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Make sure its in neutral and that the neutral light comes on, Check the kill switch on the handlebar. Then check the fuel cutoff relay. Get the service manual (linked here on the forums) if you haven't got it yet cause you'll be needing it.

 

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The kill switch not working is one of the most common causes when spark is lost. It should have continuity in the "Run" position. Another issue on rare occasion is a pushed in pin in the CDI connector, so check all of your wiring harness plugs too. Check all your grounds (green wires in the harness) and other connections too.... thats routine stuff on a 30 year old machine.

The fuel cutoff relay gets a signal voltage from the CDI while cranking to energize it and then the fuel pump runs... The service manual has the wiring diagram for your machine and it can be used to check the relay, CDI, coil and related Ign. circuits. My machine is in a gazillion pieces right now for restoration, so I won't be able to help you much more than this. Ask questions if you need to as you troubleshoot, I'm sure someone will chime in...

Also, if your diagnosis leads to a possible bad CDI you can tap lightly on the CDI while cranking and it will most likely spark a few times.

Since you had a critter making a home in your airbox... check all of the wiring throughout the machine for chewed wires or loose connections and do a good job on any necessary harness repairs.

 

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...I'll plan to unwrap all the tapped up wires, look them over carefully and locate the grounds for a look-see to make sure they are clean and connected. So far I have checked a couple easy to locate, one smaller green one connecting the fuel pump and one heavy black one on the frame to the right of the carb area and they are good. Fuses looked good too. No answer for the fix yet, but I'm still :smile
Any help pointing out ground locations?

Taped up wires? Had more than my share of fixing those, so nowadays if someone brings me a machine with a hacked up wiring harness I politely refuse to bail them out. Further ahead generally to replace harnesses that have been butchered than chase cobbles and wonder... so thats how I handle the stupid ones.

If its been hacked on you'll probably have to use the wiring diagram and trace every wire to verify it goes where it belongs and fix all the twisted and crimped connections the PO attempted. Generally takes many hours with a soldering station and shrink tubing to make them whole again...

I think I saw a few harnesses on the fLeebay at a decent price if you decide that you'll need one. Good luck and hope you get her going good soon!

 

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It's a miracle!!! Maybe...I think...? lol Anyway, it's working for the time being.
Thank you for sharing your insights with me Retro. I have read a few of your post and "you da man"! :hail:

Haha... well, thats great! Was hoping it was something simple cause it sounded like it could be.

As for being "da man" on anything 350D Honda, that would better describe a great guy here on the forums calling himself shadetree! He knows these old machines inside and out and then some!!

As far as the taped wire harness goes, actually, the tape was just at the first 3 or 4 inches of the harness. So that was good!!!
I was cleaning around the wire connection on the ignition coil when I thought I heard my fuel pump kick on. It may have kicked on earlier while cleaning grounds, but I didn't hear it. I had the key on hoping to hear it engage while cleaning grounds and wiggling wires. Anyway, I don't know if it could still be a problem that is intermittent, so I'll leave the fenders off and keep starting it over and over for a few days. Perhaps if it's something going bad it will cut out again. We shall see. Mean time, thx again!

Glad your harness is not hacked up!!!! A lot of guys will disconnect every little plug on the machine and clean them and put silicone grease in them to waterproof the wiring. Solves most of the corrosion problems and keeps the harness rubber soft and in great condition. I think its a great idea too, definitely worth your time to maintain reliability and prevent the odd intermittent breakdown out in the field. Cheap and easy too, so why not...?

Have fun with it!!!

On edit:
Sounds more like you have a bad connection in a wire plug somewhere. Gotta eliminate that possibility by cleaning them all and making sure each one is snug fitting. I doubt that its a coil but you can check it with an ohm meter. Its in the service manual...

 

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I hear ya about the weather... Try tapping lightly on the CDI module when it dies and see if that makes it come back to life. Also check ohms on the crank sensor/pulse coil. The fuel cutoff relay is inside the box under the right rear fender next to the regulator/rectifier. Check the plug on that too. Its probably one of those critters if all the wiring plugs are clean and snug on the machine.

 

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Well, yes or no... IF! ...you have gone through all of the connections and grounds in the wiring harness and verified them to be clean and snug, all making good electrical contacts with one another. And IF both the kill switch and ignition switch are working good with no intermittent continuity (electrically clean) issues.... And IF you have checked the resistance of the pulse generator according to the service manual and found it to be within specs....

You'll need to replace the CDI with an OEM Honda CDI (or optionally, a genuine Ricks Electrical Service CDI, not from one of the chinese liars pretending to be selling Ricks CDIs).

The Fuel pump must be an OEM Honda part too, else you or your family may burn up in the chinese fire under your butt.

Good luck and have fun with it! I'm happy that you are keeping your old girl running rather than parting it out!

Edit:
One more thing I forgot to mention earlier.... Sometimes the old spark plug wire can deteriorate at the end of the wire where the spark plug boot attaches. Its a good idea on these old machines to twist that plug boot off from the wire and cut about 3/8" of wire off the end, if you can, then twist-attach the boot back onto it. Try doing that before buying a CDI just to be sure.

 

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Retro,
Thank you again for all this great advice.
You sure have me second guessing myself on all those electrical connections. lol But I sure think I got them all. I even put a dab of dialectic grease on them after cleaning them up.
I'm confident that the ignition coil and wire to the plug are fine. I actually replaced it, just to be sure.
I got an Auto Star fuel pump that bragged it was made of all the good stuff and better than those cheap ones you described. You can check and tell me what you think. If I need to replace it, I will.
Fuel Pump For Honda TRX350 TRX350D 4x4 4WD FOURTRAX FOREMAN 350 1986-1989 NEW | eBay

As far as the resistance of the pulse generator goes. I'll read up on it and give it a test it asap.
Rest assure, if I end up having to purchase a new CDI after all of this, it will be the good one.

I'm happy if I can help you more than I can harm you! LOL Thanks for the kind thank you!

I didn't intend to make you question yourself though, I'm sorry if I came across that way. I just want you to be sure that we have left no relevant stuff out of the diagnosis, cause its your hard-earned cash that I may cause you to waste if I screw up with an unnecessary parts purchase recommendation! I'm being extra cautious and extra careful to cause you no financial harm is all. Its a forum and so it can be difficult to get everything sorted out correctly between two or more remote strangers.

The fuel pump you chose... I have no idea how well it will hold up. Maybe someone else will chime in if they have any experience with that. I hope it serves you well... I'd keep an eye on it in case it starts to leak gas someday...

Just for the record I do feel that you will need to replace the CDI at this point, since it responded favorably to the "tap" test. Just asking you to check the ohms on the pulse gen according to the procedure in the service manual to cover both of our butts! You are about to spend a lot of money on a new CDI...

Looking forward to hearing that this fine old girl is running again!

 

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I believe the the puls generator tested okay, but I'm not sure if I had my multimeter set up correctly.
I set my multimeter at 2K and it read .308
The manual said the resistance should be between 300 and 360 ohms.
Is that the right setting on the meter, 2K?
I checked both the ground wire and the frame and got the same reading.

Well, I can't be sure about your meter unless I'm there to see it for myself. Is there a lower ohms setting on your meter that you can use for another test? This pulse gen test may not be necessary at all... the motor runs... we just covering butts here...

 

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Hey, congrats on the grandson! I wondered who that might be cause I have a beautiful grand daughter I'm pretty proud of too! Grand kids can sure bring out the happy in us...

I think you did a great job on your 350D too. You have one of the finest and at an affordable price to boot. Hope your grandson falls in love with it!