1993 135hp tach dead

[thehermit]

Hey gang,

I have the 93 135 and it has been a great motor. I just fired it up after a winters sleep and the tach is not working. When I turn the key to on it bottoms out like it should but rev the eng and nothing. I am arem with test light and meter and manual....where do you start??? ANy clues?
Thanks
TH

 

[Laddies]

Re: 1993 135hp tach dead

Sounds like the rectifier is bad, remove the tach sender wire from 1 yellow lug and move it to the other and see if it works then.

 

[thehermit]

Re: 1993 135hp tach dead

That may wake it up ??

 

[pops]

Re: 1993 135hp tach dead

This forum is covered up with tach failure problems, and Laddies (and others) almost always go to Rectifier failure.

In actual practice, especially on the mid 90s, 115-135 HP motors, the problem is usually failure of the potted REGULATOR (two red wires, two yellow wires, and grey wire). Typical symptom is no battery charging, no tach readout, but the motor still runs fine.

CDI, and other aftermarket folks, don't even list the replacement rectifier that these motors have as original equipment.

 

[Chris1956]

Re: 1993 135hp tach dead

Pops, That motor should have twin voltage regulators. The lower one will have a plug in the grey wire. Switch the grey wire from the upper VR to the lower VR. If the tach doesn't come alive, you may have two bad voltage regulators, or some kind of wiring problem.

The 2 VRs on my '93 135HP died within days of each other. I ourchased new CDI replacements.

 

[thehermit]

Re: 1993 135hp tach dead

YUP! The motor does have 2 voltage regulators. I switched it to the lower one and still no tach. I am preceeding to the VR test in the book. The wiring harness and tach a 4 yrs old. ??????????

 

[thehermit]

Re: 1993 135hp tach dead

Also acording to the gauge. The motor is charging 14.2 with a little rpm when runing from 12.4 when sitting.

 

[hkeiner]

Re: 1993 135hp tach dead

The below linked thread contains a link to a Teleflex troubleshooting guide. Using a multimeter, this guide will help you determine what is faulty.


http://forums.iboats.com/showthread.php?t=243924

 

[pops]

Re: 1993 135hp tach dead

Sorry guys, I got confused about the 135 HP motor. The 4 cylinders went up to 125 HP, but the 135 HP was a V6 and with different electronics.

I have been waging my battles with the 4 cylinder series motors.

 

[thehermit]

Re: 1993 135hp tach dead

OK tested the TACH
1. Ign to GRND 12.2 Volts...good there
2. Send to GRND @ Idle 5.7volts Send to ground with some RPM holding 5.6V with more RPM it goes down a bit 5.2V

So Basically it looks like I am getting "ender to ground voltages"

TACH does zero at "key on" move

When testing the grey wires exiting the regs:

Top @ idle 5.9v
Top @ RPM 5.3V

Bottom @ Idle 6.9v
Bottom @ RPM 6.9V


BAD TACH???????????????????

THANKS FOR ALL OF THIS!

 

[thehermit]

Re: 1993 135hp tach dead

BAD GAUGE! I remembered I had a Seacraft tach in the shed.....swapped it out and everything is back to good. Glad to know my regulators are working happily.

FYI: Tach was a teleflex RED series. It lasted only 4 seasons. It is exposed to salt water washdowns (work boat) and that was likely the death of it.

Thanks to all for the help...especially the teleflex tach link that showed me that I was within specs and needed a new gauge.

 

[thehermit]

Re: 1993 135hp tach dead

OH NO I'm BACK!!!!!!!!!!!!

New tach is in and working except it jumps all over the place. Also vot readings charhing up to 16.2 V!!!!!!!!!!!!!

Replace one regulator rectifier or BOTH??? HELP Please...thanks.

 

[hkeiner]

Re: 1993 135hp tach dead

I suggest again switching the send wire to the other voltage regulator to see if the jumping continues to occur. If it goes away, you know that only one regulator is faulty.

I would also move the pole switch on the back of the gauge back and forth a few times (with the motor off) to see if that helps any. Sometimes the contacts inside the gauge become a bit corroded and can be cleaned by the movement of the switch.

 

[thehermit]

Re: 1993 135hp tach dead

We did some testing yesterday. Ran motor on both tach wires exiting upper and lower regulators. The top regulator produced a tach reading that was all over the place. The bottom one produced a steadier pulse but it was still a bit jumpy. I believe we traced the over chargeing to the top regulator. We ran the motor on the bottom one only and the overcharging seemed to go away. So the problem of overcharging and bad tach signla needs to be fixed. Also I did a stator resistance check and that seemed to come out just fine. I hope that stator is fine........SO long story short I decided to replace both regulaotrs! I will hook em up and report back.
TH

 

[thehermit]

Re: 1993 135hp tach dead

Well.....put in 350 bucks of regulators and....still have a problem. The tach still jumps all over the place especially at speed. The Voltage seemd to be back in check as it never exceed 14.5 on the test run.

How do I test the stator? Isnt it the only thing feeding the regulators which in turn feed the tach whic is showing a problem.

Remember; new tach and new regulators.

Thanks and HELP

 

[hkeiner]

Re: 1993 135hp tach dead

It is possible that both tach gauges are bad since they apparently showed different symptons. I understand that the first gauge was dead and the other gauge from the shed jumps around. Hooking up a known good gauge (preferably borrowed) would be my next step before replacing any other expensive electrical parts on the motor. Or perhaps you can temporarily hook up your second gauge to another motor to see if it acts the same way.

Just some thoughts...

 

[thehermit]

Re: 1993 135hp tach dead

hkeiner,

The gauge is good. I have tested it and also I have a backup tach which does the same thing. All tach connections are also good.

I feel whaterver is going on was likely the casue of the regulator failure in the first place. At this point the engine works fine but with the tack jumping I get the feeling I am on my way to frying another regulaor.

Can a stator cause regulaor failure? (chicken before egg)
Can Regulator failure cause stator trouble? (egg before chicken?)

I have some "DVA" readings and am going to try to test the stator. It did pass the resistance tests but it looks like you can test output at the switchbox. I will try that.

What does DVA stand for anyway

THANKS GANG

 

[j_martin]

Re: 1993 135hp tach dead

DVA stands for direct voltage adapter.

It is a simple peak holding circuit whose dc output aproximates the peak voltage measured.

I wouldn't think that anything about the switchbox part of the stator would effect either power production or the tachometer.

You may have something arcing over, anywhere in the boat, and putting spikes back on the battery. If it were mine, it'd be approaching the problem with oscilloscope in hand. (but i'm weird)

Try disconnecting all electrical and electronics except engine and instrument panel stuff at the battery. Also try substituting any good battery for a test.

hope it helps
John

 

[thehermit]

Re: 1993 135hp tach dead

OK pulled the flywheel and 2 magnets were broken with pieces missing. Stator took a few hits and I am unsure of its status at this point. I am now looking for a flywheel.

TH

 

[j_martin]

Re: 1993 135hp tach dead

The only way the flywheel will hit the stator is if the stator is loose, or the top bearing in the engine is really bad.

Hope it helps
John