96 Fuel or Electrical Issue?

pappy19

New member
Joined
Oct 1, 2005
Messages
21
Reaction score
9
Location
Garden Valley, Idaho
My 96 Bronco has 84k and I am the 3rd owner, for 15 years. Never had a starting issue until a month ago. It would turn over but not start. I cycled the key 4-5 times and it would start and run fine. After sitting for more than an hour it would do the same thing. Changed the fuel filter and fuel pump, no change. Changed the ignition module and still no change. Could it be the PCM? Thanks for any suggestions.
 

miesk5

96 Bronco 5.0
Staff member
Moderator
Joined
Oct 18, 2005
Messages
8,720
Reaction score
686
Location
Floating in the Pacific
Yo Pappy,
Ask local mom and pop parts store if you can rent an OBD ii cose reader with a refundable security deposit.
If you can't get an ODB2 reader to hook up while the key is in the run position (doesn't matter if engine is running or not) then you're dealing with a computer, ground or wiring problem. Or possible loss of power fuse/relay.

The ICM can fire the spark plugs independently without PCM control but the fuel injectors will never fire if the computer isn't working/operational. Have a buddy put his finger on one of the injectors while cranking the engine. You should feel them pulse if everything is working on the computer side.

Bad day here, will be back tomorrow
 

miesk5

96 Bronco 5.0
Staff member
Moderator
Joined
Oct 18, 2005
Messages
8,720
Reaction score
686
Location
Floating in the Pacific
Yo Pappy,
Sorry, eyesight went south yesterday and became light headed.

Is Check Engine Light on?

Is starter cranking engine over at a good speed?

Does ignition key spring back from start to run on it's own?
The ignition switch, mounted inside column's shroud is where the spring-back is provided, but actuator(s) is often damaged.. Ensure switch is securely mounted first.

Accessories that fail to operate with the key in RUN, or that remain on when the key is turned off, may be the result of a misadjusted ignition switch rather than a malfunctioning ignition switch.

Test the ignition system mechanical operation by rotating the ignition switch lock cylinder through all positions of the ignition switch. The movement should feel smooth with no sticking or binding. The ignition system should return from the START position back to the ON position without assistance (spring return). If sticking or binding is encountered, check for the following:
burrs on the ignition switch lock cylinder
binding ignition switch lock cylinder
shroud rubbing against ignition switch lock cylinder
burrs or foreign material around the rack-and-pinion actuator in the housing of the ignition switch lock cylinder
insufficient **** on actuator
binding ignition switch

1996 Ford Bronco Full Size
ENGINE - HARD STARTING/LONG CRANK
/STALLING
Article No. 97-9-5
04/28/97
LONG CRANK - STICKING IDLE AIR CONTROL (IAC) VALVE - VEHICLES BUILT FROM 11/1/94 THROUGH 3/30/96

STALL - AFTER STARTING WHEN ENGINE ALLOWED TO SOAK FROM 1-4 HOURS - STICKING IDLE AIR CONTROL (IAC) VALVE - VEHICLES BUILT FROM 1/11/94 THROUGH 3/30/96

FORD:
1995-96 CONTOUR, CROWN VICTORIA, ******, TAURUS, THUNDERBIRD
1996 MUSTANG
LINCOLN-MERCURY:
1995-96 CONTINENTAL, COUGAR, GRAND MARQUIS, MARK VIII, MYSTIQUE, SABLE, TOWN CAR, TRACER
LIGHT TRUCK:
1995-96 AEROSTAR, BRONCO, ECONOLINE, F-150-350 SERIES, RANGER, WINDSTAR
1996 EXPLORER
This TSB article is being republished in its entirety to include the 1995 4.6L Thunderbird/Cougar.
ISSUE:
After a 1-4 hour engine soak time, long crank times and/or long crank to start followed by a stall may occur on some vehicles. No further stalling or rough idle will occur after the engine is running. The long crank and/or stall may be due to the Idle Air Control (IAC) Valve sticking.

ACTION:
Replace the IAC Valve with a revised IAC Valve if no Diagnostic Trouble Codes (DTCs) are present. Refer to the following Service Procedure for details.

