99 K3500 454 overheats under throttle

[99BB3500]

For the 454 correct? What’s the difference between the pumps? Some have an RPO code that starts with G others an N. I have the NF2 code. Some are 24, 32, and 70 gallon per hour

 

[smokymtn65]

@0xDEADBEEF mentioned fan clutch, I don't any mention you checked this out. more likely an issue than a run lean on decent running truck. But been wrong before. Fan clutches fail a lot more than we want to acknowledge.

 

[99BB3500]

Fan clutch seemed fine to me. Under throttle the temp gauge would climb. Off throttle it would slowly go down

 

[LC2NLS6]

Absolutely, upgrade the fan clutch, and make sure its the HD version, they make a couple different ones. Even with a new HD radiator, water pump, RMI25 additive, lower thermostat 185F (I know physics it doesn't cool anything but just opens sooner), if I let it idle with the A/C on after running, it gets hot, 210 indicated, but shut it off and let it sit, then key on you'll see temps way past 210.... It is a big block chevy, it's what they do.

 

[LC2NLS6]

Fan clutch seemed fine to me. Under throttle the temp gauge would climb. Off throttle it would slowly go down

Checked for debris or blocked/bent fins on radiator and a/c condenser?

 

[smokymtn65]

I did an electro-viscus fan clutch up-grade on my 95 burb w/ 6.5 I have not had any issue with heat on the 98 7.4 but looks like a good candidate for the same upgrade.

 

[99BB3500]

Everything looked straight to me

 

[454cid]

If it's overheating at speed it's not the fan clutch.

When I replaced the original fuel pump, I went to the dealer and I believe they looked it up by VIN. I actually have a picture of that pump with the 3 digit code for future reference. It's not an RPO. It's probably a broadcast code.

 

[99BB3500]

I was looking at fuel pumps the other day. Not sure what NF2 is but it has it on the code list in the glove box. And the pump I was looking at specifically said for code NF2. I need to figure out what the flow rate is since there 3-4 different o es

 

[Schurkey]

I was looking at fuel pumps the other day. Not sure what NF2 is but it has it on the code list in the glove box. And the pump I was looking at specifically said for code NF2. I need to figure out what the flow rate is since there 3-4 different o es

NF2 is Federal emissions, Tier 1. Maybe the hanger assembly has an extra vent tube or something. I don't know how the fuel pump would be affected.

NF2 RPO Codes | RpoCode.net

NF2 rpo code meaning is EMISSION SYSTEM,FEDERAL,TIER 1.

nf2.rpocode.net