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peterld · Posted: Tue Nov 01, 2011 11:31 pm Post subject: In-Tank Pre-Pump Fuel Pump

Hi Guys.........Has anybody ever replaced the in-tank pre-pump fuel pump with something else other than the OEM # 928 608 013 00. Is there anything else out there that fits? ...and works? Or is it just a case of bite the bullet and stump up for another OEM?

Cleaned my tank and pumps about a year ago and all was fine. Added a little 98 Octane to keep pump wet and today noticed gasket leak. Pulled pump and drained, and to my horror the fuel has eaten my pre-pump.......metal filter ends have exploded and flexi hose between pump body and screw cap has also exploded. Guaze filter was lying in the bottom of the tank.
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80/81 932/8 ROW

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

what the hell does 98 octane mean to you guys down there ?

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Cedric · Joined: 27 Aug 2004 Posts: 2801 Location: Sweden

Are you sure that was petrol ? Or is it as usual, everything is just more dangerous in australia

Cant you just ask someone to send one used pump from any car in the us? It seems that 95% of the cars there are parts cars

Should be easy to get one. But I guess shipping will be a bit on the expensive side..
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peterld · Posted: Wed Nov 02, 2011 7:52 am Post subject:

98 RON. I've always used a similar rating. This however was bought at a track, so maybe they have additives that 'normal' pump fuel doesn't have. I've just been playing around with it again, and apart from the crud from the dissolved glue which holds the filter ends together, the tank is clean. The fuel, while smelling strongly, hasn't turned to glug, or discoloured.

So has anybody ever used another type of pump in that location?

Failing that, anybody got a good used one they want to part with?
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80/81 932/8 ROW

peterld · Posted: Tue Nov 08, 2011 9:40 pm Post subject:

OK ..I've had the fuel analysed, and guess what? It contains lead replacement additives, amongst other things, but majorly, it contains huge amounts of Ethanol! That's what did the trick! Big lesson to be learned.
No wonder my motor mower didn't like it. Ah well.....at least it worked as an ant killer!
New in-tank pump on its way, everything else cleaned, and hopefully new motor ready to fire in a few weeks.

Incidentally, I keep reading that once an electric pump has had fuel through it, it needs to be kept with fuel in it. Why?
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80/81 932/8 ROW

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

I think they sit on the shelf with a light oil in them, and once they are run, the oil washes away exposing the internals to corrosion.
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WeiBe (1987 924S 2.5t) - 931 S3

peterld · Posted: Wed Nov 09, 2011 9:18 am Post subject:

Now that makes sense. Ta Rasta.
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80/81 932/8 ROW

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

its the ethanol that ate your fuel pump.
good thing to keep in mind, in spring i'm going to try to run my car only on E85.
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peterld · Posted: Wed Nov 09, 2011 8:56 pm Post subject:

Gee,.......best of luck Morghen. The filter on the end of the pre-pump is glued! to the pre-pump. Obviously it handles petrol, but not ethanol. The glue was dissolved and in a pool at the bottom of the tank along with the remnants of the filter. The rubber hose which connects the the pump to the threaded end had blown up to twice it's size, and the seal on the pre-pump body had perished. It started to leak fuel and that's how I discovered the whole mess.
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80/81 932/8 ROW

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Now try to imagine what that crap is doing to your fuel lines of similar material.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

emoore924 · Joined: 13 Apr 2004 Posts: 2822

There are HUGE internet discussions on ethanol in motor fuel, and the tears it brings to us vintage car, boat and RV owners. The older fuel systems, pumps, lines and filters, are simply not made to suffer the corrosion-inducing hygroscopic ethanol-containing fuels.

We have websites here in the US that are dedicated to locating non-ethanol fuels.

I personally know of two boat fires that were attributed to ethanol-induced fuel line failures. The boats are gone. Thankfully no one was hurt.

Hagerty insurance has been running a series on this topic. You can find their research at their website.

Use sta-bil if you intend to store your engine for any amount of time.

Good luck!

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

luckly the 924 has 90% steel lines, you just need to fab an exit for the tank...use an E85 friendly fuel pump (about the same price as the OEM one) and replace about 1meter of hooses that are rubber with E85 friendly hooses.

estimated total cost of conversion ~200 euro.
you also need to re-tune the CIS as the Ethanol is dryer and you need to run ~10-15% richer.

but hey...half the price and up to 10-15% more power

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Cedric · Joined: 27 Aug 2004 Posts: 2801 Location: Sweden

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

I don't know about ROW prices, but in the US, government subsidized E85 routinely runs within +/-10% of regular fuel prices. When I was studying my planned E85 conversion for the UWB project (which I still intend to do for different reasons), I arrived at figures that indicated a 30 year payback on the costs to convert to E85. Remember that E85 offers ~30% LESS fuel economy, so you will go through more gas and decrease the range of your car.

Now, for the race fuel argument, of course, it makes complete sense. Which I suspect is what morghen is after...but worth clarifying for any noobs who might come across this thread.

The other point worth mentioning is that the corrosion concern should NOT be limited the plastic, nitrile, and rubber components in our fuel delivery system. Our steel fuel tanks are notorious for rusting, and hygroscopic fuels will only exacerbate that problem. And while the outside of our steel fuel lines appear to be coated, I've not dissected them to determine if or how they're treated on the inside, nor whether the exterior coating is alcohol-safe. On top of that, alcohol is also corrosive to untreated aluminum. What about the WUR? What about the fuel dizzy? Are those internal components that are exposed to fuel ethanol safe??? I highly doubt it. Think it's not a big concern? Then explain why ALL of the major fuel cell vendors have alcohol safe versions of the fittings and fixtures on their fuel cells.

I've read multiple reports on Rennlist of folks who have apparently converted EFI-equipped 928s and 944s to E85 without doing complete fuel system upgrades. But it seems like a big risk to take to not address the system end-to-end, especially as Rasta notes because of the high pressures involved, and the age of the CIS components. The only way I would consider it would be in conjunction with an EFI conversion.
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