Engine cranking too long before it fires.

[Freebird]

Hi All

I have a 1996 X300 fitted with an LPG system. I have a problem for a few months now where it cranks for a good 5-6 seconds before it will start from cold. Once it has started, if switched off it will re-start instantly unless left for 5-6 hours. Here are a few points and things I have tried so far.

1. It starts and runs on petrol until warm, so I don't think the LPG is to blame.
2. It re-starts fine cold or hot, so I don't think the camshaft position sensor is the cause. (could be wrong though)
3. I replaced the fuel pressure regulator (not a new one though) and fitted a new fuel filter and non return valve before the rail.
4. I temporarily fitted a pressure gauge in the fuel line before the rail and get 3 bar as soon as the ignition is switched on.
5. I have changed the temperature sensor in case it was not enrichening the mixture when cold.
6. I once connected a "power pack" to the battery and it started instantly so I fitted a new battery, the old one was dropping to 10.6V on cranking, the new one about 11.2V - no dice though.
7. There are no codes in the OBD2 apart from a spurious immobiliser code P1621 that has always been there.

So, what have I missed I wonder? Any advice always most welcome.

Cheers

Glen.

[naki]

It looks like you have checked all the obvious things.
I would look for a leaking injector seal. I had this on one of mine, though it was an XJ40. Pull all the injectors out and check/ renew the O-rings if necessary.
Worth a look anyhow.

what you can do to test the theory of if you still don't have sufficient fuel pressure, is prime the fuel pump multiple times, before attempting to start. Repeatedly turn the the key to position two, as this primes the pump. If you issue disappears then its still fuel pressure related.Let us know how you get on.

[Freebird]

I am pretty convinced there is no problem with fuel pressure. One thing I have found, which also backs this up is that if I don't use the car for a week or so it starts straight away. The next day it's back to cranking too long.

I have now done this on 3 or 4 occasions so I don't think it's a fluke.

[davidr]

Have you checked the camshaft position sensor? This is the unit that sits on the front right of the engine above the a/c pump in the position where the distributor would have been in older engines. (This is different to the crank position sensor which is used for ignition timing).
It's function is to tell the ecu where the engine is in terms of the 4 stroke cycle so it starts sooner. If it's not working properly the car will still start and run but it will churn over on the starter for longer until it fires while it finds itself.
Hope that helps
David

[Popsjag]

I would be tempted to change the crank position sensor. You don't know if it's in the early stages of breaking down - and it's only a 10 minute job!

Mine runs on Lpg and always takes about 2 seconds to 'catch' on Lpg, but is always instant on petrol.

[Freebird]

Thanks Guys

I think if the cam sensor was duff, it would always take a lot of cranking? Once it has started, it will re-start immediately.

The crank sensor is new and fitted to "Andy's bracket" too.

Glen.

[naki]

Thanks Guys

I think if the cam sensor was duff, it would always take a lot of cranking? Once it has started, it will re-start immediately.

The crank sensor is new and fitted to "Andy's bracket" too.

Glen.

So that did cure the issue then?
It proofs how these sensors can fail in certain situations/ whilst working the rest of the time. Or fail outright.
I always keep a spare in the car at all times anyhow.

[BigCatXJS]

My X300 used to suffer from excessive cranking when cold yet it would be fine when hot. Turned out that I had leaky fuel injectors thus requiring extra time to build the pressure on cold starts. We replaced them all with a set from a donor scrap car that was known not to have the issue. Problem solved - never had the issue again.