165 HP Mercruiser problems

"I have a 1974 Pen Yann with a

"I have a 1974 Pen Yann with a 165 HP Mercruiser.

I'm having two problems:

1. The starter fails to start each time the ignition switch is turned. I've changed the starter, ignition switch, battery cables, bus bar under the dash, selinoid and battery. It still acts like a bad ground and fails to turn each time the ignition is turned. HELP please.

2. The engine idles rough and stalls at low RPM when warm. Not when cold. Any ideas?

I love the boat but have begun to think more and more about what a wonderful camp fire it will make.

Thanks for any suggestions."

two person voltage drop tests

two person voltage drop tests are the way to find a starter problem like that.
I know someone that once thought anti seize compound would be good for battery terminals with all the copper flakes in it....
Luckily that same person knew how to do V drop tests.

"rough idle could be a vacuum

"rough idle could be a vacuum leak or idle mixture screw setting.
when it's cold, the choke riches it up, but hot the idle mixture screw is needed to keep it idling smooth."

Your boat has very old wire th

Your boat has very old wire that is corroded internally. That is why Hy Stat said to perform a voltage drop test. Measure the voltage across the battery terminals and write it down. That is the reference voltage.

Any voltage readings you take from the battery ground to a point in series w/the + battery terminal should not drop more than 0.02 volts from point to point.

Example: battery teminals read 12.90 vdc.; the voltage at the ignition switch hot terminal should be no less than 12.88 vdc. W/the switch to start position the voltage at the solenoid small wire should be no less than 12.86 vdc.

Ground points can be tested from the battery w/an ohmmeter using the 1K scale. Readings should be 1.00 ohms or less.

"Guy:

right thought - wrong

"Guy:

right thought - wrong math. should be two tenths of a volt, not two one-hundreds...I've seen a few military "cost-is-no-object" propelled items that were hard pressed to achieve the two tenths."

"makomark:

Duuuuuhhhhh! <

"makomark:

Duuuuuhhhhh! You are correct and I am dummer than a pet rock. Too much coffee or brain fart?

Ex: 12.90 then 12.70 then 12.50 and so on."

"No way....like most of us, yo

"No way....like most of us, you experienced a tachno-typo.

I just didn't want the new guy to unload a few bills on wire and cable when his stuff may be ok.

BTW, I've found those 'differential' voltage measurements to be much more valuable than going to the ohm function....best part is you can do it 'in-situ' without disturbing a connection."

"makomark: Glad your eyes wer

"makomark: Glad your eyes were open.

Rob: Sorry about the misinfo.

If you find a low voltage reading I have cut the wire end off, stripped an inch of insulation off the wire and found black copper strands. Take a strip of 400-600 grit sand paper and run the wire between the folded Spaper while flattening out the wire until it is bright. Twist and tin the wire w/flux and solder. Crimp the new connection (use heat shrink tubing) and solder the wire to it. Repeat it on the other end of the wire. All 14 ga. and larger wire should be replaced."