I don't like a stumbling and backfire situation. My Dad is considering selling it because he no longer trusts it. I won't let him do that. I would think a bit of time , learning and not too much money would be worth it for a restored 65 convertible. I hope I didn't damage the EEC with all the wire tracing with a tone generator and ohm meter.

As far as the tank and pump goes, that was a $500 "upgrade". Previously, he had the stock 65 tank and a external fuel pump with the return line threaded into the hole for the drain plug. It worked, except for the start 2 times issue, but it didn't have the bad start and backfire issue.
Great! Sounds like you are smart enough to figure this out
Tape a fuel pressure gauge to the windshield and take it for a drive
Then report back Thanks
There definitely is a rail and you will use it to clean the fuel injectors.
It has the port with the Schrader valve that you want to access for testing and fuel rail injector cleaning
 

JohnW63

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Jan 9, 2022
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Manic,

I'm not sure my gauge has a hose long enough and there is no path from under the hood to pass it through and drive it around.

I can easily check it after the pump primes and when it's running and see if it holds pressure after shutting it down.

Now that I think about it, I should make sure I hear the pump prime before starting it. If it does, then it is losing pressure. It shouldn't have to prime if the system is holding pressure.

Still , it's the backfiring that has be worried more.
 

manicmechanic007

5 Year Member
Sep 26, 2017
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Yes JohnW63.
IMHO fuel pressure is your issue especially on initial startup
Any way you can see the gauge while on the quick test drive is acceptable
Hang your head out the window
Put a go pro under the hood
Prime it two or three times before hitting the starter and see how it responds
Not too concerned with codes when your trouble is mainly on initial startup
I / we all would all like to see you check the codes anyway to see if any correspond to your concern
Good man John I think you should be able to figure this out
 

manicmechanic007

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Is it an ATI fuel cell?
Who made the pump?
What is the warranty if the pressure is low?
If you were my client and I put the aftermarket fuel injection gas tank setup in your car
I would be sheeting a brick wondering how I can come up with a replacement pump quick
 

JohnW63

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Jan 9, 2022
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I went over with the pressure gauge and could not find the Shrader valve to save my life. The fuel pressure regulator is at the back on the passenger side. The input on the the front passenger side. I stuck a flashlight under both sides of the intake that covers a good chunk of the engine. I did find that a tube that goes from the oil filer on the passenger side to the Mass Airflow sensor was disconnected.

When I had my dad start the car it would fire up and then shut down. A few times in a row. When I got in and fired it up, I used the throttle and it had a rather high idle speed and would stumble a lot when I tried to give it some gas. After a minute or so of trying, that it was able to throttle up when I stepped on it. What we had as popping or backfiring before must have been trying to use the throttle. The fuel mix when cold must be off a lot.

I ran the code reader I got the following.

Power on, engine off:

21 - Engine Coolent Temp out of range
24 - Air Intake Temp out of range
81 - Boost control solenoid
82 - AIRB Solenoid or stuff for 2.3 or 3.8 engine
84 - ERG Solenoid
85 - a couple of possibilities:
2 3L T/C Automatic – 3/4-4/3 Shift solenoid – Transmissions​

CANP solenoid (ALL 1989) – Solenoids​

1 9L MFI – System has corrected rich condition – Fuel control​

Here is the engine bay.

65ConvertEngine.jpg
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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The fuel lines are aftermarket so the probably does not have the schrader valve to check fuel pressure :doh: that's bad, also what distributor is that, I don't see the tfi or wires?
if you can't check fuel pressure you're handicapped when diagnosing issues. Some aftermarket fuel pressure regulators have a place to install a gauge :shrug: you need to know the pressure.
What is the timing set at?
Is it backfiring into the intake or out the exhaust?
Are there o2 sensors installed?
don't worry about the purge canister although the computer does use this for part throttle cruise but I don't know or remember how/what tank/pump setup you are running.
 

manicmechanic007

5 Year Member
Sep 26, 2017
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JohnW63,
Check the fuel pump pressure at the fuel filter if there is no tap
It has the wrong processor for the application if it is giving you any boost codes (not a deal breaker)
The first codes can sometimes set several others that are meaningless
That is why they make you diagnose and work thru the lower numeric codes first
If the pcv tube was disconnected from the maf pipe it is relearning idle now and will continue to die for a few start cycles until it relearns idle speed
Keep at it
There is no fuel coming out of the vacuum port on the fuel pressure regulator right?
 

manicmechanic007

5 Year Member
Sep 26, 2017
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Try to run it long enough to get it up to operating temp and then retest the codes so the first two go away
We all want to see the results
Get a new to you used fuel rail and some new to you more orange injectors from the junkyard
I have a spare V8 fuel rail on my bench somewhere that I use to clean and test injectors individually
Dime a dozen at the wrecking yard with injectors attached
 

JohnW63

Member
Jan 9, 2022
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General,

I think what I heard was what I thought was popping in the intake. Yes, there are O2 sensors installed. I'll check the timing. I wish Dad was around the block instead of 30 minutes away. I don't know much about what's under the hood. I wasn't in the crew that dropped the engine in. He had someone from a Mustang forum, he thinks, come by and hook up the harness and make it work. They were all surprised that it fired up the very first time. So, what distributor is in use, I really don't know.

Manic,

There may be a filter in the engine bay, but I'm not sure. I put a small canister filter at the exit of the fuel tank, that has the pump in it. It's just hoses and clamps on tubing. The engine bay has aircraft like fittings with braided lines. I wonder if there is a way to install an " inline valve " between the fuel line and the rail ? I'll check the pressure regulator. I tried to pull the line of the top, last night, but it was covered by that ribbed plastic tubing used to hide the electrical stuff and it didn't just slide off, like on my Jeep.

What should the junkyard fuel rail, come off of? Ford V8 years X-Y ? Does it need to be Mustang or any 5.0? If I get a decent one, could I just swap out the 3rd party one and have a schrader valve from now on? I don't know how hard it would be to remove the big grey elbow macaroni intake to do that.

My 65 Mustang has a 289 and 4bbl carb. This is a new learning experience.

btw... Can you tell what year or years this this 5.0 is from that one shot? It would help my Google searches. There is a possibility that it was a crate motor and the intake and electronics was from something from a salvage yard. I believe that is what the story is. It was either this one, or the one in my sisters' car that has now been sold.
 

manicmechanic007

5 Year Member
Sep 26, 2017
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It looks to be 1985-1987 to me
Any newer than 94 will have a shrader valve I believe
Not too tough to get the upper intake off
You want to take a look at those upper gaskets and the early ones have a 2nd gasket under the plate
You need to take a pic of the engine close (a few closeups would help) so we all can see exactly what we are talking about
That sure looks like a factory rail and there should not be a Shrader valve if 86-93
We used special tools like these
 

manicmechanic007

5 Year Member
Sep 26, 2017
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The top one is to clean injectors and blocks off the return line
The 2nd one is what you would use to test your pressure with no tap
3rd one is Non Naao Japanese banjo fitting type
4th one is ford rail injector cleaner adapter
5th one is early cfi Tempo T Bird too maybe
6th one is one I made for anything with FG800 or FG872 filter
People have been known to drill and tap the square block on the existing rail to add their own tap and not use the fittings
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Lets get you straightened out on the fuel lines where the schrader valve should be, in the pic is the fuel lines to the fuel rail on an 86-93 fox mustang, there is what looks like a tire valve on one line, that's the schrader valve, you don't have that because of the aftermarket fuel lines, let me look for a fuel pump regulator with a port for a gauge.
lets work on one thing at a time.
Meanwhile do you have access to a timing light?
 

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