Can a fuel pump intermittently cut-out ?

[lakemaligne]

For those of you who may recognise this fault from a previous posting , please don’t groan as I feel I am very near to solving this fault, and could really do with some more advise from you guys please. I have owned a 1996 2Ltr 16v petrol LX 406 from new ,which has now covered 167,000 miles on the original engine. Two years ago my car started to intermittently idle at 1200rpm when I coasted in neutral until the car came to a complete halt ,then the rpm would drop down to the normal 950 rpm. It would also jerk about a second after each time I came on and off the throttle. Other times the engine would try to stall during idling, and then run fine for a few days. During the last few months however ,the fault symptoms have drastically changed for the worse , it no longer jerks or revs high while coasting or do any jerking. The car will now falter/hesitate badly for a second while driving along several times each trip and will suddenly die while idling for no reason. The engine always re-starts ok ,but will idle erratically ,ie, the revs go up and down for about 10 seconds ,then settles down to a normal idle or sometimes it dies again. Then after restarting it again, it will run fine all the way home.

So far I have replaced the following.

1. Stepper Motor (IACV)
2. Throttle Potentiometer.
3. MAP sensor.
4. Oxygen sensor (Lamba)
5. Throttle cable
6. Coil Pack
7. Spark Plugs
8. Reconditioned ECU
9. Vehicle Speed sensor

The last time my 406 went in to the dealer , the Master Tech said that the ECU keeps recording an “Intermittent Irregular Fuel Delivery” code, and that when he test drove it thought that it felt rough/running lean at times and was miss firing slightly at times. He suspected that the fuel injectors could be sticking , causing a poor spray pattern, hence the fault code. He suggested I use “ Redex” injector cleaner in the tank, but this however does not seem to be making any difference.

My questions are to you guys please ,

1. Is it possible that the injectors could be sticking and causing my car to cut out now and again , and how long would the Redex take to work ?.

2. Can a fuel pump cut out now and again and be causing my fault, either through the pump itself failing intermittently or the Double Relay feeding it or could the Fuel Pressure Regulator Valve cause the fuel pressure to drop in the rail now and again.

Are there any tests I can perform to eliminate possible components.
Any comments gratefully received .

[Welly]

Have you thought about having the injectors cleaned properly on a test rig? according to the folk that do such things injectors should ideally be cleaned every 30/40K miles. As far as I know the cost is fairly small and can quite often pay-back through better MPG's.

[OdinEidolon]

Yes, a fuel pump can very well work for a week then stop for a couple of hours or just pump with not enough pressure. It can be very random at times.
The substitution doesn't cost much and is pretty easy to do. I did it myself with the help of a friend. I have an HDi but it should be pretty similar.

If you order the pump (I got one from EuroCarparts) remember to order the seal AND the closing plastic big screw (whatever you call it) from the dealer.
The first is mandatory, and I bet you'll break the second when trying to remove it, I had to use a saw.

For your car:

Pump:
1525 46 x<07482
1525 75 07483<x<07968
1525 C3 x>07969
Seal:
1528 37 x<07967
1531 24 x>07968
screwable cap:
1531 19 x<07967
1531 20 x>07968

[omega]

have you changed the fuel filter?

[lozz]

Is there A Relay for the fuel pump on the 406s?
ive had a few cars before where the Relay for the fuel pump had Dry solder joints, it made the car miss, and sometimes not start,
dont know if the 406 as one tho, but it might be worth a look,

[OdinEidolon]

By the way my HDi does this too:

Two years ago my car started to intermittently idle at 1200rpm when I coasted in neutral until the car came to a complete halt ,then the rpm would drop down to the normal 950 rpm

It does that always: when in movement the idle is around 850, when stopped it's 700. I think it's a measure taken to smooth the ride and the gearchanges. I do not see why it should be related to something wrong with the engine sensors.

[lakemaligne]

If the Redex Injector cleaner failed to improve matters,I was going to try ultra sonic cleaning.

Yes my 406 has a double relay next to the ECU,which feeds the ECU and the Fuel Pump.I dont think it is this relay because ,if that failed ,it would kill the ECU ,which i would have thought would have effected the car more ? Plus my car always starts up instantly,it just struggles to stay ticking over and dies.

Yes i have replaced the fuel filter.

My car has never idled above 950 rpm while coasting during it's first 13 years . The only time it idles above the norm,is when the aircon is running ,which is normal.

The next thing i was going to do was replace the fuel pump and fuel pressure regulator valve,but ironically my 406 broke down last wednesday. I had been blasting down the M45 at high speed and it started to falter quite badly .I managed to limp the car off the M45 and pulled into a layby .When I stopped ,the revs were going up and down, and it died. It did this each time I tried to restart the engine. The RAC guy said that in his experience and going on the symptoms ,he was sure it was fuel starvation, and suspected the fuel pump was cutting out when hot or the fuel pressure regulator valve had a small split in its diaphragm ,which may be opening up when hot. He also said that the fault code backed up his theory .

So as i desperately need my car this coming Sunday for a trip to Cornwall, I dont have time to do it myself,I have bitten the bullet and booked it in to have the Fuel Pump and FPRV renewed.I will keep you posted .

fingers crossed.

[OdinEidolon]

The same happened to me. Highway, high speed, car dies and won't start.
The recover guy says it could be the fuel pump, and the "low fuel pressure" warning backed up his theroy.
The car worked but every time I accelerated a lot (throttle on the floor) it would start wobbling and eventually die.
I replaced the fuel pump myself, the dealer also suggested to do it. Result: nothing.
In my case the cause for this are probably the old, dirty injectors. I'd have them tested first, a specialized center takes half an hour.

Redex does nothing to me too. I can use the car however, so I do not have the need to fix fast you have. I'm waiting for a quote on injector testing and cleaning for the center.

Also: it's known that on this engine this could happen.

[lakemaligne]

I have replaced the fuel pump,fuel pressure regulator valve and fuel filter,and the fault still remains. So much for the RAC guys theory ! The only thing left i can think of doing is to replace the double relay which feeds the fuel pump and ECU,and get the injectors proffessionally cleaned and tested with ultra sound.After that I just dont know what else to change. It's such a shame because the car is imaculate inside and out and runs like a dream 99% of the time. It's just this damn irratating way the engine suddenly dies or momentarily dies for a second ,then catches itself and will then run fine for a few hours,then do it again