NON Runner - HELP

[A135TAS]

Hi People,

Our 1984 3.5 EFI wedge wont run. I put a post a few threads down saying that the car was driving along, stopped suddenly and the cab filled with smoke!

Well i have repaired the burnt wiring and replaced the relay that was also destroyed beyond repair.

Everything now works as it should however the car will not start.

We have a good spark

We have Fuel as far as the injector rail and a good strong supply from the pump. However the pump only turns when in the crank position but i cannot hear it prime as i think it should when the ignition is turned on?

If easy start is squirted into the intakes then she fires and runs.

Ive had the ECU out and cant see any damage to components or board.

Please can anyone point me in the direction of a fault finding guide on the EFI system? IM guessing something has blown somewhere but have little technical information to use as a guide.

Or has anyone had the same problems and can offer advice.

Many Many Thanks!!

Ash.

[Brap_Brap]

"NON Runner - HELP"

Tried hitting the offending part with a hammer yet?

[A135TAS]

No, but i will tommorow if it doesnt burble!

[jeff m]

I note you have a good spark, but is that just when the starter is turning ?

Check for 12v on coil with key in "run" position.
Could be something simple.

[A135TAS]

Thanks Jeff. I can confirm we have a spark and good supply voltage at the coil with the ignition in the second stage and crank.

Im amazed i cant find a decent online fault diagnosis guide!

Thanks,

Ash.

[honestjohntoo]

Hello Ash

A135TAS said:

the pump only turns when in the crank position but i cannot hear it prime as i think it should when the ignition is turned on?

Very likely a steering module diode or some local wiring has been fried.

This link explains:

http://www.vintagemodelairplane.com/pages/Rover_Te...

A135TAS said:

can anyone point me in the direction of a fault finding guide on the EFI system? IM guessing something has blown somewhere but have little technical information to use as a guide.

You will find everything needed for all Efi components and other test programs here:

http://www.vintagemodelairplane.com/pages/Download...

[jmorgan]

Correct me if wrong but I thought the flapper run on turn over and the hotwire primes on ignition on?

More help in this excellent resource
http://www.tvrwedgepages.co.uk/maintenance.html

[TVR 3X]

Flapper type fuel pump only runs during cranking and then when the flap is open (due to air moving through it).

With the ignition on take the air filter off and carefully open the flap with your hand, the fuel pump should run.

Russ

[honestjohntoo]

Steering Module




Operation

The white (W) wire from the ignition switch supplies power through the right hand diode in the Steering Module (terminals 4 to 1) seen above. From there it connects to terminal 85 of the Main relay, through the relay windings to earth via terminal 86 to close the contacts when energised.

Power is now available directly from the battery via terminals 30/51 and 87 to the air flow meter (Fuel Pump contacts), Pin 10 of the ECU and to the Power Resistors which connect to the fuel injectors. However, current can only energise the injectors when the ECU completes their circuits to earth with appropriately timed injection pulses.

The Fuel Pump relay is also activated through the Steering Module but in two different modes. Initially, in engine cranking mode, power is available to the Steering Module terminal 3 via the white/red (WR) wire from the ignition switch cranking circuit. Then, as the engine starts, in engine running mode, power reaches terminal 2 via the blue/purple (UP) wire coming from the now closed Fuel Pump contact inside the Air Flow Meter, also connected to Pin 20 of the ECU.

In either mode, current passes from the Steering Module via the respective diodes at terminal 5 to the Fuel Pump relay terminal 85, through the relay windings to earth. The closed relay contacts operate both the Fuel Pump and the Extra Air Valve with power drawn from the ignition switch.

These two diodes, by their nature of preventing current from flowing in the reverse direction, ensure that operating current from terminal 3 cannot pass to terminal 2 and vice versa.

In summary, the Fuel Pump is initially energised in the cranking mode but as soon as the engine draws air through the air flow meter its internal Fuel Pump contacts close, completing the alternative circuit to keep the Fuel Pump energised until either the ignition is switched off or the engine stalls, the Air Flow Meter flap closes, thus opening its internal Fuel Pump contacts.

[A135TAS]

Gents,

Many many thanks!

I cant get access to the car today but will be going first thing in the morning with my multi meter etc!

The above once absorbed seems fairly straight forward. Ignition supplys and energises the Main Relay. When cranking the Fuel Pump relay is energised and the engine then sucks in air opening the MAF. Once the MAF is open and the car then starts it triggers the fuel pump relays to stay permanently closed until the engine is killed?

Fingers crossed - will report back.

I want to drive this bd to le mans, its sat and only used lightly, been trouble free for 18 months, typical haha!!!

Cheers,

Ash.

Edited by A135TAS on Sunday 6th July 17:03

[jmorgan]

Might be a silly question but was it flooded?

[A135TAS]

jmorgan said:

Might be a silly question but was it flooded?

Hi, No it was running as normal along a dual carriage way, running fine and Bang she just died. Then the smoke...

Ash.

[honestjohntoo]

A135TAS said:

The above once absorbed seems fairly straight forward.

Ignition supplys and energises the Main Relay. When cranking the Fuel Pump relay is energised and the engine then sucks in air opening the MAF. Once the MAF is open and the car then starts it triggers the fuel pump relays to stay permanently closed until the engine is killed?

Hello Ash, I like that! It's about as concise as you can get whilst still describing the functions.

A very concise version is: "The engine starts under control of the cranking circuits which immediately hands over control to the ECU".

Too little information unfortunately.

Trouble is, my guess of the cause is only just "intelligent" based on your descriptions hitherto. When you find, as is entirely possible, that the steering circuit diodes and the associated wiring are all OK, then I'm afraid you have to revert to the routine fault-finding processes recommended for each component on my website, and in my Efi test and operations manual.

Good luck