Low Pressure Fuel Pump

[Longboarder]

You do not need a valve in the return from the fuel rail. The pressure regulator acts like one. Remove it but I can't see how it would be a problem.

I can't see a problem with how you have mounted the HP pump.

Yes you need a breather for the tank. Mine is a 2mm hole drilled through the filler cap.

 

I don't think your problem is pump position. I still think you have either a duff pump or a blockage in the feed. Are you using the facet bullet filter attached to the pump? Pull the pipe (between the LP filter and tank) off the filter and drop it down into a bottle. Does fuel flow out happily? Do this before blowing back through this pipe so you don't dislodge any crud there may be in it.

 

Nigel

[Guest danny_samb]

Iv taken all my pipes off all fine. I'm using over braided ptfe lines. Not using the original filter I have a 100 micron filter before the low pressure pump and a 30 micron filter before the high pressure pump. Iv removed both filters and 1 had a lot of dirt in it and like a jelly which I'm guessing is the fuel. Has the fuel gone off? The high pressure pump was getting really warm and loud. Iv read this is due to fuel starvation. But when I removed the swirl pot it was over half full so would of been move than enough fuel for the high pressure pump. Just can't understand why I'm getting starvation.

My breather is where the return from the pot joins the tank I have a t piece and the breather is about 10" higher than the tank. It's the same fuel hose as I'm using with a roll over valve on the other end of it obviously upside down so the ball bearing is not covering the hole unless the car is upside down

[Peter Bell]

The 'jelly' could be bits of silicon sealer. Have you looked inside the tank itself yet?

[Longboarder]

The high pressure pump cant suck to save it's life so remove its filter. It draws direct from the swirl pot and relies on the swirlpot's fuel being clean enough to use. It's designed to blow through an injection filter to feed the injectors clean fuel.

The low pressure pump sucks better but wont suck jelly through a 100 micron filter. 30 micron filter before the LP pump is all it needs. If you have jelly in the filters then I suspect you have found a major part of the problem. Paper inline filters are a quid each off ebay. Cheap enough to put a new one on every month if you're really picky!

 

Take both filters off and only replace the one in the LP feed line with a new one. Then try it.

 

I remember a trip with Les Welsher as he got slower and slower on the M42. Eventually we pulled off and watching his engine stutter I caught a movement out of the corner of my eye. It was the fuel filter element crumpling each time he tried to rev it. Almost blocked. We washed it out as best we could and poked a hole through the element with a twig. Off we went, back up to 80mph.

 

Nigel

[Les Welsher]

That reminds me to change my filter for the spare i got after I mot the car tomorrow.

 

 

The one on the left is the type that blocked on my carb engine, the one on the right is the one I now use after the LP pump going to the swirl pot on my injection engine.

 

 

Les

[Guest danny_samb]

I have replaced both filters. Not looked in the tank but with the remainin fuel in there I gave it a good slosh around then poured it into a can so that should now be clean.

I have moved the swirl pot so it is now higher than the hp pump so it does not need to duck the fuel it will be gravity fed into the hp pump

[brumster]

Fuel does "jellify" over a long period of time; I had this on the Exmo after resurrecting it 12 or 13 years after it went off the road not sure yours has been left that long though?!

[sj-bradley]

If the fuel cannot flow freely, then pumps have to both push AND pull fuel through the pipes.

 

If this happens, then a low pressure point happens before the pump and this can lead to easier cavitation around the pump

blades. If this happens, you will hear a marked increase in noise.

 

AND, more importantly, cavitation is a HIGH WEAR phenomenon as the minute bubbles created collapse at

supersonic speeds and produce a fluid hammer effect on the moving parts leading to pitting and excessive

wear on the pump.

 

Simon.