Cold Start/Hot Start

Magnumb · January 16, 2007

Subject is a 95 Yukon 5.7 liter. This engine starts very quick when hot but when cold takes about 4 to 5 seconds. I have tried to let the fuel pump run for a while when cold but that does not help. I can not figure this out, I have changed the Coolant temp sensor and O2 sensor but that didn't help. Truck has new MSD Distributor, MSD 6A ignition, MSD Coil pack, MSD Wires, NGK Spark Plugs, Duralast battery, Throttle body spacer, Fuel injector spacer, Cold air intake, new exhaust system, Fuel filter, Red line injector cleaner, Timing set to 2 degrees advanced. This is my fourth GM truck and the only one that I have experienced this problem with.

Thanks,

Justin

95Sierra2500 · January 16, 2007

Sounds like the anti-drain back valve in the pump. Quite common from what I understand. Mine is just like this, I just haven't taken the time to fix it. I believe you pretty much have to change out the pump, although I've heard you can put a checkvalve in the fuel line between the pump and the filter.

TEE · January 16, 2007

I'm in the same boat....If you don't let it set for over a day...it helps some but, I have the same problem with my 94'

Looks like I'll be replacing fuel lines also...you may want to check yours too.

They are bad for corrosion.

Magnumb · January 16, 2007

Did not know that even existed. I am needing to replace my fuel sending unit anyhow because gas gauge does not work. What fuel pump assembly do you recommend? Is it better to stick with AC Delco or some other brand...I know these can go bad early so I want the best money can buy.

Is the anti-drain back valve included with the fuel pump assembly?

-Justin

95Sierra2500 · January 16, 2007

The valve should be included in the fuel pump assembly. As for what brands, Carter makes a good pump, and is quite a bit cheaper than AC. Thankfully older style pumps seem to last longer than newer style pumps. My dad replaced the one on his '94 at about 180k miles and he's still going strong at 260k miles. My fiancee's Jimmy just crapped its second pump at 140k miles.