long extended crank on start up on c15 acert

i would use part # 304-9385 check valve

 

I'm dealing with this on a Detroit. You need to get some short clear fuel lines and put those in the system at various spots, start at the engine and work back. This will tell you if there is a leak and where it is. The only other way I know of is putting a small amount of air pressure in the vents and plugging them, you should see a leak somewhere but this doesn't always work. It won't show pickup tube leaks.

Replace this replace that is just throwing money into the wind. It could be anything from the pickup tubes all the way to the injectors.

 

If engine stars and runs smooth it is probably not a fuel problem, start it and unplug cam sensor and plug back in, then unplug crank sensor if engine dies you have a bad sensor that will also cause hard start.

 

This is a possible problem, but usually brings on a active fault code.

I have seen the ECM not set a Check Engine Light for it though. If either the cam timing/speed sensor or crankshaft timing/speed sensor are bad, the engine will usually crank for 5 seconds or so before firing. It will run fine after it fires. As this poster said with the engine running unplug the cam sensor. If the engine dies then the crankshaft sensor is bad. If the engine continues to run then leave the cam plugged in and unplug the crankshaft sensor, if it dies the cam sensor is bad. Before you buy any sensor, make sure the wiring harness to each sensor is not bad or damaged.

 

There are two separate check valves on the c-15. I had same issue from day one. (Since brand new). I changed check valve truck still had problem. There was another check valve that did not have the rubber seal around it from factory. So truck was losing fuel pressure but only slightly which caused the extended crank. Not saying 100% it's your problem but its a cheap part to take a look at.