66 coupe with 86 5.0 not staring but runs

Aug 4, 2018
18
2
13
37
Nowata County, OK
#1
I sold a fox body and ended up buying this 66 coupe with an 86 5.0 that ran before it sat for 4 years. All fluids were drained before they left it parked. I cleaned gas tank changed fuel pump as it was dead. I changed fuel pressure regulator and fuel filter as well as all hoses with new clamps and blew out fuel lines. Car will crank but not start on its own. I spray just a small squirt of starting fluid and it fires up and runs with ease. I changed out tfi module as I was told could be it but it did not help. I can not find the plug that you are supposed to be able to use to get the codes off of computer.

I am looking for any and all suggestions and I have a page that has a list of stuff to try that I am gonna start on also.
 

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The Shemdogg

Active Member
Mar 15, 2016
127
21
38
41
san jose CA
#2
get a fuel pressure gauge and see if you have pressure at the fuel rail. If you have pressure then your injectors are not firing, start checking for bad wires and retighten all your grounds.

shem
 
Aug 4, 2018
18
2
13
37
Nowata County, OK
#3
Pressure is at 40 before starting and runs around 32 when idling.

It runs on its own but needs starting fluid to start.
 
#4
That definitely sounds like a fuel or computer control issue since it can run — although, why it would be a fuel issue during start and not during run, makes me think it may apt to be computer control-related.

You might test to see if it does it during both cold and hot start scenarios since those are two different computer strategies — meaning the computer handles those situations with different programming.

Obviously it's getting spark or it wouldn't start with starter fluid, but it might be a good idea to test for the intensity of spark during both scenarios (start and run) to see if there is a difference.

You might also check the voltage in the electrical system during both start and run — if the battery isn't providing much punch, the starter fluid may help because it's more volatile.

I almost forgot, initial timing could give you hard or no-start problems, but still allow it to run once started.
 
Last edited:
Aug 4, 2018
18
2
13
37
Nowata County, OK
#5
I bought a brand new battery for it as the one it had was shot. I will check on other items as I get chances....kids got ball practice and games staring all week.
 
#8
After running it for a bit I can shut it off and start it right back up. If let sit for about 30 seconds then it cranks and will not start again.
That's interesting. 30 seconds won't change the computer starting strategy, only engine temp will do that. You might also consider the fuel pump, or, rather, fuel drain back. That can occur given a few seconds. Usually, when a starting problem occurs from fuel loss its because it takes time for the fuel pump to pressurize the system, but it doesn't sound like that's what's happening because you're registering fuel pressure in the lines without the engine running. Just for giggles, you can try turning the key to on (provided it will energize the pump) for a few seconds then try firing it.

Not to send you on a wild goose chase, but what condition are the filter, fuel lines, pump, fuel tank, pick-up sock, rails, pressure regulator and injectors in as a whole? If each one is struggling a bit, it could lead to odd operating behaviors. For that matter, the same is true of the entirety of the ignition system — which leads me to another potential culprit: How's the coil behaving during both start and running?

I do know that a restricted fuel filter will cause hard starting, but it may still run once started — however, you have fuel pressure before starting, so it makes me think that's not likely.

The idle air bypass shouldn't fail before a start up and then work while running, but you could try opening the thottle and firing it. It's a no-no because it causes the injectors to fire excessive fuel into the engine for a start up, but if it's not getting enough air at start up, that might allow it to fire.

Honestly, what you'r experiencing could be caused by so many things because it's not a standard failure behavior.

I don't know how to link a video, sorry.
 
#9
It has a new fuel pump, new filter, and new regulator. I blew out all lines and the rails. I replaced all rubber house parts with new. I cleaned tank and cleaned filter on pick up and blew out pick up tube as well. I have not tested the injectors yet.

I have bought new plugs, wires and coil today so I will see if that changes anything. After that it is back to chasing wires looking for weak grounds and breaks.
 
#10
After changing plugs, wires and coil it will now start by itself.

My oil gauge slowly climbs to above high and temp gauge slowly creeps to high as well. I shut it off and go feel the radiator and hoses and nothing feels hot.
 
#11
Fantastic!

Well, I mean, about the ignition solving your starting problem.

You may need to check your engine's sensors. Bear with me here, because I'm stretching on this because I don't know how accurate this is, but it's possible that the engine uses new sensors intended for use with the car the engine came out of and are providing incorrect signals for the gauges in the car.

The problem is, is that I don't know anything about the specs of either the '86 sensors and gauges or the '66 sensors and gauges.

It could also be that the gauges are bad, but the chances of both of them going at the same time are low.

Beyond that, it could just be bad sensors, but it's definitely electrical signal related.
 
Mar 15, 2016
127
21
38
41
san jose CA
#12
Sounds like you have a jammed thermostat- radiator cold n engine hot. Pull the themo and run it again.

Does your car have the original engine harness? Find a wiring diagram for that year efi and find the color wires to find a signal wire for the check engine light and the aldl plug stuffed in there somewhere.

Gauges should work fine, I have the 95 motor with a 93 intake running a 90 computer and all my gauges work fine except the ammeter. I never hooked it up, I have a digital voltmeter on a gauge pod.

shem