Ok, so a low miles 109,000 95, garage kept, last couple months the truck cranks just fine ( new battery, wires,terminal ends) but when cold takes longer and longer to actually start. Once hot it starts almost immediately. Kinda illuminating fuel pump and fuel filter since runs even under hard acceleration, but don't know when the plugs, cap, rotor, wires and coil have been replaced or are OEM. Any suggestions where to start vs just throwing money into all the previously listed parts or some other direction? I'm reasonably mechanicly inclined so replacing just about anything is with my grasp, as is testing....just not sure where to go on this to start! Thanks for helping a new guy on the forum. 95 Eddie Bauer factory OEM, even down to the spare tire cover and floor mats!
Slow to start 95/ 5.8
- Thread starter 95EddieB
- Start date
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yo,
I'll post this for now and will have just today and some of Tues to add more or answer Qs; won't be back again for weeks while I get some medical work done.
Have battery tested for free @ local parts store. Inspect batty posts and clamps for clean and tight connections as well as cable strands for corrosion.
Next;
I have this Exact issue on our 96 Bronco; hard start when sitting overnight and then starts well thereafter during same day.
The in-tank fuel pump assembly has a discharge check valve (to maintain system pressure during shutdowns and to minimize starting problems), an inlet screen for protection and fuel return provision.
The Supply Check Valve, which is normally closed, 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.
FUEL PRESSURE ENGINE RUNNING 30-45 PSI KEY ON, ENGINE OFF 35-45 PSI
Note: Maximum fuel pressure is obtainable at WOT or the vacuum hose removed from the fuel pressure regulator.
Test & Diagram at the Diagnostic Link Connector in 84-95; "...Connect FP Relay to any ground to force the fuel pump on when the key is in RUN..." MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pump{s} for one second when it receives an ignition- on signal. It also runs the pumps as long as it receives a PIP signal from the Hall-effect devices, it continues pump operation even after the key is released from START. If the PIP signals fall below 120RPM, the control module cuts off the signal to the fuel pump relay or the integrated relay control module. The pump will also run when the terminals of the fuel pump test connector are jumped. the Control module signals the pump when it receives a CRANK signal, and when the Control module gets PIP signals that the engine is running. the pump does not run if the PIP indicates the engine is not running even with ignition ON {except for that first one second}.
'87-95 (black or gray) located under L hood hinge under EEC TEST cover. (WPT-743 & WPT-352)
'94-96 Bronco - do not confuse with RED 4WABS connector also under L hood hinge
Source: by Steve
If fuel lines/systems have been drained or evacuated, it may take up to 15 seconds to obtain the pressure specified.
I believe the PUMP's check valve is Stuck in open (full flow) state and allowing fuel to return to tank, thus reducing fuel pressure while engine is off.
I have a slightly similar issue when first starting in morning or after long shut-down; engine will crank over normally, but not run or run rough at low RPMs until it runs or shuts down. If I hear it stumbling, I shut it off, then turn key to start; it will fire up immediately.
I may try a Ford type fuel cleaner soon.
This is by Ryan M; "After attaching the fuel pressure tester, run the fuel pump for 10 seconds. Check that the pressure is within specs, and it doesn’t leak down more than 5PSI within 60 seconds after pump shutdown."
==========
Try turning ignition key to ON (not to start) position; should hear Pump run; do this a few times to prime the fuel lines from tank.
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded
A helper is good to assist in reading Codes; best is to take a cell fone video and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc
The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it, if possible to heat the engine up and shift thru all gears including Reverse.
Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.
Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)
Then turn off engine and wait 10 seconds.
Do KOEO test
Post Code(s) here according to:
KOEO
&
KOER
I'll post this for now and will have just today and some of Tues to add more or answer Qs; won't be back again for weeks while I get some medical work done.
Have battery tested for free @ local parts store. Inspect batty posts and clamps for clean and tight connections as well as cable strands for corrosion.
Next;
I have this Exact issue on our 96 Bronco; hard start when sitting overnight and then starts well thereafter during same day.
The in-tank fuel pump assembly has a discharge check valve (to maintain system pressure during shutdowns and to minimize starting problems), an inlet screen for protection and fuel return provision.
The Supply Check Valve, which is normally closed, 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.
FUEL PRESSURE ENGINE RUNNING 30-45 PSI KEY ON, ENGINE OFF 35-45 PSI
Note: Maximum fuel pressure is obtainable at WOT or the vacuum hose removed from the fuel pressure regulator.
Test & Diagram at the Diagnostic Link Connector in 84-95; "...Connect FP Relay to any ground to force the fuel pump on when the key is in RUN..." MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pump{s} for one second when it receives an ignition- on signal. It also runs the pumps as long as it receives a PIP signal from the Hall-effect devices, it continues pump operation even after the key is released from START. If the PIP signals fall below 120RPM, the control module cuts off the signal to the fuel pump relay or the integrated relay control module. The pump will also run when the terminals of the fuel pump test connector are jumped. the Control module signals the pump when it receives a CRANK signal, and when the Control module gets PIP signals that the engine is running. the pump does not run if the PIP indicates the engine is not running even with ignition ON {except for that first one second}.
'87-95 (black or gray) located under L hood hinge under EEC TEST cover. (WPT-743 & WPT-352)
'94-96 Bronco - do not confuse with RED 4WABS connector also under L hood hinge
Source: by Steve
If fuel lines/systems have been drained or evacuated, it may take up to 15 seconds to obtain the pressure specified.
I believe the PUMP's check valve is Stuck in open (full flow) state and allowing fuel to return to tank, thus reducing fuel pressure while engine is off.
I have a slightly similar issue when first starting in morning or after long shut-down; engine will crank over normally, but not run or run rough at low RPMs until it runs or shuts down. If I hear it stumbling, I shut it off, then turn key to start; it will fire up immediately.
I may try a Ford type fuel cleaner soon.
This is by Ryan M; "After attaching the fuel pressure tester, run the fuel pump for 10 seconds. Check that the pressure is within specs, and it doesn’t leak down more than 5PSI within 60 seconds after pump shutdown."
==========
Try turning ignition key to ON (not to start) position; should hear Pump run; do this a few times to prime the fuel lines from tank.
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded
A helper is good to assist in reading Codes; best is to take a cell fone video and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc
The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it, if possible to heat the engine up and shift thru all gears including Reverse.
Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.
Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)
Then turn off engine and wait 10 seconds.
Do KOEO test
Post Code(s) here according to:
KOEO
&
KOER
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