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Old 03-18-2018, 10:57 AM
Smoochie-Wallace Smoochie-Wallace is offline
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Default 1997 2.3l runs rich no codes - FPR or leaky injector?

Hi all, my ‘97 danger ranger has been running rich for awhile now (gas mileage dropped to ~16 mpg and can smell gas from exhaust). However, she throws no codes but runs perfectly otherwise. I put in new motorcraft upstream O2 which increased mpg to ~19, but I still smell fuel from exhaust.

New parts: coolant temp sensor, fuel filter, fuel pump (3 years ago), PCV. Tested MAF, intake temp sensor, IAC and TPS, all are fine. FPR didn’t have fuel in vacuum line, so I figured it was ok. However, yesterday I finally tested fuel pressure at the rail, and recorded the following:

KOEO: ~30 psi, drops to 24 psi after 10 minutes
KOER: ~30 psi at idle and stays ~30 psi when revving. Pressure increases to 40 psi when I disconnect the FPR

I think I’ve found my culprit(s). Based on this data, would it be a bad/failing FPR or a leaky injector that is stuck open? I would have guessed injector until the pressure spiked to 40 psi when unhooking FPR.

Thanks in advance.
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  #2  
Old 03-18-2018, 04:32 PM
12 Deg North Industries 12 Deg North Industries is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Quote:
Originally Posted by Smoochie-Wallace View Post
Hi all, my ‘97 danger ranger has been running rich for awhile now (gas mileage dropped to ~16 mpg and can smell gas from exhaust). However, she throws no codes but runs perfectly otherwise. I put in new motorcraft upstream O2 which increased mpg to ~19, but I still smell fuel from exhaust.

New parts: coolant temp sensor, fuel filter, fuel pump (3 years ago), PCV. Tested MAF, intake temp sensor, IAC and TPS, all are fine. FPR didn’t have fuel in vacuum line, so I figured it was ok. However, yesterday I finally tested fuel pressure at the rail, and recorded the following:

KOEO: ~30 psi, drops to 24 psi after 10 minutes
KOER: ~30 psi at idle and stays ~30 psi when revving. Pressure increases to 40 psi when I disconnect the FPR

I think I’ve found my culprit(s). Based on this data, would it be a bad/failing FPR or a leaky injector that is stuck open? I would have guessed injector until the pressure spiked to 40 psi when unhooking FPR.

Thanks in advance.

Your ranger has a return fuel line, NOT return-less.

If fuel pressure is low, disconnect the vacuum hose to the regulator. You should see an increase in pressure if the regulator is not leaking. No change would indicate a bad regulator. This can also be your starting point to adjust an adjustable FPR if you had one.

However, If the fuel pressure is less than specifications, the regulator could be leaking. You can pinch or block the return line temporarily to see if pressure goes up. If it does, it means the regulator needs to be replaced.

Coincidentally, if there is no change, I would believe the problem is a weak fuel pump or more so a restriction in the fuel line such as a plugged fuel filter.

There are DIY ways to pull injectors too and pressure clean them as well but they wont likely be matched injectors in production build reference.
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Last edited by 12 Deg North Industries; 03-18-2018 at 04:46 PM.
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  #3  
Old 03-18-2018, 04:51 PM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Yes, it has fuel return line. The FPR did not leak gas when I unplugged it, but I have read that it doesn't have to leak gas to be bad/failing... Does anyone have experience with this?

I do not suspect the pump or filter to be the problem as those are new/relatively new.

One option might be to try and clean injectors, and if that doesn't fix the problem, then I would suspect the fuel pressure regulator. I have a mechanic stethoscope, maybe I will try and listen to injectors while engine is running and see if one sounds different from the rest.
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Old 03-18-2018, 08:15 PM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

All injectors had the same clicking sound, so I will put on a new FPR and see if that fixes the prolem.
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  #5  
Old 03-19-2018, 06:26 AM
tomw0 tomw0 is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Unless you changed your speedo gear, your mpg is likely being influenced by the tires you have installed. I think they can also put your engine into a difficult situation given the diameter and gearing. I see a 4.10 swap, but what rpm are you turning when going say 40-45? Use a GPS to note the real mph unless the speedo has been corrected.
It may be you are forced to lug/rev the engine, and that will cause poor mpg. Raising will also cause lessened fuel mileage as will tractor tires.
tom
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Old 03-19-2018, 12:07 PM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Quote:
Originally Posted by tomw0 View Post
Unless you changed your speedo gear, your mpg is likely being influenced by the tires you have installed. I think they can also put your engine into a difficult situation given the diameter and gearing. I see a 4.10 swap, but what rpm are you turning when going say 40-45? Use a GPS to note the real mph unless the speedo has been corrected.
It may be you are forced to lug/rev the engine, and that will cause poor mpg. Raising will also cause lessened fuel mileage as will tractor tires.
tom
4.10 swap was to compensate for the larger tires/loss of power, as well as the LSD for off roading purposes. Speedo is accurate as if factory tires and gear ratio were installed. Larger tires and slight lift (2” in my case) will drop mpg of course, but only 2-3 mpg max due to increased rolling resistance. My loss in mpg is 6+ and I can smell raw fuel coming from tailpipe, as well as black soot inside exhaust, indicating rich condition.

