Help-Tech question Fuel system.

[mojocvh]

OK simple question for you.

I have a Malpaso[?]"Filter King" type filter/pressure regulator fitted between pump and carbs. Also in the feed line from the tank (to the pump)I have a in-line clear glass filter.

OK

Now I have noticed that as the engine runs, the pressure (measured at regulator output side) in the down stream line (to the carbs) starts to fall off until it is very low (.75 psi).

As this is happening the in-line feed filter empties into the pump. At the .5psi mark the regulator "opens" and the pressure rises to the pre set level (just now about 3.5/4 psi)and you get fuel flow into the in line filter again.

This operation then repeates itself. Seems odd that the regulator works this way as there is (to my mind)the possibility of fuel starvation.

Is this the normal mode of operation of the filter king type regulator????

cheers

MoJo.

[pearl nicholas]

if your in line filter is emptying as you say it would surely give you problems with air locking,perhaps your pump is in trouble,i run a filter king and the pressure never dips more than 1.5 psi when running before it evens back out,is this problem at idle?
i have set it to 6psi and as said it does dip 1.5psi before it kicks back in

>> Edited by pearl nicholas on Tuesday 21st June 10:07

[mojocvh]

New red top pump recently fitted. Regulator filter replaced at same time. Hmmmm. No leaks of petrol from any unions under pressure or in steady state.

I previously found that the in-line filter, a cleanable type with a glass body with screw on metal end caps had started to loosen off causing the seal to break thus once seal broached no suction from pump which caused fuel starvation once carbs ran dry. Tightening inline filter "cured" this, thought I was home and dry.

This is quite odd, as the effect from the pump (as seen from watching in line filter)would be as described above BUT it then "sorts" itself and fuel supply flows through inline filter and fuel pressure rises again.

However when reg operates to raise fuel pressure a small stream of bubbles flow momentarily up the already filling in line filter.

Can you adjust the "bottom" end of the regulator so that you raise the lower pressure ie opening at 2psi as opposed to .75 or .5 psi?? Top pressure is good for carbs.

MoJo.


UPDATE



OK managed to get 1/8th of a turn on filter ends. They are now marked to show any movement. Adjusted regulator screw all way out(in fact took it out) fuel press fell to .2 psi. screwed it back in all way momentarily then set fuel press to 4 psi ran car, until 1115 watched inline filter empty/fill OK fuel press stayed at 4psi OK engine ran OK. Took it up to 4000 and ensured that fuel system pressure stayed at 4psi as regulator did it's empty fill thing all OK.

thanks for advice

cheers

MoJo.

>> Edited by mojocvh on Tuesday 21st June 11:21