150 Yamaha Not Starting

edgutgesell

Petty Officer 2nd Class
Joined
Jul 18, 2004
Messages
144
Not a good start to this year. I have had a number of problems which has delayed the start of this season. One of the problems had to do with not knowing the correct year and model of my engine which caused receiving an incorrect oil controller and having to reorder to get the correct part. When I bought the boat 5 years ago, I thought I bought a 1987 Yamaha 150. I now know that it is pre-1985. I have the correct Yamaha shop manual for the engine. (150 ETXN) I ordered the manual several years ago from Yamaha using the 150 ETXN number.<br /><br />After installing the correct oil controller I attempted to start the engine and it would not start, and it did not not even kick once. Pulled the plugs and they looked wet with oil and gas as if there was no spark. I checked my shop manual to see how to troubleshoot this starting problem. I checked the resistance of the pulser coils, charge coils, and lighting coils as suggested. All of the resistances where within +- 20% with the exception of high speed charge coil. My manual said it should have a resistance of 127 ohms, however the resistance was alittle over 24 ohms. I decided to do a search here to see what the experts had to say about starting problems with early v6 engines. I found a thread topic "86 Yamaha 150 VPro" from an author named "quat" dated Nov. 25, 2004 that indicated that the high speed charge coil on his 1986 150 had a resistance of 24.2 ohms. That resistance was exactly the same as the resistance on the high speed charge coil on my engine.<br /><br />My question is: Is it possible that the stator on my engine is from a later Yamaha v6? My manual says if the resistances are not within 20% to replace the charge coils!! (stator)<br /><br />Another question I have is: rodbolt mentions in several other threads about a peak reading multimeter (Stevens CD 77) that is the only meter to have in troubleshooting CDI problems. I checked the price and it's pretty high!!! I have an ocilloscope. (Tektronics 335) Has anyone used a scope for checking these voltage readings? I am hoping that it will be a suitable substitute for the CD 77.<br /><br />In other threads there are kill switches mentioned that can cause no spark. I think that the start switch off position is a kill position. Are there other switches that can kill the ignition? I haven't tried disconnecting the white wire from the ignition controller to the CDI unit to see if it starts. That will be the week of the 4th because I won't be at the boat till then. (110 miles away!)<br /><br />Any information would be greatly appreciated!!!
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: 150 Yamaha Not Starting

test the spark<br /> you can make a tester out of almost anything. what your looking for is can the spark jump a 7/16ths gap. search the jonnyrude section and this section for homemade spark testers. I built one in south america with a 2x4 and some nails and a copper strip used to hang plumbing and some bulk spark plug wires. I dont have the specs for the tectronics input impedance nor the attenuator specs. the system can generate voltages in excess of 200 V peak. however if your machine can handle the input I dont see why ya cant. especially if you have a hold function on the display.my manual for the 84-89 indicates 24 ohms for the high speed charge coil. however if it sat a long time you may have some fuel issues to correct before running. but check spark and compression before anything else.
 

edgutgesell

Petty Officer 2nd Class
Joined
Jul 18, 2004
Messages
144
Re: 150 Yamaha Not Starting

Hi rodbolt. Thanks for the comeback. My main concern with this problem is replacing the stator. Of course the cost and time required to replace a stator is on my mind. I will test the spark first. <br /><br />As far as the Tektronics scope is concerened, I have about 4 or 5 different probes and I have looked at some high voltages with it. I haven't used it in about 10 years, however. I guess my reason for asking the scope question was that I am not sure what I will be looking at. I should be able to see the peak voltages (spikes) if thats what a CD 77 does. This scope does not have a hold function, however I can make it trigger at whatever the required voltage is. Of course, triggering a sweep will not tell me the duration of the pulse. I think that it will work and this scope has a pretty fast sweep. I used other scopes years ago to check spark on a car by wrapping a wire around a plug wire and displaying the induced signal. That method worked ok but I think making a spark tester is better because I can see if the spark is adequate. Unfortunately, I was at a launching ramp on Sunday when I tried to start the engine and I didn't have any test equipment with me. I checked the plugs and magneto resistances when I got back to my house. <br /><br />The engine was running last Nov. when I pulled the boat out of the water. Used stabil in the gas. The very first problem I had this year before the oil controller problem was that last Nov. I had about 45 gallons of gas in the tank and when I unwrapped the boat in March, I only had about 5 gallons! I thought that I had a fuel tank leak, so I pulled the tank and found no leaks. Apparently this is very common because there are gas thieves in S. Jersey. Most of the houses around mine are vacant in the winter! My boat was in the driveway and it was a sitting duck.<br /> <br />Thanks for the tips!! I think that I have a plan of attack now!!
 

ianyoung77

Petty Officer 2nd Class
Joined
Mar 28, 2005
Messages
120
Re: 150 Yamaha Not Starting

Ed,<br /><br />Coincidently I tested my electricals with a Tektronics scope last weekend. I have a Tekscope THS720P. I was mainly interested to see how the whole CDI worked. I also have a Fluke 187 that I used for comparison of my results.<br /><br />The charge coil was very peaky - from recollection about 150V positive and 100V negative spikes. This corresponded to about 45Vrms on the fluke. There are many references on the site to use a peak measuring meter. I assume this is actually a moving coil instument rather than moving iron but not 100% sure. As the charge coil provides the energy for the CDI I think RMS gives a decent indication as to whether the charge coil is ok. Obviously it helps to have a reference of what the RMS should be from a working coil.<br /><br />The pulser coils put out about 5-10V positive very sharp peaks. On the fluke this corresponds to 1.5Vrms. In this case the coil is only providing a signal to let the CDI know position and therefore fire correctly so very little rms is required. Having said that, if I was stuck with only an rms meter I think I could find a faulty coil since the 3 coils give very similar results rms wise when healthy.<br /><br />I did try connecting a HV probe to the coil to see what happened. Before I could stabilise the display my CRO had locked up so I decided not to try that again.<br /><br />I then decided just to check the spark in the old fashion way by looking at it and checking the CDI funcitonility using a timing light. Of course, my motor was running is a luxury you do not have.<br /><br />If you don't mind tinkering try your scope, however, if I was in a hurry I would check charge coil output and compare pulser coils with whatever meter I had. I would then check the ignition coil impedances and then look at the spark. In my case I found one of the ignition coils was faulty.<br /><br />Good luck
 

edgutgesell

Petty Officer 2nd Class
Joined
Jul 18, 2004
Messages
144
Re: 150 Yamaha Not Starting

Thanks ianyoung77,<br /><br />Your reply on scoping the magneto is what I was looking for. I am going to use my scope and rent a CD 77 from an electronics tool rental and use them as you did to find out how the ignition system works. Also I intend to note what I see on the scope to what the voltmeter indicates. Perhaps after doing that, I will be able to troubleshoot the ignition system primarily using the scope. <br /><br />It appears to me that I don't have a problem with the high speed charge coil. Whew! That would have been an expensive problem. Rodbolt was correct, 24 ohms is the resistance of the high speed charge coil. I verified that with a local outboard motor tech. I am not sure why my Yamaha manual lists the resistance to be 127 ohms. Thanks again for your reply!!
 

ianyoung77

Petty Officer 2nd Class
Joined
Mar 28, 2005
Messages
120
Re: 150 Yamaha Not Starting

Ed,<br /><br />I took some screen captures from the different CDI inputs and outputs which may be helpful for your comparison. Unfortunately I am not sure how to post them.<br /><br />Ian
 
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