New option for fuel filter & do I need a new fuel tank?

[pushkick]

well i got the new bosch pump tested it on the workbench before i put it in the van it ran quiet and seemed ok. but i used a 11mm hose on the inlet. once i put it in the van it was noisy. the inlet in the van uses a 11 hose reduced to a 7mm hose into the new tank. so i tried one of the clear prefilter and yes their was alot of air bubles in the intake line? anyone got any suggestions???????

well i tried a bench test with a 7mm hose on inlet side of pump and on exit side this created noise and caviation and this created bubbles in the exit line. looks like new tank has a problem. since fuel pumps use the fuel a lubricant as well as pumping it this will probably cause premature failure of pumps (pumping bubbles).

[brooklynvanagon]

Based on this post I bought a version of it... I totally pan it.

It took only about 30 miles for it to clog with rust, causing a noisy fuel pump and stumbling. It only has about 1 sq. in of filter area. Not only that its glass. As I was cleaning in I dropped it and it shattered. I'm glad it did because I was going to put it back under the car. Glass, fuel, under the car....

Learn from my mistake, choose differently.

It's so easy to jumper the fuel pump and test fuel volume and pressure, don't put glass filters under the car.

Just. don't.

I found a metal purolator which needed a brass nipple for proper fitment and tossed it on. Ahh, quiet fuel again. By the blow test, it has much less resistance to flow AND I guess about 40x the filter area.

[tencentlife]

I kinda doubt a filter that small is really going to be able to flow smoothly the volume of fuel that the pump moves. It seems like an item like that is really intended for carbureted engines, which have a one-way fuel delivery so need to flow a lot less volume than a recirculating system like most FI's have to deliver fuel.

Think about it. If your rig gets 20mpg at 60mph, you're using a gallon of fuel every 20 minutes. That's roughly 4 liters, or about a liter every 5 minutes. But the pump delivers at least one liter per minute, five times the volume that the motor actually consumes. The unused 80% is recirculated back to the tank.

So compared to a carbureted car getting the same mpg at the same speed, the filter on this FI has to let pass five times the volume of fuel in the same interval, and also needs to get the fuel very clean to keep the injectors spraying a good pattern and the keep the pintles from eroding from the high liquid velocity at the nozzle.

A carburetor fuel delivery system, by comparison, only brings to the carbs the volume of fuel that they use, no more. It wants the fuel clean, but it doesn't need to be nearly as clean as injectors demand.

So a small, relatively coarse filter can service a carburetor system adequately, but a recirculating FI system needs a large filter with a very fine medium to maintain sufficient flow and pressure. A filter upstream of the FI pump can be relatively coarse, but still needs to be fairly large, like the plastic cubes that were fitted to the earlier vans, so as to allow the high flow to the pump without restriction. The finer medium filter after the pump will flow less volume per unit area of medium, so it needs to have a much larger medium to get the fuel clean enough while not constricting flow.

Considering all that, I don't think a small filter such as that one has a place in a recirculating FI system.
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[hiram6]

Well, I had to have some type of pre-filter in place to protect my pump because I knew I had some rust debris in my old fuel tank. I'm installing a new tank tomorrow, so I'll run it without any pre-filter. I have the large aluminum canister type filter after the pump, so I'll put in a fresh one of those.
_________________
1985 Westy, 1.9L automatic (Daisy)
1996 Mazda Miata
1998 Jeep Grand Cherokee 5.9 Limited

You can't lie around on the beach and drink rum all day.................unless you start first thing in the morning.

[msinabottle]

The ORIGINAL use of those cube pre-pump-filters was to get rid of the last bits of residue left in the brand new factory tank...

If it were me, I'd put in another one. That was to save the pump. I retrofitted in the big aluminum canister. That was to save the injectors.

They pump fresh gas into drained underground tanks, they stir up things that I don't want in either. And both filters were a comfort today when they were adding gas even as I filled Winston.

Best!
_________________
'Winston,' '84 1.9 WBX Westy
Vanagon Poet Laureate: "I have suffered in
many ways, but never, never, never in silence."

[tencentlife]

Oh, man, don't fill up at a station on the day they're filling. If you see the tanker there, go elsewhere. The do stir up a lot of crap in the tanks, and much of it is water. I've seen this happen several times, and it's happened to me. You get a load of water in your tank, and it'll clog the filters fast as you please, or worse.
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Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[hiram6]

Okay, new tank installed, removed the glass prefilter, replaced the after pump large canister filter. Started it up, almost no noise!! Every once in a while, every 20 seconds or so, a little whine, but nowhere near as loud as before. I think it just wants me to know it's there.

