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How to Build and Install Fuel Lines on a Porsche 944 Turbo

How to replace an entire fuel line system front to back.

The existing fuel lines in the Porsche 944 Turbo were old, ratty, and even damaged. The rubber hoses, being over 30 years old, have a tendency to crack and leak as well. So it’s a good idea to replace it all, front to back. Check out the video below to see how we did it, or scroll further down for a quick step-by-step guide with full parts list and installation diagrams.

Part 1 of How to Build & Install Fuel Lines in The Porsche 944 Turbo

Part 2 of How to Build & Install Fuel Lines in The Porsche 944 Turbo

Multiple Issues in the Fuel System

We had multiple issues with the fuel system in our ’89 Porsche 944 Turbo, from clogged injectors, faulty fuel pump, bad gas, cut fuel pump power line (thanks to the previous owners DME relay bypass technique) and even a pinched return line which caused a high pressure issue.

Porsche 944 turbo pinched fuel line
Pinched return line causing high pressure in the fuel system.

Changes to the Stock Fuel System

We made several changes to the fuel system in our Porsche 944 Turbo. First, we installed a larger, more powerful Bosch fuel pump to meet the demands of future modifications. Additionally, we added modern Bosch injectors, which provide atomized fuel rather than a waterfall of fuel, and they fit seamlessly without requiring modifications to the fuel rail or wiring harness. However, these injectors require a 0.5 bar boost in fuel pressure, so we added an adjustable fuel pressure regulator for flexibility with future modifications. Speaking of the fuel rail, we found globe seal fuel rail adaptors that allow you to retain the stock fuel rail, so you don’t have to drop $350+/- on a new fuel rail.

Furthermore, we decided to remove the fuel damper, a modification many others have made. In the six months we’ve driven our Porsche 944 Turbo, we have not experienced any negative effects without it. This simplifies the fuel system by eliminating two connectors, one hose, and the damper itself.

Time to Get Started

We started by getting all of the correct parts and fittings. Note: The hardline adapter may not slide over your existing fuel lines if you choose not to replace the hard lines under the car. You can overcome this by filing the outer coating off of the existing hard lines so you have bare steel exposed. The hardline adapters should then compress properly. Carefully check afterward to ensure there are no leaks.

Here is a picture showing most of parts and fittings used in this install.

Products Used:

Products used in these videos:

6ft.6AN Nylon Braided Fuel Line
15/8 Adhesive Lined Heatshrink
76AN Hose End Fitting
36AN to 16mm x 1.5 Adapter
16AN 150 Degree Hose End
16AN 45 Degree Hose End
26AN to 3/8 Tube Hardline Adapter
26AN to 5/16 Hardline Adapter
16AN to 12mm x 1.5 Banjo Hose End
36AN 90 Degree Swivel Coupler Fitting
16AN to 16mm x 1.5 Adapter
26AN to 6AN O-Ring Adapter
18AN 120 Degree Push Lock
18AN to 18mm x 1.5 Adapter
16AN to M6 x 1.5 Globe Swivel Adapter
16AN Fuel Filter
25ft.5/16″ Copper Nickel Fuel Line
25ft.3/8″ Copper Nickel Fuel Line
1Bosch 044 Fuel Pump
1Hengst H127WK Fuel Filter
4Bosch Injector – Modern
1Fuel Pressure Regulator
1Fuel pressure Gauge
1Fuel Strainer and Seal
1Adjustable AN Billet Aluminum Wrench
1AN Magnetic Vise Jaw Inserts
1Injector Extension
16AN Fuel Rail Adapter
11/8″ x 2″ Aluminum Stock
Janky Fuel Rail Adaptor to 6AN

The Setup

After getting all of the parts needed for the job, we set up the old fuel pump and filter, we measured out the distance and relation between the pump and filter.

Old Porsche 944 fuel pump and filter
Old Fuel Pump and Fuel Filter

Once we had the measurements, we installed the adapters and fittings required on the fuel filter and fuel pump. We then mimicked the old fuel pump and fuel filter relation with the new Bosch 044 pump and filter. From there we were able to measure the length of the new 6an hose required for the fuel line assembly. More info on how we measured this in the video above.

We used a grinder to cut the hose as it melts the nylon while cutting; this prevents the nylon from fraying, which makes installing the fitting much easier. We highly recommend ensuring you get a quality hose, as the cheaper hoses, specifically cheap off-brand Chinese hoses found on Amazon, are likely to fail. This is one area you do not want to skimp on.

The End Result

This is what it should look like after the new lines are built and installed.

new porsche 944 turbo fuel pump and fuel filter assembly
New and Old Fuel Pump and Fuel Filter
Porsche 944 Turbo Engine Bay with Fresh Fuel Lines
Porsche 944 Turbo Engine Bay with Fresh Fuel Lines

Fuel Line Diagrams

Porsche 944 Fuel System Upgrade back of car
Fuel line setup at the back of the car by fuel tank
Fuel line setup at the front of the car under the hood and behind front passenger wheel.

If you have any questions or comments drop them below!

Disclaimer! This is provided for information purposes only. We are not responsible for damages or injury incurred from following these instructions or diagrams.

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Thanks for the great detail on the specs. Is there a reason you chose cupro over running the braided lines front to back?

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