Fuel pump issue?

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Fuel pump issue?

Postby FMuscle » Thu Jun 30, 2016 10:48 am

It happened twice now, both times about 10 minutes after I took off from work to go home. it's a 40 minutes ride on highway.

What happens is the fuel will cut, it will jerk like I had no fuel left, but I have plenty in the tank. When it happens, I hear (and can feel) a knocking from the pump. it has 12V, it has earth. Both times after a few minutes of playing around and connecting/disconnecting, it will start again and be fine for the rest of the trip and beyond.

The previous owner fitted the new pump early this year and assured me it was the proper 2psi rating. it is fitted on the LH side next to the battery. Is it the correct location? I got a feeling it has trouble pumping fuel up...

Thanks
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Re: Fuel pump issue?

Postby Panky » Thu Jun 30, 2016 2:03 pm

There is filter screen on the inlet side of the pump behind a hexagon head plug, take it out and see if there's any debris in it. Also check if there are any other after market filters fitted and bin them.
The other possibility is you are drawing a vacuum in the fuel tank, maybe an un-vented filler cap has been fitted. If the problem happens again try taking the cap off and see if it sucks in air as you remove it. Good luck :)
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Postby FMuscle » Thu Jun 30, 2016 2:35 pm

Okay, I got more details now, the pump was ordered from ebay, SKU ZPN-00922, description 12 volt SU style electric fuel pump 1-2 Psi Morris Minor
Ordered on the 12th of January this year, fitting date is unknown. The pump is New Zealand made.

The previous owner has fitted an inline fuel filter a few inches before the pump (vertical mounting). I can see the level in it being a bit low when it occurs. That's why I suspected that the pump might be mounted too high up the firewall, and could have trouble sucking the fuel up...

So I should remove the inline filter altogether and clean the pump's mesh and try my luck again?

I did remove the fuel cap, I did not notice a change of pressure, but yet I doubt that cap is sealed at all.
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Re: Fuel pump issue?

Postby Panky » Thu Jun 30, 2016 2:53 pm

The pump is usually bolted to the side of the battery tray on the side yours is situated but mounting it lower isn't a bad thing as long as it's well clear of the exhaust. In-line filters can be a source of leaks and vapour lock (happened to me) and are more trouble than they are worth on a Minor, I had a similar problem to you and ditching the filter sorted it. Not sure about your pump having it's own filter as it's not an SU, but it might be the same, SU's come in two types, pullers and pushers(normally mounted by the tank) and the valve arrangement is different between the two, Minors had pullers so if you do have one meant for another car that uses a pusher then it could be struggling to draw the fuel through. If that's the case then mounting it lower so the suction is constantly below the level in the tank should improve things.
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Re: Fuel pump issue?

Postby FMuscle » Sun Jul 03, 2016 10:01 am

Following advice from a friend, I moved the filter to the outlet side of the pump, because well it looks dirty in the tank... I will take the car to work tomorrow and see how she behaves. Worst case scenario is I stop on the side and remove the filter altogether.
I reshaped the pipe coming from the tank to bring it closer to the pump, so I have enough play in the hoses without the need to replace them if I need to remove the filter.

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Re: Fuel pump issue?

Postby geezer » Sun Jul 03, 2016 12:43 pm

I too have experienced similar problems with my fuel pump. Additionally I wanted to get rid of the irritating pounding noise. I ended up mounting the pump back by the tank using isolators. Problem solved.
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Postby FMuscle » Wed Jul 06, 2016 1:28 pm

So far so good. 3 days without issues. I guess there really is too much resistance for the pump to suck through an inline filter.
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Re: Fuel pump issue?

Postby Custard » Wed Jul 06, 2016 6:03 pm

Probably hardly worth the filter at all then, if the pump has a strainer like the SU it will only filter what gets through the strainer.

Removing completely would be less joints and one less component. I have seen the casing crack and leak.

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Postby FMuscle » Thu Jul 07, 2016 2:18 pm

I had a look at the pump itself and it's sealed, I have no way to open it to check if there is some form of filtration at all. I agree that after the pump is far from optimal, but until I can clean out the inside of the tank it will stay.
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Re: Fuel pump issue?

Postby bmcecosse » Mon Jul 11, 2016 9:37 pm

As above - throw away the filter altogether - the SU doesn't need filtering. And if necessary - mount the pump as low as possible so it has flooded suction from the tank. All will then be well.
 









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Re: Fuel pump issue?

Postby FMuscle » Tue Jul 12, 2016 9:56 am

bmcecosse wrote:the SU doesn't need filtering.

As above, my pump is not an SU original nor replica.
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Re: Fuel pump issue?

Postby bmcecosse » Fri Jul 15, 2016 9:13 pm

The SU CARB doesn't need filtering - it has no tiny jets like inferior carbs... therefore no filtering required.
 









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Postby FMuscle » Sat Jul 16, 2016 1:52 am

:oops: oops, sorry...
This is for going too fast :raz:
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