1990-91 dt65 no spark

[Frazys]

Hi all,
I recently bought a 1991 Suzuki dt65 for a 14,6ft sea nymph that I have rebuilt the transom on.
When I first attempted to start the motor the starter kicked but the engine wouldn’t crank. I remembered the previous owner had changed the impeller and found he hadn’t connected the gear linkage, now I had neutral I tried a second time. Again the starter fired but no crank.
I pulled off the flywheel cover, turned the top nut and freed it all up. Third attempt and we had the starter kick and the motor cranked but no start, checked the fuel passed the fuel pump and filter fine.
Next we pulled a spark plug and tested it against the powerhead and found no spark. An auto electrician friend came around and we tested to see if the cdi was getting power which it was.

After this I thought to research further online to which I found a similar old topic with the same outboard with no spark in which he mentioned that his started with the oil flow sensor disconnected and that a temp sensor was linked in a circuit with it.
My question now is, how do I test that the oil is flowing and the sensors are working.
Thanks for any help

[Solarman]

I think I would test the low condenser and high condenser charging coils on the magneto, to make sure they are within the manual readings. Also test the gear counting coil for proper reading, and placement, it has to read each tooth of the flywheel.

Good luck, post back on what you find out.

[Frazys]

We also tested the easy to access coils. But i will mark and remove the flywheel and test the primary ignition couls if need be.
thanks for your advice solarman.
now i just need to find the time to do it!

[Frazys]

I have to say... these dt65 are a relatively basic system and the resources available these days online makes it fairly simple to trouble shoot.
First off, Thanks for the advice solarman.

90-91 Suzuki DT65 NO SPARK!!!
Buggered CDI? maybe not lets start from the beginning and work through it logically.

The DT65 is in my mind a relatively user friendly outboard, it has a CDI (Capacitor Discharge Ignition) system. The magneto is fixed to the base of the flywheel and houses 3 pulsar coils, a gear counting coil, an ignition condenser (aka primary ignition coil) and a battery charging condenser/coil. When the magnet passes the coil a magnetic field is formed which the the condenser converts into energy and stores. The current is then sent to the cdi where it awaits a signal from a pulsar coil which tells it where and when to send the current. It is then sent to one of the secondary ignition coils where the voltage is increased and sent down the leads, through the plugs where it arcs and ignites the fuel mixture.

The remote:

1. Check the Lanyard is in position. Open the unit and use a multi-meter to test the emergency stop switch for continuity.
2. Most models have a neutral switch that on older models may still be operational, this was removed later for safety reasons as you still want your outboard to start even if it is in gear as the tide is pulling you out to sea and the linkage is broken. Mine the wire and pin were removed at the harness plug.

Ignition components:
For this testing you will want to locate and label the correct wires to be sure that you are testing the right components. The timing is set by a woodrif key in the shaft and monitored by the gear counting coil and can only be fixed in one timing location (don't lose the key and there are more timing marks on the flywheel that line up with TDC).
Test the outer (secondary) ignition coils prior to these tests.

1. Locate the pulsar coil wire and test for continuity to the earth (might work just grounding it but better with flywheel removed). Wires enter the cdi and all 3 can be tested. (170-250 ohms)
#1. Red/black wire and earth
#2White/black wire and earth
#3Red/white wire and earth
2. Test across the colored wire to the mounting stay. there should be no continuity
3. Condenser coil test the resistance between green and Black/green wires (190-270 ohms)
4. Battery coil test the resistance between the red and yellow wires (0.2-0.6 ohms)
5.Gear counter coil test between Orange/green and Black/green wires (170-250 ohms)

If after these test you are still not getting spark you will want to check the coils input to the cdi, cdi output make sure everything is wired correctly. Probably need to build a VDA (Peak voltage adapter) for that.
here's some links to help

Workshop manual
https://issuu.com/glsense/docs/suzuk...orkshop_manual

Wiring diagram (Better for printing)
https://www.repair-guidebook.com/suz...iring-diagram/

Parts diagrams (select your boat and part for an image)
https://www.boats.net/catalog/suzuki...by-model/dt-65

Hope this helps, i printed off a few of the pages from the electrical ignition section and had it on the boat with me. It has descriptions on how to test parts and other relative information.

My work place has a computer controls department so i decided to label the wires and disconnect mine. My big fat hands accidentally unplugged 2 wires but it was easy to find their correct locations. I found a wiring diagram traced the wires and found the previous owner must have had it out or something and had plugged one of the ignition coils into the double bullet connectors from the rectifier and pulsar 2 was disconnected.

Good news for me i now have spark, starter kicks, engine cracks and plugs fire but still no go lmao, now its just air and fuel. Any ideas solarman? Im going to check compression tomorrow and follow the issu website with the DT workshop manual.
Frazy

[Solarman]

Frazy, please stick with one post for the same motor. It's easier to review all the efforts tried, and what could be a next step for problems.

Thanks.

