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$$!??#%%! Fuel starvation when it's raining

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This issue has been dogging me for some time but now it's come to a head, I barely made it to work today.


At first the car would run fine for a minute or then fuel starve for a few then start running fine the rest of the day. I noticed this only happened on wet days. Filter level very low, then staying low but no further issues.... That day.


Now, if it's raining the car starts ok and is ok for a bit... Then goes to heck, nearly empty filter, the entire time you're driving until you stop for a couple hours... Then it drives ok for the rest of the day. It did this today and was atrocious on the way to work.. Then fine at lunch.


I know it's a fuel issue because the instant it happens the WO2 goes way lean if I don't modulate my foot, and the filter is never ever full.


I've replaced pump and all hoses up front. I've blown out the lines with compressed air. If I do that manually from up front, the uncapped tank gurgles ok and it's not all that hard to blow, about what I'd expect.


My thinking now is that the never replaced, 44 year old soft line back by the tank has cracks or something and it's sucking air when the humidity does something to the old rubber. Yesterday it was bone dry and I drove 100 miles no problem.... But again, the filter is never full.


Ideas? And, when I hit the parts store on the way home tonite, it's 5/16ths ID hose, right? 70 510 goon

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On my 521 the previos owner.

woould run like shit and gas gauge would go up. Found out since the tank is in the wheel well the water would run in the tank. Thus also rusting and putting alot of rust in filter.


also the dizzy bushing was wearing out causing point bounce.


the fuel line cranking in front of my fuel pump also happened. felt like it ran out of gas and did!!!!!!!!!!Replaced pump and still no work then when swapping the pump I noticed the cracked line. wasnt even 8 yrs old


has cracks or something and it's sucking air when the humidity does something to the old rubber.

Never heard this one before!!!!!!!!!!!

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Changed the filter yup, my bad forgot to mention it! That was last Wednesday.


Im going to check the screens in the SU inlets just because, but in my experience when they're clogged the pump is still keeping the filter full.


When I say I see not enough in the filter, I mean there is so little you can barely see any fuel at all.

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If I am not getting hung up on the rain thing and just writing that off as a coincidence, I am going to go with a collapsing line (like you said) or a or the tank not venting. My suggestion right now would be to pull the line from the carb, put it in a container, crank it over and see how much fuel is being pumped. By the way, my filter just has a trickle in the bottom of it right now, it runs fine. Start it up and watch the filter when the float drops and demands fuel, you will probably see a rush of fuel go through.

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I was hesitant to accept the rain correlation at first when it was a hit or miss nagging issue. For the last couple weeks however, it has been blatantly obvious. If its wet out, the car will run terrible and lean. The filter will show nearly nothing in it. If its dry, it will run fine and filter will be about half full.


Even weirder, when I got my three days of snow it was never above freezing, and the car still ran fine. The day it warmed up and the rain started was the day it ran terrible again!


It's been so long since I messed with a tank. I'm going to pray I can reach the outlet tube by reaching up around the tank or via the gauge sender hole. I think the rig uses 5/16ths ID so I'm picking up some of that on the way home then having a look tonite.

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That is nutty. If it is rain causing it, you have me stumped. I mean, the filler tube having a break in it and the tire flinging water into your tank sounds plausible. But on a none rainy day, you are probably running the same watered down fuel, so that would really not cut it. Shit, even if you said that it went really rich when it rained, I would have an answer, but not lean.

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I arrived home to a leaky basement due to heavy rain melting 19" of snow. Got the parts but didn't change anything yet. It was dry and the car drove home without a glitch.


This morning it was moist but not raining when I left home. It ran ok but I wasn't able to put my foot into it more than 1/2 without the starvation. As I neared the mountains the rain started and the problem got worse. Near work it was nearly as bad as yesterday. Thinking about the carb icing idea, I pulled off and shut down for a couple min. With carb icing, the ice melts and it will run fine till the ice begins again.


It was tough to start and acted exactly the same as when I pulled over.

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