honda b75 CDI HELP

Hi miki083,

Your English is just fine, no apologies neccesary.

That is an unusually high oil pressure reading for a Honda twin cylinder at idle and is higher than I would expect even at max rpm.
For example; a BF20D idle oil pressure reading should be ariund 20 to 25 psi as a comparison.

Are you sure that the gauge is accurate? Is there a possibility that a very high viscosity oil is in the crankcase or that the oil is full of sludge? Those are the things that come immediately to mind about the pressure reading being so high.

What happens if you simply remove the wire from the switch and run the engine? Does the lamp stay off?

its new oil 10-40w , i just put it
when i remove wire, lamp stay off, when i put wire direct on mass or negatative (body o engine ) its shy , but again on full throttle is dies ,in this case we avoid pressure switch and give the mass directly and lamp is acting the same
i think the coil for lamp on full throttle losing electric power

The coil that powers the oil lamp is the EXCITER coil that also powers the ignition coil. So if the lamp goes out but the engine continues to run, the coil is good.

But maybe I misunderstood what you were saying....??
Does the lamp go out AND the engine dies at the same time? You did use the word "die" but I thought you only meant the lamp went out.

If the engine stops also, then yes, the coil might have a fault. But, since it makes voltage at lower rpm, I would still NOT immediately suspect that it is the coil that is causing the problem.

I think it would more likely to be a bad connection somewhere that is losing contact because of the vibrations that are occuring at the higher rpms.

So, there are several electrical connections to check over before assuming the system is losing power due to a bad coil. Cleaning the connections is always good on an outboard.

Start looking at the plug in connectors where the wires come from under the flywheel. Unplug, clean and plug back in. Check the wires where they connect to the ignition coil to make sure the ends are clean and the post nuts are tight. Find the grounding point on the engine and make certain no eyelets are loose and are not corroded.

Pull the CDI connector and look for loose or worn sockets and pins. Use contact cleaner on the terminals before plugging back in.

Check the kill switch to make certain that wire isn't damaged and possibly touching ground at times.

You can use a voltmeter to monitor the EXCITER coil output too. The ac volts should steadily rise as rpm increases.

Those are all basic checks I would do before condemning an EXCITER coil or a CDI unit. These engines are old and have likely been worked on many times so patched up wires and dirty, corroded wiring and connectors are always a high probability for causing issues.

I hope you can get it sorted out.

Good luck.