CLIVE

Can anyone help confirm a fuelling problem i have on a mk3 XR3i. when you turn on the ignition you can't hear the fuel pump pre-prime. it had new fuel pump recently. I have put a electrical tester on the pump, if you turn on the ignition, there is no reading on the pump, only when you crank the engine over, is that right ?. I changed the metering unit too, I don't seem to be getting pressure back into the injection pipes and it refuses to start.
any help please
thanks

3i Jim

Have you checked the fuel pump relay?

gcfcos

I had similar problems with mine, run a separate temporary feed to the pump and see if it'll start
Then. I ran 2 wires from a battery just to test it

CLIVE

I checked the relay and it powers across the terminals,
this was my next option was to run wires direct from the battery to test the pump etc.
can i leave it connect direct to the battery for a few mins to run the engine or not.
what turned out to cause the problem with yours ?

gcfcos

Just put a fuse inline on the positive wire mate and it'll be fine just to test it. From memory I used to have a couple of the purple fuel pump relays in the glovebox as they were always packing up.

CLIVE

thanks for that, I will give it a try hopefully today and see how I get on

Cookson

Those bloody pink fuel pump relays were always a nightmare. This was mine on my last RS

haz87

They always end up a mess because of the resistance in the wiring through age.
Adding a proper +12v and new relay loom using the original as a trigger only works wonders. Will stop any further problems.

CLIVE

I did run wire direct to the pump and it continually buzzed and run, pressurising the system, but car still would not start, but I wonder if this is because the wire to the pump from the relay also feeds the warm up regulator and cod start.
I have ordered a relay and keeping my fingers crossed
thanks for all the help and any further advice is more than welcome

haz87

Cold start valve is powered off the starter motor and thermotime switch. This only energises whilst cranking and the temperature low (cant remember specific temp off top of head).

Warm Up Reg only has the heated element as part of the fuel relay circuit so isnt required to start the car.

The fact you were energising the pump directly would give fuel to both of the above.

CLIVE

Thanks haz87, I can't understand why it still won't start, bypassing the relay does get the pump working and pressurising the system, I am guessing that running the pump of the battery causes the pump to continually buzz and the relay I guess stops that.
I am struggling to start the car and if I do it is as lumpy as anything and hard to keep going on the throttle without dying,
I don't suppose you know of anyone over the Hampshire/surrey boarders who may have a look at it, if the relay turns out not to be the problem,

bigdel

Clive, you could try contacting Clayton Parmenter at CJP Autosport in Basingstoke

Top guy who should be able to help you out. Not sure if he'd come out to you though, but worth an ask.

He's a member of the Hants & Berks RSOC facebook group so you should eb able to contact him via that.

haz87

If the car starts, albeit lumpy, the relay isnt the problem.
Have you checked all the Jetronic basics - Vacuum leaks,cam timing, ignition timing, fuel pressure?

CLIVE

thanks, that was my next point to check timing etc. I was going to take the injectors out and point them into a clear jar to see how well the fuel sprays. is there a easy way to check the pressure

haz87

There are fuel pressure testers available - not cheap tho. Or you can make one with a few adaptors and bits of pipe. Good enough for short term testing.

CLIVE

finally getting to the bottom of my fuelling problems, seems to be the injectors. the car had been off the road for about 4 years and after looking at the metering unit etc, have fuel right up to the pipe fitting onto the injectors, but nothing coming out, I took out each injector and re-connected it to the pipe and pointed it into a clear jar and tried starting the car, but no fuel was coming out, so I am going to clean them , if that does not do it, buy some more,
I am guessing there is no other reason why the injectors are not spraying fuel straight into the Jar,

haz87

If you really wanted to test them, then have the injectors pointing in jars as you have already done, then manually lift the metering flap (engine off) as this will impersonate air flow. If you have mega airleaks etc then cranking wont be enough to impersonate proper airflow and the associated lift on the plate.

CLIVE

I did try that and nothing, I loosened the union and it sprayed the fuel out of the joint, so have put it down to blocked injectors,