How do you correct a vapor lock on a 93 road master?

Answer 1

Actually it is very possible to get a vapor lock type condition with a fuel injected engine. This is due in part to a combination of factors. Ethanol blended fuels combined with higher outdoor temperatures are the main reason. Usually ethanol alone is not the only reason though. A weak or partially clogged fuel delivery system compounds the problem. Fuel will not usually turn to vapor in the lines when it is kept under pressure. Check and compare your fuel delivery and psi to the specifications for the vehicle in question. If they are lower than what is specified,start checking the fuel system and try the simple fixes first such as replacing the fuel filter. If your delivery is still low then the most likely culprit is a fuel pump that is on its way out. If the pressure AND delivery are both good and this only presents a problem on start up, the probable cause is a device in the fuel system that is designed to keep fuel pressurized in the lines and is faulty. This is referred to as an anti drain back valve in some cars ,but may be called something else in different models. A quick way to check this is to pressurize the fuel rail by starting the vehicle while you have a fuel pressure gauge attached to it. Turn the vehicle off and watch the gauge. If it starts creeping down steadily until virtually no pressure or very little is left then there is your problem. Unfortunately you cant always replace just this component. It is usually sold as part of a fuel pump replacement assembly.