Carbecue awareness notice: Fuel line replacement/maintenance

[rbogh901]

My '72 had a fuel leak some time back and I'm here to say that although gas/petrol was spewing from the back of the car temporarily on the freeway, it ended well, if it was a bit more thrilling than expected. So, moving along to the here and now, it's not clear what kind of fuel line maintenance has been done on my '91. Therefore, in an effort to be proactive, I have been searching for threads detailing prudent line replacement information regarding 964s.

Obviously this is not as sexy a question as the monthly thread about which wheels will fit and how *****en' they would be, (very, I'd say), but someone must have experience or links pertinent to keeping fire extinguishers unused. Questions include which lines go bad most or are highest priority in y'all's estimations.

[BoxsterGT]

To the best of my knowledge, the 964 and later Porsche models use Polyamid fuel lines throughout most of the car. Unless kinked or disturbed from some major service work, the Poly lines are pretty much "lifetime" of the car.

Find the rubber hoses, as they are the ones you should inspect on a regular basis. Bending or flexing them should show any cracks or other issues.

Len

[rbogh901]

Thank you for that important piece of information. No replacement unless there is a failure at the junction with the metal fittings then?

[BoxsterGT]

That's where most of the failures occur.

The SC's & 3.2 Carreras have Poly tubes thru the tunnel. These Poly tubes never had a problem, but Porsche crimped rubber hoses at the front of them. When the rubber hose aged & failed the whole assembly had to be replaced.

You have a rubber hose at the fuel pump up front as well. I don't know if this is crimped to the Poly line or not. That is an area to check periodically.

Len

[BoxsterGT]

Here is one of the rubber hoses I was referring to............




A 964 Fuel Pump with a rubber hose that has a tight radius bend. I would watch this carefully. Any others at or near the engine & subject to heat are also ones to watch.

Len

[rbogh901]

Originally Posted by BoxsterGT

A 964 Fuel Pump with a rubber hose that has a tight radius bend. I would watch this carefully. Any others at or near the engine & subject to heat are also ones to watch.

Len

Hi Len, Funny that a Boxster guy would be most familiar with this topic, thanks.

It seems like there are 3 lines under the car in the front of the gas tank: supply from the tank to the pump; supply from the pump to the motor; and return from the motor to the tank. Is the one you have circled the supply from the tank to the pump? Perhaps it needs to be rubber to achieve the tight radius turn?

[BoxsterGT]

This the Hi-Press out. The supply from the tank comes in at the left in this photo.

I am sure that's the case. I would prefer to see a 180 Banjo fitting and a straight hose, but its tight in there. Probably not enough room.

Just one of the possible areas of concern.

Len

[Amethyst]

rbogh901

I just finished replacing the fuel lines on my 91 C2 136,000 mi. The reason for this
was I discovered a fuel leak in my engine bay. It appears the rubber hose part of the
fuel line had deteriorated from the constant heat in the engine bay area. The hose had numerous small cracks in the rubber and one or more finally broke through.
For two weeks I was smelling a strong odor of gasoline around the car every time I
parked the car in my garage after a trip. A couple months before that I had replaced the
fuel tank inlet fill hose and thought that odor might be what had returned. But this time the odor was stronger around the engine bay. So after every shutdown I would look for evidence of a fuel leak. Finally, I left the engine running this time and when I checked I could see a stream of fuel running along the horizontal body structure behind the engine near the fuel lines.
Next I wanted to determine exactly which hose was leaking. I removed the DME relay
and used a jumper wire to run the fuel pump as I looked in the engine bay. After about 30 seconds I saw the rubber part of the main fuel line darken in color from top to bottom. That was raw fuel running down the hose. The hose was leaking at the top which is out of view as you stand behind the car. I caught the leak because I saw the hose changing to a darker color.
I decided to change the main fuel line, return line and vent line. All three run along side each other from the engine to the fuel pump/fuel tank area underneath the car. After removing the hoses I could see the vent hose didn't need to be replaced. The total cost for the 3 hoses was $535. It might be possible to have the rubber parts replaced and reuse the metal portions of the lines for a lot less money. All the fuel hoses attached to the fuel pump and fuel tank looked good. But those hoses aren't exposed to the constant heat of the engine bay.
It was a big job replacing the 3 hoses but I do have a 2 post lift and that cut the frustration level to a third of what it would be if the car was on jack stands.
So from my case you can see that the fuel lines need to be watched after 130,000 mi.

