Fuel Pump Not Priming - Please HELP

[donboy1983]

Hello,

Having a nightmare at the moment with my fuel pump and hoping someone can help.

I have been trying to start my car and although i can get it running I'm having some fuel pump issues. I will explain what i have done so far and see if anyone can advise what to do next.

So, When the ignition is switched on the fuel pump will not prime/engage. I then tested the system by putting a link between the Grd and Fuel Pump terminals in the Diagnostic box, with the link in place i can hear the pump engage and the car starts and runs. 

Removed the link and tried again, turn the ignition on and the fuel pump will not engage. Randomly i removed the 4 pin plug from the top of the crank angle sensor, as soon as the plug is removed with the ignition on the pump starts to run.

I have replaced the CAS but still having the same issue. The only way i can get the car to start and prime the pump is by disconnecting and reconnecting the CAS?

Anyone had any issues with this?

Thanks Don

[iparnell]

I had a bit of a look round the Miata Turbo forum and there are a few guys on there with similar issues that have pin pointed the main green engine relay seeming to be the main cause. Might be worth having a look there if your still having no luck.

Cheers Iain

[donboy1983]

Cheers Iain, I will take a look at that tomorrow. Thanks Don

[phocup]

I was interested so I googled too. This seems to be the thread.

www.miataturbo.net/engine-performance-56/help-car-died-fuel-pump-not-priming-solved-main-relay-64489/

Supposed to be an NB issue only though.

[donboy1983]

I will get the relays replaced and update, i did have a look at the link above but was unsure if it was the same for the Mk1

[mawdo81]

Did you sort it?

[donboy1983]

Yes and no, I was looking to check the relays and found that when i pushed hard on the green relay for the in system it started to click. The strange thing is that the car starts and runs but its not how i imagined it would. My thinking was:

1, Turn the Ignition On
2, The fuel pump runs and primes the engine
3, Turn the key again and the engine starts.

What actually happens is:

1, Turn the Ignition On
2, Nothing happens with the fuel pump, no priming or noise,
3, Turn the key to crank the engine - This causes the pump to fire and the engine to run.

When i turn to crank and quickly release i can here the pump running fine. Not sure if this is normal or not but i just turn the key all the way quickly to prime then start with the next turn.

[gwnwar]

The prime is only for 2 or 3 sec. then pump on as you move key to start then run position.. Have you removed relay and then connected again to harness a few time to clean the connection. Sounds like a dirty connector or bad real.. Did you have a test lamp plugged into the pump connector and grounded so you can see the light when pump turns on and running. Do you have pressure gauge in fuel line on the fuel rail intake hose.