i posted the other week about my code 42 issue which means my engine which is a 4.9 liter is running rich.this is what i've done so far.I checked the engine coolant temperature sensor and it's good.i checked the oxygen sensor heater and it's good. i checked the oxygen sensor itself and it's good and also all the pins on the plug-in looked clean and no pins bent.
On a previous post on this issue a forum member suggested i do a fuel rail pressure test which i haven't done yet and is my next move.
If my pressure is high that would mean my fuel pressure sensor is bad?is there anything else in the fuel system that would make my truck run rich in fuel? i went from 17 mpg to 14 mpg and my oil gets dirty at about 1k miles and it never even got dirty before this, just dingy between oil changes.
I would like any advice i can get before i go purchase a fuel pressure gauge. thanks alot!

 

Run it for a couple of seconds & shut it off. Pull the vacuum hose off of the fuel pressure regulator. If you find raw gas, replace the regulator.

BTW, harbor freight has fuel pressure gauges for 18 bucks.

 

i would check the pressure regulator it will cause that in some cases and also if it has a mass airflow sensor it can cause a rich condition

 

i will check both of those issues tomorrow. thanks alot

 

i ran multiple tests today on my truck i will list and hopefully get some input on my issues that i think i may have found the culprit. i bought a fuel pressure tester today and here are my results:
1.KOEO fuel pressure test w/grd bypass hooked up was 46psi and the book specs say between 50-60psi is normal so i'm a bit short unless my gauge is off abit although it's new.
2.KOER test with vacuum hooked up results were 46psi.
3.KOER test with vacuum hose removed it went up to 56psi and my book said 5-10 psi increase is expected so thats ok.when i put my thumb over the vacuum port it remained 56psi and my engine idled down back to normal range but my fuel pressure remained a constant 56psi. my fuel pump seems to be holding just above midrange of expected pressure
4.i hooked everything back up and blocked my return fuel line going back to fuel tank and did a test w/fuel grd bypass hooked up and it only went to 43psi.it took it about 5 seconds to show pressure but i think that would be normal with fuel pump drain, any ideas? this 43psi is low again cuz my book says 50-60 psi is normal.thinkin maybe my regulator is going somewhat bad.
5.i took the fuel filter off on the fuel tank side and drained into a clear container and a little tan sediment settled after i let it set about 10 minutes.also there was a smidget of red indicating rust.
6. i ran my fuel pump open ended into a gallon container for 1 minute and the container was just over 3/4 full after that test...this ok?

now i can maybe bullhead my fuel pump to a psi gauge and see what it reads but the fuel regulator bypass earlier yielded 56psi which is mid range of book specs so i think this test is unnecessary and again points to my regulator...right? or am i missing something?

now my question that will make up my mind on this is..would low fuel pressure cause my truck to run rich?
i can only guess my computer is telling my injectors to open up causing this rich fuel ordeal or possibly looping because of it...appreciate your patience with me guys and thanks for your help and advice.i ordered this truck new from the factory when i was a young man and have only replaced a few alternators,bulbs and a fuel pump and it's relay otherwise this truck has never given me issues and NEVER put me on the side of the road

 

i am thinking regulator also the vacuum might be there but the diaphragm may not be acting right as it could have trash in it or just be old

 

yea billybob,

i am still trying to piece in maybe a stopped up fuel line restricting intake or return and why i'm burning rich on a low fuel pressure. my system must be looping by default to cause this rich function if the diagnosis is correct

 

Yeah. with slightly low fuel pressure it should run lean not rich.

With the key off does the pressure hold steady? If not you might have a leaky injector.

Have you looked at the plugs? Are any of them carboned up?

 

I would move to the injectors as well. A carboned spark plug will tell you which injector to inspect for leakage.

