Maestro Turbo Ignition problems

[Doctordiesel77]

If it is a mini oil pressure switch, it is definately the wrong one, they are nc...I had the part number discussion with a motor factors in about 1990...they did send the right switch eventually..but insisted that it was in fact the wrong one...

[Doctordiesel77]

Just had a look on my parts list and it seems to think that gps133 fits everything..the only variation is on the earlier list, which mentions gps129, replaced by gps 132, replaced by gps134...not sure if this is the one you need, but I do remember having the exact same symptoms that you are having, when I fitted an 'ordinary' switch to an efi... The early list also features an extension for the switch, uam1249, which I guess will keep hex away from the casting..

[Sussex Pete]

If it is a mini oil pressure switch, it is definately the wrong one, they are nc...I had the part number discussion with a motor factors in about 1990...they did send the right switch eventually..but insisted that it was in fact the wrong one...

So what you are saying is, that the EPC is wrong in stating that the GPS133 switch is used on the Turbo engine? And I've been treating it as being gospel all this time!

[Jeff Turbo]

It's GPS129, superceded by GPS132, superceded by GPS134 and lastly GPS136. You have the wrong oil switch Pete. As said previous put your old one back on if you still have it. GPS133 is for an efi and you have looked it up incorrectly

[Jeff Turbo]

http://www.leacyclassics.com/media/c...P/GPS136_1.JPG

[Doctordiesel77]

this list might be useful.. https://forums.lr4x4.com/topic/14363...switchesspecs/ montego threads are all 1/8 npt , I'm sure that diesel is nc and fairly sure that yours should be no, I think this is the right one..http://www.ebay.co.uk/itm/ROVER-800-...IAAOSwmfhX6oFD

[Doctordiesel77]

It's GPS129, superceded by GPS132, superceded by GPS134 and lastly GPS136. You have the wrong oil switch Pete. As said previous put your old one back on if you still have it. GPS133 is for an efi and you have looked it up incorrectly

not sure how I got in a knot all those years ago...but can remember the results...fun fun fun

[E_T_V]

It does sound like you have the wrong oil pressure switch. You can test if it is a normally open or normally closed one with a meter or...

You can turn igntion on (but don't start the engine) and listen. You should hear the fuel pump prime for a second or two and then stop. The oil light should be on.
If the oil light is off and the fuel pump runs continuously you have the wrong switch.

[Jeff Turbo]

, as my pump is running all the time with the ignition switched on - which doesn't look to be right! If you guys have got any further ideas, or can correct my thinking/explanation I'll be glad to read them!


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As above Pete. Dans confirmed. Thats 3-0 lol

[Sussex Pete]

As above Pete. Dans confirmed. Thats 3-0 lol

OK Already! I give in!! Old OP switch has been located, just need to decide to fit directly or purchase an adapter to move the hexagon away from the pump. Confirmed old switch is n.o. type.

[G Force]

Hello Pete I’m sure you have probably got this figured out already but for anyone else who might be interested.
The wiring diagram for the fuel pump on a Turbo engine works something like this. Fuse B8 (item 19) is an ignition controlled feed. The wire from the fuse connects to pins 87 and 85 of item 296. This is a changeover relay (DRC1820 and has 5 connections) Pin 86 has the White /Brown wire (WN) that connects to the OP switch which will earth the relay circuit once the 5psi pressure has been achieved, the OP switch is a normally open type. Pin 87a on the relay has the Brown/Red wire (NR) coming from the starter relay to starter solenoid circuit and feeds the fuel pump via pin 30 White/Purple (WP) wire to inertia switch and White/Green (WG) wire during cranking. The second WG wire in the circuit has come from the earth side of the oil pressure warning light and forms an earth path through the fuel pump on the other White/Green (WG) wire when the fuel pump is not running. Once the ignition is on and only when the engine is running and oil pressure is achieved, the relay is energised by earthing relay 296 via pin 86 White /Brown wire (WN) and the now closed OP switch. The fuel pump is now fed from fuse B8 on pins 87 and pin 30 through the inertia switch and the White/Green (WG) wire. The OP warning light is now extinguished due to the second WG wire on this circuit becoming positive cancelling out its earth path.


BL should have written "With the ignition switched on, the fuel pump is isolated, until it receives its initial electrical supply on actuation of the starter solenoid during cranking. With the engine running the pump electrical supply is controlled by the OP switch earthing the fuel pump relay coil. If the oil pressure should drop, engine stalls or an accident occurs; the pump will be electrically isolated"

Regards, Gary

[Sussex Pete]

And a further clarification is that the picture has been printed incorrectly by ARG/BL, and henced copied by Haynes in the Montego manual. The Brown and Red wire (NG) is connected to pin 87 on the relay and the green ignition feed to 87a, the opposite to the picture. The picture is drawn with the relay energised with the power coming from the brown/red wire, which of course is incorrect!!! I'm sure the wiring in my car (and all other Turbo's) is correct, but when you are using the wiring diagram to check certain circuits, it is damned confusing when the picture is wrong to what is really on the car!

[ian drew]

Despite the current issues, fantastic news that she's alive and running Pete! Your determination is definitely to be admired.

Ian

[Sussex Pete]

All (well 99%) fixed. The proper OP switch sorted the short run time problem and the OP light now goes out. The leak under the RHR of the front subframe turned out to be a big split in a flexible pipe on the spill return. New flexible has cured that. Now need to get the car out of the garage to give me space for the final jobs before the MOT next Wenesday!

[carfix]

Excellent news. Well done