Troubleshooting 1998 350 Magnum no start issue advice

[VeroWing]

Have been restoring a 1989 Grady with a low hour (280) 1998 350/260 carbed Magnum engine that sat for a while. Last year I checked engine over and replaced plugs, oil/filter, lower unit pump, thermostats, etc. Had engine running, and it ran well on the hose, not overheating, etc. Satisfied with engine, I set about fixing up rest of boat, which had been badly neglected for years. I finally got most things in order and tried restarting engine for first time in 5 or 6 months, and it would not start. Turns over just fine, and I have power to coil with ignition on when checking with a test light. I also poured some fuel down carb and that made no difference. I'm pretty sure I'm not getting spark to plugs, and I'm guessing it probably is an ignition problem somewhere. One more thing, several months ago, I gunked and pressure washed engine and compartment. I covered carb and distributor, but there was a lot of water shooting around. I'm adding some engine pics from when I first got boat to show ignition type. I would appreciate any advice on next steps I should take to finding out why engine won't start. Thanks, Mike

 

[alldodge]

Have been restoring a 1989 Grady with a low hour (280) 1998 350/260 carbed Magnum engine that sat for a while. Last year I checked engine over and replaced plugs, oil/filter, lower unit pump, thermostats, etc. Had engine running, and it ran well on the hose, not overheating, etc. Satisfied with engine, I set about fixing up rest of boat, which had been badly neglected for years. I finally got most things in order and tried restarting engine for first time in 5 or 6 months, and it would not start. Turns over just fine, and I have power to coil with ignition on when checking with a test light. I also poured some fuel down carb and that made no difference. I'm pretty sure I'm not getting spark to plugs, and I'm guessing it probably is an ignition problem somewhere. One more thing, several months ago, I gunked and pressure washed engine and compartment. I covered carb and distributor, but there was a lot of water shooting around. I'm adding some engine pics from when I first got boat to show ignition type. I would appreciate any advice on next steps I should take to finding out why engine won't start. Thanks, Mike

Looks like you have a TB-V setup, here is the troubleshooting guide. You will also need a meter, not a test light to check voltage.

 

[VeroWing]

Thanks AllDodge! I'll get on it tomorrow morning.

 

[VeroWing]

Need some info on replacement coil I purchased after following "troubleshooting guide" down to "replace coil". Ordered and received this Ignition Coil for "Mercruiser Thunderbolt Ignition, Replaces 392-805570A2 18-5438", a Sierra coil. There is a sticker on it that says Use of External Resistor Required IF Used on Non-Thunderbolt Ignition System. It also has printed directly on coil "USE WITH EXTERNAL RESISTOR". I called supplier and person said that the "purple wire" leading to coil is the External Resistor, and that the Sierra coil #5438 supplied is the correct one. Can someone please verify that this info is correct before I install and possible do damage to my ignition system? My engine serial # is K278713. thanks again. Mike

 

[Fun Times]

While the two part number are correct it' sounds like the coils may have been mixed up somewhere along the line. 18-5438 is an internal resistor and 18-5433 is external. Also the latest OEM part number is 300-8M0079202 http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=81659697&ivar=images/COMMON/37619.png&inbr=2344&bnbr=50&bdesc=DISTRIBUTOR+AND+IGNITION+COMPONENTS

http://www.go2marine .com/product/83471F/ignition-system-coil-18-5438.html... http://www.amazon.com/dp/B004AQZFIM...e=df0&creative=395105&creativeASIN=B004AQZFIM

http://www.go2marine .com/product/83466F/ignition-system-coil-external-ballast-resistor-style-18-5433.html.... http://www.amazon.com/dp/B00027GL2C...e=df0&creative=395105&creativeASIN=B00027GL2C

Read the bottom questions & answers as well, http://www.go2marine .com/category/13801/mercruiser-plug-wires-and-coils.html
^ You'll have to bring the .com as one with marine and search it online because the link don't work here.

This may be your problem with the vendor,

-The following feedback was originally submitted on 5/29/13 for the seller of this item, Marine Parts House: "The ignition coil shipped was not a replacement for the Sierra 18-5438 as indicated. The Sierra 18-5438 has a primary resistance of 0.6-0.8 ohms for use on a Thunderbolt system. The product shipped measures 3 ohms on the primary, will not work on a Thunderbolt ignition system. Seller was contacted by phone, stated the part was correct; it is not. I need the Sierra 18-5438 coil or refund please."

UPDATE: After seller feedback was submitted, Marine Parts House (MPH) contacted me and immediately replaced the coil with the Sierra 18-5438. The correct coil was sent overnight, without waiting for the original order to be returned. MPH indicated that all 6 of their remaining Sierra coils had been replaced with the correct product. It appears that the problem may have occurred as a result of a cross reference error for the genuine Sierra product. Resolution with this vendor was very satisfactory; we received good customer service and negative seller feedback was deleted because it could not be updated within the Amazon system. Both the original order and the replacement part were received within the time frame promised.

