fuel problem
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fuel problem
got '86 bronco II.has been running rough at lower rpm's.now it has died and won't start.seems to be either fuel pump,reset,relay or filter.
where is reset and relay?
how do i diagnose the problem without replacing all the above?
leftfield
where is reset and relay?
how do i diagnose the problem without replacing all the above?
leftfield
Last edited by leftfield; Apr 25, 2006 at 09:01 AM. Reason: repitition
Postmaster
Joined: Dec 2001
Posts: 3,742
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From: UT
Fuel pump relay is under the hood, passnger fender.
Reset (usually called inertia switch by repair manuals) is in the cabin, attached to the firewall, just to the right of the transmission hump, near the passenger's feet. Has a button on top you press to reset it (assuming it's been tripped).
How to diagnose? 1st question: What have you done that leads you to think it's fuel delivery? 1st thing I would do if I suspected a fuel delivery issue would be to put a fuel pressure gauge on the fuel rail and see what the fuel pressure is. If the fuel pressure test shows problems, then R&R as needed. If the fuel pressure test looks fine, then look into other systems (pull codes from the computer, etc.) Ken00 posted some instructions for a fuel pressure test in his tech info post at the top of this forum.
Reset (usually called inertia switch by repair manuals) is in the cabin, attached to the firewall, just to the right of the transmission hump, near the passenger's feet. Has a button on top you press to reset it (assuming it's been tripped).
How to diagnose? 1st question: What have you done that leads you to think it's fuel delivery? 1st thing I would do if I suspected a fuel delivery issue would be to put a fuel pressure gauge on the fuel rail and see what the fuel pressure is. If the fuel pressure test shows problems, then R&R as needed. If the fuel pressure test looks fine, then look into other systems (pull codes from the computer, etc.) Ken00 posted some instructions for a fuel pressure test in his tech info post at the top of this forum.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Whenever you have a BII/Ranger that dies or runs rough at low RPMs, replace the TFI module first!
It is the cause of probably 90%+ of all non-starts or driveability problems.
Cost is $30 from just about anywhere. The Wells ones seem to last the longest.
Then start worrying about fuel pumps or other ignition problems.
It is the cause of probably 90%+ of all non-starts or driveability problems.
Cost is $30 from just about anywhere. The Wells ones seem to last the longest.
Then start worrying about fuel pumps or other ignition problems.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
TFI module is the ignition module attached to the distributor.
Several steps to testing an ignition module:
1) Pull codes: ICM and EEC-IV computer work together. Some failures of the TFI module will leave codes in the computer.
2) There's a write-up in the tech info article on how to test the TFI module with a voltmeter.
One thing to note when testing the TFI module: It often only fails when hot. Test it cold and it will check out fine. But, installed in the engine, it can get hot and then fail. Basically, just because a TFI module tests good on the bench doesn't mean it is good.
Several steps to testing an ignition module:
1) Pull codes: ICM and EEC-IV computer work together. Some failures of the TFI module will leave codes in the computer.
2) There's a write-up in the tech info article on how to test the TFI module with a voltmeter.
One thing to note when testing the TFI module: It often only fails when hot. Test it cold and it will check out fine. But, installed in the engine, it can get hot and then fail. Basically, just because a TFI module tests good on the bench doesn't mean it is good.
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Originally Posted by mrshorty
Fuel pump relay is under the hood, passnger fender.
Reset (usually called inertia switch by repair manuals) is in the cabin, attached to the firewall, just to the right of the transmission hump, near the passenger's feet. Has a button on top you press to reset it (assuming it's been tripped).
How to diagnose? 1st question: What have you done that leads you to think it's fuel delivery? 1st thing I would do if I suspected a fuel delivery issue would be to put a fuel pressure gauge on the fuel rail and see what the fuel pressure is. If the fuel pressure test shows problems, then R&R as needed. If the fuel pressure test looks fine, then look into other systems (pull codes from the computer, etc.) Ken00 posted some instructions for a fuel pressure test in his tech info post at the top of this forum.
Reset (usually called inertia switch by repair manuals) is in the cabin, attached to the firewall, just to the right of the transmission hump, near the passenger's feet. Has a button on top you press to reset it (assuming it's been tripped).
How to diagnose? 1st question: What have you done that leads you to think it's fuel delivery? 1st thing I would do if I suspected a fuel delivery issue would be to put a fuel pressure gauge on the fuel rail and see what the fuel pressure is. If the fuel pressure test shows problems, then R&R as needed. If the fuel pressure test looks fine, then look into other systems (pull codes from the computer, etc.) Ken00 posted some instructions for a fuel pressure test in his tech info post at the top of this forum.
Postmaster
Joined: Oct 2003
Posts: 4,516
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From: SoCal
When you turn the key to run, do you hear both fuel pumps for 2 seconds?
if both pumps are running, hook up your timing light to any plug wire & crank it, does it flash?
if both pumps are running, hook up your timing light to any plug wire & crank it, does it flash?
Last edited by 87 XLT; Apr 26, 2006 at 01:58 PM.
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fuel pump
Originally Posted by 87 XLT
When you turn the key to run, do you hear both fuel pumps for 2 seconds?
if both pumps are running, hook up your timing light to any plug wire & crank it, does it flash?
if both pumps are running, hook up your timing light to any plug wire & crank it, does it flash?
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Posting Guru
Joined: Sep 2004
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From: Yokosuka, Honshu, Japan
check your fuses and fuel pump relay and the intertia switch. if all of that is good, then check for ignition spark. if you get no spark, more than likely the TFI module on the distributor needs replacement.
Postmaster
Joined: Oct 2003
Posts: 4,516
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From: SoCal
Since the pumps are not running you need to check for voltage at the inertia switch which is under the dash/passenger side.
Pull the connector off of the switch & connect your voltmeter to the orange/light blue wire and to any handy ground screw under the dash.
Turn the key to run & you should see 12
volts for 2 seconds.
If your not sure where to ground your voltmeter connect a long wire to the negative post on the battery & use that for your ground.
Post back with your results.
Pull the connector off of the switch & connect your voltmeter to the orange/light blue wire and to any handy ground screw under the dash.
Turn the key to run & you should see 12
volts for 2 seconds.
If your not sure where to ground your voltmeter connect a long wire to the negative post on the battery & use that for your ground.
Post back with your results.