I think I have water in the fuel

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VIKING_MECHANIC

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Here are some screenshots of the live data after the truck decided to start running better. Keep in mind, the EVAP system is kinda F**ked, so it runs rather rich.

I took these when it was showing the P0307 misfire and hadn't cleared it. After I cleared it, I went back into the live data and the fuelsys1 and 2 were no longer there.

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Erik the Awful

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I'm wondering how an EVAP system, which simply applies a vacuum on the gas tank to reduce the emission of fumes when you pull the cap, would cause your engine to run rich. The only thing I can think of is if you consistently overfill your tank and over time you've filled your EVAP canister with gas. The only fix for that is a new EVAP canister.

I don't think that would cause an "EVAP system flow during non purge", that sounds like a failed valve. But it's also been twenty-plus years since I've had to do anything with an EVAP system, so YMMV.
 

Schurkey

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I'm guessing that the EVAP code has nothing to do with the way the engine runs...but I learned long ago to never say never, and "anything is possible".

Having no experience with that scan tool, I'd shut it off and turn it back on, and see if the missing data comes back.

Plug wires need to be tested with an ohmmeter; it's common for the conductor to fail while the outside of the wire looks pristine or at least "serviceable". And the insulation can be faulty, leading to the spark shorting out, or loss of spark power via "corona effect".
 

kauila

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A possible cause is moisture in the distributor as several have pointed out. I had a recent problem with my 1988 Chevy which had similar symptoms with idling etc. as you described. It turned out to be the Ignition Control Module connection inside the distributor. The module connectors outside the distributor are pretty waterproof, but the one inside is not waterproof at all. Mine had considerable rust on the two terminals when I disconnected it. It must have been giving a weak spark for some time. Don't just clean those two flat terminals, but also clean the spring connectors where they slide into. I'm not sure if your truck has the same setup, but I recommend anyone with the same module check that inside module connection. I had always overlooked that connection until I was forced to figure it out. Don't forget to use some dielectric grease on the connection too.
 

Ken K

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Bank 2 was the same when I took that picture. This engine runs rich mainly because of a worn out EVAP system.
Don’t forget that warmed up engine is running the purge valve to evacuate the activated carbon canister all the time. On or off as later models use PWM. So water can come in thru tank valve, rust vent tube all behind the left rear wheel. A brilliant place to put everything as if in the engine compartment like an 86 MonteCarlo with round canister and serviceable filter underneath, today’s canisters are rectangular and sized by how much fuel the can hold. Dust & dirt on county roads fill the tank vent valve as it is alway open unless 8 hours of run time (Varies by programming) then closes once powered to check for system leaks. This result in “Small Leak EVAP” codes. This check only runs between 80% of full and 20% of empty plus at op. temp. and highway speeds (Varies by year). Water in EVAP from engine is unlikely due to purge valve just sitting there and “Green Cap” on test line for smoke test or vacuum or both. Don’t forget gas cap. Since a small EVAP leak is a type “B” code, it only sets code after two failures in a row, only then light comes on. On new vehicles after a refill even and fuel drops below 80% then if test fails, the drivers info center says “Check Gas Cap”. This is all part to the enable criteria required for the test to run & fail or pass and move on. It also will run this test if other codes are current such “Purge Solenoid Resistance Too High, Too Low, Open circuit. This system called OBD-2 has been out there since 1994 yet no one knows how it works. Strange?
ASE Master Tech since 1978, Retired
 

Ken K

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A possible cause is moisture in the distributor as several have pointed out. I had a recent problem with my 1988 Chevy which had similar symptoms with idling etc. as you described. It turned out to be the Ignition Control Module connection inside the distributor. The module connectors outside the distributor are pretty waterproof, but the one inside is not waterproof at all. Mine had considerable rust on the two terminals when I disconnected it. It must have been giving a weak spark for some time. Don't just clean those two flat terminals, but also clean the spring connectors where they slide into. I'm not sure if your truck has the same setup, but I recommend anyone with the same module check that inside module connection. I had always overlooked that connection until I was forced to figure it out. Don't forget to use some dielectric grease on the connection too.
If this distributor there is a fin or fan shape on the bottom of the rotor. If yours has this, it means that there is a screen in the bottom. If plugged, it builds up with oxygen ozone and creates an acidic coating on the rotor terminals, cap terminals even the connector to the ignition module. Now if apart, shine a good flashlight all the way around the timer core on the shaft. You are looking for hairline fractures that will interfere in producing the 450 Mv required to trigger the ignition module off to collapse the coils magnetic field producing spark. I am happy to see Dielectric grease mentioned but as it should be used on every electrical terminal in the vehicle, under the ignition module, the grease used there was a white paste. This is thermal conductive heat transfer grease. Purchased at Radio Shack, electronic parts stores, Amazon it is different and a little more than Dielectric Grease. Inspect timer core for cracks, use heat transfer paste under ignition module and use compressed air to clean the vent at base of distributor. As far as Dielectric Grease, but it at the home improvement stores in the auto section where epoxy is hanging, it cheap. I use it on headlight connectors, PCM, stop lamp switch, behind tail lights so they don’t turn green and stick, but flashlight, beard trimmer, smoke detectors 9 volts, electric toothbrush, well, you get it. ASE Master Tech since 1978 Retired.
 
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