So, I got out the rotozip god-awful cutting wheel, and sliced the top of my old tank. Having laid my eyes on the monstrosity of intank lines, recessed fuel pickup pie plate, baffles, etc, I am hereby prepared to make a statement:

Ahem.

No Vanagonite shall ever successfully clean and/or coat the inside of said fuel tank completely. I simply don't see how it can be done.

Honestly, the key area to get at to clean/coat is completely inaccessable. The fuel pick-up is underneath a welded-in disc of metal in the center of the tank. How one could ever be sure that the successfully cleaned and coated under there I have no idea.

If you're getting crud in your filter, just buy a new tank. Having seen what I have seen, I'll never attempt to clean a tank again.
_________________
1985 Westy, 1.9L automatic (Daisy)
1996 Mazda Miata
1998 Jeep Grand Cherokee 5.9 Limited

You can't lie around on the beach and drink rum all day.................unless you start first thing in the morning.

[tencentlife]

Excellent point. I was always skeptical of the value of relining a used tank, and really glad that in my climate, I would probably never have to consider it. Seeing that cut open tank, like you I now fully grasp the utter futility of that approach.
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Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[pushkick]

yes i agree the glass filter is not for everyday use but it does let you look at cavitation (bubbles ) and whether their is rust. its a great diagnostic tool for the amature. besides it was only 6.00 @ autozone and it had different size screw in nipples which allowed me to go from 11mm to 7mm. so that the filter wasn't causing a problem i just took the small filter out of the glass just to see the state of the fuel going into the pump.
i have used them on our outboard boat engines all the time but no chance of breaking them with water. great for visually seeing if you were getting fuel and the oil injector was working.

[vinnyvango]

After a search I ended up on this thread. After reading it in it's entirety TWICE i'm still stumped. I bought an aftermarket pump from Bus Depot while troubleshooting an unrelated Subaru problem. (Those of you with Subaru engines need to OVERTORQUE the timing belt tensioner:-). So I've replaced the small square pre-filter, then another, then the pump, and another filter. There's nothing in the filter, but I'm covered in gasoline from the last iteration. So I think I have good flow. I dropped the tank about 3years ago for the top tank lines R and R. Inside of the tank looked good and I got very little rust when flushing. The bus runs fine, but the fuel pump sounds like a hornet's nest. I'm starting to wonder if the small square filter can keep up with the Subaru. Any thoughts other than throw more parts at it? I may try replacing the line from the tank to the pump and bypass the filter as a test.

Thanks.
Shawn
84/90 Westy/Soob

[bucko]

[morymob]

Lots of yes & no answers to PRE-PUMP FILTERS.Having a fresh/clean tank now will be history after a few fill ups. Here the gas comes into local terminal with a water (plug) to separate the diff brands etc. The plugs are diverted to a settling tank (not all times a success) and water gets into delivery trucks.Ever wonder why u suddenly have a lot of water in your tank?? Fresh deliveries to dealers stirr up all the crap in their tanks too. If u have ever taken apart a fuel pump u will find it to be a fairly close tolerance unit-has to be to pump the press u need-prefilter-YES.

[brooklynvanagon]

The thing is it will break the 1st time it's hit, by anything, pebbles, hubcaps, etc. And right there under the car it will be hit eventually.

[hiram6]

I don't think anyone is disagreeing with you. Pushkick is simply saying that for diagnostic purposes, sitting in the driveway, it gives you a way of seeing air bubbles, rust scales, or whatever. And, if you wanted to leave it there for a few days of driving to see how much stuff you're accumulating, you could wrap the glass portion of the filter in some foam rubber to shield of pebbles, etc. Obviously don't want to off-road in your Syncro like that, but you could do it for a few days of street driving.

[terryg]

It sure seems like instead of trying to find the next low buck solution to an immediate problem, there should be a focus on how to provide filtration of the large particles coming from a 30 year old tank so that the pump doesn't suffer, and then, finding a second filter that provides less particles for the injectors. I kinda think that the second filter would be adequately served by the stock waterboxer can filter, and that the filter between the tank and the pump needs to be defined. All of the filters I've seen discussed are super fine particle types. Maybe some sort of crude large particle filter would better serve for between the tank and the pump. Sure VW didn't design it that way, but they didn't plan on all of the years and changes that would happen since their design. It's left to the consumer to solve the issue at this point in time.

Anybody got a good solution to filtering large gas tank scale from the pump with a filter that doesn't have to be replaced for 10-20k miles?

[randywebb]

other cars have aftermarket replacement fuel tanks made for them - somebody could redesign this one for more capacity and a removable filter screen...
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1986 2.1L Westy 2wd Auto Trans.