49 replies to this topic

[Sprok]

Im thinking injector - trying to figure out how to take it apart !

[Wiggy]

As I say, I'm not really up on the SPi.

What happens if you hold the meter on both the grey and yellow wire, whilst cranking? Trouble is, I doubt the meter can update quickly enough to register the pulse, but you never know. I'm guessing the yellow wire is the switched earth in the ECU.

The injector could just be clogged, too.

[Wiggy]

You can get it cleaned, buy a new one, or unblock it yourself. I've managed to unblock both my MPi ones with a syringe.

[Sprok]

Thanks Wiggy

Just looking how to do this. There is a square retaining plate with 4xT20 bolts holding it down then the yellow cap with 1 bolt.
Presumably clamp fuel lines and undo all 5 bolts or do i need remove the whole injector housing (top bit) ? I see thats held down by 4 x T30 bolts.

Hope you can help

[Wiggy]

According to Haynes:

Remove injector connector cap retaining screw. (That's the single Torx).

Use a rag to mop up any fuel.

Lift cap off.

Lift out injector.

Edited by Wiggy, 19 April 2019 - 05:57 PM.

[Sprok]

Mine must have been stuck. Thanks ill let you kniw how we go

[xrocketengineer]

Ok, go back a couple of steps. I am not up on all the SPI details but reading out of the second PDF link I previously posted, the ECU cycles the earth wire and not the power. So, to check for pulses you need to connect your voltmeter to both injector wires and if my brain works right, your voltmeter will read nothing on DC but when you switch to AC it should read some voltage.      

[Sprok]

Electrics just not my forte. But ill have a play and try and do that

Got the injector out - its spotless. Not alot to clean?

What is the little motor looking thing next to the injector ? Is it a mini pump ?

[Sprok]

Ok i connected my multimeter to the black plug wires. Set in volts im getting a reading that seems to pulse at about 3.4v ??

I think the other object is a pressure regulator maybe its that?

[xrocketengineer]

Electrics just not my forte. But ill have a play and try and do that

Got the injector out - its spotless. Not alot to clean?

What is the little motor looking thing next to the injector ? Is it a mini pump ?

 It is probably the pressure regulator. If it is, it has a diaphragm and a spring (similar to mechanical fuel pump). If the fuel pressure is too high, the diaphragm pushes against the spring and opens the bypass to the fuel return line. The thing to check on the injector is the continuity through the coil on both terminals for the connector. It should read very low next 0 Ohms. If it reads infinity, the coil is open. 

 

If the 3.4 volts was AC, it looks like the ECU is sending the pulses to the injector.

[Wiggy]

Electrics just not my forte. But ill have a play and try and do that

Got the injector out - its spotless. Not alot to clean?

What is the little motor looking thing next to the injector ? Is it a mini pump ?

It's the inside that gets clogged with dried up fuel residue. You won't be able to see it. The professionals ultra-sonically clean them.

I have used a small syringe full of Unleaded, pushed into the injector with the plunger pushed hard to create pressure; then pulsed the injector with a 12V supply. Worked very well.

[xrocketengineer]

 

Electrics just not my forte. But ill have a play and try and do that

Got the injector out - its spotless. Not alot to clean?

What is the little motor looking thing next to the injector ? Is it a mini pump ?

It's the inside that gets clogged with dried up fuel residue. You won't be able to see it. The professionals ultra-sonically clean them.

I have used a small syringe full of Unleaded, pushed into the injector with the plunger pushed hard to create pressure; then pulsed the injector with a 12V supply. Worked very well.

 

 

That sounds like good idea. Carburettor cleaner spray would probably do the job too.  

[Sprok]

Im just thinking out of the box. Ive not wired everything on the loom up yet. Could it be something like the accelerator pedal switch or radiator temp sender not being wired up thats giving the ECU problems ?

Does anyone still sell the injector housing complete?

Think the easiest thing would be a replacement ?

[xrocketengineer]

Well, there should not be an accelerator pedal switch on a 96, there is no radiator temp sender, the coolant temp sensor is underneath the intake manifold and even if disconnected the engine would run in "limp mode". If there is no crank sensor, there is no injection and no spark. 

 

I don't think you can get a new injector housing anymore.  

[Sprok]

Its an early 1996. It has a position sensor on the accelerator pedal at the top. The radiator has a screw in sensor with spade end connectors at the bottom front of the rad. This is a new rad from minispares. I cant recall if the original rad had one it was so long ago.
Crank case sensor is wired up or i guess it would run with fuel poured into the throttle body?

How can i test the fuel pressure regulator ? I took the cover off but the unit seems to be bonded into the housing?