Fuel pump issues - Fixed

[Matt]

Is there a relay that controls the fuel lift pump? if so where is this located?

(on a 2.0 HDI 110 exec)

Thanks

[steve_earwig]

As far as I remember it depends on the year, earlier cars it's in the box with the engine ecu, later cars it's part of the ecu.

[Matt]

Cheers Steve, mines a 1999, I think my lift pump has failed but id like to check the relay (if there is one) before I pay for a pump, Its refusing to start most of the time, then only running for a minute or two before cutting out again, acceleration also stalls the car, seems to have got significantly worse since changing the fuel filter which has got me worried

[Doggy]

Haynes (book of lies) shows the double relay arrangement common on older PSA cars. Pump output on pin 4, then via MF12, (engine fusebox), to the pump. (There are lots of variations, so treat this as likely rather than certain).

You should be able to hear the pump run for about 4-5 seconds each time you turn on the ignition. You may be able to prove you get power to the fuse each time and determine whether or not the pump starts every time. Alternatively, do the same test at the pump connector under the back seat. Pin 3 is motor +ve, pin 4 earth.

A Xsara I had developed a wiring problem which interupted the fuel pump feed. I got it home by putting a temp supply into the fuse holder socket with a male spade connector, (the side connected to the pump). Obviously you need to be certain yours matches the description and exercise great care attempting anything like this......

[Matt]

Cheers doggy, i can hear the pump working when I turn the ignition, it's just not firing up, there's little bits of brass coloured swarf in the bottom of the filter housing, is this likely to be the lift pump? I took the pump out and noticed a lot of sediment inside it, this can't be good either

[steve_earwig]

Oops, swarf is not a good sign - it really does say the pump is toast. When you change it you should clean all that out of the system especially the filter housing because if any of it gets to your HP pump it'll kill it.

[Matt]

thanks Steve, how should i go about cleaning the system out? wouldnt the filter & housing catch all the swarf before it enters the hp system?

[steve_earwig]

Until you change the filter, then there's a good chance of some of it dropping in the filter bowl & ending up on the wrong wide of the filter. Let's see what others say, although if it was me I'd get a new filter along with the pump, drain the filter bowl, strip it off the car and wash it with Jizer or whatever, then push petrol down the fuel line while the pump was off.

[Matt]

cool, i've ordered a new lift pump and filter housing from ECP so hopefully that will fix it

[Matt]

I fitted the new filter housing and lift pump today, i also fitted a replacement throttle position sensor as that was another code on my reader, the car now starts first time every time which is great however i'm still in limp home mode and it will still cut out if i spend too long with my foot flat out, does this seem to be more likely a sensor problem as there doesnt seem to be anything mechanically wrong with the car?

is there a sensor that could cause the engine to run on a few seconds after switch off? The fuel pressure regulator perhaps? or the rail pressure sensor?

[Matt]

Just for the record after fitting the lift pump and replacement filter housing the other day i have since taken out the High pressure fuel regulator to find the tiny filter element on the end of it clogged, (we are only talking about a very small amount of swarf to cause this issue) i have cleaned it off with carb cleaner and a nylon brush and everything now works and the engine management light has gone after 4 ignition cycles as expected

I figure the events that lead to this problem happening were:

1. The mechanical failure of the lift pump in the fuel tank (this was probably deteriorating over a long time)
2. pieces of swarf from the lift pump were deposited in the filter housing
3 the swarf was drawn through the housing over time (possibly through vibration or a badly seated filter element)
4. recent investigation into the filter and possibly the initial filter change have inadvertently allowed more swarf to get through to the high pressure pump meaning that the magnetic tip of the regulator has caught them.
5. this has prevented the correct operation of the regulator and lead to the ecu displaying fault codes and limiting the pressure of the fuel system


In order to get to the regulator on my D9 406 i waited a while for the engine to cool down then i needed to first unlcip the filter housing (but keep it fully connected to the fuel lines) so it was movable then remove the bracket it sits in (3x6mm hex nuts) this allowed me enough space to use my T30 star drive socket on the two retaining screws, the regulator then could then be popped out, a small amount of fuel leaked from the hole but i was ready for this.

I've heard people saying that dealers quote for a replacement pump when this happens to customers cars, imo Its worth checking that the regulator is not blocked or faulty before going straight for a replacement pump, this didnt cost me very much to fix compared to replacing the pump!

[Doggy]

Great news Matt. A really helpful write up too with some info that could potentially save others a lot of money.

I understand the fuel is also the lubricant for the HP pump and running one dry will kill it fairly quickly. Good chance yours wil be fine since you've dealt with the problem promptly.

[jamest]

Thanks for this info...
Wife filled car with petrol which flushed the system but some debris made it to the pressure sensor.
Same symptoms you described exactly!!
Took out sensor and cleaned...
Now runs fine...
Still got anti pollution flagging up but i imagine thats the petrol residue in the deisel
Thanks again for this great info..