Non start MI16 after engine removal/refitting

[All Praise The GTI 3]

Hey guys and girls I need some help/advice please:

Mi16 no spark or fuel pump prime after engine removal/refitting.

Ok so please bare with me, electrics are my weakest area especially being a conversion loom that I didn't do. Il try explain best I can
So I recently brought an Mi16. It was running when purchased, only did about 30 miles getting it home etc and then I removed the engine for maintenance and upgrades etc.
I tried not to touch the loom going into the car much just disconnected all the plugs from engine, photographing as i went and Iam fairly sure it's all back as it was. Now refitted Iam not getting any action from the pump and no spark.
The car has an immobilizer fitted and 'it appears' to be functioning due to led flashes etc.
12v put to the pump/or relay and it runs so pump is operational.
Both mi relays in the engine bay have 12v with ignition on and there's 12v at all 4 of the ignition coil pins.
I linked the fat wires to both relays and makes no difference other than putting the pump on but stil not starting.
I've checked all I can that I know I touched or what could be an issue but can't find any problems.
Really stressed out over this as been working non stop every evening and weekend doing a light restoration on the car so I could use it this summer 

Any help and advice welcomed and if there's anyone in the Suffolk area that could take a look or help It would  be much appreciated and rewarded 

[jackherer 543]

You don't mention the crank sensor, have you looked at that?

 

You need to go over every plug that's been apart and make sure they are properly connected, check the pins haven't been pushed back into the housings too.

 

What "maintenance and upgrades etc." did you do?

[All Praise The GTI 3]

The crank sensor was cleaned while I had the box off. The plastic protection on the lead was cracked and peeling but the shielding looked intact so I taped around it all. And it's plugged in obviously.  I don't know how to check it's functioning tho but either way that wouldn't stop the fuel pump priming as the sensor isn't picked up until it's turning over anyway?

 

No major upgrades just new cambelt, waterpump, thermostat, BBM hoses etc. Just general maintenance really .

 

Wiring really isn't my strong point but I can do basic stuff with a multimeter

[All Praise The GTI 3]

So I did some more checking and finally got spark! I had an issue with the crank sensor wiring. 

But Stil no fuel!! Although after some reading I've seen it mentioned that perhaps the mi actually doesn't do a prime and only kicks the pump in once the engine is cranking over, is this correct?!

bridging the relay to kick the pump in permanently and it runs, but stalled when I didn't so seems pump isn't working. Don't see why when it ran ok previously. 

Not sure if iam clued up enough to find the issue so iam planning on fitting a new relay to the car to run the pump directly. Any issues with this as a permanent fix??

[jackherer 543]

I don't think they do prime, mine runs an Emerald now which does prime and this is making me doubt myself though. I will check my mates car tomorrow as it runs motronic and it is here currently.

 

From what you're saying though it sounds like it might be a dead fuel pump relay. You can swap the main relay and the fuel pump relay for each other on an Mi16, so swap them then bridge the main relay socket like you bridged the fuel pump relay and see if the main relay then works in the fuel pump relay socket. If that works you have one dead relay.

 

The wiring to the relay sockets is often troublesome especially with BX 16v looms, the wires tend to fatigue and break right at the relay socket.

 

As is often the case due to the age of these cars and their wiring looms a problem is usually caused by two or more small issues rather than one big fault which makes troubleshooting logically much harder.

 

It's not a good idea to run a fuel pump relay that isn't connected to the engine management, it's critical that it turns off when the engine stops running so in the event of a crash it doesn't continue to pump high pressure fuel.

 

You're not a million miles away so I can probably come and take a look sometime but I'm not sure when at the moment. Or if you can get it to run well enough to drive it here that could happen much sooner.

[All Praise The GTI 3]

I have a spare green relay and I've swapped them all around etc and I had previously bridged both to test. But that was before I had read that perhaps the mi doesn't prime. So maybe I need check it tomorrow swapping relays around while it's running once I've pumped some fuel through. Hard to do checks on my own tho. 

That's very kind of you Kieran, thankyou. your profile says your in Ipswich? Iam in a village the other side of Bury but it's not that far so if I get stuck I could always bridge it and drive over. I've taxed it this evening now I know it does run so it's legal to drive now atleast

[All Praise The GTI 3]

So she runs!!

Not sure if I magically fixed it fiddling with wires etc but she's fine. Turns out the mi does not prime and the pump kicks in once it's cranking. Did a quick test drive and all seems fine and coincidentally the D Day planes flew over as I'd pulled over for a quick check

happy days!

[jackherer 543]

Good news!

 

Keep an eye on the wiring though, you may have an intermittent problem, especially with the connections to the relays. I've seen so many Mi16 looms with issues there.