Volvo 940 wont start.
 

Hi all hope someone can help me.
I have a 1997 940 lpt auto.
Hasn't been used in a while.
The battery was flat so put some jump leads on and when you turn the ignition on you can hear the fuel pump
Prime but won't start. Then every time you turn the ignition on the pump doesn't prime again.? But if I take the jump leads off and put back on again it does prime once but not again till I cut the power again?
On my other turbo 940 the fuel pump primes every time I turn ignition on.
Any help would be much appreciated please

has it got sparkto the plugs?
Is it getting fuel to the cylinders?
Has it got compression?

Do you know how to check for these things (not being nasty - serious question)?

Change the battery for a known good one. Even if you take it off your other car to prove the point.

I've known many batteries over the years that are so flat, they hog all the available power from a jump pack or even another vehicle that is running.

Then if it still won't start, go through the checks Ash has suggested. ;) :D

Priming
 

My 940 LPT only primes for a few seconds when the ignition is turned on the first time, so that does seem right.
However, if you try to crank it with jump leads, without success as you describe, the voltage level will drop so deep that it might sort of reset the ECU. Not sure what that does for the priming sequence.
Running the electrical system with jump leads is one thing, but powering the starter motor is something else. It will draw a high current and every bit of electrical resistance will suddenly become a major issue. Supermarket quality jump leads is usually not good enough. You will find that when you try to crank all electrical power is suddenly gone.
To reduce the resistance as much as possible, connect the + jump lead to the battery and the - clamp directly to the engine block.

Hi thanks for replys. I will try another battery.
I am trying to jump from a large land-rover battery..
What I don't get is that with power connected it will only prime once . Then when u turn ignition off and back on it should prime again. But doesn't untill I remove either the fuel pump fuse/ relay or battery /jump leads.
My other volvo primes every time I turn the ignition on??
Before cranking

If my suspicion is correct and the existing battery is hogging all the power then there wouldn't be any power left to re-prime the pump the second time until you disconnected and reconnected the slave battery.

Time will tell when you fit an alternative battery. ;) :D

Yeah my first task would be to clarify that you're revving the donor with the leads on while starting.
Rev that sucker! (Obviously two-man job.)

After that : Some fresh new fuel, Fuel pump relay, Crank position sensor, in that order.

I may have misunderstood but i thought he was just using a spare battery from a Land-Rover rather than the vehicle it's meant to be attached to?

Hi just to clarify, I'm trying to jump start from my land-rover defender which has a large battery and some decent jump leads. What I'm finding is that when I turn the ignition on( dash lights on) I hear the fuel pump Prime...... Go to start and just turns over. Then if I switch the ignition off and back on the fuel pump doesn't prime again...... So even if I put a new battery on it will only prime the first time I put the ignition on then never again unless I discon the battery????
What can stop the pump from priming? I've swapped relays and checked fuses.
Cheers Darren

Have you actually fitted a different battery Darren?