ECU error 29?? help thanks

[Steve0011]

hi

i have had just a few problems with a C14SE :( anyway the ecu flags up error 29 = low fuel pump relay voltage

can anyone give me a clue what to check and how low volts would occur?

i have btw swapped the relay

steve

[Rysee]

Fuel pump relay?

[andy_mk3]

Could be a wiring fault, something shorting to earth would cause low voltage to come up

[Steve0011]

Could be a wiring fault, something shorting to earth would cause low voltage to come up

that sounds more like it, i will meter the relay supply see if it earths. to be honest i would have thought a fuse would have blown?

i have 4 relays 3 second hand and 1 new....what are the chances of all being faulty?

steve

[andy_mk3]

May also be the pump itself at fault.

[Steve0011]

the pump is a brand new walbro 255 motorsport and filter the fuel pressure is fine at 3.5bar

[andy_mk3]

I guess its not that then!

What problems are you actually having with it?

[Steve0011]

right here goes lol

fuel pressure as said is fine

getting a good spark (new coil, amp, rotor arm, dizzy cap and leads)

spark plugs are new and gap is correct

timing spot on and checked with a lamp

new CTS and TPS

car really really tries to start takes about 10 goes before it finally ticks over but it is very 'lumpy' as soon as you hit the throttle the engine dies :(

from then on it starts first time but dies again

today was the first time the CEL came on and showed code 29, no other codes (apart from 12 ;) )

i have half a tank of fresh petrol

also compression is good on all cylinders

steve

[andy_mk3]

Has a compression test been done?

[Steve0011]

dam it, could'nt edit fast enough :)

and before you say it, i have changed the injectors :d

oh yes and i have a spare ecu

AND A BOX OF MATCHES :d :d

[andy_mk3]

Hmm, bit of an odd one that is! You have air, fuel, spark, compression all happening at the right time, you'd expect it to work lol!

I don't really know what else to suggest. I'll have a think about it, someone else might be a bit more clued up than I am though (it wouldn't take much!)

[Steve0011]

i will check your original idea of the 12v earthing out to the relay, do you know if the fuel relay fused ? if its not then a voltage drain to earth could quite easily be the problem

[andy_mk3]

As far as I can tell there's no fuse between the power feed and the relay. There's a fuse between the relay and the pump though.

[Steve0011]

you know what? its sounding more and more like what you said

i will let you know how i get on

thanks for the help

steve

[andy_mk3]

Well, it's a possibility worth looking at! :)

[mowgli]

ok, is this an engine that has been previously run in this car, or is it a fresh transplant?

[Steve0011]

it is/was a transplant

i fitted it along with a complete loom and ecu

the engine was running fine a while back, even drove it round the block a few times. now it just wont start straight away once it does start its lumpy and dies when given throttle

i suspected fuel and now code 29 has come up its starting to check out, either the relays OR a wiring issue for the 12v supply to the relay

steve

[Steve0011]

update

another fuel relay fitted 12.2 volts at the relay, this drops to 10.1 when cranking fuel pressure is constant 3.5 bar

i have noticed something???? the 12v supply shorts to ground when the ingnition is off and 0 volts, is this normal?

i hate electrics :(

[andy_mk3]

10.1v when cranking is fine.

I don't think it should short to ground with ignition off though. You should have an ignition live and permanent live feed to the relay, output to pump and connection to the ECU.

[Steve0011]

sorted now :) :)

i ran a complete new wire for the relay live

thanks for your help buddy

steve

[andy_mk3]

Ah right cool. It must've had something wrong somewhere along the line then. Glad you got it sorted :)

[Steve0011]

sometimes i just feel like ragging the whole loom :) but you have to take a deep breath, count to 10 etc ;)