2001 geo prism you have changed the plugs and fuel filter and pump The car stalls after sitting Runs OK after warming up or using 91 Octane gas What else would cause the stalling?

Answer 1

First of all you are wasting your money using 91 octane fuel. It provides no benefit whatsoever. No more power, no better mileage, nothing! Anyone who tells you different is dead wrong. It is nothing more than a myth that using a higher octane fuel than your engine is designed to runon will help in any way. Use 87 octane fuel as is required and save your hard earned money. Of course the use of a lower octane that required is not the thing to do as engine damagemay occur from pre-detonation. Your Prism requires 87 octane and not 91. Is the check engine light on? You need to replace the plug wires if you have not done so. Purchase2 cans of Seafoam fuel injector cleaner at most Auto Parts stores. Fill your tank and add 1 can. After driving this tank out repeat the procedure. Also replace every single vacuum hose under the hood. Replace then one at a time as to not get confused. This car is 16 years old and I will assure you some are cracked or leaking if you have never replaced them. Cheap repair that is often overlooked. You also may have a defective fuel pressure regulator or leaking injector. After replacing the wires, using the Seafoam, and replacing the vacuum hoses, see how it runs. If you still have the problem, seek professional help and do not start throwing unnecessary parts at it. You will be money ahead in the end.