How you do a fuel flow meter installation can effect its performance, so pay close attention to these flow meter installation tips. Otherwise, your screen might read 2.0 when it should be reading 0.2.
1. Make sure all of your fuel lines are straight and supported for at least a foot in either direction beyond the meter. Bends in the line beyond a foot should be at as low an angle as possible. Abrupt bends cause turbulence, and when the air bubbles get sucked into the meter’s paddlewheel, it causes inaccuracies.
2. Ensure your hose clamps are stainless-steel. Many that are advertised as stainless (and are shipped with these units) have screws that are a lower grade metal, and will corrode away. Check out the hose clamps on this Northstar fuel flow meter:
This Northstar fuel flow meter was installed with "stainless" hose clamps with bad screws; note the discoloration, soon to become serious corrosion.
See the discoloration? Even though these clamps were marked “stainless,” they’re corroding. Check ‘em out by running a magnet across the clamp and screw. Good stainless won’t attract the magnet, but cheaper metals will.
3. Choose flow meters wisely. You currently have three main choices for add-on flowmeters: Yamaha, Northstar, and FlowScan. I’ve used ‘em all, and found that FlowScan, while the most expensive of the bunch, also tends to be the most accurate. Take the time to calibrate them and you’ll usually get between two and three percent accuracy. Yamahas are less expensive and tend to do very well at engine RPMs over 1,500, again reaching two or three percent accuracy. At lower RPM, however, they often jump around quite a bit. Northstar’s are the least expensive, and in my experience, the least accurate. But they still usually get in the five percent accuracy range – not bad, considering that they only cost a couple hundred bucks.
4. On twin-engine applications, install dual meters. It’s tempting to install one and simply double the flow, but this does more harm then good. You won’t know if the engines aren’t synched up properly, you won’t know if one’s burning more fuel then the other because of mechanical issues, and you may be deceived into thinking there’s more (or less) fuel aboard then there really is.
Of course, the whole topic is moot if you get a new engine which calculates fuel flow electronically. What a great excuse to go out and buy a new motor – and just think of all the work you’ll save, not having to install a flow meter!