Koenig-Specials 928

I couldn't find any definitive suggestion for what to replace this hose with.
My Bosch 044 pump became noisy and according to Greg Brown they prefer to be fed. Therefore, I checked my internal pump and found it similar to the one pictured here (borrowed picture within this RL forum). I powered the pump up in the fuel I drained out and it runs (pump is < 5years old).

Any suggestions for a replacement hose?

Please and thanks

hacker-pschorr

Start here:

https://rennlist.com/forums/928-foru...fuel-pump.html

Then here:

https://rennlist.com/forums/928-foru...pump-ever.html

Koenig-Specials 928

Thanks Hacker. I found the best information here (to save others some reading)

05-02-2008, 09:51 PM
Earl Gillstrom

In 2002 when I got my '91 GT running, I found the intank pump hose broken. I replaced it with a Porsche original hose. 2 years later I checked the hose and it was split like the original. I replaced it with SAE 30R7 hose. Now, 3 years later with no symptoms of problems I checked it again and the 30R7 hose was fine. I replaced it anyway with USCG type A1 SAE J1527/ISO 7840 1/2" hose. Both of these hoses have braid. The Porsche hose had no braid. The A1 hose is much heavier than the 30R7 hose. I would suggest either of these hoses over the OEM Porsche hose. I would have used 30R10 hose if it was available in 1/2" ID. It appears that somewhere around 1990 or 1991 that Porsche started using this inferior hose.
The initial symptoms that I had with the split hoses was missing above 3000 RPM.
__________________
Capt. Earl '91 GT Zermattsilver (factory special)/Classic Gray
http://members.rennlist.com/captearlg

SeanR

If you are running an 044, just put the strainer in the tank and forget about that internal pump.

Livio928

will an 044 pump be starved of fuel if the internal pump is caput? I changed over to an 044 pump and my fuel pressure guage doesn't seem to want to register much fuel pressure. I am wondering if the internal pump is DOA and is starving the new exterior pump of a fuel supply.

jcorenman

If you go that route, I would suggest Tim's oversized strainer. The 044 circulates substantially more fuel, which means a higher fuel flow through the strainer. A higher flow means more pressure drop, which means lower pressure at the pump inlet (negative relative to atmosphere). Add a hot climate and a low fuel level (which heats up faster) and maybe some altitude and you have moved closer to vaporizing fuel at the pump inlet.

The purpose of the internal pump is to keep the pressure at the main pump inlet above atmospheric, to avoid fuel vaporization. It is a low-pressure high-volume turbine pump.

I replaced the short hose on the internal pump for our GT with 30R7, it is ethanol-rated for the internal tube but not the exterior. I checked it after a couple of years and it was showing some cracking at the ends of the exterior layer, past the clamps, but was otherwise fine. I just got a piece of cosmic blue hose from Greg B to replace it.

jcorenman

Maybe, or the FPR may be foobar'ed. Run the flow test described in the WSM. (Disconnect the return-line at the tank and run it- with a fitting and an extension hose- to a collection jug, jumper the pump and measure fuel pumped in 30 seconds). With an 044 you should see at least 1600 cc's in 30 seconds (stock spec is 1250 IIRC).

hacker-pschorr

Here is a data point to consider.

Todd's twin turbo is powered by a pair of 044 pumps running parallel.
No internal pump, but he did modify the tank fitting so each pump has it's own fitting:

http://www.erik27.com/todd/turbo/fuel/index.html

https://rennlist.com/forums/928-foru...-a-veyron.html

SeanR

Great comment about the larger strainer. I picked one up a couple years ago and forgot about it. Is he still producing them?

Koenig-Specials 928

Looks like I found my solution to the internal pump i.e. use the larger strainer instead.
Thanks guys!
Also one less electrical thingy to worry about now.

BTW, where do I get this larger strainer? I see Tim's name coming up, does he sell it direct or through Roger or one of the other RL Vendors?

Thanks

Koenig-Specials 928

Looks like I found my solution to the internal pump i.e. use the larger strainer instead.
Thanks guys!
Also one less electrical thingy to worry about now.

BTW, where do I get this larger strainer? I see Tim's name coming up, does he sell it direct or through Roger or one of the other RL Vendors?

Thanks

928 at last

Fred,
Picked mine up from Tim directly.
I'll note though that my 044 still gets noisy sometimes. Seems heat sensitive.
Been running it for two seasons now though with no issues.

Koenig-Specials 928

Thanks Rob

Livio928

Anybody have Tim's contact info? Fred, if you are placing an order for the strainer, I would like to piggyback my order for one as well. We can split the shipping and the brokerage fees.

GregBBRD

Three points here.

Point 1:

Almost everything I do to repair these cars involves logic.

"What part can cause this problem?" is virtually my entire life, these days.

Porsche used the "in-tank" pump at the very beginning of the 928 model line. They left it out, from 1980 to 1989. They then put it back in place from there until the end of the model run.

There's no doubt that the in-tank pump feeds the stock fuel pump. There's no doubt that a strainer is cheaper than a pump....plus the wiring had to be modified for the pump....so it cost money for them to install it.

Logically......For what reason did Porsche put that pump in the tank and how do you arrive at the conclusion that arbitrarily removing it is a good idea?

Point 2:

Has anyone actually measured the fuel flow through a stock strainer to determine the need for a larger strainer?

I haven't actually measured this...but I've had hoses break while I'm working with them....dumping fuel like crazy, until I can grab a hose crimping tool and stop the fuel flow.

I can tell you this....I don't have/couldn't afford any engines that can burn that much fuel....even in my huge cubic inch hot rod BBC collection!

Point 3:

You guys talk each other into doing the strangest things, without even a whisper of logic or qualitative measurements.