Na8 fuel delivery problem...

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 5:08 pm

Hi guys, this is a new thread from my post a week or so ago about no spark. Turns out I do have spark ( discovered after I replaced CAS) but i found no fuel coming into the engine bay when cranking the engine.
I swapped circuit open relay under dash ( no change) main relay in engine bay ( no change)
So I just jumped the fuel pump and ground terminals on the diagnostic port and the pump does run and I had fuel coming out of the engine bay line no problem...
So I think I read somewhere that this could be ECU or even MAF sensor?? I did have an error code for the air temp sensor in the MAF mentioned in my previous post.. I think it was 0110 code??
Anyone come across this issue?
Many thanks

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 5:54 pm

Update, it was pumping with the diagnostic port jumped but now it seems it's not. The car ran for 30sec then stalled again so I checked with the jumping technique and the pump wasn't working must be something intermittent..

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 6:10 pm

Up date of the update ;) just noticed the fuel inj fuse was blown... Swapped it for the cooling fan one 30 amp and no change no pump running..

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 6:33 pm

What model is it? I just looked at the schematic for an NA8. Fuel pump relay is controlled by ECU. Light green wire connects relay coil to ECU Plug 2 pin T. ECU pulls relay coil to GND. Do you hear the relay click in when turning ignition on? The fuel pump relay is under dash. PM me if you want me to email you schematic diagram.

If you have access to a multi metre then check circuit from Data link port to pin 2T on ECU. If you have a circuit, based upon what you said about bridging it at the data port and fuel flowed it could be the ECU.

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 6:52 pm

Yes thanks, I pmd you by the way..
The pump did work via jumping initially but then when I checked again it didn't.
I suppose the ECU could be suspect? but my diagnostic skills aren't the best especially with this on again off again symptom.
The fuel pump was done just before Christmas but who knows it could be a bad part..
Thanks again

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 7:14 pm

I PMed you back, I need your email address to send schematic.

If the relay does not click in each time you turn ignition on then you need to fix that problem first.

If the relay clicks in each time then the problem lies in the fuel pump circuit.

A relay is just a switch, you put a bit of current into the coil, it magnetizes closing a bigger switch which feeds 12 volts to the fuel pump.

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 7:45 pm

Yes ok, well I did swap both fuel pump relay under dash and main relay in engine bay to no effect so I was kind of looking elsewhere for the problem?

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 7:50 pm

It will all become much clearer when you have the schematic. If you want the schematic you need to PM your email address. :frown:

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 8:22 pm

You have email with the schematic.

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 8:53 pm

Thanks for the schematic... Cheers

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 9:25 pm

The fuel pump and relay circuits are at the top top left of the large photo. Let me know if you have any questions.

Chicane8 · Postby **Chicane8** » Sun Jan 29, 2017 9:41 pm

Will do thanks mate ;)

chefie · Postby **chefie** » Sun Jan 29, 2017 10:19 pm

Ive got the same issue with a 93 clubman,

in the process of painting and will be faced with this issue in a couple of weeks, looking forward to the fix outcome.

i have a feeling it could be ecu coolant temp sensor and or a vacuum leak / inlet manifold leak

Red_Bullet · Postby **Red_Bullet** » Sun Jan 29, 2017 10:28 pm

Wow chefie, that was from left field! :shock:

93_Clubman · Postby **93_Clubman** » Mon Jan 30, 2017 10:31 am

Chicane8 wrote:The pump did work via jumping initially but then when I checked again it didn't.
The fuel pump was done just before Christmas but who knows it could be a bad part.

For an intermittent fuel pump, also check for the so called 'blackwire' issue:
https://mx5cartalk.com/forum/viewtopic.php?f=55&t=46425
&
https://mx5cartalk.com/forum/viewtopic. ... 55&t=70835