Hard starting once engine is warm

DUB305

MEMBER
2002 CHEVROLET SUBURBAN
5.3L
V8
2WD
AUTOMATIC
261,000 MILES

So far, I have replaced the fuel vapor canister, fuel pressure regulator, spark plugs, fuel filter, and fuel pump never had this problem until my truck gave out on me one day. After that I changed the fuel pump, and it was fine turned right on first crank but the next day after driving to the store coming back out 30 minutes later, I experienced hard starting and it been a couple of days now. Keep in mind every morning it turns on first crank just has hard starting once engine is warm

Also, I have checked the fuel pressure after turning it off 30 seconds later it seems to have no pressure just a little bit of air which comes out and no fuel. Also, I tried with ignition on and still no pressure or fuel shoots out of the fuel rail valve.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,289 POSTS

Hi,

If you are not getting fuel pressure, something is preventing the pump from running.

I need to better understand. First, when you say it's hard to start when warm, does it even try to start, or does it have an extended cranking period?

Also, have you checked the fuel pump relay? It may be failing. It's in the under-hood fuse box. Try this: Switch the relay with a different one in the box having the same part number to see if it changes things. If there isn't one, here is a link that explains how to check one:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find. I attached the wiring schematic for the relay for your reference. Also, pic 2 shows the relay to check. Note this is in the under-hood fuse box.

Let me know if you hear the fuel pump run when you have no pressure at the fuel rail.

Take care,

Joe

See pics below.

Images (Click to make bigger)