'94 Cobra: Won't start

[MrMeanGreen]

My dad's '94 Cobra decided to not start the other day and he had it towed home. The culprit is lack of spark.

 

He's replaced:

 

Cap

Rotor

Ignition Control Module

Coil

 

He's also checked all of the leads and wiring between the above parts. He's now thinking maybe the reluctor on the distributor unit itself. Before going this route, however, we're looking for anything else that it may be. All parts have been replaced with Motorcraft parts.

 

Thanks.

[grease monkey]

you need to get an ossocillo (sp) scope and see if the sensor on the the distributor is functioning normally, No I unfortuneatley do not have one, you may be able to use the mt2500 scan tool and see if the computer is reading the rpm, if it not, then you need to find out why......

[NTHER91]

throwing a code?

[stolen 5.0]

is there spark at all? is the coil/ distributor getting power? it could be a relay

[MrMeanGreen]

Everything is getting power to this point. There is fuel, but no spark.

 

We're now looking at the Hall effect sensor for the distributor. There's also some sort of free-spinning bushing with four "ears" under the housing right by the reluctor which seems to serve no purpose. Anyone have an idea what this thing is for?

[wnaplay1647545503]

Anthony not sure if this will help but found on another site.

 

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

 

1.) Remove push on connector from starter solenoid and turn ignition switch on. Place car in neutral or Park. Remove coil wire from distributor & and hold 3/8” away from engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.

Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.

No spark, possible failed items in order of their probability:

A.) Coil

B.) TFI module

C.) PIP sensor in distributor

D.) ECC relay next to computer

E.) Fuse links in wiring harness

F.) Ignition switch

G.) Computer

 

2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability:

A.) Moisture inside distributor – remove cap, dry off & spray with WD40

B.) Distributor cap

C.) Rotor

D.) Spark Plug wires

E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

 

3.) Spark at spark plug, but no start.

Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.

Two reasons:

1.) If it backfires, the chance for a serious fire is increased.

2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.

If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t ,then it is a computer or timing issue: see Step 4.

 

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/articles...-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In pinch you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have

 

No fuel pressure, possible failed items in order of their probability:

A.) Tripped inertia switch – Coupe -& hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch

B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter.

C.) Clogged fuel filter

D.) Failed fuel pump

E.) Blown fuse link in wiring harness.

F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

 

4.) Spark & fuel OK.

A.) Failed IAB (no airflow to start engine). Press the throttle ¼ way down and try to start the car.

B.) Failed computer (not very likely)

C.) Engine ignition or cam timing off only likely if the engine has been worked on recently).

D.) Firing order off: HO & 351 use a different firing order form the non HO engines.