Doesn't idle, only starts when I drop fuel filter

[layhew]

Hello again, Im back but with a new mind boggling issue.

It all started last week, my van has been running beautiful ever since i got her back, until I had to drive up and down a few steep hills. Afterwards it decided to die. I discovered it was a dirty fuel filter so i dropped it, put it back in and off i went. A few days ago, i went to start it in the morning and it was no go. i inspected, everything was fine except it sounded like it lost power changed battery, no go, for some strange reason i thought i should drop the fuel filter again, so i did and she started right up. Today it was the same issue, except its worst. Now it doesn't keep idle unless i give it constant gas. Ive changed the fuel pump thinking it may be blocked. It still only seems to starts when i drop the fuel filter and let it sit for a few minutes and a few good pumps off the accelerator on start up (fuel coming from the filter is clear)

Im thinking it could be chocking itself on fuel but my brain hurts so i could be wrong

[Silverghost500]

With having to drop the filter a couple of times and getting junk out of it I suspect your fuel tank is really rusty inside.
That could be blocking the proper flow of fuel. You could try running a supply line and return line to a 3-5 gallon gas can to test. If the engine idles and behaves then it’s time to replace the fuel tank.
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1986 Volkswagen Vanagon Westfalia "Von Westy"
Honda K24A converversion-Road Testing Phase
3-Speed Automatic

Von Westy YouTube Channel
https://www.youtube.com/channel/UCbhyZYxJEQrUuLnMbLleeIA

[DanHoug]

sounds like your tank is full of swarf and puking up sediment, plugging fuel filters. dissect the filter you took out and see if it is full of crap.

if so, probably best is a new gas tank. if that just isn't an option, they can be taken down, emptied, and flushed out with a garden hose and detergent. put new seals in everywhere before it goes back in. bottom should be completely shiny, new looking metal. if it isn't you'll fight issues for the life of the van.

DO NOT run without a filter, even briefly, as it will push sediment into your fuel injectors causing expensive issues.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[danfromsyr]

not sure where you are in Australia or what your environmental conditions are
but you can accumulate sediment in the tank from a bad seals on top of the fuel evaporation/expansion tanks in each of the wheel wells.

there is a roll over valve and grommet on the top that dries out and cracks..

fine silt can then run down into the tank and end up in the filter.

check these as you don't want the same issue with a new tank.
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[IdahoDoug]

What vehicle, what year, and what engine are we talking about here?
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[MarkWard]

Sorry, cranks but won't start? Or turn the key and it does not crank?
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[E1]

Are you using the stock filter between tank and pump, or a canister filter after the pump?

If the latter, you might be blocking the fuel pump inlet, easily cleaned with a cotton swab.

If the former, and a new filter still blocks up, you should see the particles clogging it in the filter and it does sound like you may have rust in the gas tank.

Before diving in to replacing the tank, it'd be worth draining some fuel to be sure you have no water separation (takes maybe a half-hour to fully separate), meaning water in the tank from long periods of humidity, leaking crossover tubes, or leaks in the white, plastic evap containers in the wheelwells.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Jeffrey Lee]

You say "... it was a dirty fuel filter so i dropped it, put it back in and off i went."

It's not clear to me whether you replaced the fuel filter with a new one, or whether you removed + reinstalled the original filter. If the latter, and if that filter is plugged with contaminants and preventing sufficient flow, then merely reinstalling it will only reinstate the problem.

If, on the other hand, you've replaced the filter with a new one each time, and the problem soon returns, there are two possible causes:
A) the new filters are soon becoming plugged, because the fuel & tank are quite contaminated and should be cleaned and inspected, or
B) the problem is somewhere else entirely: fuel supply and return lines, pump, injection system, etc.

One way to help isolate the problem is to install a generic, aftermarket, transparent fuel filter in the supply line immediately after the tank. This will not only serve to pre-filter the fuel before it contaminates the finer, expensive stock filter, but also allows you to observe whether/what is clogging the filters. This pre-filter may quickly become plugged up, so buy a handful of them.

Also remember that there is an in-tank pre-filter screen which can become plugged and choke off the fuel supply. When you open the supply line to replace the filter, or blow a bit of compressed air into the tank via the supply line, the brief back flow can dislodge the obstruction, but the fix may be only temporary unless the contaminants are actually removed.

As others have suggested, for testing purposes you can also remove the tank from the equation entirely by running the engine on a separate fuel can connected to the supply and return lines.

Good luck!
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Camp Westfalia
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[Tbob]

I have even had a bad tank of gas respond this way. I filled up my 1986 at a Murphy gas station near where I worked, and immediatly after refill, it ran poorly. I limped it home, swapped out the fuel filter for a new one and all was fine, for about 100 miles. Then, it started running poorly again. Another new fuel filter and all was ok for another 100 miles, then problems resurfaced. I finally started blowing out the spare fuel filters I had and would re use them. Whatever was in the gas I do not know, but it was not water and not volatile. after a few months of this hassle, I finally got it all out.
I could have and most likely should have dropped the tank, but time and hassle constraints made that project stillborn. I had also dropped and cleaned and resealed the tank about a year before, so I knew there wasn't much crud in it. Also, in back feeding the fuel filters, no particulate matter came out, whatever it was in the gas, it plugged up the fuel filter and wouldn't fire. Didn't bead up like water when blown out, but who knows.
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1969 Deluxe, owned since 1973
1973 Westfalia, owned since 1983
1980 Westfalia, watercooled conversion
1985 Westfalia, stock!
1986 Westfakia, Audi I-4 conversion
A couple of trucks and a couple of Jeeps

[layhew]

Okay thanks for the advice friends!

Ive found the culprit a while back actually so ill share with you. It was airleaks and a lot of them apparently. After looking dumbfounded into the engine bay for a solid week i decided to take it to a vw mechanic 4hrs away. With a lot of praying, rubing the dashboard and promises to wash her if she got me there i limped into the mechanic.

I had a cracked gasket where my air intake pipes connect to the engine. A few of my vacuum lines were misplaced and i had a pretty big air leak in my throttle body and this lead to my airflow meter (brand new) going haywire. So it was dumping in a heap of petrol when ever i hit a bump hard enough and pretty much flooding the thing while it was driving

The good news is that i replaced my old fuel tank with a shiney new one in the process