No Start problem
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 397
Likes: 1
No Start problem
My truck: 1990 F150 351W 4x4 automatic
My truck will crank,but not start. No fuel,no spark
I have replaced: plugs, wires, cap/rotor, TFI module, coil.
basically I have tracked it down to that for some reason I'm getting under voltage to required devices.
I am only getting 3.6v from key on circuit and 12v from constant source for the fuel pump relay. If I jumper 12 v to output both tank pumps work correctly.
I am only getting 8.7v from key on circuit for the TFI module to setup coil firing. again 12v from the constant source and good grounds.
I do not get any spark with or without spout and I have also bypassed inertia switch just to eliminate any possible weird issue there.
Any insight or help would be greatly appreciated.. thanks
this issue has consumed 2 of my weekends already.
My truck will crank,but not start. No fuel,no spark
I have replaced: plugs, wires, cap/rotor, TFI module, coil.
basically I have tracked it down to that for some reason I'm getting under voltage to required devices.
I am only getting 3.6v from key on circuit and 12v from constant source for the fuel pump relay. If I jumper 12 v to output both tank pumps work correctly.
I am only getting 8.7v from key on circuit for the TFI module to setup coil firing. again 12v from the constant source and good grounds.
I do not get any spark with or without spout and I have also bypassed inertia switch just to eliminate any possible weird issue there.
Any insight or help would be greatly appreciated.. thanks
this issue has consumed 2 of my weekends already.
More Turbo
Joined: Jun 2012
Posts: 520
Likes: 4
From: Deepwater Mo.
I can't tell you were to begin other then wow! No fuel and no fire? I'd recommend checking for error codes on your OBD-I reader. Here is a couple links that may or may not help.
Ford Ranger/Bronco II TFI Ignition Diagnostics
and here is another link for you..
Motor turns over but doesn't start
Ford Ranger/Bronco II TFI Ignition Diagnostics
and here is another link for you..
Motor turns over but doesn't start
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Sounds like no load voltage checks.
Put the meter away and get a test light with a light bulb in it.
You will find you have no voltage where you got the low readings.
Does the engine crank?
Check the NEG (-) ground cable, does it go to the engine block (it does not go to the frame)?
Do you have a 10GA wire from the NEG (-) ground post to the Body (not the frame)?
If you have good grounds to the body and the block and it cranks unplug the computer and crank it and see if the spark returns.
If so ground pin #6 of the self-test plug and turn on the key. Does the selected fuel pump run?
Put the meter away and get a test light with a light bulb in it.
You will find you have no voltage where you got the low readings.
Does the engine crank?
Check the NEG (-) ground cable, does it go to the engine block (it does not go to the frame)?
Do you have a 10GA wire from the NEG (-) ground post to the Body (not the frame)?
If you have good grounds to the body and the block and it cranks unplug the computer and crank it and see if the spark returns.
If so ground pin #6 of the self-test plug and turn on the key. Does the selected fuel pump run?
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 397
Likes: 1
Sounds like no load voltage checks.
Put the meter away and get a test light with a light bulb in it.
You will find you have no voltage where you got the low readings.
Does the engine crank?
Check the NEG (-) ground cable, does it go to the engine block (it does not go to the frame)?
Do you have a 10GA wire from the NEG (-) ground post to the Body (not the frame)?
If you have good grounds to the body and the block and it cranks unplug the computer and crank it and see if the spark returns.
If so ground pin #6 of the self-test plug and turn on the key. Does the selected fuel pump run?
Put the meter away and get a test light with a light bulb in it.
You will find you have no voltage where you got the low readings.
Does the engine crank?
Check the NEG (-) ground cable, does it go to the engine block (it does not go to the frame)?
Do you have a 10GA wire from the NEG (-) ground post to the Body (not the frame)?
If you have good grounds to the body and the block and it cranks unplug the computer and crank it and see if the spark returns.
If so ground pin #6 of the self-test plug and turn on the key. Does the selected fuel pump run?
The engine cranks great. I have large grounds to both frame and engine, also have new grounds from body to frame.
I have unpluged the spout still no spark.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
The frame does not need any grounds to the battery or the body. The only time the frame needs a ground is if you are pulling a trailer and you are using the frame of the truck for the ground return of the trailer.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
...and? More grounds won't hurt anything.
Sounds like you have an issue with your ignition switch, or some wires from the switch. Do your radio, heater, etc..work correctly?
Try running 12v directly to the TFI module and see if spark returns. I assume you have the proper wiring diagrams for the connectors?
