1999 Suburban 1500 5.7L
Engine starts but wont stay on. I changed the fuel pump and the fuel relay and no change. Second time this has happened the first time I blew out the fuel lines with an air compressor and the problem was fixed. Any ideas?
The basic test to perform would be a fuel pump pressure test and also check the fuel pump volume. The volume test checks the fuel output of the fuel pump for the duration of 15 seconds. It should put out about 1 pint. Fuel pressure should be about 60 to 66 PSI with the Key on engine off.
If you have access to a scanner the computer system should be scanned for any trouble codes. Repair any that may come up.
Check the EGR valve operation. If it is stuck open it will make the engine hard to start and run poorly.
Check for any vacuum leaks just to be safe. This could contribute to a hard start/running condition.
Have you ever had a fuel injector cleaning? This is when a cleaning solution specially made for the fuel system is run through the fuel rail. There may be contaminates clogging the fuel injector causing a hard start/no start condition.
There are a few Service Bulletins on a hard start. Service Bulletin number 04-06-04-008C dated 08/24/2006 states that the connector on the fuel pump should be replaced when replacing the pump. Failure to do so will cause a voltage drop at the fuel pump and cause a reoccurring problem.
Try these few suggestions and let me know how you make out.