305 EFI electrical problem Please Help!

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Im doing the best I can here Don without having the boat with me. I couldnt tell you 100% which ignition it has because I cant look at it. Im 99 percent sure it is the Thunderbolt ignition. I also said in my response I will figure out the serial number on Friday. Im sorry I didnt have all of this information already for you guys that are helping me. As I said before this is my first EFI boat and I was unaware that there were so many variations of the 305 in that model year. Sorry......

There is a buzzer that sounds when the igniton is turned on and the kill switch is in the run position and everything powers up. When the kill switch is in the off position no buzzer and no power "sounds" from anywhere. ie: the only things that come on are accessories. The kill switch is the toggle type with the lanyard snap that pulls the toggle down if you go overboard. Not the most technical method of testing. I will get in there with a meter on friday.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Instead of running the risk of apparently aggravating board members, lets postpone discussion I guess until I can go get a serial number and exact specs. Also i will meter test everything and replace the coil to see what happens. (I already have an extra)

Don,... If you have any idea where to look for those fuses on the engine (location) it would be great. for the life of me I saw nothing on the engine that resembled a fuse. There was a breaker reset below that Mercathode thing that I pushed but it wasnt tripped to begin with.

 

[Reel Poor]

Re: 305 EFI electrical problem Please Help!

The Mercathode is an electronic system that helps protect against Galvanic Corrosion.

 

[newport dave]

Re: 305 EFI electrical problem Please Help!

A 2001 EFI smallblock would have a Thnuderbolt V ignition. I doubt you have a coil failure, they don't go bad that often and the injectors would still pulse if the coil was bad.

When you said that the kill switch would "reset like it's supposed to", I guess you mean the shift interrupt switch. So if the interrupt switch is operating correctly my guess would be Ignition Sensor failure, a very common problem on the Tbolt distributors, and would cause the symptoms you are talking about.

Dave

 

[Reel Poor]

Re: 305 EFI electrical problem Please Help!

So if the interrupt switch is operating correctly my guess would be Ignition Sensor failure, a very common problem on the Tbolt distributors, and would cause the symptoms you are talking about.

Dave

With the exception of this statement made in his first post.

I also put a test light to the 2 posts on the coil and turned the key to the on position and there was no power.

 

[newport dave]

Re: 305 EFI electrical problem Please Help!

Reel poor,
My bad. It also says he has a Bravo drive, so he doesn't have a shift interrupt either.

I try to filter out the stuff that could be misleading, for instance he said "I put a test light to the two posts on the coil", does that mean he put the ground side of the test light on one post and the positive side on the other post? If so, it means nothing. When he said that the fuel pump comes on when you turn the key, that tells me there is probably power at the coil.

So yes, I'm guilty of trying to "read between the lines" and maybe not reading all the information posted.

My "gut" still says Ignition Sensor.

Dave

 

[Don S]

Re: 305 EFI electrical problem Please Help!

Dave, if you have a look in manual #24, is shows using both the TB and the EST ign systems on 5.0L engines. He also has an Alpha drive (see post #6).

bhdau, do you have a standard round based coil? If so, that is the Thunderbolt coil. The EST is a bit of a small box shape.
If you have the thunderbolt, your fuses on the engine will be in a fuse holder about 3" long and 1/2" thick with 6 wires going into it. Pull the cover off the top and there will be 3 fuses underneath.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Thanks for so much input. I just got back from Vegas (thank god) and Im about to head out to where my boat is stored to do some more testing and searching for those fuses!!! Also, yes the coil is the round cylinder standard chevy looking type. And when I tested the coil I grounded the neg wire on the block and the motor mounts and probed the positive side of the coil. I think that was the right way

 

[Reel Poor]

Re: 305 EFI electrical problem Please Help!

If you don't find the problem remember to get the serial number.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Is replacing the ignition sensor a complicated job? If not, what do those things cost? Just curious b/c my boat is a long way from a parts dealer, maybe I should buy one pre-trip. Also do you know if those fuses that he was talking about are just inline with the rest of the wires or if they are mounted somewhere specifically on the motor?

 

[Reel Poor]

Re: 305 EFI electrical problem Please Help!

The sensor, which is in the distributer, ia about 60 bucks and is not hard to change but you will probably destroy the rotor when trying to remove it ("it" being the rotor). I doubt it's the sensor because that would not cause no voltage at the coil. It sounds like you checked for power right if you had a good ground, the key was on and the test light works. I really believe you will find a fuse or ignition system relay problem. If your fuel pump is running you could switch places with the ignition system relay and the fuel pump relay to eliminate relay problems. If the problem moves......wa laaa

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Crap.... No luck. Replaced ALL of the fuses and the coil. Still no power to coil and no fuel injector function. Literally everything else has power. I wedged myself in places in that engine compartment that I didnt think I could possibly get into and could not find a loose wire or connection anywhere. I am completely stumped. The engine serial number is 0L6207 and 8 or 3 and 4 or 0 for the last two digits. They were too worn to read accurately. It has a Packard International wiring harness on it? And it is a Thunderbolt ignition. ANy more ideas? Also how do I find the relays and you can just switch them?

 

[Don S]

Re: 305 EFI electrical problem Please Help!

