IcemanG17

Its weird how some 928's have the problematic internal pump...then others don't....it varies by MY...& sometimes inbetween model years! I was lucky I DIDN't have one when my external failed! 1 less thing to check...since the tank was full!

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.

worf928

Great info. Thanks Earl!

kingsmen11

I have found this fuel line 20% fluoroelastomer hose Grade A, 1/2" ID, 0.84" OD, 4.32mm wall, Max 248 degree F, 300 PSI from Dudadiesel.com. Minimum one foot lengths, $4.49. I will get back with the results, when the hose is applied.

Hilton

Intersting Gerry - shame they don't have the viton-only hoses in the larger sizes, just the 20% stuff. It will likely hold up better than regular fuel hose.

I was wondering whether using 1/2" teflon braided hose might do the trick - or rather, stripping off the braid and using just the teflon hose inside to replace the factory one.

I might have to see if I can track some down for the next time I'm taking the fuel tank out of my 89 (its been a few years since I repaired my in-tank pump - would be good to check and make sure the fuel hose I used is still intact).

ALKada

Gerry, was that the cause of your pump failure on our trip to Rockport? Is it running fine now?

kingsmen11

The Rockport trip failure is still unknown, as I haven't gotten around to removing the external pump, or dropping the tank. The car is running fine, just waiting on this new line. I've been driving around on almost no fuel in the tank, fixing to drop the tank. After some conversation I was told about the 30R7, or 30R9 hose yesterday, I jumped on the web. I looked up this thread, and then did further checks, and came up with this hose, which seems from the chart discussed on the seller site, to be able to handle the task. MTF

kingsmen11

I just checked the Gates SAE30R10, which is for submersible applications. It is available only in 5/16, and 3/8 ID sizes. The only difference I have seen discussed in either write up is the Gates hose has the aramid compound found in bullet proof vests. It is not discussed in the Duda Diesel site. MTF

BC

If its 20% flouro - what is the other 80%?

Hilton

Yep, SAE 30R10 is the specification for submersible fuel hoses, and the only supplier I could readily find of it is Gates which as you note only comes in 5/16 and 3/8.

The 20% viton one should have some resistance (the other 80% is nitrile I believe?).

My understanding is that Teflon (PTFE) hose shouldn't break down at all in fuel?

Nicholbry

"....5/16 and 3/8"

Are either of these sizes compatible with our application or are they out of range to fit?

Ninespub

I just replaced my broken internal pump (again) with the filter solution and also had to replace the main pump, hose and hard line too. Don't play with fate, just get rid of the F***ING internal pump. You'll feel better.

123

Not sure what you mean by "the filter solution". Did you mean using one of the stock internal strainers that were used on some cars?

jpitman2

My car did 10 years in 120F environments with no in-tank pump....In hot, high, and high load usage, maybe its necessary, but for most of us I think the in-tank is an unnecessary extra point of failure.
jp 83 Euro S AT 53k

nc_growler

Just finished doing exactly this on my GT. Pulled the in-tank pump (broken hose), didn't bother to check to see if worked or not, and replaced it with the in-tank strainer, replaced the external pump, and the fuel filter. Then replaced all the rubber fuel lines.

It's been running great since.