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[bootie]

OK, can somebody please help me to understand the relationship between the Fuel Pump relay, ignition and 12v at the pump.
I have done the bridge on the FPR socket and get a clear 12v at the pump which proves the wiring is OK. Bought new FPR over here from the Opel dealer after reading the hundreds of posts about this fabled bit of kit.


What I would like to know is, when can I expect to see 12v at the pump connection? Should it be with just ignition on or should it be when engine is cranking?
If it should be when ignition is on but not cranking engine what else do I need to look at?

I guess one of the answers will be in the form of a question, have you done the blink test, well no, not yet, but I will now, well not tonight but tomorrow and see what it comes up with.

Just wanting to pose the question first to see if any of the electrickery genuises have an instant solution.

Cheers

Also posted on ABS and Total carlton to get as many answers as possible.

[Omegatoy]

Hi Jon,

tech 1 wil power fuel pump!! lol
basically when ignition first put on, it will power pump for 3 or 4 seconds till pressure is reached, this will cut it off, untill engine cranks where it will or should pulse it again, this will fire the engine then when it senses alternator voltage it will be or should be getting 12v supply to pump
however the fabled fpr is connected to many circuits!! and just one being faulty will stop or hinder it working!! lol

[bootie]

Hey Graham, yes I know digs about the tech 1.....also LOL, I will get over one day, I promise.

Now here's the thing, the pump itself is off the car, took it right off including the mounting plate, a, to test it with 12v (OK) and b, to clean up and paint the mount.

So, I would expect to see 12v at the pump connections when ignition on as there is no pressure being generated, nothing in the fuel rail, but at the moment, according to my multi meter there is nothing! Don't want to refit the pump until I can get a clear indication that it will all work or should I?

So what else does the FPR run then? Lambda? Hall sensor? I'm baffled (easily as it happens)

PS, have you read your messages?

Jon

[Kevin Wood]

I'm not familiar with that vehicle but I wouldn't expect it to sense fuel pressure on a system of that age. I'm guessing it just runs the pump for a few seconds.

[bootie]

Your pobably right Kevin, but I would have thought I would see 12v in the meter even fleetingly, when the ignition is turned on?

[2woody]

Hi Jon,

tech 1 wil power fuel pump!! lol
basically when ignition first put on, it will power pump for 3 or 4 seconds till pressure is reached, this will cut it off, untill engine cranks where it will or should pulse it again, this will fire the engine then when it senses alternator voltage it will be or should be getting 12v supply to pump
however the fabled fpr is connected to many circuits!! and just one being faulty will stop or hinder it working!! lol

this is spot-on - as I'd expect.

[Murph]

What happens is: Turn on ignition switch.....this sends Batt+ to ECU pin.27
                         ECU pin36 sends -earth to (85) relay A
                         Relay A operates and sends Batt+ (87) to the injectors & one side of Relay B
                         Engine is now cranked on the starter motor
                         Crankshaft sensor now sends a stream of pulses to the ECU
                         ECU thus 'knows' the engine is turning & from it's pin 3 sends -earth (85b) to relay  B
                         Relay B operates and sends Batt+ to the fuel pump (via fuse 16)
                         Engine now starts.....

 Relay pin 87 feeds the injectors Batt+ ready for them to receive earth pulses from the ECU to fire them in dual sequence, it also feeds (batt+) to: i) Board Computer
                                                                                                                ii) Intake Valve (dual ram)
                                                                                                               iii) Idle Control Valve
                                                                                                               iv) Tank Vent
Relay pin 87b; besides batt+ to fuel pump, also supplies batt+ to the lambda (O2) sensor heater.

Lastly, when you first turn on the ignition, the ECU earths relay pin 85b for about 1.5 secs to run the fuel pump momentarily, to pressurise the injectors ready for starting, the pump then stops & doesn't run again until the engine is being turned over, i.e. the crank sensor is producing a signal generated by the teeth on the crankshaft pulley.

[bootie]

Excellent Murph, just what I was after, now I have a number of other components to check. I have a feeling that this will be down to wiring.
After the recent body repairs I have found a number of small faults, one of which is the lack of the schrader valve assembly.

What I don't understand is the fact that she started and drove fine coming back from the workshop and after that started after standing for a month (as usual) left her to run up to temp and put some charge back in the battery.... then she just died and has never started again. Did the basics, spark at all the plugs but found no fuel at the rail, plenty in the tank which led me to believe the pump had failed (which it hadn't!) so that's where I am now, no pump connected just a multi meter on the connections to see if there is 12v there. Like I said, proved the wiring is good by bridging the relay socket.

We'll see how I get on today.

Jon

[Murph]

Would you like a spare rail with the schrader fitted?

[bootie]

Murph, sorry mate I didn't make that clear, it's the schrader valve for the rear suspension, need that plus the lines to the shocks.

I still have a spare fuel rail complete from the old blue 2.6 should I need it. Is there another fuel regulator on there as well as the one on the pump plate at the rear?

Anyhoo, rain has stopped play at the moment so no further forward.

[Marks DTM Calib]

Pretty run of the mill Bosch injection setup on these from memory, seem to recall its an early Motronic type

[henryd]

Has the Carlton got an inertia switch in the fuel system ?

[Murph]

I'll have a look in the parts store - we might have a set or airlines with the valve.
The fuel rail has a fuel pressure regulator and a return valve fitted.

[bootie]

Motronic 1.5 and no, no inertia switch as far as I know.

Murph, it's OK, I'll chat to you later about that mate.

Jon

[bootie]

She lives!!!!

No idea exactly what I did but found as many connections as I could this morning, disconnected each one and re-connected about 3 times (none appeared dirty) put everything back together and using a visual spark connector fired her up, primarily to check for a spark on each plug.... she fired up after about 8 turns, settled down nicely (cleaned the ICV while I was under the bonnet) and just ran up to temp (new thermostat as well) well chuffed.

Now all I have to do is get the interior back in after a good clean and wizz her down for the ITV (MOT)
note to self: remember to put the cats back on!

Now I can move her to flat ground and get the camper van back near the house to sort the gear change linkages on that.

Happy days......oh and the sun is shining today!

Jon