Starts when it sits, rough start when it’s warm 97 5.7

[Dlipp_]

Truck fires right up when you let the fuel pump run, then start… let it warm up, turn it off and try to start it right back up and it doesn’t wanna hear it unless you give it throttle. Has the brand new spider injection conversion. Plugs, wires, all brand new. Distributor was brand new last summer.

 

[Schurkey]

Connect a scan tool, verify ALL the sensors especially the throttle position, coolant temp, and crank position sensors.

"New" distributors have a nasty habit of being supplied with crappy caps 'n' rotors.

Check your fuel pressure. Does it leak-down excessively? Is the pressure high enough? Does the fuel pump prime like it's supposed to when the key is turned from "Off" to "Run"?

 

[Dlipp_]

Connect a scan tool, verify ALL the sensors especially the TPS, coolant temp, and crank position sensors.

"New" distributors have a nasty habit of being supplied with crappy caps 'n' rotors.

Check your fuel pressure. Does it leak-down excessively? Is the pressure high enough? Does the fuel pump prime like it's supposed to when the key is turned from "Off" to "Run"?

The fuel pump does prime, if you turn the key on for a couple seconds, if you turn if off and turn it right back on it won’t prime, I’m assuming thats supposed to be like that.. I do believe it bleeds off too fast after you shut it off.. but if I wait like 20 min or so it’ll start fine and run fine. It’s been doing it for quite some time now. I swapped IAC sensor, that didn’t work and threw a misfire code which was weird… the temp gauge and temp on my code reader are pretty much the same.

 

[Schurkey]

The fuel pump does prime, if you turn the key on for a couple seconds, if you turn if off and turn it right back on it won’t prime, I’m assuming thats supposed to be like that.

Yes. Typically about a ten-second delay after the first prime cycle.

I do believe it bleeds off too fast after you shut it off.

That's probably your hot-start problem. Epidemic on 7.4L, not such a problem on 5.7L that I know of. But anything can happen especially with so many car parts being sourced from China.

I swapped IAC sensor, that didn’t work and threw a misfire code which was weird.

The IAC is not a sensor, it's a motor or actuator. There may be recommendations in the service manual, which you should download from the links posted in a Sticky thread right here in the Engine forum.

If this isn't working right, it might explain why you need to tickle or hold the gas pedal to get it started and keep it running.

the temp gauge and temp on my code reader are pretty much the same.

TPS?

 

[Dlipp_]

Yes. Typically about a ten-second delay after the first prime cycle.


That's probably your hot-start problem. Epidemic on 7.4L, not such a problem on 5.7L that I know of. But anything can happen especially with so many car parts being sourced from China.


The IAC is not a sensor, it's a motor or actuator. There may be recommendations in the service manual, which you should download from the links posted in a Sticky thread right here in the Engine forum.

If this isn't working right, it might explain why you need to tickle or hold the gas pedal to get it started and keep it running.


TPS?

Replaced the ignition coil and control module, still doing it. Saw some people say maybe the temp sensor? Idk it’s really annoying, want this thing to run 100%

 

[Zepp]

I've had this issue a couple times on different k1500s and an escalade. Temp sensor said it was -40F. Started cold like a champ. Wouldn't start warm because it'd flood itself.

 

[Dlipp_]

I've had this issue a couple times on different k1500s and an escalade. Temp sensor said it was -40F. Started cold like a champ. Wouldn't start warm because it'd flood itself.

I replaced the temp sensor with a gm genuine one, same thing, replaced the crank sensor, same thing, still stumbles… and when I put it into gear it dies, I’m lost now lol