anyone running floscans w/o pulsation dampers?

I was originally going to leave my canister filters in place and install a 30 micron filter before the sensor.

Well, I wound up removing the canister filters all together since I couldn't find a 30 micron pre-filter. For filtration, I have the 10 micron and then the screen at the carb.

My issue is the need for a pulsation damper after the sensor and before the pump. The way I mounted the Racors, I don't think I have enough clearance for the damper to fit. I'm just looking at the pic online and they look to be pretty tall. I made a bracket mount which is attached to the underside of my deck.

I called Floscan and they said w/o a damper, my low/idle readings will be off. Do I care?
I'm more concerned about my cruise speed/consumption but if I have to re-work the bracket and fuel lines to get the damper installed, I'll do that.

They're suggesting the damper and then a 45 fitting before the fuel line so that the damper is always on the "downhill" side and flush full of fuel. I hate to add two more things for the fuel to flow through.

I have 454, carbs with new mechanical fuel pumps.

Bob

I have a similar setup. Mechanical pumps, no engine mounted filter, 10 micron before the sensor, about 2' of hose between the sensor and the pump. I ran for 10 years without dampers, and there was always some fluctuation in the readings, at all flows. Like about +/- 1 to 1.5 gph. Both my sensors went out within a few months of each other at about the 9 year mark. I replaced with a newer style sensor and added the little "bombs". I put them right at the output of the sensor, using a brass "T". There is a about 1/2 the fluctuation I was seeing before.

I don't understand your statements "45 deg, downhill and flush full of fuel", however. I had assumed that the "bombs" should be full of air not fuel, in order to actually dampen? Or, maybe they have a diaphram in them?? I mounted them with the opening down and they are a bit below the level of the fuel pump.

ok, let me clarify the 45 degree statement. I had to mount my Racors and sensors pretty high up, much higher than the pump. The sensor would have been in the bilge otherwise. I talked to Ed at Floscan and he said it's not critical that the sensor is physically lower than the pump. The reason that they recommend that is it guarantees that fuel leaving the sensor is always flowing up hill which keeps the sensor impellor bathed in fuel.

If you can't do that, like in my case, the way around is to fabricate the "uphill" part some other way. That's why he suggested a 45 degree fitting AFTER the damper pointing UP and then connecting to the fuel line. That will accomplish the same thing. I would rather avoid putting another 45 inline, I already have one on the port side coming out of my shutoff valve.

I think I'm going to hook it up and see how it works as is. I need to run all the wiring anyway, I'll just leave a little loop in case I wind up dropping the filters down to make room for the dampers. I took it out for a run tonight to test the Racors, new fuel line fittings and make sure my WOT didn't change. That's all good.

So you must have your Racors at the front of the engine? I have mine behind and up high. I probably have about 6-8' of fuel line before it gets to the pump. I don't know if distance smooths out the fluctuations, if so I might be ok.

The dampers look to be about 4" in height. Is that about right?

Our canister filters were removed ages ago. The Floscan sensors are the 'inboard' style that they offered when we installed the unit - almost 20 yrs ago. The normal fluctuations we see are similar to DD's 'old' readings.

I ran on two boats that had the same sensors were the dampers were installed to get rid of those oscillations. One capt noted they made no difference and the other was 'very happy' with the dampers. I saw some reduction but no 'elimination' of the oscillations.

Based on my 'dated' experience, I'd be inclined to put the money in the fuel tank, not the plumbing. I'd define the fluctuations as normal. Furthermore, they don't impact our use of the instrument. When some goes wrong (spark plug lead goes intermittent), the average value of the pointer rises and you know it is time to find the problem. The newer styles may improve things but I wouldn't expect 'perfection'.

I've run both. No difference.

Jeff

ok, I'm going to try and get all the wiring done tonight so I can test over the weekend. We're coming down the home stretch in the Northeast and I would like to have this done and tested for next year. Plus I want to have the whole winter to think about how much fuel I wasted all season

One thing I thought of last night was moving the sensor and installing an inline filter. There's a 238 micron unit I saw referenced in some old posts. Height is my issue, inline wouldn't be a problem.

I can live with some fluctuations in the needle. I know these things are accurate but close enough will be 100% improvement over what I have now which is just guessing.

Bob

bobct said:

ok, I'm going to try and get all the wiring done tonight so I can test over the weekend. We're coming down the home stretch in the Northeast and I would like to have this done and tested for next year. Plus I want to have the whole winter to think about how much fuel I wasted all season

One thing I thought of last night was moving the sensor and installing an inline filter. There's a 238 micron unit I saw referenced in some old posts. Height is my issue, inline wouldn't be a problem.

I can live with some fluctuations in the needle. I know these things are accurate but close enough will be 100% improvement over what I have now which is just guessing.

Bob

Click to expand...

Bob; if you have the racors before the sensor, you are fine on filtering.

agreed... not really for filtering per se but a "smaller" way to get around the damper issue by moving the Racor in front of the sender. That would eliminate the need for the damper which I can't fit w/o some re-work. The Racor would then act as the damper and the in-line filter would keep the sensor clean.

I'll wire it up and leave some slack. This will be plan B if I feel like the needles jump around too much.