924Board.org

wally509 · Joined: 06 Dec 2024 Posts: 10 Location: Burlington, WI

Hello,

Sorry for making so many posts as a noob. I responded to a thread about this tank but in the 931 section (which the tank apparently does not fit), it probably should have gone here.

Has anyone bought or installed one of these new tanks yet?

https://jpgroup.dk/en/p/Fuel-tank--62-L/14426371/14426371/

This was my question from the 931 section:

I have a '77 NA and need to do the fuel tank. If I use one of these new Dansk repro tanks, what all will I need to do this? Obviously, I will need the screw in filter with the hose connection, but will I need a different gauge sending unit? I thought the early sending units used a screw on locking ring and the later ones used regular screws. Will I need a new one that uses the screws?

Also, I will definitely want to change the filler hose and whatever breather hoses that are trapped between the tank and the body since it is out. Are there any problems finding any of those or are they just generic fuel hose? The car smells of gas somewhat inside and I get a blast every time I make a hard left turn.

Thanks!
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1977 Martini 924, 1985 Mercedes 300SD, 1956 Austin-Healey 100

Kenodog · Joined: 25 Jun 2003 Posts: 2663 Location: Vancouver,B.C.

I'm curious why they say this doesn't fit a 931.....

Pretty sure the 924 & 931 have the same tank.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Kenodog · Joined: 25 Jun 2003 Posts: 2663 Location: Vancouver,B.C.

924RACR · Posted: Thu Dec 19, 2024 11:26 pm Post subject:

The earlier fuel tank sender fitting has a bayonet style install into the top of the tank; 1/4 turn or so to lock in, vs the 5 or 6 screws of the later style...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

wally509 · Joined: 06 Dec 2024 Posts: 10 Location: Burlington, WI

Thanks so much for your help!

I apologize, I should have started with the root problem before jumping to "I need to replace this tank".

The problem is the previous owner noticed the fuel pump making excessive noise and I think there were associated running issues. It was found the pre-filter before the pump was clogged with "trash" as he called it. His mechanic decided the solution was to remove the pre-filter altogether, which made the car run again and call it a day without investigating the source of the "trash". Yes, unbelievable. But here I am with it. I didn't notice any running issues, but the pump is loud and the fuel gauge is stuck at 5/8 tank. In the past for me, when a gauge gets stuck with this style of VDO sending unit, it's because the drain holes in the sending unit tube are plugged up by junk.

Since the initial posting I have done some more investigating into the root problem and am starting to re-assess the direction I need to go to fix this.

First off, I have spoken to both the person who restored the car and coated the inside of the tank plus the technical people from the company who made the product he used (POR-15). I have utmost confidence the restorer properly prepped the tank and the tech people at POR-15 insist their product is impervious to ethanol-based fuels.

Also, I have stuck my borescope down the filler neck and attempted to look inside the tank. I could see black with shiny speckles goop/gunk near the entry to the tank, with rather large flakes that look to be peeling off. I could look across the tank to the other side of the car where the sending unit is with the side camera and that all looked really nice with a smooth, silver-gray finish to it (the color of the POR-15 coating). I am going to do more borescoping when it warms up some here as I couldn't really see the bottom where the pickup is or the sides of the tank on the passenger side of the car.

I am starting to wonder if the connector hose from the filler neck to the tank could be breaking down from ethanol?
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1977 Martini 924, 1985 Mercedes 300SD, 1956 Austin-Healey 100

924RACR · Posted: Fri Dec 20, 2024 12:50 am Post subject:

Can't speak to the ethanol concerns, but as for the stuck fuel gauge, my experience in sample size of two is that the float inside the sender unit gets stuck due to corrosion on the wires it slides on.

Details with photos here:
http://www.924.org/techsection/technical.htm

Go to section 11, and click on 8 - Fuel Level Sender Cleaning
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Raize · Joined: 18 Sep 2013 Posts: 281 Location: Scotland

Kenodog · Joined: 25 Jun 2003 Posts: 2663 Location: Vancouver,B.C.

I have scrapped a boat load of these, most of them originals. Seldom whave I found a donor I would rebuild ,lol. A properly maintained motor with a quality main pump ran my old 931 perfectly for years, never a hiccup.

Unfortunately for you Europeans everything is insanely expensive, here things go in the bin because there is just so much of it.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Raize · Joined: 18 Sep 2013 Posts: 281 Location: Scotland

Fifty50Plus · Posted: Wed Dec 25, 2024 4:38 am Post subject:

On my race car, I removed the tank to clean out the rust particles near the pickup. I removed the in=tank pump and replaced it with the later plastic filter. I run the car on a factory main pump with no problems as its flow rate is more than sufficient for the higher demands of the race engine.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

Raize · Joined: 18 Sep 2013 Posts: 281 Location: Scotland

924RACR · Posted: Wed Dec 25, 2024 5:32 am Post subject:

Fifty50Plus · Posted: Wed Dec 25, 2024 5:45 am Post subject:

What Vaughan said above. In a hard right turn, all the fuel goes left and leaves the pick-up area dry unless you have about 1/4 tank of fuel. The main pump in its standard location works fine for pick up otherwise. Even an in-tank second pump down in that right hand side tank well will go dry momentarily until you straighten out. Occam's razor.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

Raize · Joined: 18 Sep 2013 Posts: 281 Location: Scotland

Fifty50Plus · Posted: Fri Dec 27, 2024 5:33 am Post subject:

The exit of the fuel tank is at the lowest point of the tank. Inside the tank is where the internal pump (or filter) is. That pump or filter feeds the external pump so no height differences.
The red fuel light is fed from the fuel sender that is put in from the top of the tank and doesn't get down to where the tank exits to the external pump.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car