Hot start problem, have fuel and spark?

mastrdrver

New Member
Feb 19, 2003
82
0
0
O-Town, KS
I bought my buddies 86 LX and he said that it had hot start problems. I thought it was the ignition module, but last night I drove out to another friends and was there maybe 2hrs at night and the car wouldn't start. I know I had fuel bcuz I could smell it. He took off a plug and said that there was spark. What gives? :shrug: The car is mostly stock, except for the lts hpipe and dumps. Has 170k+ miles. The car would just sit there and crank, but never fire. I at a lost for what it could be. I did some searches, but couldn't find anything that fit.

thanks
Jeremy
 
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/electronics/eec-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.
 
How likely is the failed IAB?

I was thinking about how my friend said that he use to start it and he said that if he lightly pressed on the gas it would start, but havn't been able to do that of late. The car will not start when the sun is out and it is hot. I just cleaned the IAB valve, but thought it might be the solenoid? The car will start when it is cloudly out and kind of cool, but if the humidity is up, not a chance.
 
Does it not start because the car is hot from driving or because it is hot outside? I am thinking you mean that you drive it, warm it up, shut it off and a few minutes later try to start it? I have seen computers get hot but usually they shut off when they get hot and you would be driving and it would turn off. So, I would lean towards replacing or at least testing the TFI ignition module and/or fuel pressure regulator. Something is getting hot and needs to cool before it will work again. It is obviously a major part/sensor that is getting hot so I would look towards that direction. I can't imagine something like a cap, rotor or bad injector causing a problem like this. This is one major part.

I would Switch the ignition module out first. Then test the fuel system as explained above. Or if you want, test the fuel system and then change the module, however. I always keep a spare TFI ignition module in my car because they frequently go out and sometimes they are little devils to trouble shoot so I just keep a new one to rule out any problems with my, or other 94-95's I may help with. let me know if I can help more.

Chris
 
No, it doesn't start when it is hot outside. It can sit all night, but if it is hot outside the next day, it won't start. :shrug: I thought it might be the pump bcuz, if I remember right, you don't ever heard it prime when it doesn't start.