Good luck
mike

[Amethyst]

After further reflection on the repair, let me say, the removal and installation of the
fuel lines can only be performed with the car 6 feet above ground. As the fuel lines are preformed metal tubing 5+ ft in length and are required to be almost vertical when moving them past body structures and engine. Additionally, the air cleaner, MAF, and passenger side intake was removed from the engine in order to provide space to disconnect and connect the fuel lines.

[rbogh901]

Wow. This is a very useful reply for your first posts to the forum. Thanks. We had better get a look at your ride just for good measure.

It makes me wonder if people avoid it because of the difficulties. it is impressive that very few others seem to have replaced their fuel lines despite these cars being greater than 20 years old. I wonder if any of the other owners have found ways to replace their lines without elevating the car on a lift.

[BoxsterGT]

Amethyst -

Any chance you have photos or part Nrs of the main fuel line on the engine you refer to?

I thought all of this assy was Polyamid. I wonder if the rubber part can be re-hosed at reasonable cost?

Also, you mention the long lines under the car are metal. I wonder if they are aluminum w a black plastic coating as some of the other lines (A/C) are. Do you still have the old lines you could photograph for me?

Len

[creaturecat]

fwiw:
my 91 had an ugly fuel line on the engine.
caught it in time. before it caught me.
: )

[rbogh901]

Originally Posted by creaturecat

fwiw:
my 91 had an ugly fuel line on the engine.
caught it in time. before it caught me.
: )

Yes, that is what scares me. I'm surprised there hasn't been more posted on this kind of preventive maintenance. Did you do any other lines while you were at it?

[creaturecat]

Originally Posted by rbogh901

Yes, that is what scares me. I'm surprised there hasn't been more posted on this kind of preventive maintenance. Did you do any other lines while you were at it?

i did not.
from what i can see, the rest look fine.

[Amethyst]

Here are the part numbers to the fuel lines I replaced.

964.356.061.02 Fuel Line{12} $281.82
964.356.063.03 Return Line{14} $170.34
964.201.051.00 Vent Line{13} $69.42

I ordered the replacement lines before removing the old lines. I figured
if one rubber end was bad they could all need replacing. It was a lot of work getting
the old lines out and if I only replaced the one line I might have to repeat the same job
a few years down the road.
It turns out that the only rubber end that deteriorated was the fuel feed line at the engine. The fuel pump end of the fuel line that has the curved hose with the banjo fitting was still usable. But I did end up cutting that hose in order to help twist the banjo fitting from the fuel pump.
I attached some pics to show both ends of that line. You will need to remove the air cleaner box in order to check the condition of that line.

Regards,
Mike

[BoxsterGT]

Thank you.
Looks like one was made the 19th week of 1991.
I have two salvaged 964s out back, I wonder what condition they are in.
Time to take a look.
Len

[rbogh901]

Mike, thanks,

That's not so subtle. I'm now very motivated, at a bare minimum, to pull my airbox and get a good look at the engine end of things. 1991 was a long time ago.

[greg1990964]

My car is about to have another engine put in after a motor fire. My fuel lines are crispy by the motor. Any way to remove lines on jack stands? It was mentioned the car must be 6 feet in the air. Not happening. Any way to do it on stands?

[greg1990964]

No need for an answer. I did it very easily on jack stands. Lift absolutely not necessary. Easy peasy.
Thanks anyways.

[porterdog]

Fast question on this job- are the new lines fully formed, or is bending required?

TIA!