My hope was to see if anyone on here has experience with faulty fuel pressure regulator that doesn’t/hasn’t leaked into the vacuum line yet or leaky fuel injectors that stick open and dump fuel into cylinders. I know the FPR is bad if fuel is in vacuum line, but I’ve also read it can still be compromised without visibly leaking fuel?

I appreciate any feedback and thoughts
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  #7  
Old 03-20-2018, 05:36 AM
tomw0 tomw0 is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

If the problem was a rich fuel mix, you would smell partially burned fuel. If indeed you smell fuel, it may be you have a leaking inlet pipe or connector.
Do you smell raw, unburned fuel? Does it smell more after filling the tank?
If it takes 10 minutes for fuel pressure to drop after shutdown, you don't have much of an internal leak. It does not take much volume of fuel to lose pressure. The only things that will keep the pressure after some fuel has leaked are the walls of the fuel line, generally. The pressure will drop to zero almost instantly if any fuel can leak out if it was in a 'hard' container. The fuel line can expand just a bit under pressure, and will maintain a bit of pressure(dropping) as it relaxes back to an un-pressured condition. (Ain't much fuel to drop to zero.)
Have you looked at any OBD-II scan data? LTFT and STFT, reported air & coolant temps, engine load, ignition timing for a few thoughts.
tom
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Old 03-20-2018, 05:29 PM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

I suppose it is partially burned fuel? Not sure though. Fuel smell only comes from tailpipe, I have recently replaced the fuel filler neck due to cracking/leaking while filling up the tank, so it’s not due to that. Only smell rich condition while truck is running.

And to your second question, no, I don’t have access to a scan gauge to look at that data. I wish I could see that data as it would answer a lot of questions I’m sure. However, I would need to take it to a shop or something to use one.
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  #9  
Old 03-21-2018, 06:45 AM
tomw0 tomw0 is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

This may be low:KOEO: ~30 psi, drops to 24 psi after 10 minutes
KOER: ~30 psi at idle and stays ~30 psi when revving. Pressure increases to 40 psi when I disconnect the FPR

I think the high should be higher, but that would just flow more fuel, so mpg help? Does not seem likely.
Did the mpg drop happen over time, or all-of-a-sudden? Getting 19 with large tires may not be unusual.
The odor from the exhaust may be a function of the blend you find in CA, even just your local area. Could be the mpg drop is from 'winter blend' which may have more ethanol. Have you checked the ethanol actual vs 'admitted' blend? You can do a test by combining measured amounts of fuel & H2O, and measuring the final volume. ETOH will absorb some HOH, leaving a lowered volume than one would expect. If the volume is less than it should be with 10% ETOH, you are being sold fuel with excessive amounts of ethanol... leading to lowered mpg.
tom
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  #10  
Old 03-21-2018, 09:39 AM
jeff18 jeff18 is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Have always been told that unburned fuel after it goes through the Cat smells like rotten eggs, not raw fuel.
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Old 04-17-2018, 10:39 AM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

Got ahold of a scan tool to look at fuel trim, sensors, etc. All sensors look good, as expected. Long term fuel trim (LTFT) is high at idle (b/w +11 & +15%) and STFT is not compensating, usually staying b/w -1.8% and +4.5%. However, at 1500rpm and 2500 rpm, the LTFT drops to normal levels (0-5%) with STFT compensating (b/w -5 & 0%).

This to me indicates a vacuum leak somewhere? I tried doing the cigar smoke trick into intake tube with engine off (no smoke leaking) and spraying carb cleaner onto vacuum lines and intake gaskets, but I didn't hear an increase in engine rpms.

So I guess I am stumped? Anyone know of a better way to detect vacuum leak or other reasons why fuel trim is high at idle? Could be leak in EVAP lines or solenoid?
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Old 04-19-2018, 12:03 PM
Smoochie-Wallace Smoochie-Wallace is offline
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Default Re: 1997 2.3l runs rich no codes - FPR or leaky injector?

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