Slow start Yukon

'99 Yukon. Starter spins engine fine but engine won’t start. Spray a quick shot of starter fluid or drip some gas on the air filter and it starts fine. After sitting idle for a half hour or so the situation returns. Car will run highway speeds (70-80mph) fine and will handle stop and go in town. Local mechanic wants to replace the fuel pump, which was replaced a couple of years (30,000 miles) ago. This seems an expensive first step with no diagnostics done. Any suggestions would be appreciated. Thanks!

Next time it won’t fire up prime up the fuel lines with pressure before trying to start: turn the key to the run position without cranking (dash lights all on); wait a few second; key back off; back to run for a few seconds; back off…do that about 7 or 8 times. Now crank it & if it fires right up then I’ll probably go with the mechanic on this one.

I agree with cigroller 100%. This is a very common failure mode for the fuel pumps in these vehicles, and if using this priming method will get the engine to start, the diagnosis is firm.

If it starts hard after sitting for awhile then more than likely the pressure is bleeding off. It could be the pressure regulator or the check valve on the fuel pump.

The pressure regulator has a vacuum hose attached to it. Pull the vacuum hose off and check for fuel in the vacuum line, if fuel is present the diaphram in the regulator has ruptured. Replace the regulator.

Thanks to all who responded. I had the fuel pump replaced and it starts fine now. I had the transmission flushed at 75000 and I’m at about 135000. Any suggestions on whether to flush again or drop pan change filter and fluid?