Also check for +12v at the coil.
Sounds like you have an issue with your ignition switch, or some wires from the switch. Do your radio, heater, etc..work correctly?
Try running 12v directly to the TFI module and see if spark returns. I assume you have the proper wiring diagrams for the connectors?
Also check for +12v at the coil.
Trending Topics
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 397
Likes: 1
I have grounds (new) from battery to engine, battery to body, battery to frame, frame to engine, frame to body. I put in all new grounds because when I bought truck they were either rotted off or major corrosion. I have 12v at coil on with key on. I have 12v on pin 3 at TFI with key on. Spout on and spout off no spark out. Also no fuel pump relay on.
everything else works. lights, radio, windows, gauges, turn signal, etc.
I'm just stumped because everything except engine works. Original failure just driving along engine shut down, would not restart. Put indifferent old coil fired up ran 5mins died, put in new spark plugs, wires, cap/rotor and coil. again fired up ran 3mins died, put in a new TFI again started ran 2mins died.. Every time I change something it will start and run about 3mins and never start again.
I appreciate the help this is really stumping me and frustrating me.
just for clarity when you guys say unplug computer do you mean the spout or actually take the huge harness off the computer(10mm bolt, large connector)
again thanks
everything else works. lights, radio, windows, gauges, turn signal, etc.
I'm just stumped because everything except engine works. Original failure just driving along engine shut down, would not restart. Put indifferent old coil fired up ran 5mins died, put in new spark plugs, wires, cap/rotor and coil. again fired up ran 3mins died, put in a new TFI again started ran 2mins died.. Every time I change something it will start and run about 3mins and never start again.
I appreciate the help this is really stumping me and frustrating me.
just for clarity when you guys say unplug computer do you mean the spout or actually take the huge harness off the computer(10mm bolt, large connector)
again thanks
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Cargo Master
Joined: Jan 2011
Posts: 2,791
Likes: 8
From: Edmonton AB, Canada
also regarding the fuel, have you checked for fuel pressure at the fuel rail with key on?
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
The Power Relay (Brown bottom) may be bad or the wiring under the relay may be bad.
Bad wiring under this relay is very common.
Check for power with the key on at the red wire at any fuel injector plug with a test light.
It sounds like the PCM Power Relay is not powering the red wire. This could also be that the fuse link at/near the battery coming off the Battery side of the starter relay is bad. This fuse link is powering the Yellow wire to the common contact on the Power relay. Check also that the Power relay clicks when the key is turned on.
If the fuel pumps run for one second when the key is just turned on then it is not the PIP sensor. Also it would not be the power relay and you would also have power on the red wire.
Yes I would try unplugging the big plug at the Computer to see if spark returns if the red wire at the fuel injectors have power with the key on. The SPOUT works for this most of the time but the computer could also be grounding the PIP wire.
Also with an unplugged computer you will not flood the engine with fuel while you try to find out why there is no spark.
Bad wiring under this relay is very common.
Check for power with the key on at the red wire at any fuel injector plug with a test light.
It sounds like the PCM Power Relay is not powering the red wire. This could also be that the fuse link at/near the battery coming off the Battery side of the starter relay is bad. This fuse link is powering the Yellow wire to the common contact on the Power relay. Check also that the Power relay clicks when the key is turned on.
If the fuel pumps run for one second when the key is just turned on then it is not the PIP sensor. Also it would not be the power relay and you would also have power on the red wire.
Yes I would try unplugging the big plug at the Computer to see if spark returns if the red wire at the fuel injectors have power with the key on. The SPOUT works for this most of the time but the computer could also be grounding the PIP wire.
Also with an unplugged computer you will not flood the engine with fuel while you try to find out why there is no spark.
Thread Starter
|
Senior User
Joined: Nov 2010
Posts: 397
Likes: 1
Thanks for all your help. I found that I had a faulty fuseable link over by the starter solenoid. wiggle it correct everything turned on and worked, wiggle again all shut down..
again thanks all for the ideas and help.
again thanks all for the ideas and help.
Thread
Thread Starter
Forum
Replies
Last Post
DENVER43
1987 - 1996 F150 & Larger F-Series Trucks
10
Nov 11, 2011 08:56 PM
StreetEXtremes
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
10
Jan 18, 2011 10:20 AM
conderd
1973 - 1979 F-100 & Larger F-Series Trucks
5
Dec 29, 2010 09:31 PM
ckb2steelers
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
2
Oct 20, 2003 12:38 AM