305 EFI electrical problem Please Help!

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
I have a 2001 Sea Ray Sundancer 240 with a brand new 305 in it. Took it out and put about 10 hours on it since new engine, ran great, no problems. Trailered it under cover and took it out 2 weeks later and the thing wont start. Starter turns it over but I have found upon further investigation that A., Im not seeing any fuel coming out of the 2 throttle body injectors, and B., there is no spark coming from the coil. Its almost like there is no power being sent to the ignition or fuel injectors. I can hear the fuel pump run and I have reset the kill switch several times, it seems to be working fine. All of the fuses are fine and I cant find any loose wires anywhere. I tested power to the coil by pulling one of the wires to the distributer and there was no spark when I held it close to the cap. 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. Does anyone have any idea what could be wrong here?? Would a bad coil cause all of these problems including no fuel being shot into the throttle body? I would think that it should at least still shoot fuel into the engine. Also, what exactly is that thing called a Mercathode that sits on top of the engine? Mind you, this happened while the boat sat under cover. It worked fine last time out. Any suggestions would be great, Thanks!!
 

Rob454

Chief Petty Officer
Joined
Oct 9, 2005
Messages
508
Re: 305 EFI electrical problem Please Help!

Im assuming you checked the fuses. Sounds liek either a bad coil or a blown fuse. your motor will turn over but if the fuse is blown for the fuel injection or the ignition then it wont start but will turn over
Rob
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

So if its a bad coil the fuel injection will not work either? As in, it wont dump fuel into the throttle body if there is no spark coming from distributer? If thats the case I cant thank you enough. My folks are coming in this weekend and all marine repair places here are backlogged up to 4 weeks. And I checked all the fuses and circuit breakers and they are all fine. Also I should mention it was put on a new trickle charger for the time it sat on the trailer.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 305 EFI electrical problem Please Help!

What Year and Make and model of 305 EFI do you have. Systems are different between Merc and Volvo, and others, along with differences from year to year.

Did you make sure the emergency kill switch lanyard is hooked up properly?
 

bjcsc

Lieutenant Commander
Joined
Jun 1, 2006
Messages
1,805
Re: 305 EFI electrical problem Please Help!

And I checked all the fuses and circuit breakers and they are all fine.

"Checked" as in looked at them or "checked" as in verified current passing through with a meter?


Also I should mention it was put on a new trickle charger for the time it sat on the trailer.

Which would cause me to suspect a fuse or breaker even more...
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Its a 5.0 Mercruiser 305 EFI Alpha I believe.(chevy/GM) Its got the twin throttle body injection. It has a coil and points igniton. It has a circuit breaker that doesnt list anything directly related to the ignition and I checked all of those. It also has a fuse panel underneath the helm that has several blade type fuses and a listing for what each of them are. It has a test button with a green led next to each and every fuse that lights up when you press the button if there is a complete circuit. All of the leds lit up when the button was pressed and I also pulled the clear plastic cover off and pulled the fuses to visually inspect them. The ignition fuse was a 15 amp fuse and looked great. I couldnt find any other fuses anywhere or circuit breakers.(including inline fuses along the wiring harness) Do you know perhaps what the Mercathode thing I asked about is? It has four wires attached to it via loop ends and screws and is a sealed unit that is attached with 2 screws to a bracket that sits atop the engine. The outdrive unit is a Bravo3 twin prop lower. Also should the coil show power to it when a test light is attached with the key in the on position? Or will it only show power when the motor is running or turning over?
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Also it is a 2000-2001 model motor. It is a new block, 1 month old. Used only once and it ran great when I trailered it after last outing.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 305 EFI electrical problem Please Help!

Its got the twin throttle body injection. It has a coil and points igniton.

I would assume you mean the throttle body has 2 injectors. As far as a points ignition, NO WAY. Merc has NEVER used points on an EFI engine of any kind. And hasn't used points on a V8 since the early 80's
What is the Mercruiser SN. of your engine.
You can NOT check fuses, circuit breakers, switches or anything else by looking at it. You need to test with a meter.
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

It has a ignition coil that runs to a cap with contact points on it. I sanded them a little to clean them up while taking it apart. Is that not a points system? sorry if i am mistaken. It has a rotor I think?? Maybe not but it looks like it. The injection system consists of a twin barrel intake with 2 injectors that sit over top of it. When the key is turned on the butterflies open to the intake. So even if you can see that the fuse is not burned out visually it still can be bad? Also do you know if the injectors would still shoot gas into the intake if the coil was bad? In other words, shouldnt the gas still be shot into the intake and just not be ignited if the spark plugs arent firing? Or does the coil firing also trigger the injectors to apply fuel to the intake? is it all linked together or are they completely seperate and self contained? Im not sure of the serial number.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 305 EFI electrical problem Please Help!