Amazing what a few numbers can tell you. the (8 or 3) was the first I checked. the 8 was used with some 4.3L engines, the 3 with the 5.0.
The last number (0) was for a SeaRay also, but a 29 with twins. the (4) was for a boat like you mentioned.
Here are some other SN and Model numbers you may want to right down and keep somewhere near your computer. You need them for parts also.

Product
ENG: 0L620734 4M32037M1 MERCRUISER 5.0L BRAVO EFI
DRV: 0L740970 5441500LS MERCRUISER BRAVO 3 2.20:1
TRN: 0L815944 6211001LS MERCRUISER BRAVO TRANSOM
SeaRay 240DA HIN SERV1864H900

It's actually a 2000 boat and power package, not a 2001.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Thanks for the info. The boat was my wife's fathers. He passed away from cancer before we met and there was some confusion over what year the boat was. It was bought in 2001 so I guess thats where the idea came from. I guess a holdover from the previous model year on the lot. It had been in storage since 2003 and has 17 hours total on the boat itself. So as you can imagine its in great shape overall. With the new info that you have any other ideas? Also, just curious, are you a hunter/fisherman? I have always wanted to go to Alaska. My dad has been; caribou and salmon trip. Said it was one of the most memorable experiances of his life. Anyway, I am thoroughly stumped on what to do next. There isnt a boat mechanic around here that will touch it for weeks and I really would like to get it running by sunday to take my parents out...

 

[Don S]

Re: 305 EFI electrical problem Please Help!

I have Service manual 24 right here in front of me. This would take a while to go thru the several pages of wiring diagrams and figure out what was what if the boat was in front of me. Till you find that cluster of 3 fuses and find out if they have power to and from each fuse, and find the 2 relays and trace the wires for the system you have. Hate to say this, but it just ain't gonna happen by Sunday.
Since you have power to the fuel pumps, the main connections that feed the ign wiring uses the same power feed. It has to be in the fuse, or relay or the wiring. But I can't tell you every wire to check and what you will get in all cases.
Here is a wiring diagram showing the wiring for the power to the coil. Hopefully it will help.
15 is the ignition relay
14 is the fuel pump relay
16 is the fuse block with 3 fuses
18 is a connector to the start / charging harness
19 is a connector to the engine circuit breaker

These engines change every year, so I have no way (or pictures) of telling you where to find the connctors, fuses, or relays. Except that they are on the engine.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Thanks Don. I found those fuses earlier when I was out there and replaced them even though they didnt look blown but my multimeter is apparently broken. Looks like a trip to home depot is in order.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

By the way, awesome wiring diagram. Its really gonna help. I saw those relays earlier today. Not sure whether it would be wise to switch em and see if the problem moves b/c the wiring doesnt seem to be even close to each other(grounds, etc). Might just buy the ignition relay and hope for the best along with a new multimeter if the relay doesnt work. What a pain in the *** this has been already with this boat. Been on the water once with it so far this year.........

 

[Reel Poor]

Re: 305 EFI electrical problem Please Help!

Locate the three fuse cluster and check the fuses first and identify the relays.

Disconnect the ignition system relay, (you should be able to identify it by wire colors from the diagram RED, RED, PINK. & BLACK) with the key off check for power on the red wire. One of the red wires should have power. Now connect test light clip to 12 volt source and probe the black wire in the connector. If the ground is good the test light will light. Now reconnect the test light to a ground source. Turn the key to the run position and check for power on the pink wire, you should have power. If not check ckt from ignition switch, kill switch, main engine harness connector, and charging/start system harness to ECM/EFI harness connector (Ref #19). If you have power on the pink wire, use a jumper wire, and jump the two red wires in the connector together and check for power at the coil. If power at the coil the engine should start and the relay is bad. If no power at the coil the ignition system fuse is bad or there is a wire problem between relay and the fuse or between the fuse and the coil.

Although the wires may look different the relays are interchangeable.

I believe you are going to find a bad fuse in the three fuse cluster.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

That is awesome. That you for the instructions. Headed back there now after I print this off. Going to go ahead and buy a relay on the way. Thank you so much. Hopefully I will be up and running shortly.

 

[bhdau1]

Re: 305 EFI electrical problem Please Help!

Just a quick update and a very big thanks to Reel Poor and Don S. After replacing all the fuses I could find and tracing every electrical connection I could I figured out that it was in fact the IGNITION SENSOR in the distributer and a bad coil. So it was in fact 2 different problems at once. Through the instructions you both gave me along with that very helpful wiring diagram I was able to trace it to those two things. I replaced the coil. Then I had power to the coil showing and power inside the cap, but no power getting to spark plugs. I was in fact able to remove the rotor without damaging it and found the only ignition sensor at the lake on a used motor with a cracked block at one of the marinas. The guy sold it me half price and voila! She fired right up and I enjoyed time with my parents on the lake yesterday. Thanks a milllion. Im headed back to the lake here in a few minutes to enjoy memorial day on the water. By the way Reel Poor, Im down in Gulfport Ms quite a bit. We do some serious fishing down there. I was in the Gorenflos Cobia Tournament a few weeks ago and will probably be down there again before too long.(no ling, only caught a bunch of mahi) Ill send you a PM when I come next time if you likle to fish and have nothing to do.