Need help with a 1997 3/4 ton

[C10NEWGUY]

In June 2010 I bought a 1997 C2500 8 lug 5.7 liter fuel injected long bed. About a month into the summer I had issues with the truck stalling out on me while driving or even sometimes at idle. Truck would not start back up after stalling. I thought I found the problem to be the fuel pump relay. See the relay would get very hot to the point where it started melting. I changed relay and the truck ran good for a few days but then stalled on me again. I had the old relay on me in the glove box so on the side of the road I put the old relay back in and the truck started back up. In this time the (new) relay i just had removed was very hot to touch and showed signs of melting near one of the prongs. I went the whole summer last year in Arizona changing the two relays back and forth every few days on the side of the road. See when either relay had faulted, once it cooled down it would function again.

Here comes the real kicker. As the outside temperature cooled off around halloween in arizona i had NO issues anymore with relay. Well today our first 115 degree day the damn relay blew again. luckily i still had the spare in the glove box. I was thinking it may be a short or the fuel pump was going but why did i have no issues for 6 months of cool weather and now as the ambient temperature starts to get hot the problem comes back. its as if the fuel pump cant stay cool enough in the summer months in AZ???

[ChevLoRay]

You might want to examine the socket, where that relay plugs in. If there's any dirt/corrosion/etc,, the current draw will increase regardless of the load on the circuit. I realize you live in AZ, but that may not matter. Once there is any arcing in a connection, the resistance will increase. Factor in the ambient air temp and it just adds to the consequences of the overheating relay.

You can get some electrical contact cleaner that will clean the socket. Spray it into the socket, then work the relay in and out several times. Follow that with a final spray, then use some canned air (computer quality stuff) and dry it out.

If it helps, good. If it doesn't, you at least know that it isn't the problem. Then, you can look elsewhere. I'd be sure that all of the connections to the pump are good, and also not corroded. Check the grounds in the circuit, too.

[C10NEWGUY]

I forgot to mention i did spray compressed air it the socket already from the compressor with a blow gun.

[Hoods69BadBowTie]

Hmm I wonder if your tanks not venting properly would that maybe cause the relay to over heat?
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