EGR valve/ starting issue

Nope. A failed EGR valve on a 12D will not cause you to have to prime the fuel system before starting. If you have to prime the fuel system to get the engine to start there are 4 possible causes. The overflow valve (most common if you don`t have any other rough running or performance complaints *in most cases), a failed injector cup, cracked head or injector o-ring (in the case of a cracked head or leaking o-ring you will likely see diesel in the crankcase), leakage in the suction line to the engine or a failing fuel pump. In my excperience, if the engine is hard starting right away after it was just shut down, either an injector cup leak or an overflow valve is the primary suspect. The worst failure that I`ve seen from an egr valve is if it is stuck wide open and the EPG (exhaust pressure govenor) kicks in as it should in warm hold. The added exhaust backpressure will cause the engine to die due to excessive EGR. But the engine will start. It will never cause a failure to start if all other systems are working as normal.

 

Going on a limb here, how about the cam sensor, do you have any codes that pop up on your dash.

About a year ago I had a problem, hard starting,

I was mentioning my problem to the part desk at Volvo, a mechanic came in and herd my conversation and said Cam sensor.

 

To address the previous cam sensor reply.. A failed cam sensor will usually trigger a complaint that the engine cranks excessively beofre starting. But the engine will still start. It just cranks longer as it only has the signal from the crank sensor to go by. Crank sensor is primarily used for engine speed. Not position. The engine ecu will eventually figure out which companion cylinder is on the power storke. The fault will show inactive when not running but active as soon as it starts. It will not require priming of the fuel system.

That`s a lot of parts changed. Ok, taking a step back, try running the engine out of a pail of fuel to the inlet line at the filter base. Shut it down and wait the 15 minutes and attempt to restart. See if it is an engine issue or a supply to engine issue. If it seems to be an engine issue, I recall having one 12D that had a hair crack at an injector bore. The unit had `trace`amounts of diesel in the oil when an analaysis was done. Localizing the failure required draining the fuel from the head, installing a plug at the return and an air adapter at the supply. Remove the valve cover and pressurize the fuel rail with 10-20 psi of air. Spray around the injectors with soapy water.... Ya I know that sounds rediculious but it worked. Customer`s complaint was hard starting after sitting.

 

One other thought that came to me at the dinner table... Ya.. I have no life.. I ran into one other issue several years ago that caused a hard start complaint. There is another check valve in the return system. It's located in the bulkhead fitting that connects to the return line from the engine. The valve had jammed and the engine was not returning any fuel to the tanks. A 12D will run totally fine like this but the issue occurs when there is air trapped in the system and cannot exit out. It circulates in the engine and if it is a small amount, will not cause any performace issue. Once the engine was allowed to sit, the air would rise to the top (head area). Priming the system would get the engine to start. Quick check for this is just to pull the return line and see if the engine is in fact returning fuel to tanks when running.