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SOHC - 2.3L & 2.5L Lima Engines Discussions and Topics specific to the Lima 4 cylinder engines

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  #1  
Old 07-01-2016
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Fuel problem

I have a 97 ranger 2.3. it will start and die unless I fan the throttle or spray b12 in the breather but dies as soon as I stop. Fuel pressure is in spec in my book at the Schrader valve while it's running but goes to 0 when it's not running. If the pressure is there why won't it run without the spray. Confused.
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Old 07-01-2016
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Fuel pressure on a '97 is 35-42psi, but engine should run/start down to 20psi, engine off pressure should only drop to 25-30psi, and should hold there for a few MONTHS, not minutes, hours or days...........months

0 psi, without an obvious fuel leak/smell, means 1 of 3 things.
1. Fuel pressure regulator valve is leaking or open
2. Fuel Pump has a check valve inside, just a flap that closes when pump is off, it is broken
3. Fuel injector is stuck open

Fuel pressure regulator(FPR) is on the fuel rail, the Return fuel line is attached to it, Return line is a rubber hose with a metal mesh over it, if you are careful you can compress the hose to stop flow.
Then with pressure gauge hooked up, cycle the key on a off a few times, you should get +10psi each time key is turned on
If pressure holds then replace FPR
If pressure still drops to 0 psi then fuel pump is likely the problem

A stuck or leaking injector should allow engine to run, so long shot as the problem in your description.


As for the no start/run with pressure, I assume truck hasn't been sitting for a long period, so water in gas tank settled out and is now being sucked in to fuel system.
Could be a vacuum leak, bigger one, you could block off Power Brake Hose, and PCV hose, and try to start, they are the only ones big enough to cause that symptom.

Also just to take it off the table, unplug the wires on the throttle position sensor(TPS), then try to start.
A short in the TPS can turn off fuel injectors, unlikely problem but not 0 odds

Last edited by RonD; 07-01-2016 at 01:28 PM.
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Old 07-01-2016
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Thanks I'll check that. One thing I read said that depending on which fuel pump you have one kind holds pressure but the other doesn't. But don't remember where I read it.
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Old 07-01-2016
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All fuel injected engines need pressure in fuel system to start, and run.

A broken fuel pump would be the only kind that doesn't hold pressure.
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Old 07-01-2016
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Thank you. I have to work for a few days before I can look into all your advise. But if you think of anything else I would love to have all the knowledge I can before I jump back in. Really appreciate your time and help. So does my son, his truck. Thanks
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Old 07-02-2016
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The injectors have 12v on one lead when the key is ON. The computer provides a ground signal for the injectors to complete the circuit and enable the injector to pulse.
You can check the presence of the 12V using a VOM, and you can check the complete circuit using a 'noid' light. They plug into the connector and flash when the injector should be squirting fuel. You can also use a fingertip to feel the injector function, as it should have a slight mechanical buzz at each valve open/close cycle.
As was noted, the throttle position sensor can stop the injectors if the computer 'feels' Wide Open Throttle with zero engine rpm. That would be when you floor the gas pedal to clear the intake of excess fuel and crank the engine when you have somehow flooded the engine while trying to start.
tom
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Old 07-02-2016
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Thank you. I can't wait to look into all the advice. Also wonder why I can make it run if I crank the idle speed up to like 35 or so. Thought I would add that little tidbit.
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Old 07-02-2016
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Explain what idle speed 35 means?
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Old 07-02-2016
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Idle speed 35 must mean that his IAC is not working ... and allows the engine to die w/o putting a foot on the gas pedal, or 'cranking the idle up to 35'.
Who knows. 3500rpm?
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Old 07-02-2016
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I'm sorry I shouldn't abbreviate a number. 3500 or so. Don't really know just pretty high. No tach
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Old 07-02-2016
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So if I understand correctly, if you open the throttle at least 3/4 or more the engine will start and stay running?

If so then you have fuel leaking in to the engine.
Either from the fuel pressure regulator's vacuum hose or from the fuel injectors.

That would also explain the 0 psi fuel pressure, so probably not the fuel pump.


Have you noticed any wiring issues in the past?
As tmwalsh said the fuel injectors all get 12volts when key is turned on, but stay closed because they are not grounded.
On a '97 4cyl each injector would have its own Ground wire running back to the computer, so 4 wires, if one shorted to Ground then that fuel injector would be fully open all the time.

