Ive noticed a problem with my 4x4 saff,
When I switch on the ignition the fuel pump primes and runs on for 8 to 10 secs.
Even with pressure gauge fitted and holding pressure it still seems to prime for a longer time than usual every time over and over.

The car starts and runs fine although I do have a problem at high revs with leaning out and thought this problem could be related.

I was wondering what in the ecu controls the fuel pump relay?
Is it the chip?

Any help would be much appreciated.

 

forgot to mention the car is usual stage 3. greens, t34, 3 bar map, etc

 

you sure its no tthe ABS your listening to?

 

Could be a tell tale sign of a fault condition.

I know the best part of fuck all about cossies, but on EEC IV ECU's in the event of a fault the ecu resorts to limp home mode, and the pump runs continuously with the ignition on

 

rapidcossie - no mate deffo the fuel pump

 

Mine does exactly the same, doesn't seem to cause any problems with mine though!

 

8/10 seconds abolutely normal, it's not how long it primes but more that it does, it is working ok.
As for the "leaning out", what makes you think this do you have a guage(AFR) ?
May be wise to change the fuel filter in that case, the AFR at all speeds loads is controlled by chip with trim inputs, a dodgy CTS can do this but would effect it at all times not just at top end.
If you know your car is defo leaning out it can only be lack of fuelling which could be something as simple as a new filter needed or pump/regulator on way out.
tabetha

 

Thanks for you comments,
It deffo is leaning at top end evidence is melted spark plugs. Had Steve Scott hang a pectel on it all sensors ok, flow tested the grp a pump thats ok too.
Im under the impression that it is a problem with the chip, the fuel pump never used to prime as long as it does now.
I was thinking that if the chip controlled the fuel pump then that could point to the problem also.??
Also last time I drove it at high speed it held back, a few seconds later it cut out. I pulled to the hard shoulder switched off waited awhile then restarted fine drove home...

 

Chip does NOT control, the fuel pump or fuell pressure the.
If pump and pressure output have been checked, you need to check the
RAIL PRESSURE at the SHRAEDER VALVE.
A melted plug does NOT indicate a LEAN MIX SINGULARLY, it can also be caused because the plugs have the WRONG HEAT RANGE or that the engine has overheated.
What state of tune is the engine ?, what plugs are you using ?
tabetha

 

The engine has not overheated and I use 57 C's
low comp engine holding 22 psi.
fuel pressure set to 3.5 bar at idle with vac pipe off.

 

Ok thats strange Ive just gone out to check the car again and now ive noticed the fuel pump is NOT priming with ignition. If I flash the starter the pump comes in and primes for 3 secs. Again it seems to start and run ok. This is doing my head in now...
I dont want to start changing parts over as I will never find the problem

 

Looks like we have got the same problem.

Also got a sierra cosworth 4x4 and I noticed when switching on the ignition the pump doesn't stop after a few seconds. Also at a recent rolling road session it made some good power at 322bhp with greens, 3 bar map, chip etc. but it was very lean.
Checked all the sensors and even did the LED test at the ECU and all the sensors are ok.
Even change the chip back to a standard one, but still the pump kept running when switching the ignition on.

Contacted Stu about this and he told me that this is the sign that the ecu detects some kind of fault and gets in 'lOS' mode...

I am also still searching what this can cause.

 

Mine does the same but is a standard L6, and doesn't appear to have any ill-effects.

Sometimes it primes as per the book, sometimes it takes longer, sometimes it doesn't prime at all, but runs fine in between.

All I've ever thought it might be related to is maybe a vacuum leak(?) or a sticky relay. Maybe even a poor earth/supply to the fuel pump, but as it runs normally I'm not sure that'd be the case.

Dean Saff

Mine always fires on the third or fourth turn of the crank regardless of the pump priming the line, does yours have a problem starting?

 

Priming is only there to ensure suffecient start pressure in fuel rail, and it does it only sometimes depending on where the engine has stopped.
If it is close to a TDC sensor notch this will be picked up, and cause a RUNNING signal to be received, if not it wont.
Most engine stop in the same postion but not always, this is why they oftenm wear a particular point on the ring gear and give trouble with worn teeth on it.
tabetha

 

OK with Tabetha.

2 strategy are apply by ECU : cold engine and very hot engine.
With cold engine, and contact on, fuel pump start just during 1 or 2 seconds, just to obtain suffisant fuel pressure in the rail. And it restart as soon as engine crank is in suffisant speed.

