Good Morning.

My 1999 VDP SC has started to require much longer cranking to start, particularily when hot. A couple of times, I thought it would not start.

Fuel pressure reg? Loss of pressure in the rail? Is there a one way valve?

I had both pumps replaced a short time ago.

If I could be directed to a suspect, that would be great,
Thanks,
Rob

 

A bad camshaft position sensor (at the back of the LH cylinder head) could be the reason. If this sensor is bad, the engine will run fine but it will take very long to start The easy test is to try starting the engine after a 40-45 sec. wait at the ignition "on" position. If the engine then starts immediately, it is a sign of a bad cam sensor.

 

Camshaft sensor code P0340 ?

Do you notice a difference in starting performance in the amount of time after the last engine run , one hour vs, one day ? This is independent of temperature .

There is a check valve in the fuel pump that holds fuel pressure for days and if it leaks back into the tank the fuel pumping time to get the fuel pressure back up to proper range is longer

You are using only the # 1 fuel pump in the staring sequence by design but can be leaking by the # 1 or # 2 and there is a history of that from others .

An easy try is some fuel injector cleaner if you have under responding injectors as they may be binding and not giving you the proper cylinder fuel charge .

 

Since it happens mostly when hot I suspect loss of pressure and a vapor lock. Check valve likely.

 

There is a design feature of the X308 2 fuel pump operation in the # 2 fuel pump will turn on if the # 1 fails to start the engine after a while . If this happens after a certain number of revolutions or seconds or failed starting times is unknown to me . If you were to place your finger on the # 2 fuel pump relay you may or may not feel it being commanded on . Otherwise the # 2 does not come on until 4000 RPM . This is something to keep in mind during troubleshooting as the # 2 could be compensating for the lack of # 1 starting the engine .

Did you replace the # 1 fuel pump relay when changing the # 1 fuel pump as a failing fuel pump will damage the associated relay ? Since the # 2 relay is not used as much it may be a good candidate to swap with .

Any new part is suspect coming out of a box . Did you feel for 3 clicks on the # 1 relay on - off - on where the 3rd command click on comes from the Crankshaft sensor seeing rotation in the starting sequence . Did you hear that the pump motor runs in this on - off - on sequence . You wouldn't be the first person to have a new pump bad off the shelf .

Did you inspect the connector on the # 1 pump for burnt sockets as it happens and the connector is available at the local parts store .

Have you looked at the noise ​​​suppressor near the pump connector that is sometimes on this model ?