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HELP - long crank on start - tried everything


RonD

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The 1997 and earlier Rangers only used 30-40psi running fuel pressure, and key on one time should give you 10psi if it was 0psi which should be enough to get a startup or firing at least
But low fuel pressure at startup is the most common issue for long cranks and/or no starts

I would swap out ECT sensor just on speculation, this is what sets the Choke on cold start, or sets NO Choke on warm start
Either being incorrect would cause slow or no start

Watch CEL(check engine light), it should go OFF as soon as engine is turning, so as soon as starter motor is activated
This means computer is seeing the timing signal from crank sensor so will start spark and injectors
If CEL doesn't go off instantly then crank sensor may be failing or not inline with tone ring so not generating a good signal


Gas pedal on fuel injection is more of an air pedal, same as it was on carb engine, but with No Jets(or accelerator pump) opening the throttle doesn't add more fuel, just more air on a EFI engine
And computer doesn't add more fuel when you press down on gas pedal UNLESS engine is already running, above 400rpms
So if opening throttle helps with startup then clean the IAC Valve, it should be open all the way for start up, for max air flow, it may be sticking sometimes
 


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Eddo Rogue

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for some reason, my air pedal helps it start.
 

RonD

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It shouldn't, that would mean something is wrong

Key on
Computer boots up and opens IAC Valve all the way
Computer checks ECT sensor for setting air/fuel mix ratio, i.e. choke or no choke
Computer checks outside air pressure, DPFE sensor or MAP or BMAP to adjust air/fuel mix for elevation above sea level
Computer checks Air Temp, IAT or ACT sensor to adjust air/fuel mix for intake air temp

Without touching gas pedal
Engine should start and REV above 1,400rpm, warm or cold
Then drop as computer closes the wide open IAC Valve to set cold or warm idle RPMs based on ECT temp

Pretty much any fuel injected engine does this, the REV may be less pronounced on some models but is there if you watch(tach) or listen

There is no IAC Valve position sensor, computer just grounds it fully and expects it to be wide open, so if you are missing the REV then IAC Valve may be sticking and not opening all the way, clean it and all will be well
So you can keep your foot off the air pedal :), at startup anyway, lol
 
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fiddlermd

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OK so I got a fuel pressure gauge.. only to find out there's no damn fuel pressure test port on this engine?! am I missing something?
 

RonD

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No, its possible they didn't install a test port

Do you see this: https://www.ford-trucks.com/forums/attachment.php?attachmentid=199753&d=1501289847

Here are the selections of what Ford used on the ends of fuel rails in the 4.0l SOHC: https://cimg4.ibsrv.net/gimg/www.evolutionm.net-vbulletin/2000x1504/1_345281927677f9c03772c2536cc9c1689b88b0f7.jpg

Top center is a fuel pressure wave damper, vacuum port was for safety
On the left are just end caps, no function other than that
On the right are the schrader valve fuel pressure test ports, also an end cap with a function

These 3 are interchangeable
 

fiddlermd

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RonD

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Can't say I have seen one that fits your description, so not sure what would fit that one

It would be a long shot but may be Mazda used a different size schrader valve setup on their engines so the one you have fit Mazda Dealer service testers, extreme long shot, lol
 
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fiddlermd

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I'll try to take a photo and a measurement a little later
 

fiddlermd

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so this is strange.. i've been working on replacing my seats so the car was off for like a week or 2.. i did have a bluetooth obd2 scanner plugged in all the time.. anyway.. suddenly i find that the car starts just fine.
i thought maybe something weird with grounding via obd2 .. disconnected it.. still starts just fine.. however, what i notice now is that the temperature gauge on the dash jumps to center as soon as I start the car every time, regardless of engine temp.
could this all be due to some bad temp sensors?
I did replace the chain tensioners just before this started so i had to pop those out.. wonder if maybe i damaged either the sensors or the wiring?
oh and the low battery light is still on all the time .. but the car runs fine and starts fine
 

RonD

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so this is strange.. i've been working on replacing my seats so the car was off for like a week or 2.. i did have a bluetooth obd2 scanner plugged in all the time.. anyway.. suddenly i find that the car starts just fine.
i thought maybe something weird with grounding via obd2 .. disconnected it.. still starts just fine.. however, what i notice now is that the temperature gauge on the dash jumps to center as soon as I start the car every time, regardless of engine temp.
could this all be due to some bad temp sensors?
I did replace the chain tensioners just before this started so i had to pop those out.. wonder if maybe i damaged either the sensors or the wiring?
oh and the low battery light is still on all the time .. but the car runs fine and starts fine

Your Temp SENDER is failing, has failed, part is DY1004 I think
Computer uses a 5volt temp sensor
Dash uses a 12volt temp sender

In a 2003 4.0l SOHC Ranger both of these will be on top of the thermostat housing
The SENDER will have red/white and black/white wires

These are held in by a clip, not screwed in, clip slides out side ways
The Plastic thermostat housing is a known leak point on the 4.0l SOHC, so just a heads up, to have a good look while you are in there
Good how to seen here: https://howtoreplacefordthermostathousing.com/

There are Metal replacement housings now

Just as a test unplug the Senders 2 wire connector and turn on the key, engine off
Temp gauge should stay down, if not you may have a partial short to ground on the red/white wire

If you Ground the red/white wire, key on, gauge should go to HOT
If you put a jumper between the red/white and black/white wires, key on, gauge should go to HOT, this tests that black/white wire is a good ground
 


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