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Problem starting 3.9 V8 Injection


julianngrant

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I have just fitted a 3.9i V8 lump into a BIG LandCruiser with a Milner bell housing conversion, etc.

You can see the vehicle on http://blessedarethefew.com/JulesLCbuild.htm

The engine was a runner when it came out the donor (rolled) Disco.

It is all plumbed in and wired in but it won't start.

Well it will start on easy start so I know its firing and timed up ok, etc but no fuel is being injected coz as soon as you stop spraying the easy start it stops.

I know fuel is on the fuel rail as I have checked the pressure at the rail and it is 37psi which it is supposed to be.

So I reckon the injectors are not firing?

How can I check this?

I figure the injectors themselves and the ECU are probably ok as they worked before the engine was removed from the Disco so it is probably down to the wiring or something related.

I have dowloaded the EFI checklist pdf form this site and I can measure power to the ECU connector on the riight pins with the ECU unplugged but for the rest of the tests you have to plug the ECU in. This means I cannot then get a tester onto the connections.

Does anybody know if there is a test socket or something that can plug between the ECU and its socket so you can test voltages etc at the pins with the ECU plugged in?

Or does anybody know any other way of working out why it is not squirting?

Arghhhhhhh! Its driving me mad. Please help.

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Its obvious and don't shout at me

But, are you sure the fuel pipes are plumbed in the right way around :) ?

Nige

Yes they are the right way round.

Only the fuel feed has a high pressure fitting so you can't go wrong and in any case if I press the "tyre valve like" thingy on the fuel rail with the rump running it squirts petrol at me.

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If the white/black wire is connected to the coil, also cheak that the resistor that is inline with the white/black wire is still connected. Its found on the loom where the air flow meter wites com out.

I had the same simptoms as you on a disco and that was the fault.

Mark

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Look in the technical archive -> V8 Hotwire EFI Diagnostics manual and work through it.

The ECU will not inject fuel if it doesn't see the signal from the coil -ve (which tells it the engine is turning).

I will go and check the white/black wire thing this mmorning.

I already looked at the V8 Hotwire EFI Diagnostics manual as per my original post and I can measure power to the ECU connector on the riight pins with the ECU unplugged but for the rest of the tests you have to plug the ECU in. This means I cannot then get a tester onto the connections.

Does anybody know if there is a test socket or something that can plug between the ECU and its socket so you can test voltages etc at the pins with the ECU plugged in?

Otherwise I don't see how it is possible to follow the V8 Hotwire EFI Diagnostics manual coz you can't get onto the ECU pins.

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Just open up the back of the plug, from memory there's a couple of screws inside the connector face and the cover falls away, you can then slide it up the loom to allow better access to the back end of the plug :)

Much easier to do all this with the ECU out of course, didn't read whether it was out of it's home or not...

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Just open up the back of the plug, from memory there's a couple of screws inside the connector face and the cover falls away, you can then slide it up the loom to allow better access to the back end of the plug :)

Much easier to do all this with the ECU out of course, didn't read whether it was out of it's home or not...

OK Thanks I will go and look at unscrewing the cover on the ECU plug. Couldn't see how to do this yesterday but I will have a proper look to see if there are screws inside the connector face.

The ecu, relays and loom are all exposed as I wanted to get it runnig before I found a home to mount them all.

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Bowie69 you have made my year!!!!!

Couldn't see how to open to connector yesterday but with you saying there were screws on the plug face I looked harder and found them hiding under a rubber gasket.

So then I followed the procedure in he EFI diagnostic manual.

Which lead me to believe the main relay was not working on both sets of contacts (It has 2 contacts 87 and 87a which are supposed to both switch live and only one did).

So I bypassed the relay with a bit of wire (just a temporary measure) and hey presto it started and runs a treat.

A big thank you to everybody that contributed to this thread.

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Not sure about your relay.

A relay with 87 and 87a is a change over relay so only one of those pins will connect to pin 30 at any time.

I suspect the relay you have actually has 2 pins both marked 87.

Worth knowing before you go to buy a replacement.

Steve

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Not sure about your relay.

A relay with 87 and 87a is a change over relay so only one of those pins will connect to pin 30 at any time.

I suspect the relay you have actually has 2 pins both marked 87.

Worth knowing before you go to buy a replacement.

Steve

Thanks Steve

You are exactly right although I had already sussed it out.

Basically at some time between the engine coming out the Disco and me getting it somebody put the wrong relay in the main relay socket.

They put a changeover relay in there when it should have been one where bot contacts got connected to to the common one when it switched.

Anyway problem now solved

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Thanks Steve

You are exactly right although I had already sussed it out.

Basically at some time between the engine coming out the Disco and me getting it somebody put the wrong relay in the main relay socket.

They put a changeover relay in there when it should have been one where bot contacts got connected to to the common one when it switched.

Anyway problem now solved

Just to clarify for anybody else reading this thread....

The relay that should be in there has contacts both marked 87 and when it is switched these are both connected to the contact marked 30

The wrong relay was in there and it had contacts 87 and 87a this is a changeover relay where either 87 or 87a are connected depending whether the relay is energised or not.

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