Bosch Fuel Pump Lifespan?

[Cubes]

Hi ppls,

Over the last few weeks I've been experiencing the occasional lean conditions; sometimes when I first start the car other times just out of the blue.

The car will be driving fine then all of a sudden I notice a slight surging at light/moderate throttle and a rough idle; check the pfc's sensor check and see the o2 sensor going lean.

Driving the car it tends to surge a little and feels as if it has a bit of a flat spot at the start of the throttle.

It used to come good once getting up on boost.

A simple pull over and shutdown and restart 9 times out of 10 would get it going smooth again.

Now (today) it began going lean once up on boost and also knocking easy.

Nothing I could do would get it driving nicely again; it would however come and go as I drove; lean then it would smooth out and afr's would return to normal.

All sensors (afm *that is/was new* etc) check out and are reading as they usually do, apart from the o2 obviously.

The external bosch pump appears to to be buzzing away as it usually does however the intank std pump that is well overdue may be failing.

Could the intank pump have failed causing a restriction to the external fuel pump? I'm not sure if that is possible. Maybe...

Do note that I threw the external pump on the car as the std pump couldn't keep up with only 150rwkw at the wheels when the RB20DET was in it running 12psi. That was ermm..... Over 130,000km's ago.

So....... Any one had an experience similiar? The come and go surge/lean conditions that progressively get worse.

I'm going to look at the pump first; if its not that then my first place of call is the PFC. Just a gut feeling.

[Interloper]

if you've still got the stock lift pump, then i'm gonna say that its probably at the end of its long life....

[paulr33]

are u running with 02 feedback on or off? have u changed the 02 feedback co-efficient?

[Cubes]

if you've still got the stock lift pump, then i'm gonna say that its probably at the end of its long life....

My hopes it is also... and not one of those expensive hard to track down bugs.

are u running with 02 feedback on or off? have u changed the 02 feedback co-efficient?

I've tried with with both; haven't changed the o2 feedback co-efficient.

I've init. the pfc and simply selected vg30 maf and applied inj correction. Still the same.

I'll rip off the intanks plate tomorrow and see if I can hear the intank pump working.

Fingers crossed it isn't so its an easy fix.

I just came back from a drive then... Its really strange; cold start it was good, 1km down the road it started surging; pulled over did the pfc reset; drove off it was ok for 500m then began playing up again. 10km's later and it came good for another 5km's then went to crap again.

Some times on cruise it will go lean; accelerate a little and it comes up and the o2 begins cycling again; back off slightly and it goes lean. But note that is some times.. Othertimes it simply stays lean then gradually becomes richer again.

Whats strange is if I were to give it a bit it doesn't completely go lean it surges a little then takes off, but I suspect it is going lean a tad as it does tend to det a tad.

Which isn't good.

Hope that made sense. lol

[FATGTS-R]

From your details it sounds like it could be the stock lifter has shat itself but it could just as easily be the Bosch item from experiences I have seen.

My best mate has a full tilt turbocharged Holden rodeo V6 ( turbonetics Y2K) and it has had more than one bosch pump fail. And they were not by any means long in the tooth. He has now resorted to using 4 of them with allowance for two of them to die on a dyno pull/drag run and still be safe.

From what he,the builder and the tuner have diagnosed is that the bosch pumps, although being very capable of supplying fuel are very very susceptible to failure from any type of foreign matter that may pass through them which is what they have put the failures down to. Hence there are now filters before the pumps.

Not sure if it has any bearing at all in your situation but just thought I would add it as I have indeed seen bosch pumps fail early in there life. ( to Boschs credit, they were all replaced without question)

[Cubes]

Thanks FatGTS-R.

The pump is what I would consider long in the tooth. Its around 4.5yrs old and as mentioned around 135,000km's old, well maybe closer to 145,000km's.

Tomorrow I'll ensure the turbo to afm pipe isn't split or leaking as I'm sure this could also do what I am experiencing.

[rob82]

If your suss on the intank than I would fix it real quick as if it is not supplying pressure to the back of the bosch then you might be up for two pumps!!

And as for bosch pumps not liking foreign matter - no pumps like it, however I still believe the bosch will handle it better then most others.

[Cubes]

Thanks Rob.

I'll replace it for good measure; something I should have done some time ago.

[Cubes]

Well this is going to be one of those niggly problems thats difficult to get to the bottom of.

I had a fiddle with it today and and its almost normal.

Idle is now fine but partial throttle cruise goes lean to the point where the o2 sensor can't pull it back in; slight throttle to accelerate the car has the o2 sensor flicking againl or with the feedback off has the sensor reading from 0-0.04v to the usual 0.9v.

I've disconnected the external pump and had the stock pump blowing through the disconnected external. The fuel pump appears to still be working fine as there was no difference with the external connected or not.