91 TBI 350 randomly dying

[Additivewalnut]

Hey good news, depending on how you look at it. The gas tank seal went bad and let a bunch of water in.

I guess I'm gonna order up a water fuel separator on Amazon and rig something up for the time being. I'd drain the gas but I'm not really sure what I'm expected to do with 40 gallons of water logged fuel.

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[Road Trip]

Hey good news, depending on how you look at it. The gas tank seal went bad and let a bunch of water in.

I guess I'm gonna order up a water fuel separator on Amazon and rig something up for the time being. I'd drain the gas but I'm not really sure what I'm expected to do with 40 gallons of water logged fuel.

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Good troubleshooting! You can really chase your tail when there's water in your fuel
throwing everything off in fuel delivery land.

By the way, do yourself a favor and don't fool around with trying to run that old
watery fuel through lawnmowers. And storing 40 gallons in your basement or garage is
just too sketchy, safety-wise, for us everyday civilians.

Anyway, I took a hint from your location, and looked up where you take bad gas in
St. Louis county, and this is what I got:

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Again, good catch on the water in your fuel.

Best of luck with your troubleshooting hunt --

 

[Additivewalnut]

Good troubleshooting! You can really chase your tail when there's water in your fuel
throwing everything off in fuel delivery land.

By the way, do yourself a favor and don't fool around with trying to run that old
watery fuel through lawnmowers. And storing 40 gallons in your basement or garage is
just too sketchy, safety-wise, for us everyday civilians.

Anyway, I took a hint from your location, and looked up where you take bad gas in
St. Louis county, and this is what I got:

You must be registered for see images attach

Again, good catch on the water in your fuel.

Best of luck with your troubleshooting hunt --

I did see that, only issue there is I've got a full tank and they charge $1.70 every pound over 50... That sounds like it'll get expensive quick. Guess I'll be getting rid of it 5 gallons at a time LOL

 

[Road Trip]

I did see that, only issue there is I've got a full tank and they charge $1.70 every pound over 50... That sounds like it'll get expensive quick. Guess I'll be getting rid of it 5 gallons at a time LOL

The weight of gasoline varies a bit, but in all cases it's slightly less than 6.5 lb/gallon.
So back of the napkin math says you can take ~7.5 gallons per trip. Roughly 5 trips
instead of 8. (Depending upon how close you are to a full 40 gallons.)

NOTE: Water weighs ~8 lb/gallon, but all the numbers above still work if you just
have contamination, not a 50/50 mix. :0)

I feel your pain. They shouldn't make it that hard for you to do the right thing in this
situation.

Play it safe.

 

[Schurkey]

Gasoline weighs about 6.5 pounds per gallon.
Water weighs about 8.3 pounds per gallon.

Gasoline floats on water. Pump the gasoline into a clean container, let the water settle to the bottom. Retain the gasoline from the top half or two-thirds, reject the bottom third.

Gasoline with ethanol will probably have "phase separation"; the water will settle to the bottom--but again the gasoline that floats on top of that is likely usable--in the lawnmower if not in the truck.

Around here, water-contaminated fuel is sometimes kept until winter. Water freezes, the liquid gasoline is skimmed off.

 

[Additivewalnut]

EDIT: it occurred to me I never updated this as I was doing things. The new ignition components clearly weren't the issue but they seemed to help. New dizzy got put in and the engine was timed back to 0* base. Truck stalled and wouldn't restart one night, next morning we were cool and idling which made me think ICM, but that didn't do anything. Obviously. Which brings us to present day!

I just want to sanity check before draining this big ass tank.

The fuel looks like lemonade. The truck idles fine-ish, and sometimes will run under a load but generally speaking sputters out and dies. It usually restarts and idles again. No check engine lights to go off. Runs "better" if I pull the MAP to make it run rich.

Is this a water problem like I'm 90% sure it is? Or do I need to keep ohming out sensors until my head explodes?

I guess I'm confused since water would sink to the bottom of the tank, where the fuel pump pickup is, how is it running after having sat for a couple days? Wouldn't it be pulling straight water?

 

[Schurkey]

I should have been more clear in my prior post.

IF the fuel is ethanol-fortified, the ethanol will keep the water in suspension until the ethanol is saturated. Then the water/alcohol undergoes "phase separation". The extra water goes to the bottom.

So E10 with just enough water to be absorbed by the ethanol is likely fit for the lawn mower; may not be suitable for the pickup.

 

[Road Trip]

Around here, water-contaminated fuel is sometimes kept until winter. Water freezes, the liquid gasoline is skimmed off

Brilliant! Maybe run the skimmed gas through a coffee filter lined funnel and possibly go ahead & place it back in service?
(Assuming the truck is now running well on fresh go juice from a busy gas station?)

If the weather was cooperative (sub-freezing) I'd be tempted to try Schurkey's 'freeze it to fix it' tip.

 

[Additivewalnut]

I should have been more clear in my prior post.

IF the fuel is ethanol-fortified, the ethanol will keep the water in suspension until the ethanol is saturated. Then the water/alcohol undergoes "phase separation". The extra water goes to the bottom.

So E10 with just enough water to be absorbed by the ethanol is likely fit for the lawn mower; may not be suitable for the pickup.

It could be that it's 11:38 pm and I'm tired or... I'm just stupid. But you're saying that the gas that "may contain up to 10% ethanol" absorbed some of the water which allows it to burn but really poorly and the water it didn't absorb is chilling at the bottom of the tank? Is that why it looks like lemonade?

And secondly, it's going to be about 15 degrees here in a couple days, do I need to worry about my gas tank turning into ice?

 

[Schurkey]

They sell lil' tiny bottles of "gas line antifreeze" to move small quantities of water through the fuel system and out the tailpipe as steam.

For reasons I have never understood, folks fill their gas tanks with ten percent alcohol in their fuel, and people like my mother would still put a lil' tiny bottle of alcohol in the gas tank as if it would do some good.

Point is, alcohol in gasoline will absorb a certain amount of water. The water absorbed in the alcohol doesn't freeze. Any more than that will drop to the bottom of the tank. THAT stuff can freeze.

Ideally, you'd move the contaminated fuel out of the tank before it freezes, put it in clean buckets, or a clean metal drum, or whatever.

The gasoline you pour off after the water freezes is still going to be saturated with water mixed with the Ethanol. So either pour it back a little at a time into your fuel tank, or burn it in your lawn-mower/garden equipment (run it out of gas after each use so the carb doesn't corrode.)

All of this assumes that you've got E10 in that tank to begin with. No alcohol in the tank would allow virtually all of the water to drop to the bottom.