 

ok today i looked at the spark plugs and the #3 counting from front to rear was the one with the most carbon and it wasn't real bad. there was like a clump of carbon on one side of the ceramic maybe 1/8" . they all had a light carbon coating as they've always had since i bought the truck.My #6 or furthest plug evidently was never tighted completely because it was handy when i put the socket on it but that wasn't an issue
As for the fuel pressure leak down it leaked off like 23 lbs. of pressure in about 5 1/2 hours.
After i checked the plugs i reset the computer by pulling ground in middle of code check.Then warmed the truck redid the code tests.Code 67 for neutral switch came up for KOEO.the CM gave me an 11 or passed. and i got 42 code KOER which is No HEGO switching detected always rich (right side).
Now i think it's my plug in at the oxygen sensor or somewhere in that area. The oxygen sensor is fairly new.

 

Your fuel pressure regulator is fine. What you describe is exactly how it should work. Your fuel pump is not quite putting out the right pressure though. If it gets much lower your truck may not start, so I would put that on the list of things that need to be replaced but aren't part of the problem.

How did you check the water temp sender? Even if it tests good, are you sure the engine is getting up to the proper operating temp? How did you test the O2 sensor?

 

i checked the water temp sender two ways. first i took it off and put the sensor probe in boiling water which didn't work out too well. so i put it back on the truck and brought it up to temp while holding my ohm meter probes on the pins. the ohms lowered as the temperature increased i wanna say it started at just under 200 ohms and went to around 10.also tested the temperature sensor plug and got close to 5 volts, i think it was 4.66.
My oxygen sensor test was kinda haphazard. i cranked the truck and let it warm up and probed the pins in the plug with my volt meter until i touched two that gave me a reading. i forget the reading i got and didn't write it down but it was like 1.67
i put a new thermostat in it a few yrs ago and i couldn't get OEM but my temp needle goes to the same place. the only difference in my new thermostat and the old one that i noticed is my old thermostat would migrate up to operating temp and my new one goes above normal operating temp before it opens then my temperature drops down to normal range which is like 1/4" above cold mark
This issue i'm having took place when i had to change OEM exhaust system because of exhaust leaks.The people that put my new exhaust on didn't put a catalytic converter on and this is when i first experienced this issue.i could tell by my oil getting dirty it was running rich. I had a catalytic converter installed and bought a new oxygen sensor changed my oil and same thing, it got dirty prematurely.
Either my problem coincidentally occurred at the same time i put the new exhaust on or there is something not right with my emission HEGO.

 

i took my MAP sensor off today and went to autozone where they have a tester.they attached the test eqpt to a 6 volt lantern type battery and used the Hz method of test.It started out at 3.59 and dropped to 3.34 Hz. at 15 psi vacuum which equals a 25 Hz drop in frequency. the guy said my MAP sensor was bad because it should have dropped atleast 30 Hz. i'm not sure if this is correct or not. anybody familliar with the Hz type sensor and is this analogy correct?
i helped in the test by holding the ground probe and operating the vacuum pump. would a weak 6 volt battery cause a flaw in this test?

 

i put in the new MAP sensor today and got a coupla new codes along with the old ones.Is my new MAP sensor assisting in giving me correct data or?
I will list my codes and their meanings:
KOEO: code 67, Neutral safety circuit failure.
CM: 1. code 41, HEGO sensor circuit indicates system lean (right side).
2. code 95, Fuel pump secondary circuit failure. The EEC senses infinite resistance to ground from the fuel pump on the Fuel Pump Monitor circuit.
KOER: 1. 42 No HEGO switching detected always rich (right side).
2. 18 SPOUT circuit open or spark angle word failure.
Why is my new MAP sensor giving more codes? Is it because it's functioning properly?
on CM code 41 & 95 are new on KOER code 18 is new.I just reset my computer KOER and redid the test and the same issues came out.
thanks for any input
jimmy

 

think i found my problem. there was a leak on drivers side door that got my carpet wet. so today i took the trim off the windshield and the plate over windshield wipers.pulled my carpet and the little drivers side kick panel and there was my computer.i hooked my sprayer up on shower spraying in the glued corner and looked inside and water was dribbling in. i felt the top of the computer where the vents are at and they were moist. with water droplets on it
now i gotta read how to remove the computer and pull it out. can it be tested?
appreciate everyones input and i'll hopefully get to give final analysis and close this thread.