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Discussion Starter · #1 ·
Hey guys, 93 TT stock, the car sat for 5 years with old gas by the previous owner that rusted out everything in the tank so I cleaned the tank really well and everything inside the tank is now new (pump, sending unit, fuel pump hanger etc). I also did replace the main lines going till the fuel filter just for the heck of it since I had the gas tank out and obviously replaced the fuel filter as well. I haven't put fuel in just yet and that's why I wanted to ask what is the best way to circle fresh gas without starting the car? I plan on putting a long hose from the return line by the tank to a bucket so if any crud is there in the system I can drain it before starting the car. So how can I do this? I've read somewhere to bridge B+ and FP and other places it say to bridge e1 and fp.
 

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Discussion Starter · #3 ·
Turn the key on and jump FP and B+. That will force the fuel pump on.
Thanks, would it be a good idea to put inline filter on the return line before it goes to the fuel tank, something like WIX 33003 for a few days?
 

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I would want to filter it before the injectors, not after. I would just run the return line into a can like you said and run the pump. Then put it back together and add some Seafoam to the gas to dissolve any additional varnish, that stuff is strong.

Al
 

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Discussion Starter · #5 ·
I would want to filter it before the injectors, not after. I would just run the return line into a can like you said and run the pump. Then put it back together and add some Seafoam to the gas to dissolve any additional varnish, that stuff is strong.

Al
Right I bought a bottle of redline fuel system cleaner already. Also, I used I dabbed seafoam to a microfiber cloth and dabbed any metal things going in to the tank just for the peace of mind, that top hat on the fuel hanger really likes to rust. The idea behind return filter is so I can just dump the gas back in to the car after it gets filtered. How long do you think it will take for lets say a 2 gallon tank to get filled from retun line after I jumper the pump?
 

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Discussion Starter · #7 ·
right but that would mean dumping at my country's hazardous location which is like 30 mins away and no entry without an appointment so the easiest way is to filter out the gas by putting a return inline filter and dump the gas back in to the tank. It will be fresh gas but it'll just be circulated through the system.
 

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Personally if you're intending on reusing the old gas... I'd use it on a daily driver, mix it into a tank before you top it off to try and shake it all up.
 

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Discussion Starter · #9 ·
Personally if you're intending on reusing the old gas... I'd use it on a daily driver, mix it into a tank before you top it off to try and shake it all up.
not intending on using the old gas, my point is to clean the lines of any gunk, especially the return fuel line BEFORE it goes to the fuel tank. I have spent two weeks cleaning the mess that was in the fuel tank so really dont want any gunk going back in there again.
 

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Sounds like a solid plan then. I feel your pain, the tank on my Mk3 was nasty and rusted pretty badly, I did everything I could to clean it out, but didn't feel good about reusing the tank with a freshly built engine, just didn't wanna risk it. Fortunately the Mk4 tanks are a fancy plastic, so the tank itself won't rust on ya. The metal bit inside, perhaps, but not the tank structure itself.
 

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Discussion Starter · #11 ·
Sounds like a solid plan then. I feel your pain, the tank on my Mk3 was nasty and rusted pretty badly, I did everything I could to clean it out, but didn't feel good about reusing the tank with a freshly built engine, just didn't wanna risk it. Fortunately the Mk4 tanks are a fancy plastic, so the tank itself won't rust on ya. The metal bit inside, perhaps, but not the tank structure itself.
Yeah man although the tank is plastic but my fuel sender rusted and disintegrated and blocked the baffle lines, it was a PITA to clean the baffle inside the tank since it is riveted to the tank but thankfully all that is behind me. Previous owner should've known better.

So I have another question, If I bridge FP and B+, would any crud go in to the injectors while the fuel is circulating? im guessing it wont since the injectors wont have 12v to power on. Correct?
 

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Sorry for the delay in response, I usually only pop on here once a week, sometimes less. Where the 'crud' ends up would depend on the design of the fuel rail, I would think. If your return is in the center of the rail... I suspect a lot of crud might be pushed toward cylinders 1-3, whether or not it flows back out the return... hard to say.

If the fuel rail is a dual feed design, where you have inlets on both sides, I would think it could be flushed out pretty good if you have an inlet on one end and the return on the other.

That said, hmm. I've never taken apart a fuel pressure regulator. I'm not sure how prone it might be to trapping crud inside it. Is it feasible to attach a cleanable filter to the feed line, to catch the crud before it gets to the fuel rail? I had one from Aeromotive, but didn't run it long enough to comment on effectiveness.
 

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Discussion Starter · #13 ·
Sorry for the delay in response, I usually only pop on here once a week, sometimes less. Where the 'crud' ends up would depend on the design of the fuel rail, I would think. If your return is in the center of the rail... I suspect a lot of crud might be pushed toward cylinders 1-3, whether or not it flows back out the return... hard to say.

If the fuel rail is a dual feed design, where you have inlets on both sides, I would think it could be flushed out pretty good if you have an inlet on one end and the return on the other.

That said, hmm. I've never taken apart a fuel pressure regulator. I'm not sure how prone it might be to trapping crud inside it. Is it feasible to attach a cleanable filter to the feed line, to catch the crud before it gets to the fuel rail? I had one from Aeromotive, but didn't run it long enough to comment on effectiveness.
@te72 thanks for replying. So my fuel rails are stock, but dont know if they are single or dual feed?

So this is my plan, Fuel pump (new) --> Main fuel line till filter (New) --> Factory Fuel filter (New) --> Fuel lines to fuel rails and back to return (old with crud) --> Wix filter --> Gas tank. Hope that explains it.
 

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That explains it well enough. Stock fuel rail should be a single feed. In one end, out through the regulator, back to the tank.

Looking at your flow chart, I'm guessing that your primary fuel filter will catch most of the crud, the Wix filter after the regulator should hopefully catch the rest. Doesn't sound like a bad plan on paper, but be mentally prepared to cope with it if it doesn't work out as well as we hope. These cars (well, cars in general) have a way of making you do things again haha. Just make sure whenever you're done with this flushing process you replace those filters.

In a worse case, you might have to remove your fuel rail for a thorough cleaning, and have the injectors serviced. Wouldn't be the end of the world. :)
 

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Discussion Starter · #15 ·
That explains it well enough. Stock fuel rail should be a single feed. In one end, out through the regulator, back to the tank.

Looking at your flow chart, I'm guessing that your primary fuel filter will catch most of the crud, the Wix filter after the regulator should hopefully catch the rest. Doesn't sound like a bad plan on paper, but be mentally prepared to cope with it if it doesn't work out as well as we hope. These cars (well, cars in general) have a way of making you do things again haha. Just make sure whenever you're done with this flushing process you replace those filters.

In a worse case, you might have to remove your fuel rail for a thorough cleaning, and have the injectors serviced. Wouldn't be the end of the world. :)
haha yeah exactly, going from easy to hard and like you said even if the injectors are toast, its not the end of the world but just taking that rail out will be a pain im guessing since the throttle body is in the way. Well im not going to think so far ahead, hopefully wont even have to do it fingers crossed

Also, the fuel line like I said is already new till the stock fuel filter so dont really have to replace that filter again since tank is pretty clean as well. I think it would be a good idea to add some redline fuel cleaner in there too. Lets see im planning for this weekend now that I have finally have it all back together (was waiting on the sending unit)
 

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Be aware that if you use Seafom, you're gonna see a LOT of smoke come out the tail pipe.

Al, is that hard on the cat, if the car is so equipped? I can't imagine the cat being happy with all that...
 
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