(G) Seicento Sporting 16v fuel pump problem? thoughts please!

Right, seicento sporting 2001 mpi (1242 16v engine)

To try and cut a story short, had fuel tank changed last week as a free safety change, by Research Nuneaton as it had developed a leak.

Since the tank change if the tank is full upto around a third of fuel or more the car pulls as it should for the engine and no problems.

If tank is under around a third full of fuel the car pulses under full load, like the pump is struggling to pick up fuel. It did this mildly before it went in, but not until it was nearly out of fuel (to be expected).

I whipped the fuel pump out today and had a look and a clean up all is fine, and seems to be sat nice and low in the tank.

Could the pump be on the way out? seems odd as it runs fine when it has plenty of fuel in it and pulls well at any load.

Is there anything else to check for? any thoughts much appreciated.

Try replacing the pump but thats an expensive option.

Sadly the filter is part of the pump, not sure if you can replace it seperatley.

You 100% it the pump thats faulty and its not something entirely different?

Kristia

Well maybe not??

lol.

Just would be the logical option as when the car is full with fuel, it pulls fine, then when fuel lower down problems start, aka fuel pulsing meaning car pulsing under load.

What would you suggest it could be? Possibly a fuel line problem? Just seems odd that all works fine when the fuel tank has more fuel in.

Like you say new pump is expensive option, and why would it work fine when full with fuel and not when level gets down??

Also seems odd, that prob has only really been there, since they changed tank!

Maybe i don't know where the fuel pump is meant to sit mind you, just guessed, so maybe they didn't seat it low enough, although when I took out today, only seemed to be one level it would sit at.

fuel filter???

means new pump I think, not seperate like cento's.

I'm not sure about the fault to be honest. The pick up is at teh bottom...you can't adjust the height it sits..even if its amost empty it should pickup until it literally starts to cut out.

Are you still using the sei mpi pump in it?

Kristian

perhaps a blocked breather?
fill up with fuel - no probs
as the fuel gets lower the fuel is replaced by air
but with a blocked breather you get a vacuum the pump works against.
does it struggle at idle when the fault occuers? if so take the filler cap off and see if it 'fixes' the fault

Ah, thats interesting.

re : blocked breather.

It is coming off the cam housing atm, and the feed back to inlet manifold has been plugged. On the other end I have a max power breather filter (i know i know, but only temporary)!

Could this be the problem, sounds possibly right. What would be the best solution, just clean the breather pipe out? also a bit alarmed as doesn't the inlet manifold end actually need plugging into inlet manifold?

Can post pics if makes easier.

Just seems odd the fault only started occuring majorly since the tank was changed by fiat. Could they have replaced the pump wrong?

It is on an original mpi pump so 3 bar.

Thanks for your comments.

and yes it struggles all over the range inc idle. but is worse at full load, drives ok on part throttle.

nah im talking on the actual fuel tank.usually right on the top of the tank.
could have been kinked/blocked on installation

my tank has no breather and after removing opennignt he filler there is usually a gasp as air rushes in or out. I know some have small holes on the cap, but mine never has and it seems to cause no problem.

I would imagine the charcoal cannister allows for a slight pressure adjustment though, as the solenoid will be opening and allow gasses in/out of the tank and TB/intake.

I can't remember where you cannister joins the TB, is it on the left like mine? The pipe ok on it?

As custard said, its going to be nothing to do with the crank case breather. The samll hole you have blocked is ok, so is the filter on the crank case, althought not MOT legit

Not sure what else it could be tbh

if it is a pressure thing. When it starts doing it, as its lower on fuel, take the filler cap off, and try it for a little bit. Should spill and out.


Kristian

Well thanks for the help again.

I have a spare charcoal canister solenoid at g/f's so will try that at weekend.

Had pipes off the solenoid to inlet manifold other day they appear ok, mine joins to left of inlet manifold (near map sensor) so at a guess same as yours Kristian.

Just seems such a coincidence that since the tank change its had difficulties. Although ran sweet as a nut today on nearly full tank.

Whatever its going back to Research next thursday and even if they can't find anything really its there liability so I have nothing to lose and maybe they'll point me in the direction of the fault.

Its definately picking up fuel as the fuel level drops below a third of a tank as its not cutting out all together regularly, but like I say its pulsing especially under load and idle can be occasionally rough. Like not enough fuel is getting through or there is air in the system!

Will keep you posted and if you have any more thoughts let me know!

Also havn't had the 'gasp' when you open the filler for a while or noticably for a while, although i know it always used to do it.

I think next I will try a new solenoid seeing as I have one lying around.

Then take it back if no avail.

yeah your right ot look around whats changed on the tank.can anyone confirm no changes were made to the tank design?

Well I assume not, they all ordered it for me corresponding to my chassis number, so would be very odd if different.

It all seems to correspond, but whatever its their liability really, but will let you know if any developments.