tach is suddenly misreading

[greasemonkeyjmj]

can someone tell me why after changing my stator, trigger, and my powerpack on a merc 500. my tach is suddenly reading way off ? before the parts change, it was reading 5100 at WOT now it is reading 6100.we used a handheld direct drive tach held to the top of the crank, and at idle the handheld is about 300 rpm lower. the higher up you go the greater the distance. at 2000 according to my in dash tach. the handheld shows 1400. i asume the handheld is correct, since it is brand new, but i ahve no way to know for sure..........thanks

 

[roger3645]

Re: tach is suddenly misreading

Did you replace the power pack with the corredt one. I had an 850 mercury 4 cylinder and replaced the power pack with one froma six cylinder. It worked but threw the tach off. Put your old power pack back on and see if it corrects the tach.

 

[greasemonkeyjmj]

Re: tach is suddenly misreading

the one i ordered supposed to be the correct on for my engine,according to the part numbers. if i get a chance i will try the old one. .thanks

 

[greasemonkeyjmj]

Re: tach is suddenly misreading

o.k i looked at my part numbers on my order. the pack that was on my engine was a 332-5772a1. that is the same number that is on my order form. the pack they sent was a 332-5772a7. i dont know if it makes a difference or not, but when i looked it up, it shows it fits 50 hp mercs with a starting serial number higher than mine. so i am not sure, but they may be the problem

 

[roger3645]

Re: tach is suddenly misreading

Boy you bought that bugger new! I know that set you back some.

 

[Barnacle_Bill]

Re: tach is suddenly misreading

o.k i looked at my part numbers on my order. the pack that was on my engine was a 332-5772a1. that is the same number that is on my order form. the pack they sent was a 332-5772a7. i dont know if it makes a difference or not, but when i looked it up, it shows it fits 50 hp mercs with a starting serial number higher than mine. so i am not sure, but they may be the problem

A7 is just the revision level.

 

[greasemonkeyjmj]

Re: tach is suddenly misreading

Boy you bought that bugger new! I know that set you back some.

trueit did, but as many things as i have repaired on this rig, i didnt want to mess around and get ahold of a pack that wasnt any better than what i had

 

[greasemonkeyjmj]

Re: tach is suddenly misreading

A7 is just the revision level.

in that case, i guess it is back to the drawing board on this problem