the problem: my 98 XJR will barely start after the engine has cooled down completely (6+ hours, such as in the morning) it cranks and cranks, but will not fire at all.....or will fire on the 3rd-4th try. After it's been started once, it will fire up immediately for the rest of the day, until it has sat again for 6+ hours.

Someone has suggested the fuel pump check valve. Makes sense; however, being a layman mechanic I tend to rely on my JTIS manual for most repairs. The JTIS has no mention of a fuel pump check valve. The only mention of a "check valve" is for the fuel tank check valve (which is obviously not related to my problem). Does anyone have any suggestions???? I'm getting sick of being stuck in the parking garage cranking my car after a full day's work. Thanks in advance..

 

There is a valve in the fuel pump that holds pressure in the fuel system for a short time but not all night. If it is hardto start in the morning after sitting all night, the check valve is not the problem. I would check the fuel pressure just be sure though, easy to do on the XJ8. Get a kit from Harbor Freight or equal.It should be around 41 psi running and 21 psi after a10 minutes of sitting. It will gradually go to 0 overnight though. I would get the car scanned and see what the sensors are doing. It is very possible that the simple $15 coolant temp sensor is bad. I never recommend replacing sensors without testing though, you could end up a sensor warehouse.

 

Thanks.. How would a bad coolant temp sensor lead to a no-start after engine cooling? I'm not doubting it.......just want to understand.

 

You know, the symptom sounds like you could also have leaking fuel injectors, which flood the engine after shutdown. Not a bad idea to check on that.Since they are a pain to test, save this until you put the car on the scanner to look at the sensors.

A badtemp sensor could tell the computer the engine is hot and it does notsend enough fuel to start in the morning until it cranks awhile.

 

thanks oldmots. The only scanner I have access to is OBD II nothing comes up there. I ordered a coolant temp sensor (only $5, so not much to lose by trying). Hopefully that will get it. Injector problems can get expensive.