fuel pump failure

After getting my car back on the road with the new 02M box conversion I've had a few issues with fueling. The car was tuned at efi parts so the map shouldn't have been far out if not perfect with the few minor changes I've made.

It all started leaning off just at high revs so I adjusted the map a little but it made no difference. So I checked the fuel pressure and it seemed fine I even tweeted it up slightly and it made no difference So I presumed I would run it round while monitoring the afrs to see how it went and also bed the clutch in a little too ;)

Driving from work on Tuesday it starts to lean out on any positive pressure and by the time I got home it was almost stalling out on normal driving. So I checked loads of bits and the fuel pressure regulator seems to work fine with no leaks and can't see any leaks on any fuel lines or rail or injectors. Next I take the fuel return off to check the flow of fuel to find it's only a trickle. So I can only pressure the pump has gone wrong as it had new filters on it only last month.

So while looking for a new pump I found most new bosch pumps come with a one way check valve. Now when I installed my pump I removed this to put a an-6 fitting on and must have binned it.

Does the pump need this to protect the pump as some people I have asked seem to say not needed and other info I have read says it can damage the pump with out.

On a good note I've gone twin bosch set up now ready for more tuning later this year.

A bran new pump I had gave up the ghost, after only 50 or so miles, when I did a little research It became clear that a lot of modern design EFI pumps are prone to picking up even the slightest bit of shite in the fuel. So I pre-filtered my next one and all has been well since:agree:

Something to do with extremely small tolerances in the pump internals

To throw a spanner in the works I have just remembered I have since removed the pre-filter and ran without for 3k or so and it's been fine. :laugh:

It's pre filtered already just think as I've had the pump 4 years or so now and it's only done 1500 miles at most it may have just given up.