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Mech Fuel Pump Issues ?
https://ausmini.com/forums/viewtopic.php?f=2&t=92434		 Page 1 of 2
Author:  78Clubbie [ Tue Apr 19, 2016 7:17 pm ]
Post subject:  Mech Fuel Pump Issues ?
Hey All,
Wondering if anyone has experience with mech fuel pump woes.
Our LS is back together and ready for roadworthy, but suddenly started to misbehave - backfire, stutter under load, missing and general badness with the engine. Suspected the worst and went through the following checks/diagnosis: (No particular order)
1. Dissie/Elect - Checked timing - OK, checked with timing light and cross checked static timing on the flywheel
- swapped dissie and coil with known good one - no change
- swapped leads. No go

2. Checked spark plugs, cleaned and gapped. All good but no better
3. Valve clearances - All good
4. Compression. Down (135-150) but even. No leakdown test performed (yet)
5. Carbie. Stripped, cleaned and installed new jet, float valve and gaskets. Didn't do a full rebuild tho'
Was better for a bit (till warm - 5-10 mins) but then went bad
6. Dumped fuel from the fuel tank (Suspected water) and then topped up and bled through
Also installed fuel filter. No better and fuel filter not always full and has signs of air bleeding through when engine off !

Still no go.
Am down to fuel pump OR valve/head issues. Was running okay (Just up and down driveway / street) so thoughts are that valves arent the issue.

Help needed. Any thoughts ?
Can fuel pump cause these issues ? No sign of leaks from the pump although havent been able to check properly in daylight hours
Author:  Bill B [ Tue Apr 19, 2016 8:31 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Can check fuel pump by removing hose from float bowl inlet and cranking motor to see how much fuel is pumped into an empty tin.
Maybe if it runs OK at idle but staggers on load, there's a blockage (dirt, Silastic etc) in the fuel bowl pipe before the needle/seat - that isn't easy to find? Blow through to test.
Keep looking - it will be obvious when you find the problem!
Author:  winabbey [ Tue Apr 19, 2016 8:39 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Is it possible you got dirty fuel recently?
Author:  78Clubbie [ Tue Apr 19, 2016 8:39 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Bill B wrote:
Can check fuel pump by removing hose from float bowl inlet and cranking motor to see how much fuel is pumped into an empty tin.
Maybe if it runs OK at idle but staggers on load, there's a blockage (dirt, Silastic etc) in the fuel bowl pipe before the needle/seat - that isn't easy to find? Blow through to test.
Keep looking - it will be obvious when you find the problem!


Indeed, isn't that always the case :D
Thanks for the tips. Is there a filter gauze in the later pumps?
Author:  78Clubbie [ Tue Apr 19, 2016 8:42 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
winabbey wrote:
Is it possible you got dirty fuel recently?


Yep. Its been off the road for a while (a few years) and may have accumulated some moisture and/or grit. We drained the tank and put a fresh 10 litres in, stripped down the carb and then ran for a while. Was better for a short time but no go.

Bill may be onto it. Wasn't sure if there were some potential blockage points at the pump. Put the filter after the pump.
Author:  Minicooper4me [ Tue Apr 19, 2016 9:23 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Is it any old wife's tale to add a litre of metho to the tank which will clean out any accumulated water and just run it through the carby as normal ?
Author:  carter [ Tue Apr 19, 2016 10:08 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Coil or condenser
Author:  simon k [ Tue Apr 19, 2016 10:18 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
run it till it stops, take the lid off the float bowl and see if there's fuel in there... then do what Bill B said

best way to check if a mechanical pump is any good is to take it off, smash it with a sledge hammer, then throw the bits in the bin and fit an electric pump...
Author:  drmini in aust [ Tue Apr 19, 2016 10:21 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
carter wrote:
Coil or condenser


My bet too. Or the points have closed up, they run weird when set real close.
Author:  78Clubbie [ Wed Apr 20, 2016 4:18 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Thanks guys. Pretty sure its not the distributor/coil. Have swapped it out to a known good one running in my GT, and they are both electronic.
Float valve in the carb has been changed out and a filter added upstream. Not to say that it still isn't getting clagged tho'.
I like simon's answer - and that was my comment to my son (Whose car it is) but he's on a budget and doesn't want to stump up the $250 for a facet or SU.

Anyway. I'll keep looking. Will update when solved !
Author:  davem [ Wed Apr 20, 2016 4:24 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Would it worth while, to replace the fuel line from the pump to the carb and install a filter in the line (engine bay), pretty cheap, a long shot but at least it will eliminate a possible issue
Author:  gtogreen1969 [ Wed Apr 20, 2016 7:51 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
Ebay have knock off facet pumps for $18 postage included from Sydney. Not sure about the quality - may only get a few years out of it. Cheap diagnostic tool anyway if you want to keep the mechanical pump. http://www.ebay.com.au/itm/131318770921
The Facet pumps are only $50 anyway. http://www.ebay.com.au/itm/131459667018
Author:  Phil 850 [ Wed Apr 20, 2016 9:43 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
gtogreen1969 wrote:
Ebay have knock off facet pumps for $18 postage included from Sydney. Not sure about the quality - may only get a few years out of it. Cheap diagnostic tool anyway if you want to keep the mechanical pump. http://www.ebay.com.au/itm/131318770921
The Facet pumps are only $50 anyway. http://www.ebay.com.au/itm/131459667018

What :x
I paid $168 at Repco the other day :cry:
Author:  drmini in aust [ Wed Apr 20, 2016 10:07 pm ]
Post subject:  Re: Mech Fuel Pump Issues ?
The square $50 Facets or knockoffs are cheap, but they work. One feeds my 45 Dellorto just fine, also with the HS6 when it was on. No regulator needed, one less thing to eff up.
I've run one on this car for 25 years.
Author:  Maelgwn [ Thu Apr 21, 2016 12:39 am ]
Post subject:  Re: Mech Fuel Pump Issues ?
Just a thought, I had similar issues with the XJ6 and found it was a tiny split in the vacuum hose to the dissy, so when cold and at idle it was working fine but once warmed up and under load it went bad. If it's not fixed by your fuelling issues look in that area.

Maelgwn
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