Fuel filter vacuum gauge

[zoidberg]

They seem to range in price from well over £100 ( Racor ) to £30 ( Faria Beede ) to about £5 ( eBay ).

What's to choose between them and what's the point....?

 

[pvb]

The more you pay, the better built the gauge is. The Racor one is oil-filled, for example. But a cheap one should work fine. Ideally, you need one which reads 0 to -60kPa. When a filter starts to block, the vacuum will rise to about -20kPa and then rise progressively as the blockage becomes more severe. At around -40kPa, the engine will probably struggle to suck fuel through.

 

[lw395]

If you fit a cheap one and it leaks, the engine won't work.

 

[Trundlebug]

The point is to be able to identify when the fuel filter is getting blocked (seeing increased vacuum on the fuel line between the filter and the fuel pump), to help identify problems accurately (i.e. knowing that is the problem) rather than wondering why the engine is struggling, thinking prop might be fouled, etc.

As filters block gradually it will give early warning to enable you to prepare, this can be convenient if motoring on a long passage. It also ensure you get the most out of your filters, so you don't change them unnecessarily (e.g. annually) regardless of whether they need changing or not. Saving you money.

As for difference between them, well I've purchased a couple of VDO gauges from the US so they match the other gauges on the boat. Similar price to the Faria gauges, a reputable brand and give a look that will blend in with my other instruments.

I did look at both the Faria (when I looked they were white background, didn't match my other gauges) and the ebay ones which in most cases didn't appear to be panel mountable.
As for Racor, well the less said the better IMO. I've always thought their stuff was over priced and over rated for what it is, but each to their own. I for one would never pay £100 for something when I could get it for way less than half that. I didn't even consider it if I'm honest.

Choice is personal. We all have our own circumstances, requirements, reasoning and preferences.

 

[lpdsn]

I just bought a cheap 2" diameter one from a Chinese website. The sort aimed at Boy Racers soop'ing up their cars. Measures in Ins/Hg. Change filter at 8"/Hg, expect problems at 10" and stopped engine at 12". Figures for your engine might vary but that'll give you a general idea.

At low vacuum readings the gauge needle vibrates a bit. That's the only weakness, which I guess an oil-filled one will overcome, but in reality it is trivial. Once up to 4 or 5"/Hg it steadies and any readings below that just mean all is good.

You'll also need a T piece. Something like this. https://www.brickwerks.co.uk/t-piece-8mm-4mm-8mm.html I had to reduce down to 4mm hose for the gauge, but of course for you it'll depend upon what you buy.

 

[zoidberg]

Thanks, chentlemen. I'll get me a T-piece and a modestly priced gauge, and fit this 'something else to peer at' next to the viewport I have for peeking at the raw water filter top......

Edit: those <https://www.brickwerks.co.uk> people seem to be of the right stuff.

Question: I've never handled a vacuum gauge/don't have one handy to inspect. Does it simply fit via a T-piece into the fuel supply line AND does it need 'bleeding'? If so, how?

 

[ghostlymoron]

I'd get an oil filled one otherwise the needle will vibrate so much you won't be able to read it.

 

[prv]

I'd get an oil filled one otherwise the needle will vibrate so much you won't be able to read it.

Mine isn't and doesn't.

Pete

 

[Malish]

If you fit a cheap one and it leaks, the engine won't work.

Fit an inline valve to isolate it should the worse happen

 

[KellysEye]

What I did is what Mobos have, fit 2 filters in parallel with an on/off switch, if one blocks switch to the other and change the blocked filter.

 

[prv]

What I did is what Mobos have, fit 2 filters in parallel with an on/off switch, if one blocks switch to the other and change the blocked filter.

I did that too, but I’d still rather be able to check that the suction is good before I start a tight transit between Channel Islands rocks in a cross-tide. There’s not much time to dive below, open the engine bay, and start turning valves if the engine stutters there.

Pete