- My model of MX-5 is: ?
- I’m based near: __Lanark
- I’m looking for technical help or recommendations on: __fitting an engine
Hi folks my question is on an MX-5 where the two fuel pipes come up and join the rubber pipes at the engine I notice there is a third pipe looks like it comes from the charcoal filter( the black canister mounted on the drivers wing, is this a charcoal filter?) Is this a breather pipe from that filter or does it go all the way back to the tank.Im fitting this engine into a 1973 Jensen Healey so do I need that filter??
Cheers Gavin
Is this still the Mk2.5 (NB) rather than the ND in the tags?
If so, the pipe is a vent that usually pokes into a hole in the front subframe to keep the muck and bullets away from the open end.
You probably don’t need it, but beware that if you also remove the associated solenoid valve (the ‘purge valve’) AFAIK it will trigger the ‘Check Engine Light’.
Yes but the Jensen won’t need all the engine lights etc that the Mazda would have I probably don’t need half the wiring loom I’m using(from the same car the engine is from) so there’s a load I can do without ie. air bag, abs, power windows so can I do away with the charcoal filter? If so what do I do with the pipes going to it and the two valves mounted on the wing beside it?
I think the options are:
Remove it all and ignore the CEL;
Remove it all and fit a suitable(*) resistor to ‘spoof’ the presence of the solenoid to keep the CEL off;
Remove the cannister and piping, but leave the solenoid connected to keep the CEL off;
Leave it alone.
In all cases except the last, you’d need to plug the hole in the inlet manifold & direct the vent from the tank to somewhere suitable.
I think that purge system only has one solenoid associated with it… There are also some components relating to the EGR system in that general area (if your engine has EGR - I suspect that it will).
(*) I don’t know what value that would be - some research needed.
Thank you I might just leave it as is for now until the car is finished and on the road and then I can mess about👍
Ok so over the weekend I have managed to get the Mazda wiring loom in to the Jensen and have connected all the engine plugs starter alternator etc. The engine now cranks over but won’t start I have primed the fuel pump by bridging the main wire to the pump and giving it a live feed that brought fuel through the pipe. On the two fuel pipes coming from the engine which one is the feed and which one is the return? One of them appears to go onto the bottom of the little valve at the front of the manifold the other disappears further back? Does the fuel pump only go live when you crank the engine ? If so it’s not doing that there’s no power at the main wire when you crank the engine?
Have you got the gauge cluster connected?
Does the immobiliser light come on and go off again when you turn the ignition on?
Do you see any RPM reading when cranking?
Fuel pump only runs when cranking AFAIK. There is a way to prime the pump by bridging contacts in the grey Mazda diagnostic socket (not the OBDII socket) - a search should reveal which ones.
I don’t think there’s a fuel return on these - the supply from the tank goes to a small pulsation damper (round thing) and from there to the fuel rail. The other pipe coming from the tank is a vent.
Are you aware of the exploded diagrams that are available at ‘PartSouq’? They may be helpful.
I have plugged the gauge cluster into the loom and when I turn on the ignition all I have is the battery light and there is no rpm showing when cranking the engine. The oil pressure gauge is going up to the middle when the ignition is turned on ??
Do you have the immobiliser and the pickup loop around the ignition switch plugged in also?
Immobiliser light should come on for a second, or so, then go off. If it doesn’t (or if it keeps flashing), there is an immobiliser related fault, and it will never start, as the ECU won’t trigger spark (nor fuel, I think).
Oil pressure gauge is triggered by a simple pressure switch: it shouldn’t move until the engine is running, and then it will head for the middle of the gauge - maybe check your earths; there are many in the MX-5 loom!
That’s what I thought! Yes the plug with the two little black wires going to the ring around the barrel is plugged in and both wires have around 3.5v at them but no light comes on. I also took all the loom from the Mazda dash ( which came from the same car) and plugged everything in so I wasn’t missing anything apart from lights wiper heater etc all main stuff is connected.Is it possible the ecu or immobiliser is gubbed? I have looked on eBay and I can get a set as they call them key, barrel, ecu for about £70 so might be worth a try unless you have any contacts through the club for bits?
Cheers
Is there a separate immobiliser like a stand alone unit somewhere?
Yes, there is a separate immobiliser module. I think it usually lives under the steering column somewhere. It talks to the ECU (by passenger’s feet) and to the transponder in the ignition key via the sensor ring around the key barrel - you are using an original key? - Once it has seen the key, it sends a code to the ECU that allows it to function. (ECU = PCM in Mazda speak.)
It would be worth reading the diagnostic codes in case this gives any clues. It’s always possible that something has been damaged, but I wouldn’t automatically assume that this is the case - My 2p: triple check that you’ve found and connected all of the ground wires in the looms.
Someone was advertising an immobiliser emulator here fairly recently, which may be an option to consider.
Just for clarity: I’m not affiliated with the club, other than being registered on the forum.