Fuel delivery (again)

[Simon P]

Had an interesting (long) drive home last night across the country I had had some power-loss problems with my car earlier in the year (see here) and I seemed to solve it by replacing the fuel filter, now the car's not missed a beat for 10K miles, and then last night powering up a long steep(ish) hill with about half a tank of fuel the car had a little hiccup a bit like in my old problem days. So it's got me wondering again if there's perhaps a problem with the fuel pump/sender that only seems apparent when the tank gets to maybe 1/2-1/3 empty. I'd have thought that a fuel pump would either work or not, and not be affected by tank level?

By other question is that I had felt before (see here) that the car was low in power with a bit of a flat spot around the 2K-2.5K rev range. Before the journey, i checked the wate-gate actuator and gave it a quick waggle in and out and it seemed to move OK. Earlier in the same journey (after a refuel), the car felt excellent, it really felt like it was giving me MUCH better boost between 2-3K, it was giving me that kind of poke in the back feeling that you expect from a turbo. However this feeling was not long lived, and it went back to the flat-spot feeling later on (after maybe 10-15mins of nice boosty driving). I therefore think that there is something amiss with the waste-gate or the boost control (standard Volvo configuration, no mods) maybe the waste gate actuator sticking or the valve not seating properly, me giving it a wiggle maybe helped a bit, but obviously not permanently.

Any advice appreciated...

Simon

[vcup]

Simon,

I had roughly the same problem. My S40 (1.6 1997 with 106000 km). Our one has even stopped with my wife but re-started without any problem when I got to the place after a few hours. Anyway, it ended up with some 60 kms of towing and fuel pump replacement six months later ...

Cheers,
Balage

[manoman48]

Originally Posted by Simon P

I'd have thought that a fuel pump would either work or not, and not be affected by tank level?

I have been told this but believe me it is just not true, even if only with this particular car. My fuel pump was pretty random in its failure, and got steadily more frequent until I decided to bite the bullet and change it.

No problems for a while now (touches wood).

[Simon P]

So it seems that replacing the Fuel pump would be a good plan then - is it likely that the fuel pump is the cause of all my problems or r that the flat spot problem is not related, and is more likely something around the turbo/wastegate.

Could be an expensive Cristmas if I get a new pump - I guess it would perhaps also be prudent to replace the presure regulator too, to eliminate this from possible issues? Both of these jobs seem Ok to do DIY - anyone done them themselves, and can offer any pointers?

[vcup]

Simon,

I have replaced the fuel pump myself. I have the Haynes book so I had a pretty good guide :-) However, to remove the plastic ring which holds the pump assembly within the tank was a real challenge. The hand-made tool recommended by the book did not work or better to say I did not have the proper material to make it.

Finally I used the oil filter removal tool (with 3 arms) as it was also recommended by the book. However, as you turn the tool it starts to distort the ring preventing it from getting loosened. After having the tool tight on the ring I inserted a flat screwdriver between the teeth of the tool to avoid putting more force on the ring. It helped. The rest is a sinch I think.

Good luck,
Balazs

[Simon P]

Is it possible to replace only the pump, or is the pump-sender-unit the only thing available? I can get the entire sender-unit (Scan-Tech) from Parts For Volvo for about £176, but of course, if there's a cheaper option to just replace the pump then I'd prefer to go for that unless I am totally 100% confident that the component replacement will solve all the issues.

As a side note, I tightened up the waste-gate actuator half a turn to see if that helped the apparent flat spot, but it's still there, so I'm back to thinking that a replacement fuel pump might sort things out, by enabling better fuel delivery. What's the best way to empty the fuel tank before doing this job?

Also can anyone recommend a way of measuring the fuel pressure? Is it possible to put a pressure gauge on the Schraeder valve on the end of the injector rail, if so, where can I get a suitable gauge?

Thanks.

[vcup]

Simon,

It is possible to replace the pump only - the rest of the assembly is mainly a bunch of fine filters. The pump is sold separately, too. To be honest I have not drained the tank just disconnected the battery and - of course - did not smoke :-) ...

Cheers,
Balage