With very hot engine, and contact on, fuel pump start during 10 seconds, to obtain a big flow on fuel rail to avoid vapor lock.
You can easely check this with disconnecting WTS and shunt connector directly on (use cutting paper clip). This shunt is , for ECU, same than very hot engine.
(resistor = 0)

Regards.
Claude

 

Considering the flow rate of the pump and the working pressure of the pump at 10 bar, it does not and could never evaporate enough fule in all the lines to warrant 10 seconds of running to replenish.
I am not saying it does not just that 10 seconds is way OTT, mind you ford don't always do things right!!
tabetha

 

I'd say it sounds as though either the pump or the regulator IS a bit weak(some times) and the pressure drops and thats why some times it primes for longer depends also how long a break there is before you try to start it!

ps with the car being a stage 3 and running 57's do you find it has abit of a rough idle?

 

This seems to make sense and I will try what you suggest.
Alvyn No It idles very smooth I run a grp a coil so no need for ultra small plug gaps which is what I found to cause rough idle on mine.

 

It always starts and runs fine mate.

 

yes it will prime to ensure sufficient rail pressure for start up, but the engine will never "always " stop in the same position or anywhere near ????

the ECU controls the fuel pump relay, when the ignition is turned on the ECU supplies an earth signal to the pump relay for approx 5 seconds. when the ECU receives an engine start signal the pump relay is then re activated...

when the ECU is turned off " engine off " the relay is turned off...

if you have a problem with it running " lean " or holding back, melting plugs, get it to a rolling road to have it checked before it melts a piston....

if you have a fuel pressure gauge, you should see 3.5 bar @ idle ( vac off )

when you are on full boost you should see 3.5 bar plus what ever boost you run ( 2 bar boost + 3.5 bar nominal pressure = 5.5 bar fuel pressure ) vac on

if this is OK it could be the fuel map ( injection timing / duration )

if you don't have an O2 sensor boss in the exhaust front pipe, get it done for the set up to be sure...

if you are having pressure/ pump problems don't forget that poor connection's ( inc alarm / immobilisers ) will increase the resistance in the circuit and reduce the amp`s to the pump ( reducing the flow out put )

best of luck.....

 

I also noticed the pump on mine priming/running longer than "normal"... but it doesn't always happen and when it does there is no ill effects in relation to the startup, idle or fueling under high boost. With a fuel gauge connected there are no signs of insufficent line pressure but the pressure does drop rather quickly after shut down. I have a wideband monitor so I know what my AFR is at all times and it well within spec. My car is also a stage 3 4x4 with an MSD closed loop chip.

 

Spent two hours on mine yesaterday and here are the results.
It DOES NOT PRIME, as a result of hot cold period.
It runs starts perfect everytime, has been on rollers and made very good power.
It primes when in contact with a lug on pulley/CPS, it stopped 13 times out of 15 within 5/10mm of lug/CPS.
tabetha

 

Don't get this piece, what you mean with "as a result of hot cold period"?

So what you are saying is that the pump at your car does not prime because the lug on the pulley is mostly 5/10 mm of the cps?

 

When the igntion is switched on voltage is supplied to the fuel pump.
The Ecu briefly earths the fuel pump relay contact 85 at terminal 28 of the Ecu.
This energises the the relay winding which closes the relay contact and connects voltage from terminal 30 to terminal 87 thereby providing voltage to the fuel pump circuit.
After approx 1 second the Ecu opens the circuit and the pump stops.
This brief running of the fuel pump allows pressure to build within the the fuel pressure lines and provides for an easier start.
The fuel pump circuit will remain open until the engine is cranked or run. One the Ecu receives a speed signal from the CAS the relay winding will again be energised by the Ecu and the fuel pump will run until the engine is stopped.
***Taken from the Weber Marelli Technical Data.***

Just to add, the NRV in the pump is designed to maintain pressure when the engine turns off to enable restarting easier. Perhaps this is where some of you are getting confused.

Hope you get it fixed...........

 

Mine does not prime wether HOT or COLD.
tabetha

 

If it DOES NOT PRIME at all then surely you have a fault

Maybe wiring fault, or are you using a custom loom???

If it does not prime how can it make any pressure in the fuel rail prior to starting???

 

Oh dear think Ive opened a can of worms here...

So it seems I defo have a problem, Can this fault in any way be related to my running lean problem? If not then there's no need to fuss as it always starts fine

 

As Tabetha already said, likely suspects are as above, failing that it can only really be down to the mapping..........