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Hi, I just replaced a faulty fuel pump with a Bosch unit in my 1990 NA6. The procedure has not been succesful I'm going to try and sort it out tomorrow, but wanted to check my diagnosis with the group mind.

The car kicks over and stumbles, more than just cranking on the starter, but never quite manages to fire up properly.

I know the pump is good, because I can hear it pumping (when I ground it through the diagnostic box).
I know the engine side of things is good, because spraying a few ml of petrol into the manifold will see it rev up happily for a few moments.
I know a little bit of fuel is getting there, because of the stumbling.

So I suspect the pump outlet is not sealing properly. There is an o-ring that might not be properly seated, so I hope just removing and replacing the pump might work.

However, between the o-ring and the receiving pipe, there's a little molded plastic sleeve thingy. Its split. It looks like its just to aid mechanical location of the o-ring, and I assume the o-ring does the sealing. But could this be the problem?

Any thoughts appreciated.

OK, I just got it fired up. Turns out the pump was not correctly seated and there was a leak past the o-ring. Fixed now.

Glad to see it's all fixed, is the fuel filter still good? The other pump might have died because of the extra load caused by a semi blocked filter.

Thanks for the tip Okibi. I replaced the filter a month ago.

The pump was clogged due to contamination in the tank. I decided to try just cleaning the primary filter, to see if the pump would then be OK, but I kept a spare + tools in the boot in case I ran into trouble. I wound up doing the replacement in a shopping centre car park yesterday, a month later.

The real solution is replacing the tank, but I got quoted a ridiculous number to do that. I'm inclined to just replace the pump roughly once a year.