One for the really mechanically minded

[GreiginFife]

Today I decided it was time to start work on resurrecting my "other" car - a 3.0 V6 Mk4 Astra that I built a few years ago.
It's essentially a 2.5 from a Vectra that I had re-bored to 3.0 with uprated cams and followers. Lightened flywheel and a few other wee tweaks to make it slightly nippy and a big bit fun.

However, due to work and family commitments, not to mention golf, it's been a bit neglected and has sat in the drive for about 9 months without moving. So yesterday I put the battery on charge and today went to move it in to a position where I could start work replacing the running gear etc and get it back on the road.
Well, that was the plan. Battery in place I turned the key and it turned over but wouldn't start. couldn't hear the fuel pump priming so went about investigating that. Fuel pump relays are working (as I tested bridging them with a screwdriver) but are not getting a signal to prime the pump.
Relays worked in my other Astra so it's definitely not the relays.

Anyone got ANY ideas as to why the relays wouldn't be getting a signal to prime the pump (when bridged the pump was getting a signal and the fuel system was pressurised)??

It's got me stumped.

 

[Iaing]

Are ye not in the AA ?

 

[GreiginFife]

Are ye not in the AA ?

Ha, they would take one look at what's been done to that car and run a mile. Non-Standard seems to render them inoperable.

 

[Oddsocks]

3 litre Astra..... Sounds a tool!

 

[GreiginFife]

3 litre Astra..... Sounds a tool!

It's a really good motor, very quick but at the minute it's just a heap of useless metal.

 

[Mark_G]

Have you tried to jump the car? This can damage the engine ecu, alternatively a likely cause would be crank sensor or a dry electrical joint due to corrosion. It could be as simple as unplugging the electrcal connections of ecu, etc and reconnecting them. Has the engine got a spark when cranking? If it has, that rules out the crank sensor. Does the engine start after manually priming the fuel pump?

 

[GreiginFife]

Have you tried to jump the car? This can damage the engine ecu, alternatively a likely cause would be crank sensor or a dry electrical joint due to corrosion. It could be as simple as unplugging the electrcal connections of ecu, etc and reconnecting them. Has the engine got a spark when cranking? If it has, that rules out the crank sensor. Does the engine start after manually priming the fuel pump?

Not jumped the car, has a fully charged battery so no need to jump it. I was leaning to crank sensor as wouldn't start even when manually primed. Just wonder if it's maybe a DIS pack issue as had a problem before with this before so may just not be sparking.
(P.S - you aren't Mark_G from Migweb are you?) Cheers

Oh yeah, ECU is a Bosch Motronic 2.5.2 so is a sealed 32 pin bus unit, can't plug them in one at a time.

 

[Mark_G]

No nothing to do with Migweb, you need to check to see if its sparking or not, that will then give you a clue to the area to concentrate on. Does the Mil lamp on the dash display correctly? If it doesnt then check the ecu feeds and earths. Do you have a fault code reader that could give you a clue to the area you need to look at? The main relay supplies the coil and the fuel pump so it could be a good idea to investigate the connections at the relay, as the relay should pulse the fuel pump at ignition on.

 

[Mark_G]

Found this for you as well

http://opel-scan.ru/files/Opel_Motronic2.5.pdf

 

[GreiginFife]

No nothing to do with Migweb, you need to check to see if its sparking or not, that will then give you a clue to the area to concentrate on. Does the Mil lamp on the dash display correctly? If it doesnt then check the ecu feeds and earths. Do you have a fault code reader that could give you a clue to the area you need to look at? The main relay supplies the coil and the fuel pump so it could be a good idea to investigate the connections at the relay, as the relay should pulse the fuel pump at ignition on.

MIL is a red herring due to ECU diagnostic being send/receive seperate (engine) and send/receive blinkback on car loom so non compatible. I have Tech2 but it doesn't detect the engine ECU (detects body, UHD and RHD controllers).
Will check for spark tomorrow. Connections at the relays seem ok, when you say "main relay" what are you referring to as the system has fuel pump relays (purple) and one other (green) in the engine bay.
As I say, I can get the pump to prime by shorting out B5 and B5a on the relay but still won't fire.
Cheers for the input, gives me a few more good locations to check, kinda stumped myself today by getting really frustrated in the freezing cold (whole point was to get the car into the nice warm garage to start the rebuild work).

 

[Andy808]

I think you may know the car pretty well from what you say has been done so I'm going to throw an outside thought your way.
As you have no power to the fuel pump unless you short the relays, you can't get it to run and it's on an after market ECU, have you tested that the power supply to the ECU is live?
Had a similar problem on a laguna a couple of years ago and finally found it was a broken power lead to the ECU. New cable, gracefully slung across the front of the engine bay, and it worked pike a dream. Just a thought that's all.

 

[GreiginFife]

Thanks Andy. It's not an aftermarket ECU it's got, the Bosch is the original ECU for the engine.
Gets more weird. Got spark at 2 plugs I checked and the DIS pack is getting +12v across all 6 HT's. Cam and crank sensors both getting +12v when cranking, can't find any obvious corrosion on any wires or connections.
Just doesn't want to prime the fuel pump. Looks like a strip and rebuild job on the cards.