Idles for 3-4 mins then stalls

[oblark]

I`ve fitted a 96 940 lpt engine and box into my 83 240.

It`s been starting and running fine for the last few weeks until today.
When I turn the ignition on the fuel pumps run for a few seconds then stop, start the car and the fuel pumps start up. After about 3-4 mins the idle drops quickly and then stalls. Turn the ignition off then back on again and NO fuel pumps but if left for 3-4 mins with ignition switched off and restat the car the fuel pumps work but only for 3-4 mins then the car stalls with no fuel pumps. I`ve checked the white fuel pump relay and it is all ok it appears that something is timing out and shutting the fuel pumps/relay off. According to the wiring diagram the ecu grounds the fuel pump side of the relay so I`ve tried another ecu and the same thing happens.

Does anyone have any ideas ?

Thanks Rob

[t5 pete]

Have you tried by passing the fuel pump relay just make 100% sure

[oblark]

Have you tried by passing the fuel pump relay just make 100% sure

I`ve had the thing apart and watched what it did when the car stalls, the fuel pump side of the relay drops out, tried shorting the contacts but the fuel pumps would run. Have spoken to Matt who has give me a few things to check tomorrow :)

[oblark]

First thing this morning start the car and wait for it to stall, didn`t take long about 2-3 mins. Checked for a spark coz the ignition module is known to fail and hadn`t nice big fat spark. The time of running was getting less and the time of waiting for the pumps to come back to life was getting longer. So I connected the fuel pumps to a fuse that was live when the idiot lights where on, Guess what car ran for 2-3 mins then stalled. This now ruled out the relay and pointed towards the main fuel pump. Removed the pump from the car and set up a little rig so I could run it pumping petrol, it ran for 30 mins no problem. So this is wierd, the pump will run fine off the car but not when on it. The only thing it could be is the connection on the fuel pump, these are the ones from a 240 which I`ve soldered into the wiring loom, so I cut them off and soldered the wires straight onto the pump terminals. Once the pump was refitted the car started up and ran for a good 15 mins, fingers crossed i`ve sorted the problem.

http://i1067.photobucket.com/albums/u433/oblark/Project%20240/20150503_130219.jpg (http://s1067.photobucket.com/user/oblark/media/Project%20240/20150503_130219.jpg.html)

[Ettienne]

At least it didn't cost much to fix other than being a pain.

[960kg]

The only thing it could be is the connection on the fuel pump, these are the ones from a 240 which I`ve soldered into the wiring loom, so I cut them off and soldered the wires straight onto the pump terminals. Once the pump was refitted the car started up and ran for a good 15 mins, fingers crossed i`ve sorted the problem.


I hope you have sorted the problem Rob.....just a tip when soldering ( as i repair the old reel to reel tape recorders with pcb`s and all that etc)

People think that just because two wires are soldered that that is ok but the problem is the wires should touch before it is soldered!.......if there is a large gap and the wires are joined by a lump of solder then ok it will work but there is more resistance for the joint to overcome so that may be why the pump stops as its not getting the full wack of electric through the soldered joint...

[oblark]

more resistance for the joint to overcome so that may be why the pump stops as its not getting the full wack of electric through the soldered joint...

The pump was cutting out with the standard volvo push on connectors. Seens soldering the leads directly onto the pump I`ve not had any problems :)