SERVICE PROCEDURE
1. Perform normal diagnostics and correct any DTCs as required by referring to the appropriate year Powertrain Control/Emissions Diagnosis (PC/ED) Service Manual.
View attachment 172770
2. If no codes are present, replace the AC Valve by referring to the appropriate model/year Service Manual, Section 03-14. Refer to the following Idle Air Control Valve Application Chart for proper IAC usage.
View attachment 172771
OTHER APPLICABLE ARTICLES: NONE

SUPERSEDES: 96-22-3

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage And Emissions Warranty Coverage

OPERATION DESCRIPTION TIME 970905A Replace Idle Air Control 0.2 Hr. (AC) Valve - 1995-96 ******/Tracer 1.9L 970905B Replace Idle Air Control 0.2 Hr. (IAC) Valve - 1995-96 Contour/Mystique 2.5L 970905C Replace Idle Air Control 0.2 Hr. (IAC) Valve - 1996 Taurus/Sable 3.0L 2-Valve 970905D Replace Idle Air Control 0.2 Hr. (IAC) Valve - 1996 Taurus SHO 3.4L 970905E Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995 Taurus 3.0L 2-Valve And SHO 3.2L 970905F Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995 Taurus/Sable 3.0L 2-Valve And 3.8L 970905G Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Crown Victoria/Grand Marquis/Town Car 4.6L 2-Valve 970905H Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Continental 4.6L 4-Valve 970905I Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Mark VIII 4.6L 4-Valve 970905J Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1996 Mustang 4.6L 2-Valve And 4-Valve 970905K Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Ranger 2.3L And 3.0L 970905L Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Aerostar 3.0L 970905M Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995.96 Windstar 3.0L And 3.8L 970905N Replace Idle Air Control 0.4 Hr. (IAC) Valve - 1995-96 Econoline 4.9L 9709050 Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Econoline 5.0L And 5.8L 970905P Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 F-150-350 Series 4.9L, 5.0L And 5.8L 970905Q Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1996 Explorer 5.0L 970905R Replace Idle Air Control 0.4 Hr. (IAC) Valve - 1995-96 Econoline 7.5L 970905S Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 F-150-350 Series 7.5L 970905T Replace Idle Air Control 0.2 Hr. (lAC) Valve - 1996 Taurus/Sable 3.0L 4-Valve 970905U Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Thunderbird/Cougar 4.6L 2-Valve 970905V Replace Idle Air Control 0.3 Hr. (IAC) Valve - 1995-96 Bronco 5.0L And 5.8L

DEALER CODING
CONDITION BASIC PART NO. CODE 9F715 41

My 96 had symptoms of @ faulty Supply Check Valve, that is normally closed, but opens when the outlet pressure from the energized pump exceeds the opposing check valve spring force. When the pump is de-energized (i.e., engine is shut off), the supply check valve closes to maintain pump prime and fuel supply line pressure.
The valve is not repairable or available.

My issue was on first start of the day; starter cranks normally with ignition key, engine turns over with slight, hesitant stumble @ low RPMs for no more than a few seconds then engine gets up to fast idle and runs well. It runs and starts as new the rest of day with shut-down periods running from 5 mins to 4 hours. Lately, it is starting like new.
 

miesk5

96 Bronco 5.0
Staff member
Moderator
Joined
Oct 18, 2005
Messages
8,720
Reaction score
686
Location
Floating in the Pacific
Yo,
Table 1:
Screenshot_20210922-074546_Gallery.jpg
Ignore Scope Engine for now.
Quick Test is Test for Diagnostic Trouble Codes
Fuel/Throttle Body: may need to Test fuel pressure by obtaining kit from parts store with refundable deposit.
 

Tiha

Well-known member
Staff member
Moderator
Joined
Jul 22, 2020
Messages
580
Reaction score
498
Location
Midwest
Cycling the key always work?

I would put a fuel pressure gauge on it first, and maybe do a fuel flow test.

Cycling the key, cycles the fuel pump, charges the rail. Replacement pumps are spotty. Could still be a pressure regulator.

Scanning for codes would be the easiest step.
 
OP
OP
P

pappy19

New member
Joined
Oct 1, 2005
Messages
21
Reaction score
9
Location
Garden Valley, Idaho
Yo Pappy,
Ask local mom and pop parts store if you can rent an OBD ii cose reader with a refundable security deposit.
If you can't get an ODB2 reader to hook up while the key is in the run position (doesn't matter if engine is running or not) then you're dealing with a computer, ground or wiring problem. Or possible loss of power fuse/relay.

The ICM can fire the spark plugs independently without PCM control but the fuel injectors will never fire if the computer isn't working/operational. Have a buddy put his finger on one of the injectors while cranking the engine. You should feel them pulse if everything is working on the computer side.

Bad day here, will be back tomorrow
Thanks for the suggestions, will give them a try.
 

Members online

Latest posts

Forum statistics

Threads
22,069
Messages
131,573
Members
24,408
Latest member
dbarber76
Top