Na8 fuel delivery problem...

chefie · Postby **chefie** » Tue Jan 31, 2017 8:49 pm

Wow chefie, that was from left field!

aggh too many reds before posting is not wise :beer:

I am really interested in the outcome with the chicane8 NA8 issue, i have a na8 with same problem but currently respraying when the paintings done ill hopefully apply the fix the Chicane has used to fix

or update if i solve it first

Red_Bullet · Postby **Red_Bullet** » Tue Jan 31, 2017 8:58 pm

It would be interesting if the ECU is refusing to pull the Fuel pump relay in because of some other input being out of range. I thought you might well know something about the MAF causing this. I was reading between the lines.

StanTheMan · Postby **StanTheMan** » Tue Jan 31, 2017 9:39 pm

On the NA6 the diagnostics GRD/fp bypasses the AFM
Does the same test on the NA8 bypass the MAF?

Red_Bullet · Postby **Red_Bullet** » Tue Jan 31, 2017 10:00 pm

NA8 diagnostic port grounds fuel pump relay directly. It is a parallel circuit to the fuel pump relay output driver transistor in the ECU.

I was wondering if the ECU was refusing to ground the fuel pump relay because of some other reason, that the software had another reason to not enable fuel supply. Mere speculation on my part.

StanTheMan · Postby **StanTheMan** » Wed Feb 01, 2017 5:47 am

I've had issues with fuel delivery previously.
In my case twice it was the faulty connection on top of the fuel tank.
Once the actual fuel pump itself
Once where I'd re installed the fuel lines incorrectly.

If the relays click? They probably work.
If the diagnostic test is intermittent. I'd check the connector & the pump itself.

Everyone is getting so complicated. Unless the ECU got flooded recently. I'd be going that direction.

I've had 1xfried ECU. In my case 1x to many floodings. There was green sh*t & coliflower all over the inside of the ECU.

Not sure why I picked it when it happened. Maybe because it got flooded a few weeks prior? But engine characteristics were quite different to not just starting.

93_Clubman · Postby **93_Clubman** » Wed Feb 01, 2017 9:31 am

A few NA8 & NA6 ECUs are also burning out (for want of a better term), ie blackened & damaged PCB around component/s. I bought one on here last year & opened it up before using & it didn't look like it's ever gotten wet, but burning out. Worth a visual inspection of the PCB etc if problem persists & other easier possibles have been checked & ruled out.

Red_Bullet · Postby **Red_Bullet** » Wed Feb 01, 2017 7:45 pm

StanTheMan wrote:I've had issues with fuel delivery previously.
In my case twice it was the faulty connection on top of the fuel tank.
Once the actual fuel pump itself
Once where I'd re installed the fuel lines incorrectly.

If the relays click? They probably work.
If the diagnostic test is intermittent. I'd check the connector & the pump itself.

Everyone is getting so complicated. Unless the ECU got flooded recently. I'd be going that direction.

I've had 1xfried ECU. In my case 1x to many floodings. There was green sh*t & coliflower all over the inside of the ECU.

Not sure why I picked it when it happened. Maybe because it got flooded a few weeks prior? But engine characteristics were quite different to not just starting.

Yes, I agree. Complications where none are needed. It really is quite simple. And it is all on the schematic which the OP has.

1.Ignition on, ECU grounds fuel pump relay coil. (diagnostic port FP to GND does the same thing!)
2. Fuel pump relay pulls in, contact supplies 12 volts to fuel pump
3. Pump sends fuel to fuel rail via fuel filter. Done.

StanTheMan · Postby **StanTheMan** » Thu Feb 02, 2017 4:37 am

And the funny thing is Red Bullet
When I did try to figure out my recent issues with lack of fuel.
I went & checked the fuel lines near the tank. There was fuel everywhere . Even both sides of the filter . Heaps of pressure and all. I then automatically assumed I'd clogged the fuel lines to the fuel rail. LMFAO.
Rather than realising I'd connected the fuel lines in the incorrect direction after working on the car for a few months.

I'm also a complications offender :lol:

Chicane8 · Postby **Chicane8** » Thu Feb 02, 2017 10:12 pm

Ok guys thanks for everyone's input and help, I just fixed the problem. I had the fuel pump replaced just before Christmas and it seems that the solder joInt ( the workshop did ) was covered with a really poor thin heat shrink. So it took just two weeks for it to rub through and short out. I had just bought a new fuel pump to eliminate it as the blown fuse made me think the pump was bad. They had cable tied the wiring to the metal piping. My friend and I used the crimping joins supplied with the bosch unit and then taped it and cable tied the tape just to make sure!
It will be an interesting phone call to the mechanic tomorrow....;)
Cheers

Chicane8 · Postby **Chicane8** » Thu Feb 02, 2017 10:15 pm

Thanks red bullet for the schematic I'm sure it will come in handy another time...;)

Red_Bullet · Postby **Red_Bullet** » Thu Feb 02, 2017 11:41 pm

No worries, glad it's fixed. Its a PITA when something new is the culprit.

speed · Postby **speed** » Fri Feb 03, 2017 8:11 am

Chicane8 wrote:Ok guys thanks for everyone's input and help, I just fixed the problem. I had the fuel pump replaced just before Christmas and it seems that the solder joInt ( the workshop did ) was covered with a really poor thin heat shrink. So it took just two weeks for it to rub through and short out. I had just bought a new fuel pump to eliminate it as the blown fuse made me think the pump was bad. They had cable tied the wiring to the metal piping. My friend and I used the crimping joins supplied with the bosch unit and then taped it and cable tied the tape just to make sure!
It will be an interesting phone call to the mechanic tomorrow....;)
Cheers

Thanks for updating with the solution.
Glad you fixed it.

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