Have a 1999 Suburban ? 350 engine ? battery is fine ? sounds like it is going to start ? does not start when having been left for a few hours or more ? finally does start after numerous attempts or after being left alone ? once it starts it will restart until left for a while. it may take an hour to restart it ? fuel and air filters have been changed ? authorized dealers say everything checks out fine but of course that is after it has been started and driven to the dealer
If the fuel pressure has’nt been checked try this smple little test.
Turn the key to run, wait 2 seconds & turn the key off then back to run for 2 seconds then off.
Repeat 5 times then turn the key to start.
If it fires right up, have the fuel pressure checked.
Could be a weak fuel pump not building pressure instantly as it should.
You can do the same thing just by turning the key to “ON” and waiting 10 seconds before turning to “START.” I don’t see the point of the on, off, on, off, etc.
Why haven’t you left the vehicle overnight at the repair shop so they can experience the problem for themselves?
Each time the key is turned the pump only runs for about 2 seconds. If the pump is good thats all it takes to build pressure.
If the pump is weak it might take 4 or 5 pump runs to build presure & allow the engine to start.
The problem you have is the fuel pressure is bleeding off. The problem is either the fuel pressure regulator or the check valve on the fuel pump.
The fuel pump itself could be fine but some diagnosis is needed to determine which component is causing the pressure to bleed off.