1993 Chevy K-1500 5.7 L TBI Starts normally when cold - Difficulty starting hot - Have to hold accelorator to floor to start - Takes 2-3 mins. at approx 1/3 throttle (with much smoke) and everything is normal

This is almost certainly caused by a lack of fuel pressure . The fuel pressure will be fine while the engine is running but when it is switch off the pressure won't hold . In the trade we call this residual pressure . What happens when this fault occurs is that the fuel in the engine fuel rail will vaporize and hence the hard starting .

There are three possibilities : leaking injectors , a faulty pressure regulator valve or a faulty check valve in the fuel pump .

First thing to do is to check the fuel pressure while the engine is running and then switch the engine off , if the pressure drops drastically over a period of 20minutes then you will know you have poor residual fuel pressure . Note if you have not done this before seek help as this can be dangerous as you could set your car on fire .

Next , use fuel hose clamping pliers to pinch the fuel inlet hose ( having restarted engine and then stopped again ) . If the residual pressure drops you have a faulty check valve ( replace fuel pump ) . On the other hand if the residual fuel pressure stays remove the injectors and get them serviced . If the problem is still there replace the fuel regulator .

Note use an approved fuel pressure gauge - the fuel pressure is very high ( 250 - 500 kpa )










If the residual fuel pressure was ok do the same procedure on the fuel return line whilst