Troubleshoot SP wont start and shutdown while driving

[bmchi]

My black sp has broken down the engine shut down while i was driving around a roundabout the other day and now it wont start.No funny noises it just lost power all of sudden when i tried to accelerate out of the corner. Im quite sure the problem is electricall we have tested for spark and is fine. Have found out there is no signal going to the fuel pump, ive checked and tested the fuel pump and even changed it for good measure and its all working. Looking under the driver dash for the fuel pump relay now and cant tell the difference with all the wires and different plugs!!

Does anyone know where the fuel pump relay is on an sp?

Does anyone know if the setup will differ on sp's? It looks different from the pics that ive seen but i also have a turbo timer wired in under there which might also be why.

[davekmoore]

If same as SE it's in a rectangular black box at the back of the engine bay all the way over on the driver's side.

[Magpie]

A popular statement but, "check the CAS sensor". The CAS controls the injectors, no CAS no fuel.

[bmchi]

Isnt the relay in the box the egi relay?

Ive checked the cas she works good and i only replaced it 6months ago too.

Any other ideas?

[Magpie]

I had a constant CAS fault that was caused by the connection not the sensor itself. A quick test was suggested by omgpham (forum sponsor) and it turned out to be the solution! Another test is to get a noid light and see if the injectors are getting the signal.

[93_Clubman]

Yeah EGI relay is the one in the main fuse box in the engine bay. NB (including SP) fuel pump relay should be on the firewall inside the cabin above the accelerator pedal.

Have found out there is no signal going to the fuel pump

However, given what you found above, first check for continuity at the electrical connector block on the outside of the top of the fuel tank, as the connectors of that electrical connector block deteriorate on the inside of the tank, & stop power to the fuel pump. See here:
http://mx5cartalk.com/forum/viewtopic.php?f=55&t=46425
Btw, just out of curiosity how did you determine the above in your quote?

[bmchi]

how do i test the CAS connection? will definetely be worth checking.

I didnt bother checking the main/egi relay as i can hear and feel it click when i turn the keys to on, my thoughts as this means it works, should i check it anyway? its a SOB to get out.

in regards to testing the pump i pulled it out of the tank and jumped the wires going to the pump to to my car battery and it is whirring/buzzing away. then when we put it in and wired it up again i pulled the fuel lines off the top of the tank and directed it into a bucket while i cranked it.no fuel came out which led me to believe the pump isnt getting any power.

So i double checked the plug going to the fuel pump at the top of the tank with the multi-meter and i only got 0.3 voltage reading (i used the diagnosis connector and jumped GND to F/P which apparently should pull in the fuel pump when switched to on)

[93_Clubman]

You need to check with a multimeter if there's resistance or continuity of the circuit inside the tank from the outside of the top of fuel tank connector block as per in this thread: http://mx5cartalk.com/forum/viewtopic.php?f=55&t=46425
From what you've already said I'd expect you'll find there's resistance or very little or intermittent continuity. If so, remove the assembly from the tank & check the inside of the connector block by pulling the inside connector off it. If there's a problem it should be evident from blackness of the metal connections, & indeed sometimes even from the blackness of the plastic surrounding them.

[bmchi]

Thanks for the help guys really appreciate it

I'll do a check on that and report back, the first thing we actually did was replace the fuel pump although we should have done some other checks first to mak sure. so i have spliced in a new one to that connector.

[bmchi]

ok guys bit of an update.

this is really puzzling me here is a full explanation of the situation

sunday - car broke down while driving, the engine shut down as i tried to accelerate out of the corner. The car still had power all lights and accessories were ok and tried to start and the engine cranked fine but just wouldnt turn over and start.towed the car back to my girlfriends house around the corner.

Monday - checked battery, checked fuses, checked spark all ok, but no fuel

Tuesday - Changed fuel pump but accidentally left the keys in the on position and drained the battery, jumped the car to try and start it, engined cranked over again but no start.

sunday week after it broke down decided to call RAC and get it towed back to my place. the breakdown assist guy came first,jumped the car battery and went to check spark and then when i turn the key so he can check it starts up! i shut it down and he plugs it back up and i turn the key again and it is fine and starts up and runs.

i have no idea what is going on!

[93_Clubman]

Just means the issue is intermittent, as some issues can be, especially electrical issues like the deteriorating electrical connection inside the top of the fuel tank amongst others. When that problem occurred it similarly wouldn't start one day, but the following day started ok.

[noobee]

heres a picture of the sort of thing I found in my fuel pump connector inside tank.


viewtopic.php?f=55&t=70835

Mick

[Caffeine]

I'd say EGI main relay. Big green one in the fuse box under the bonnet. I'd had about 5 or 6 go.

$25ish to $100 depending on your Mazda dealer.

Part number is B5B4-18-811.

[bmchi]

Update

Since the visit from the rac ive sent the battery in to mazda as it was still under warranty and theyv confirmed the battery was buggered. So theyve given me a new battery and the car starts and runs.

But the cranking time is now extended before it starts..... Any ideas gang? i rechecked my work for the fuel tank replacement that i did and changed the fuel filter too. Still no luck with getting it to run like it was before it broke down on me... Takes at least 6-7 cranks or so before it starts up