Starts and runs for 5 - 10 seconds

NeilBisby · Post by **NeilBisby** » 19 Dec 2018, 10:21

Hi, Thanks for looking at my post.

The previous owner of this 2001 V70 T5 said "This car became hard to start at times and began cutting out intermittently and now won't start at all.

The engine was replaced 3 years ago and has only done about 25k miles since the replacement.

Sometimes when I try to start the car, it seems to misfire and other times it runs smoothly for a few seconds and then cuts out.

I do notice that when it starts, just before it cuts off, the dashboard lights get slightly brighter which I think means that there is a bad electrical connector or relay.

I put an ODBII on the car, but it does not show any problems. If I had a wiring diagram I might be able to trace the problem.

So far I have tried:

1 Drained some of the gasoline out of the tank and put some new gasoline in, so what is in the tank is a mix of old and new.
2 I purchased a special spanner and took out the fuel pump and then refitted it. The mechanic said it has a new fuel pump.
3 I changed the in-line fuel filter and replaced the fuel pump relay. I have not measured the fuel pressure at the cylinder head.
4 I changed the spark plugs.
5 I replaced the Crank Shaft Position Sensor
6 I checked the fuel pressure at the cylinder head and it reads a steady 50+ psi.
7 I have also done some small jobs like replacing missing fuses and fixing the fuel cap cover back on.

I have run out of ideas ...

Thanks

Neil

Post by **abscate** » 20 Dec 2018, 04:10

Cheap way...a three second shot of starter fluid will help determine if you have good fuel delivery or an ignition problem

Correct way

have not measured the fuel pressure at the cylinder head.

Yep, that’s whats needed.....

NeilBisby · Post by **NeilBisby** » 20 Dec 2018, 04:40

Dear abscat,

Thank you for your reply, most appreciated.

I apologise for the omission, I did check the fuel pressure but forgot to add it to the list.

As I say, it actually runs for a few seconds, then the dash gage lights get a bit brighter as the engine cuts out so I am leaning towards an electrical problem.

Neil

Post by **abscate** » 20 Dec 2018, 09:30

Check for 12 volts at coils, monitor while running to see if it drops and is killing ignition.

Will it restart after it dies?

The electrical stuff isnt too indicative, the fluctuation could just be alternator to battery load switching

Post by **mrbrian200** » 20 Dec 2018, 11:01

Note: this is all technically 'brainstorming'. Try not to get stuck on any specific idea. At this point we have no real idea what is going on here.

Check with a voltmeter across the battery terminals to see if the system voltage is indeed rising and if so, how high. I'm leaning toward a voltage regulation problem (either courtesy of the control circuits inside the CEM or on the alternator), not a 'bad connection'. It could be various modules either shut down to protect themselves or begin to malfunction when system voltage gets to high.

Note instrument lighting intensity may be controlled via CAN data between the headlamp switch to various modules. I'm not sure how that works on an '01. This might be indicative of a loss of communication for reasons not yet determined.

NeilBisby · Post by **NeilBisby** » 27 Dec 2018, 15:04

Dear mrbrian200,

I hope you had a good Christmass, I apologise for the delay in responding, I tried to record a video that showed as much information as possible. Then I put the video on Youtube:

The battery is in the back cargo compartment under the floor, so I put the volt meter on the terminal that supplies all the fuses in the engine compartment with power. The normal state is 12.5 volts and although it varies when I try to start the car, it does not vary when the engine drops from running to, missfiring / running roughly. Also, one day I tried to start the car it was dusk, so I could see the tail lights reflected in the window.

The video shows my attempts to start the car. At 33 secs, for a short period the engine runs smoothly at about 1,500 rpm then cuts off, sometimes it goes back to running roughly at just under 1k rpm.

When the engine is running smoothly, pressing the accelerator peddle does not seem to do anything.

As you can see, the gas pressure at the head is good and holds at about 60 psi.

I used an OBDII Scanner and it came up with P0335 - Crankshaft Position Sensor "A" Circuit Malfunction.

Thank you for your assistance, I hope to hear from you soon, have a great new year.

Neil