Fuel pump and immobilisor issue

Sam-s_Volvo · Post by **Sam-s_Volvo** » 29 Nov 2011, 22:25

Hello

Firstly I should mention that recently me and my dad have rebuild the engine (new ring, gaskets, valve stem seals and cylinder head machined). After a few day of timing the cams, we encountered an issue with the immobilisor. There is a glass fuse between the immobilisor and a cable leading to it (the cable is active) and everytime the immobilisor is connected, this fuse blows (no other fuse in fuse box is affected).

Now, with the immobiliser removed, the starter motor work and we can crank the engine, But we have no fuel coming in. However.. at one stage there was fuel coming in (with immobilisor removed that is). The diagnosis unit states 1-1-1 in fuel system. Also cannot see any power in any of the cables going to fuel pump (tested with an auto tester circuit tester pen).

I did recieve fault codes in A7 (combined instruments) as follows:
1-3-2
2-2-1

If someone has an idea of why that fuse is blowing and if it is suposed to affect the fuel pump, it would be greatly apprecieted. Wanna make sure it's not something I can do before I take it to an auto electrician and pay for towing, etc.

Thank you for all help in advance.

Sam-s_Volvo · Post by **Sam-s_Volvo** » 04 Dec 2011, 15:58

I found the fuel pump to be faulty. It would start only when I gave it a few knocks, but no chance without the help. I wonder if a faulty fuel pump could be blowing that glass fuse to immobilisor (the fuel pump fuse in fuse box remains unharmed). I bought one for $140 today, apparently same one they fit to fords and VL's..; so going to give that a shot.

Post by **Ozark Lee** » 04 Dec 2011, 22:16

Sam-s_Volvo wrote:I found the fuel pump to be faulty. It would start only when I gave it a few knocks, but no chance without the help. I wonder if a faulty fuel pump could be blowing that glass fuse to immobilisor (the fuel pump fuse in fuse box remains unharmed). I bought one for $140 today, apparently same one they fit to fords and VL's..; so going to give that a shot.

There really shouldn't be a glass fuse for anything in a Volvo 850 except maybe the CD changer. Is your immobilizer an aftermarket product that has been added on?

The factory Immobilizer just kills the power to crank the starter but nothing else. If it is aftermarket we can't be of much help without a specific make and model number of the product.

...Lee

Sam-s_Volvo · Post by **Sam-s_Volvo** » 07 Dec 2011, 01:49

Ok. Then this must be an after market immobilisor. Replacing the fuel pump fixed the problem with immobilisor, to the immobilisor was definitly associated with the fuel pump as well as the ingition. Car runs great, but you can really hear that fuel pump working in/outside of the car

Will not having an oem fuel pump cause me any trouble in near future? Also the service light is constantly on. This light was on before the engine rebuild, but would go out after few minutes. I have tripple checked everything to be connected and changed the oil (plus filter) and coolant once more.