Questions and Answers

Volkswagen Jetta Hard Hot Restart Q. I have a 1986 Volkswagen Jetta, 1.8 liter engine. I am sure that this crosses over with the Golf, Rabbit and others. Anyway, the latest problem I believe is the check valve causing hard starting after no driving for more than 15 minutes. However, I am very curious about the Fuel Pressure Regulator mounted on the front of the engine block. Could this contribute to the problem also?

What would happen if this failed and is there a test for it?

Thank you very much,
RR

PS... I have 332,500 miles on this car and have seen just about every problem now. Your site helps tons. I would also like for you to note that the timing belt pulley should not be tightened as all manuals say, 33 ft. lbs. which leads to failure after about the fourth change and a major nightmare.

A common fix for Idle fluctuation is to clean the air sensor, change the plugs and check the timing. I have seen a piece of dirt once stuck in between the air sensor cone and the plate, even though the main problem was a loose ground wire off of the valve cover.

A. This Fuel Pressure Regulator is a diaphragm type pressure regulator that maintains system pressure at approximately 5.4 bar (78 psi), and control pressure at 0.2 bar (3 psi) below system pressure. The pressure regulator also acts as a one way check valve to maintain pressure in the system once the engine has been shut off.

The High Pressure Main Pump has a replaceable check valve holds about 2 bar (29 psi) of residual pressure and works in conjunction with the accumulator and the piston seal in the fuel distributor to ensure good hot starting.

To check them, you will need a fuel pressure tester. Hook up the fuel pressure tester, start and run the engine for a few minutes. Then shut it off and see if the fuel pressure drops. If it does then one of the two check valves is leaking.

Start and run the engine for a few minutes. Then shut it off and pinch off the fuel line from the fuel pump to the fuel rail. If the fuel pressure still drops, then the fuel pressure regulator is bad. If it remains withing specifications, then the fuel pump check valve is bad.

This is assuming that the injectors are not leaking which would also cause the same symptom.