Hi Guys,

I have 90,000 miles on her now. A bit of history first. In the fall of 2019 as I was driving at 65 MPH the motor just stopped running. It would crank over but not start. Let it sit for a while and it would not start. Called AAA for a flatbed. Before he got there I tried it again and it fired right up and ran fine all the way home. No codes, everything checked out ok. Ran fine for the rest of the season. Last year (2020) I did not drive it much but ran fine.

Getting her out of winter storage today she fired right up and ran for 50 minutes as I checked everything over. As I was pulling out I stalled it (been a while since I drove a standard transmission car) It would not start but cranks over fine. I put on my fuel pump pressure gauge and it pressured up fine. Started to pull things apart to test the spark and gave it a try. Started right up. Went for a slow 60 minute drive around the neighborhood. Stopping 2 times to see if the motor would restart and it did.

Driving home the motor stopped as I pulled onto my street and I was able to cost into my driveway. Same thing crank and no start. Let it sit for 42 minutes (I timed it) and she started right up just fine.

The weather was 65 F and clear out. The motor was not overly warm. It was a dry day.

My thinking is the crankshaft position sensor as I have seen them be temperamental SOB's on other motors.


What do you think????

 

Testing 2 or 3 wire sensors =

 

Bad fuel pump. Do a search.

 

Please explain to me how the fuel pump is the problem when the pressure at the fuel rail is in spec during the entire time the motor will not start?

Thanks

 

A quick question, is the fuel level when this occurs towards the lower end of available "range", "miles to empty"? Like 80 miles or lower?

 

No, I keep my tank almost always full unless I am on a trip. It was on full this weekend. She is a weekend car.

 

Crankshaft position sensor would throw a check engine light very quickly, I think.

I have read a lot of fuel pump threads here, engine dying while driving down the highway and then starting again is common for bad fuel pumps. My fuel pump would be fine, particularly when cold, but caused no end of problems. Intermittent failure. Could be the time you had the pressure sensor in place the pump worked fine but it can't maintain pressure. But I agree with you, it should have at least started and then stalled if you had 50-55 psi at the rail. If you have a cheap code reader and the free Torque app you can log crankshaft position signal and fuel pressure. Looking at your data it should be obvious if one is failing.

 

The pressure was at 50 PSI and not starting or even trying to fire.
I did put a can of starting fluid in the car to see if it will pop over the next time it stops.

I do have the free Torque app but have not used it much. What gauges do I need to load to monitor the fuel pump and crank sensor? What should the reading be?

Thanks

 

You've probably read about the other fuel pump "test". If the car isn't starting, whack the bottom of the gas tank on the passenger side. Fuel pump usually kicks in when you do that I'm told.

In Torque I would go to Settings (the little gear shaped icon), click on Data Logging, then Select What to Log. There you can pick from a list of available channels. Fuel pressure is one. Engine RPM is also there. I don't know for sure if that is reading the crankshaft position sensor. When you get in the car to start a trip hit the Settings and Toggle Logging to start logging data. That way you can pay attention to the road and let the phone watch the data for you. To look at the data I do Toggle Logging to stop recording data, then Email Logs and send myself the file. It is a CSV so I open it in Excel and make a graph. If you don't do spreadsheets there is an option to upload to the Torque website where it will generate graphs for you. For cranskshaft sensor I would look for short "drop outs" where the engine RPM data suddenly looks different, high or low, maybe only for a second. For fuel pressure the engine maintains a constant change in pressure across the fuel injectors, which basically means your fuel pressure can change a little depending on manifold pressure. Mine reads 55 psi most of the time (with brand new fuel pump last week) and the one log I made since replacing it the pressure stayed between 53 and 55.5 psi all the time. Maybe someone with more experience can give you a better range. Best of luck.

 

I just had another thought. If your crankshaft position sensor is going bad as you suspect it might not be "bad enough" to throw the check engine light. Bad sensor readings cause pending fault codes. The pending fault will clear if the sensor does what the ECU expects it to do over some miles/minutes/revs. When it acts up again use Torque to look at pending codes. You might find the crank sensor problem in there.

 

Hi, I had this exact problem a couple of months ago and it turned out to be a fuse. The garage where I took it changed the fuse and I have had No problems since. Sorry I don’t have the paperwork with me right now so I can’t tell you which fuse I will have access next week if you want.
Hope this helps

 

I recorded fuel pressure today on a 30 minute drive in the country. The pressure as reported by the Torque app stayed between 53 and 57 psi for the entire 30 minutes except for 1 time it dropped to about 47 psi for 1 or 2 seconds when I floored the accelerator to avoid someone who didn't understand how traffic circles work.

 

KatLady, Yes please let me know what fuse they replaced.

dh53, Very good information. I was playing with the app in my truck trying to learn more about the log feature. I have not had the Jag out yet. The weather has not been the best. I will start to check the pending codes each time I drive it.

The weather is looking better for this weekend

Thanks, everyone!!!!!