It has a ignition coil that runs to a cap with contact points on it. I sanded them a little to clean them up while taking it apart. Is that not a points system?

No, that is not what is meant by a points ignition system.

When the key is turned on the butterflies open to the intake.

That shouldn't happen, the throttle plates are cable controled from your helm control. Is not electrically controlled.

So even if you can see that the fuse is not burned out visually it still can be bad?
Sure they can be bad and look good........Duh!

Also do you know if the injectors would still shoot gas into the intake if the coil was bad? In other words, shouldnt the gas still be shot into the intake and just not be ignited if the spark plugs arent firing?

The injectors will not fire if they do not have confirmation of ignition from the distributor to the ECM, and that isn't going to happen with points.

Here is something else. If you want to troubleshoot this system, you need a Service Manual (OEM, not aftermarket), you also need a way to read codes and better yet read information from the ECM. But just a code reader will work. You also need a DVM or DVOM and REALLY know how to use it, or you will NEVER figure this system out.
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Thank you sooo much for your help. This is the first fuel injected boat I have owned. All the others were carbed and a little easier to understand. Sorry for the confusion on the whole "points" thing. Hopefully the coil is just bad and a new one will fix this mess. Are there many differences between a Mercruiser OEM coil and a standard small block chevy coil? Or did they use the regular automotive version? One more question, I have a code reader for GM/Chevy products. Is the plug the same on these motors as the auto versions? Or do you have to have a mercruiser diagnostic reader to check for codes? Also are you familiar with the Mercathode thing on the engine and what does it do?
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Again, I want to thank you guys for your help. It is so nice to talk with people who know what they are talking about and who will take the time to help someone new to marine engine troubleshooting. I can pretty much fix anything on my dirt bike, fourwheeler, and car, but this is a different animal and a completely new system to work with. My parents will be very happy if I can take them out on the lake this weekend and it will be owed to the advice and help you have given me. (hopefully if I can get this thing running!)
 

Reel Poor

Vice Admiral
Joined
Jan 29, 2005
Messages
5,522
Re: 305 EFI electrical problem Please Help!

I doubt seriously it's a coil problem. With no power to the Batt+ side of the coil it's not going to run, even with a new coil.

Can you post your engines serial number ?
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Should it show power with the key just in the "on" position? Or would it only show power with the engine turning over? Should I run a jumper wire from the battery to the + post of the coil to test it? I dont guess it will damage anything........
 

Windykid

Lieutenant Junior Grade
Joined
Apr 17, 2007
Messages
1,177
Re: 305 EFI electrical problem Please Help!

It should show power to coil with key on. You need to scan it. But if I were betting I would say your ign module is out, that is what triggers the dist and the injector. You can test the injectors for sure with a set of noid lights. Or take it to a mechanic.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 305 EFI electrical problem Please Help!

Do you have the Delco EST distributor, or the Mercruiser Thunderbolt V distributor?
There are 3 fuses on the engine for either, one for the ECM, one for IGN. and one for Fuel pump. Did you check them with a meter or test light?
There is also 2 relays on the engine, one for fuel, one for ign. Did you check power to them and from them?

One more time
Did you check your emergency kill switch?
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Yes I checked the kill switch. It resets just like it's suppossed to. The thing is, I couldn't find a single fuse on the actual engine anywhere. The only fuse that I could find directly related to the ignition was that 15 amp blade fuse under the helm. Everything points to a bad fuse for me as well. That was my first impression, but for the life of me I climbed all over that engine and couldnt find a loose wire or a blown fuse anywhere. Like you told me, I havent checked with a meter yet. I wont be able to until Friday when I get back from Vegas. Also, Im not sure what the serial number is. Ill have to track that down as well. It is a new long block Jasper reman engine with swapped over accessories. The original motor was the merc 5.0 305 built in 2000.
 

bhdau1

Cadet
Joined
May 22, 2007
Messages
25
Re: 305 EFI electrical problem Please Help!

Oh yeah, another thing, you can hear the fuel pump run when the key is turned on. I feel like such a idiot not being able to figure this out. It is so frustrating. Will that GM code scanner work or is there a specific scanner for Merc?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 305 EFI electrical problem Please Help!

Do you have the Delco EST distributor, or the Mercruiser Thunderbolt V distributor?

You have to answers some questions if you want help. and looking won't tell you if a fuse is doing it's job or not. You have to use a meter or test light to see if power is going thru it.
And trust me, there are 3 fuses on that engine, may be all in one holder or 3 seperate holders, hard to say since you won't post SN, or answer questions.
I tried this, but it won't work today for some reason.

Crystalball1.jpg
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: 305 EFI electrical problem Please Help!

Yes I checked the kill switch. It resets just like it's suppossed to.

How did you check it?

What do you mean that it "resets just like it is supposed to"?
 
Top