How to Revive Your Porsche 914: Bringing It Back From the Dead

Maybe it clicks. Maybe it cranks enthusiastically without firing. Maybe it coughs to life for three seconds and immediately returns to the grave. Before you order a starter, blame the fuel injection, convert it to carburetors, or start searching for a replacement engine, there is a much better approach.

A non-running 914 is not necessarily a dead 914. You simply need to work through it one system at a time.

Before touching anything, identify exactly what is in the car. Stock four-cylinder 914s generally used D-Jetronic fuel injection on the 1.7- and 2.0-liter engines and L-Jetronic on the 1.8. After five decades, however, many cars have been converted to carburetors, received different engines, or accumulated a mixture of parts from several model years.

Take pictures of the engine compartment, distributor, fuel injection components, wiring and hose routing before taking anything apart. Do not assume the engine lid badge tells the entire story.

If the car has been sitting for years, resist the temptation to throw in a battery and see what happens. Remove the spark plugs and make sure the engine can rotate freely by hand. Inspect the plugs, look into the cylinders if you have access to a borescope, and make sure there is no obvious evidence of water, corrosion, or mechanical binding.

While you are there, look underneath the engine tin and around the cooling fan. Mice, shop rags, leaves, and other debris have an uncanny ability to find their way into an air-cooled engine. A 914 can run surprisingly well while something is blocking its cooling air, right up until it doesn’t.

Gasoline that has been sitting for years does not become good gasoline because you pour five gallons of fresh fuel on top of it. Drain the old fuel and inspect the tank for rust, sediment, and contamination. The 914 also has a pickup screen inside the fuel tank that can become restricted, so do not overlook it simply because you plan to install a new external fuel filter.

Next, follow the fuel system from the tank all the way to the engine. Inspect the rubber hoses under the tank, the lines running through the center tunnel, the connections at the engine compartment, and the short hoses associated with the injectors or carburetors. If the age or condition of a rubber fuel hose is questionable, replace it with the correct fuel-compatible hose for the system.

Charge and test the battery, clean and inspect both battery connections, and then examine the major ground paths. One particularly important 914 ground is the transmission-to-body ground strap. It lives above the transmission and is easy to forget, yet the starter depends on it to complete the electrical circuit.

Next, determine whether the starter solenoid is actually receiving its start signal when the key is turned. If it is not, work backward through the ignition-switch circuit and wiring rather than immediately replacing the starter.

Start with ignition because it is relatively easy to prove. Use an appropriate spark tester and verify that you have a strong, consistent spark. Check the coil connections, distributor, cap, rotor, plug wires, and ignition points or electronic ignition components where fitted.

The four-cylinder firing order is 1-4-3-2, but do not simply copy the plug-wire position from someone else’s engine. Establish cylinder No. 1 at top dead center on the compression stroke and verify where the rotor is actually pointing. After decades of repairs and distributor changes, appearances can be deceiving.

D-Jetronic cars generally operate at roughly 29 PSI. L-Jetronic cars operate at a somewhat higher pressure, roughly in the mid-30 PSI range under the appropriate test conditions. Carbureted cars operate at dramatically lower pressure, which is why an injection pump and a carburetor require very different fuel-pressure strategies.

Correct pressure also does not prove that the injectors are actually opening. If you have pressure but dry spark plugs, the next question becomes whether the injectors are receiving a signal and delivering fuel.

Dirty, loose, or disconnected grounds can cause seemingly mysterious injection problems even when the battery ground is perfectly fine.

Another particularly important D-Jet detail is inside the distributor. In addition to the ignition points, D-Jet uses a separate set of trigger contacts to tell the injection system when to fire the injectors. That means you can have perfectly good ignition spark and still have no injector pulse.

Finally, inspect the manifold-pressure sensor and its vacuum hose. The hose needs to be intact and the sensor needs to hold vacuum properly. Resist the temptation to adjust the sensor internally simply because the engine will not run correctly. Adjustment should come only after the rest of the system has been proven healthy.

L-Jet is also extremely sensitive to air leaks. Inspect the large intake boot between the airflow meter and throttle body carefully, especially its underside. Check the intake-runner hoses, injector seals, and vacuum hoses. Even the oil-filler cap seals and filler housing can introduce unmetered air into the system.

If the engine has backfired through the intake, make sure the airflow-meter flap still moves freely and has not been damaged.

If the car has been sitting, expect dried fuel deposits and varnish inside the carburetor bowls, jets, and passages. Check float operation, needle valves, and linkage movement before attempting to tune anything.

Most importantly, verify fuel pressure. Carburetors require much lower fuel pressure than the original electronic injection systems. Excessive pressure can overwhelm the float valves and flood the engine.

Once the carburetors are mechanically clean and the ignition system is correct, establish the manufacturer’s baseline settings and synchronize the carburetors properly. Randomly turning mixture screws until the engine stays running generally creates more problems than it solves.

Once the engine is ready for its first controlled start, establish oil pressure before allowing it to run. Disable fuel or ignition as appropriate and crank the engine in short intervals while watching for oil-pressure indication.

When you are ready for the actual start, do it outside in a well-ventilated area with the car securely in neutral and an appropriate fire extinguisher nearby. Having a second person watch the engine compartment for fuel or oil leaks is extremely helpful.

When the engine starts, watch the oil pressure, listen carefully, and look for leaks. Do not immediately start revving it because you are excited to hear it run. Fuel pouring onto the engine, no oil-pressure indication, or a serious mechanical noise means shut it down and find the problem.