F80 loud trapping noise

[Yamajoe]

Happy New Year.My 1999 F80, recently developed a tapping noise following a spate of bad fuel in the system. I cleaned the carbs, 4th carb blocked main jets, in boat fuel/water separtor filter was dirty, replaced with new, checked fuel pumps, the diaphram in one of the pumps is stretched, but no obvious tears, refitted these, have ordered kits and will overhaul pump. Compression numbers are #1 = 138, #2= 135, #3 119, #4 =138. Drained oil and installed new oil filter. Motor starts promptly, idles smooth and no smoke, the problem is this tapping sound which starts at idle and occassionally stops for a second or two and keeps on ticking on, it increases in volume when power is applied up to 1000rpm ( i am running the motor in a bucket and will not increase rpm beyond this point).The rectifer/regulator had melted down, it is removed waiting for a replacement to arrive. Looking forward to your help with thanks.

 

[rodbolt]

Re: F80 loud trapping noise

check the valve lash, but most likly you have a fuel restriction or an air leak.
if the fuel pumps on a four stroke get low on fuel,vapors or air in them they tap like crazy.

 

[Yamajoe]

Re: F80 loud trapping noise

I forgot to mention i did check the valve gaps and all have correct gaps, no obvious signs of wear and rattle, i removed the inline portside filter and installed a clear tube and observed air bubbles in the fuel line, i will now track back to bulb, filter and lines. Thanks for you quick response Rodbolt.

 

[BruceAML]

Re: F80 loud trapping noise

You mentioned that the rectifier melted down. Was this due to an overheat condition? Have you tried Ring Free in the fuel? What make and type fuel line are you using?

 

[Yamajoe]

Re: F80 loud trapping noise

I suspect the rectifer died some time ago, i bought a new battery for this season i just did not notice the rect. was inoperable as i regularly charge my battery. There is no external heat signs on the motor nor have i had the alarms go off, aprt from the burn marks on the location the rect. was attached. I do not know about ring free, what is it, where can i get info about its use? cheers

 

[Yamajoe]

Re: F80 loud trapping noise

I will check on the make/type of fuel line tomorrow am (australian time).

 

[rodbolt]

Re: F80 loud trapping noise

biggest reason for melted regulators is loose/corroded battery connections.
if your still using wing nuts on the battery scrap them and use SS lock nuts.

 

[Yamajoe]

Re: F80 loud trapping noise

Yes i am using wing nuts they will be scrapped.

 

[BruceAML]

Re: F80 loud trapping noise

Here is a link that describes Ring Free.
http://www.yamaha-motor.com/outboard/apparel/apscitemdetail/3/122/all/1/346/detail.aspx
It is described thusly:
Ring Free Fuel Additive
Helps prevent ring stick and wear. Cleans carbon and varnish.

 

[Yamajoe]

Re: F80 loud trapping noise

very much appreciated BruceAML.

 

[Yamajoe]

Re: F80 loud trapping noise

The fuel line was supplied by local yamaha dealer it is a Silverado 1000 Fuel Line, 3/8".

 

[rodbolt]

Re: F80 loud trapping noise

find a real dealer
if you suspect the fuel pump is tapping simply bring it to the RPM it taps at, squeeze the primer bulb.
if the tapping goes away find your fuel supply problem.

 

[BruceAML]

Re: F80 loud trapping noise

This is the genuine Yamaha fuel line for your engine; 6Y2-24306-41-00. See if you can find one and look at it. It is of very high quality. As I recall, all Yamaha fuel lines are metric sized.

 

[Yamajoe]

Re: F80 loud trapping noise

I have ordered the fuel lines, i also found a restriction at the connector to motor, i followed Rodbolts advise and pumped bulb at 1000 rpm and higher and bingo, no more tapping. Thanks for your help guys.

 

[Yamajoe]

Re: F80 loud trapping noise

Ok, my F80 has starting tapping again, at idle there is a faint ticking noise, but when i rev to 1500rmp, she sounds like a steel bucket full of marbles: I have replaced thermostat and PCV, put new head gasket on, cleaned valves and V train but did not remove valves entirely from the head, 4 valve pads needed replaced with thicker pads, 2 new fule pumps installed in January, checked for air in the fuel line, no air leak, haven't checked vacuum and fuel pressure at WOT yet. The compression numbers (cold) are:-
#1 = 120 (cold)
#2 = 98
#3 =135
#4 = 125
The cams are aligned, have carbs tuned, the motor starts one first try all the time, no missing, just this machine gun rattle.

Could it be stuffed valve springs, i am now kicking myself i did not tear down the valves? When i listen through a stethoscope? the noise is certainly being generated around the cams in the vicinity of the fuel pumps.

 

[Yamajoe]

Re: F80 loud trapping noise

my bad, ignor those compression numbers, i didn't have a fully charged battery, open up the accelerator and i will warm the motor up as well and repost. but i need your help with this one, it has got me stumped.

 

[rodbolt]

Re: F80 loud trapping noise

give up the compression test, its mostly useless.
run a leakdown test, much more accurate.
faster too.

 

[Yamajoe]

Re: F80 loud trapping noise

Did a leak down test and have the following results:

#1 less than 5% leakage
#2 up to 25% leakage air exiting dipstick and can hear air from the other cyl;
#3 up to 30% leak air exit from dipstick air form the other cyl
#4 less than 10% leak