A (34)heads up(34) on inaccurate tachos...-gctid827667

[boatbum]

For years it has bugged me that my tachos have always read differently between the engines.

I've replaced 2 of them, swapped them all around, cleaned up the contacts, even spent $600-00 on getting the whole lot calibrated.

They would read fine up to about 2400 rpm, than as more throttle was applied the port one would start to lag behind.

At 2500 it would be 50 behind, at 2700 it would be150 behind and at WOT it would be 200 behind.

But just recently.....

I replaced my fuel tanks, and guess what....

Both engines now read identical revs right across the range!

So after trying to get my head around why I should suddenly be so fortunate.... my conclusion is, that the port engine was starving for fuel at higher revs due to a partially clogged fuel pick up... how simple!

So for those with tacho's reading similar to mine.... your engines might be trying to tell you something.

I hope this helps.

[Mr._Darcy]

A very informative post. Thanks!

Greg

[guntar]

Or was a connection problem fixed during the tank replacement?

[canoel]

So you are saying that the tachs were fine but one engine was not revving as high? Would you not have noticed that they were not synced? It drives me crazy when I hear my engines not synced. I rarely even look at my tachs.

[Mr._Darcy]

"canoel" post=828165 wrote:
So you are saying that the tachs were fine but one engine was not revving as high? Would you not have noticed that they were not synced? It drives me crazy when I hear my engines not synced. I rarely even look at my tachs.

+1 Very good point. I can't stand that pulsating noise either. Didn't think about that in the earlier post. There are people who are unaffected by harmonic imbalance. The Admiral is such a person; she does seem to notice it.

Greg

[diveguy]

Can the fuel pickup line be removed from the tank for cleaning? I thinking I should investigate this as the first season or two I was pulling some sludge which was showing up in the primary filters. I was getting water as well when I realize the o rings in the filler caps were missing and allowing rain water in the tank.

[Mr._Darcy]

[quote]"diveguy" post=828178 wrote:
Can the fuel pickup line be removed from the tank for cleaning? I thinking I should investigate this as the first season or two I was pulling some sludge which was showing up in the primary filters. I was getting water as well when I realize the o rings in the filler caps were missing and allowing rain water in the tank.[/quot

Yes the fuel pickup can be unscrewed from the tank after removing the fuel hose. The one in my old tank had some sort of check valve in the end of it.

Greg

[boatbum]

Yes, that is correct. the new tanks are fitted with the old pick up fittings, it was only upon removal that the gunge was displaced.

As to the syncing.... I did that by ear, which would mean I would pull the "good" engine back to match the starving one.

[RDH3818]

You have dicribed exactly what I think is going on with my 38 I put new filter in and in 2 miles my vacuum Gage's read 5 inches

Switched from 2 micron to 10 micron same thing

I'm heading to Seattle and BC Saturday for 2 weeks for fun and work but will pull my pickups when I return

Great answer on your original post

Cheers

Roy

Ketchikan Alaska