[Frazys]

Ok

So the previous owner had connected some of the wiring to the cdi incorrectly, when I resolved this it was starting to get dark and I could see what I thought was a nice strong spark.
Today when I checked again for spark and it is really weak but definitely spark on all cylinders. We tried one of the spark plugs on the mower and it was fine, I’m about to test the one of the secondary ignition cables but I don’t think that is the problem.

The other day I tested the condenser charge coil/primary ignition, battery charge coil, 3x pulser coils and the gear counting coil.
CONDENSER COIL: 0.212k ohms (the workshop manual says it should be 190-270 ohms, I tried all the different ranges and this was the highest result I could get 0.212k)
BATTERY COIL: continuity but no reading .000 (should be 0.2-0.6)
GEAR COUNTER: 0.210k ohms (should be 170-250 ohms)
PULSER COILS: all pulser coils were between 0.208-0.211 (should be 170-250)

All components passed the testing except the battery charging and I don’t know if that would affect the strength of the spark but I wouldn’t think so.

Any ideas on what would cause a weak spark.
Thanks

[Frazys]

I have a few spare 85 dt55 that have a similar ignition and tonight tried swapping over both the ignition and battery coil, back to no spark. Solarman I’m down to the last test to confirm that the problem is the cdi. Could you tell me where to find information on the specs and how to test the voltage input and output of the cdi, will I need to use a vda/peak voltage tester to get a reading?
Thanks

[Frazys]

So I built a dva and did test the condenser voltage input to the cdi on Saturday and all seemed good.
I then tested the output from the cdi and got an erratic DC reading, but on AC i got (I didn’t record this lol I will check again tomorrow evening and edit this post, maybe because it runs through another diode it could convert it back to AC? I don’t know, I will get the computer control guys to check out my DVA tomorrow and make sure it works properly)

Sunday I had the young fella make a video of the process so I could review it later. Just after retesting the ignition components and wiring for continuity, my uncle arrived and saw us testing for spark (which again was back). He suggested we check the fuel system together, of course I had missed one test and found the spring in the fuel pump had corroded failed.
I installed one from the spare motors and tested that, now I had fuel and somewhat of a spark.
The starter kicked, engine turned and it almost fired. It seemed like it got compression but the sparks not strong enough and the starter dropped back in place. I kept trying and then eventually got a few back fires, I thought it sounded like it was about to start so moved the boat closer to the hose and plugged in the muffs. We tried a few more times then the back firing stoped and the battery started to run low, checked for spark and it’s gone again.

Any ideas Solarman? Hoping the loss of spark at the end might be just be related to the battery running low or a safety switch and the cdi is fine. But I will keep persisting with it until it runs or I diagnose without a doubt it is a faulty cdi (then I’m gonna go all mad scientist and open it up). I’ve attached the ignition coil specs chart I have and a video of just how weak the spark is.
On another note the battery I’m using is rated up to 65hp, maybe I should have gone for the next size up 65-145hp? Could this provide to low of a voltage for the ignition system? I wouldn’t think so but maybe.
I’ve attached a copy of the ignition coil specs I have and a video of the of the weak spark.

The chart of the ignition coil specs(see attached), has measurements for the DT25C-30C and DT75C-85C that I found on: https://issuu.com/glsense/docs/suzuk...orkshop_manual, it doesn’t have any specs for the DT65, is it the same specs as the DT75-85? and it also doesn’t have any specs or how to test the cdi input and the output voltages.

Do you know where or if this information is available.
Thanks for any help

[Frazys]

Sunday I had the young fella make a video of the process so I could review it later. Just after retesting the ignition components and wiring for continuity, my uncle arrived and saw us testing for spark (which again was back). He suggested we check the fuel system together, of course I had missed one test and found the spring in the fuel pump had corroded failed.
I installed one from the spare motors and tested that, now I had fuel and somewhat of a spark.
The starter kicked, engine turned and it almost fired. It seemed like it got compression but the sparks not strong enough and the starter dropped back in place. I kept trying and then eventually got a few back fires, I thought it sounded like it was about to start so moved the boat closer to the hose and plugged in the muffs. We tried a few more times then the back firing stoped and the battery started to run low, checked for spark and it’s gone again.

When I came home today I tested again and no spark, I started to disconnect one plug at a time and then test for spark. I disconnected the white plug which is the circuit for the resistor, throttle sensor and would you believe it the emergency stop which I had tested and still might not be the problem but now I know which circuit to test.
I left the plug disconnected and tried again, I must have flooded the carbs but after a few cranks the motor fired and I had her running for a solid 5mins.
Tomorrow I will be testing the complete emergency switch circuit and other components on the plug.

[MIKEVILLA80]

no spark DT55
Hi, I'm new to this forum, my name is Mike, sorry to bother you.
I have a 1992 Suzuki DT55 very similar to DT65.
I have similar problems, I have no spark in any spark plug.
Could you tell me if you solved your problem?