tvr s2 2.9 fuel relay & transistor part numbers
Discussion
i finally got round to investigating the mess that is the wiring in my passenger footwell.
i did the bare minimum years ago to get the wreck running, which included bypassing and removing the kaput alarm immobiliser and bypassing some melted fuse holders and running free hanging single fuse holders where wires to the melted parts of the fuse block were cut.
now i have an intermittent running fault so i thought i would start by looking at this mess, where i cut the power wire to the fuel relay where the immobiliser used to interrupt it, it is now corroded and almost broken all the way through, so i have cut it again and joined clean wire to clean wire and that let it fire up straight away but i want to take this opportunity to tidy the whole lot up and secure it to a drop down panel that i will make up to make access to the fuses, relays and wiring much better in the future as well as making it all more secure.
NOW what i need help with, is identifying the broken part next to what seems to be the fuel injection relay. there is a brown and white multi terminal connector block part, brown body with white clip on bottom through which the wires go, the wires are 3 thin black, one thin brown, one thick black and one thick red. the thick red, thick black, thin brown and one thin black wire go to a brown ford relay number ford 85GG14N089CA, but next to it where it seems there should be another boxed component with a part number is just what looks like a bare transistor with a red and yellow wire either side of the transistor which go to the spade terminals on the other half of the brown base /block connector and the other two thin black wires. i am pretty sure the transistor or diode should not be bare but cased in another little ford box with a part number. can anyone tell me what this should be?
sorry for the long winded question, just wanted to give as much info as possible to help anyone reading know what i am on about!
i did the bare minimum years ago to get the wreck running, which included bypassing and removing the kaput alarm immobiliser and bypassing some melted fuse holders and running free hanging single fuse holders where wires to the melted parts of the fuse block were cut.
now i have an intermittent running fault so i thought i would start by looking at this mess, where i cut the power wire to the fuel relay where the immobiliser used to interrupt it, it is now corroded and almost broken all the way through, so i have cut it again and joined clean wire to clean wire and that let it fire up straight away but i want to take this opportunity to tidy the whole lot up and secure it to a drop down panel that i will make up to make access to the fuses, relays and wiring much better in the future as well as making it all more secure.
NOW what i need help with, is identifying the broken part next to what seems to be the fuel injection relay. there is a brown and white multi terminal connector block part, brown body with white clip on bottom through which the wires go, the wires are 3 thin black, one thin brown, one thick black and one thick red. the thick red, thick black, thin brown and one thin black wire go to a brown ford relay number ford 85GG14N089CA, but next to it where it seems there should be another boxed component with a part number is just what looks like a bare transistor with a red and yellow wire either side of the transistor which go to the spade terminals on the other half of the brown base /block connector and the other two thin black wires. i am pretty sure the transistor or diode should not be bare but cased in another little ford box with a part number. can anyone tell me what this should be?
sorry for the long winded question, just wanted to give as much info as possible to help anyone reading know what i am on about!
phillpot said:
... some how it stops power feed back to the fuel pump in the event of a crash or something?
It is a diode, but I can't imagine how a simple diode could act as an inertia switch 
But I'm willing to be educated. 
Maybe it gets ejected/dislodged from the plug just before the air bags inflate !
TVRees said:
But I'm willing to be educated.
Try reading thisNot explained very clearly (to me anyway) but think the idea is that the pump can't get power unless the engine is cranking/running. In a crash engine usually stops so pump will not continue running, possibly spraying petrol everywhere?
Electronics is not my strong point but I've read somewhere about diodes in fuel pump relays to prevent the pump (basically an electric motor) feeding a "back EMF" to the ECU and blowing it?
Definitely a Zener diode - really useful little things could have several purposes. They are voltage specific so could be used as a regulator to limit the max and min voltage going to the pump and therefore the speed to an extent. Or could also be used to supply the pump when cranking but to ensure that nothing else is powered when supplied (back fed).
Dunno if that makes sense but nothing wrong with Mikes electrical knowledge!
If you really want to find out you will have to put a meter on it and see when the end with the stripe is positive.
Suppose it could also be used to dump any emf after the pump or starter are turned off so that things don't blow up!
Dunno if that makes sense but nothing wrong with Mikes electrical knowledge!
If you really want to find out you will have to put a meter on it and see when the end with the stripe is positive.
Suppose it could also be used to dump any emf after the pump or starter are turned off so that things don't blow up!
Slightly OT but diodes are also used in some relays to prevent damage to the ECU as the contacts open. The voltage collapses in the relay coil in the same way as an ignition coil when the points open; this can cause damage to the ECU.
The little wiring diagram on a relay (equipped with a diode) will show the diode in the circuit.
If wiring a relay with a diode, the diode should always point to the + connection, so be careful which way around you connect to pins 85 + 86.
The little wiring diagram on a relay (equipped with a diode) will show the diode in the circuit.
If wiring a relay with a diode, the diode should always point to the + connection, so be careful which way around you connect to pins 85 + 86.
Edited by Oldred_V8S on Thursday 14th January 09:57
phillpot, mk1fan (in another thread0 mentioned that you had cleaned up your engine castings, assume he is refering to cyl heads and maybe inlet manifold? and that you have fitted a different cam to your 2.9 and have 189bhp, please tell me more, what exact cam have you fitted and where did you get it and what did it cost? what else did you do exactly? am now interested in getting more power out of my motor and the most bang for buck, obviously i understand you can end up throwing thousands at any motor with ever diminishing returns but what are the first things i should/could do to my so far standard 2.9 12v to get best results for least cash? thinking in terms of hundreds not thousands! cheers, drak
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