Thank you Darin from Marine Parts House for your prompt assistance.

http://www.amazon.com/dp/B004AQZFIM...e=df0&creative=395105&creativeASIN=B004AQZFIM

 

[VeroWing]

Thank you very much Fun Times for providing me this information. I will again contact supplier and try and resolve this issue. Looks like another week or so on land. Your last sentence is really making a lot of sense. Spoke to supplier again, and he repeated that this is correct coil and the one needed for my Thunderbolt V system. He stated that this is where many people get into trouble using an internal resistor where this is the correct one. Therefore, I took pic of part, box, and writing and will send to him to be sure wrong coil was not placed in box. Pics below.

 

[VeroWing]

Well, I sent this question, along with pics of coil I received to the supplier, and received their reply:

Dear xxxxxxmarine,

Hi, I bought this item for my 1997 Thunderbolt V Ignition system, which your ad states the Sierra 18-5438 coil is good for. Receiving the part I see sticker stating "Use of External Resistor Required on Non-Thunderbolt Ignition System", and below that a stamping stating "USE WITH EXTERNAL RESISTOR". I have been advised that possibly supplier (you) may have gotten the wrong coil in the box stating Sierra 18-5438 coil. Below are several pics showing coil I received as well as box and writings on coil. Please verify to me that this is indeed a genuine Sierra 18-5438 coil, and that it is proper replacement coil for a Thunderbolt V ignition System, so I can go ahead and install it without worrying. Please forgive my questioning your product, it is only that I just don't want to endanger my Thunderbolt Ignition and have to replace it. Thanks in advance. Mike

Dear mike, Hello, Yes the Thunderbolt Ignition system used an External Resister, you should have a Purple ignition wire going to the coil, that is a "resisted" wire, so the use of a external resisted coil is necessary. Kyle - xxxxxxmarine

---

The supplier seems to be confident that they are correct about this product being correct for the Thunderbolt V ignition system after two phone conversations and the above email. I researched this for hours last evening and found some supporting info that the Thunderbolt wiring harness may in fact be the "external resistance" supplier is speaking of. I also found info stating that Sierra 18-5438 is "internal resistance". I guess the only way to find out is install it and see how things go. Not very reassuring.

 

[Fun Times]

Use of External Resistor Required if Used on Non-Thunderbolt Ignition System.

Well after reading the "coil" in your photo carefully, it seems you do have the correct coil since it states if used on Non Thunderbolt Ignition System which you do have a Thunderbolt Ignition System.

Sorry for the confusion.:redface:

Good luck.

 

[VeroWing]

Well, it made no difference anyway. Still not starting. This is after installing new sensor, coil, cap, rotor, wires, plugs. Have to walk away for a few days and then start back at basics. I'm missing something, OR the thunderbolt is bad. I'll redue troubleshoot.

 

[VeroWing]

Anyone have any ideas that I can try to get this engine started. To date I've disconnected tach, replaced ignition switch, ignition sensor, rotor, cap, plug wires, plugs, coil, etc.. Following Thunderbolt V troubleshooting guide I have 12v to coil positive and to red/white bullet wire from module. I also get spark from spark plug tester on high voltage coil wire when striking green/white bullet plug quickly against ground. Today I removed distributor and cleaned mounting/grounding areas for ignition module, plus I disconnected/cleaned main harness plug connectors from engine compartment to dash area. I also disconnected shift interruptor in case that was killing spark. I'm out of ideas, and could really use some advice on other items that could be stopping this engine from running. Any help is greatly appreciated. Mike

 

[Fun Times]

If you have good spark to the spark plugs and plug wires then you may have a fuel problem or internal mechanical or upper engine gasket problem.

Have you tried pouring a little fuel down the carb to see if it will try to start?

 

[VeroWing]

:joyous::joyous::joyous: Hallelujah, success at last!!! Went out again this morning to run through the Thunderbolt V troubleshooting guide for the umpteen time and had the same results, which was spark and power where it should be. I knew there was spark in the coil wire but none going to plugs. Decided to connect spark tester to one wire going to a plug, turn key on, and jump solenoid by engine so I could observe spark. To my surprise, engine started!! Quickly shut it off and reconnected spark plug wire to plug and tried to start from ignition. No good. Placed ignition on "on" and went back and jumped solenoid again, and it fired right up. Took out NEW ignition and reinstalled old one, and now it starts fine every time and is running perfect (as it should with all the new parts). Turns out that ignition switch was disconnecting power to purple wire when "starting position" was engaged, but reestablished when key was let go, so every time I checked power to purple ignition wire it was there, but lost when trying to start. I want to thank you Fun Times and AllDodge for helping and sharing your knowledge. Sure appreciate it! Now to get back and finding the next obstacle! Mike