I live in the Northeast and have a 1996 Chevy Cheyenne pickup with a fuel injected small block that has 50k miles. Earlier this summer the truck developed a problem where it is very hard to start when cold (after sitting overnight or after sitting for many hours on my flat driveway). When the engine is cold (say the first start of the day) I can only get it to start by giving small bursts of cranking power to the starter. That is, it won’t start if I hold the key in the cranking position but is more likely to start if I give it a short burst of cranking power (when I hold the key in “start” position) for a second or two.
After the first start of the day, the engine runs fine and subsequent starts are quick and normal. The “Check Engine” light is not on and there are no trouble codes…. Other than hard starting there are no issues with engine performance.
Any suggestions?
One possibility is a bad check valve in the fuel pump. This allows gas to drain back into the tank as it sits. The ECM only powers the pump for about 5 seconds each time you try to start. This is why extended cranking can have no effect but repeated start attempts do. Next time try the old test; cycle the key from off to run (not all the way to start) 5-10 times with 5 seconds sitting in run position each time. Then try to start. If it starts, you know the pump is losing prime.
Thanks for your help. I will try this test and dust off my Chevy repair manual.