Fuel injectors make a loud "click" when they open, if possible have someone turn the key on and off while you listen or have your finger on each injector, see if one is clicking open with the key on, it shouldn't.
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Old 07-02-2016
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Thank you both lots of information. Can't wait to tues when I can start trying all your suggestions. I did check tps with a meter and all the numbers where what it said they were supposed to be but from past experience I know that doesn't always matter.
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Old 07-03-2016
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Just unplug the TPS, engine can run without it, that takes it off the table, assume it's wires are not shorted :)
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Old 07-07-2016
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Still not going.

Quote:
Originally Posted by RonD View Post
Just unplug the TPS, engine can run without it, that takes it off the table, assume it's wires are not shorted :)
Checked everything all seemed right. Holds fuel pressure now. Maybe other gauge had a problem. Checked iac. Resistance check was good but the pin in it wouldn't move so replaced but no change. Seems to have very little vacuum but don't find any leeks. When you force it to run it back fires a little thru intake.
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Old 07-07-2016
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"Very little vacuum" needs to be tested, vacuum gauge is not expensive and a very good tool to have, works on any gasoline engine.

Good read here on vacuum levels and testing: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine

Since you have a starting issue you should also check "Cranking vacuum level"
On an engine with good valve timing and good compression you would expect to see 3" of vacuum while engine is turning at starter motor speed.

2.3l has a timing belt, these stretch over time, tensioner holds it tight but does have its limit.
If belt is loose or slips a tooth, valve timing is off so compression drops, low compression means low vacuum and very hard to start and run

If exhaust pipe is blocked you also get low vacuum, you can remove O2 sensor giving exhaust an open exit and then try to start, if it starts and runs, it will be loud, then exhaust pipe is blocked, collapsed Cat or muffler
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Old 07-07-2016
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Ok

Quote:
Originally Posted by RonD View Post
"Very little vacuum" needs to be tested, vacuum gauge is not expensive and a very good tool to have, works on any gasoline engine.

Good read here on vacuum levels and testing: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine

Since you have a starting issue you should also check "Cranking vacuum level"
On an engine with good valve timing and good compression you would expect to see 3" of vacuum while engine is turning at starter motor speed.

2.3l has a timing belt, these stretch over time, tensioner holds it tight but does have its limit.
If belt is loose or slips a tooth, valve timing is off so compression drops, low compression means low vacuum and very hard to start and run

If exhaust pipe is blocked you also get low vacuum, you can remove O2 sensor giving exhaust an open exit and then try to start, if it starts and runs, it will be loud, then exhaust pipe is blocked, collapsed Cat or muffler
I'll start looking into that. Thank you.
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Old 07-08-2016
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Amen

Quote:
Originally Posted by RonD View Post
"Very little vacuum" needs to be tested, vacuum gauge is not expensive and a very good tool to have, works on any gasoline engine.

Good read here on vacuum levels and testing: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine

Since you have a starting issue you should also check "Cranking vacuum level"
On an engine with good valve timing and good compression you would expect to see 3" of vacuum while engine is turning at starter motor speed.

2.3l has a timing belt, these stretch over time, tensioner holds it tight but does have its limit.
If belt is loose or slips a tooth, valve timing is off so compression drops, low compression means low vacuum and very hard to start and run

If exhaust pipe is blocked you also get low vacuum, you can remove O2 sensor giving exhaust an open exit and then try to start, if it starts and runs, it will be loud, then exhaust pipe is blocked, collapsed Cat or muffler
Finally running. Ended up being the first thing I checked. Maf. Checked it using a meter and all the voltages and ohms where all to the specs of the test i found on the Internet so I moved on. Finally yesterday oriellys loaned me a obd code reader and the only code it gave was the mass air flow sensor so I changed it and runs better than I can ever remember. Thanks for all yalls help. Hope this helps someone else. Don't always trust it's good just because it test good on a multi meter.
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Old 07-08-2016
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Good work

Thanks for posting the fix

Never read about a MAF causing a no start no run before, good info
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Old 07-08-2016
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yes ron

the older style MAF sensors have a heated wire , over time the small thin wire will burn out and snap

thus causing a no start issue

there is a mod you can do to the burned out wire

you simply solder on a resistor to emmulate 12.48 degrees celcius constantly to maintain maximum fuel economy

https://www.google.ca/search?q=vehic...eAcYDzMwPpM%3A
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