Mercruiser 3.0 Delco EST wont start

Maxum2006

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Feb 24, 2012
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PLEASE HELP!!

I have a 2006 Maxum 1800mx with a Mercruiser 3.0 Inboard engine with the Delco EST ignition system.

Just for background info - we bought the boat brand new in 2007, so no previous owners or aftermarket modifications etc. The engine is as standard, and has done no more than 15-20 hours in Sea Water of the coast of the UK.

The problem- the engine is very very difficult to start, last weekend I tried to start but just heard a clicking noise, replaced battery and still same problem. I eventually traced problem to a bad connection in the battery isolator switch (red key breaking the positive terminal from battery) and once replaced the boat cranks but would not start.

Next we drained the fuel tank and put 20 litres (4 gallons) of fresh petrol (just incase this had an effect) but still no luck. When removing the air filter I could see fuel squirting into the carb.

Next we replaced the spark plugs x4 with the exact same that have been on the boat from delivery from the factory when new.

Next we gave the carb some (easy start) and still it kept cranking.

I ensured that the boat was level on the trailor when starting as I noticed that the back plug (nearest the prop) seemed to be wetter than the front plugs when the boat was at a slight angle when hitched to the car, so I unhitched the trailor and made the boat engine level. ( I am not sure if having the boat level makes a difference but I tried that just in case)

After leaving the boat for some time it did eventually start, the water flushed out looked a little orange but nothing you wouldnt expect after being idle for about a year or so.

I let the boat idle for about 30 mins and engaged forward and reverse and revved while in neutral. I switched the engine off, then on, then off etc and it worked perfectly. However after switching the engine off to go for a 30 min break, upon returning the engine wouldnt start. Just kept cranking and cranking, even with aero start in the carb. Eventually like last time it fired up and ran fine.

This is very very strange as it sometimes starts and sometime doesnt.

My next steps of attack are;

1. Test for a spark when the engine wont start again. I have bought a spark tester, a tin of carburettor cleaner just incase the jetts are blocked up.
2. I have a mercruiser manual for the engine, where I will be testing the coil, ignition module and pickup coil. I will post the results on here but have a feeling that they are all fine as it does run sometimes

Before I start these tests, can anyone suggest anything else? Certain people have said to check the carb to see if the choke is sticking on, others say to check for bad connections etc??

I may be jumping the ahead slightly, but when checking to see that all wires where not loose I noticed a switch that is situated on top of the shifter plate (where all the mechanisms are for selecting forward and reverse). I believe it is called a 'shift interuptor switch', and primarily stalls the engine whilst running to allow the selection of neutral from forward or reverse position, I checked this switch using my ohm meter and seems to be working fine, however, whilst doing some google searches on this switch, it appears that if you where to alter the timing of the engine, if you follow the manufacturers and many procedures online exactly, it specifically says to disconnect the wires to this switch, and bypass the switch by connecting the harness wires together (bypassing switch), when I did this it causes the engine to stall (apparently it is just supposed to reduce the revs), now surely this is something that cant be right on my engine, how on earth am I supposed to set the timing on the engine if it stalls when I bypass the shift interuptor switch? The only difference I did compared to when you set the timing according to mercruiser manual is that when I connected the two wires together (bypassing the shift interuptor switch), I did not also ensure that a jumper lead was inserted to connect the two normally hanging free wires from the ignition module (apparently this puts the engine into base timing). Personally I cannot see how connecting those two wires from the igniton module would stop the engine stalling when the shift interuptor switch is bypassed. But I may be incorrect? Just some further info? Maybe my timing is so out that its causing the engine to stall when bypassing the shift interuptor, but his is just my theory and limited knowledge so please dont quote me on it????

Any suggestions as to what to do next would be greatly appreciated, sorry about all the long text but want to fill you in with all info!!

Cheers Dave!!
 

SeattleMatt

Petty Officer 1st Class
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Jun 22, 2004
Messages
237
Re: Mercruiser 3.0 Delco EST wont start

I think stuck choke sounds possible, are you checking to make sure the choke is fully open when you restart the engine after sitting for 30 min? There is some trickiness to the adjustment screw on the mercarb holding the choke open/closed. Make sure it is fully open and watch it when you are starting the motor to make sure its stays that way. Also give it a little gas when starting, I usually use about 2/3 throttle to get it going.

Carbs are junk design, especially on mercs, they should make them illegal to build. I'm surprised they are still allowed in Europe.
 

SeattleMatt

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Re: Mercruiser 3.0 Delco EST wont start

Also, the shift interrupt, WILL kill the motor completely, it is designed that way.
 

Maxum2006

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Feb 24, 2012
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Re: Mercruiser 3.0 Delco EST wont start

Also, the shift interrupt, WILL kill the motor completely, it is designed that way.

Thanks for the reply, however, why when reading the SELOC Mercruiser manual
And other sources that describe how to set the timing, they all say to bypass the switch and connect the two wires together. I know it does kill it but surely it shouldnt or the manual and all literature online is incorrect?
 

Maxum2006

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Feb 24, 2012
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Re: Mercruiser 3.0 Delco EST wont start

I think stuck choke sounds possible, are you checking to make sure the choke is fully open when you restart the engine after sitting for 30 min? There is some trickiness to the adjustment screw on the mercarb holding the choke open/closed. Make sure it is fully open and watch it when you are starting the motor to make sure its stays that way. Also give it a little gas when starting, I usually use about 2/3 throttle to get it going.

Carbs are junk design, especially on mercs, they should make them illegal to build. I'm surprised they are still allowed in Europe.

Thanks for the reply Matt, event with slight throttle then it doesnt start. It normally starts with no throttle, it should do at least! Anyway, back to your theory on the carb and the choke, the choke is electronically controlled
on my motor, I have limited knowledge on the carb choke but will use my manual to diagnose. Could you briefly describe how to diagnose if my choke is sticking?

Many thanks
 

presley2

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Re: Mercruiser 3.0 Delco EST wont start

As far as the shift interrupt switch is concerned it temporally kills the ignition (NO Spark) when activated on all MerCruiser carbureted engines. It only retards timing on EFI engines regardless of what your aftermarket service manual says. The reason this happens is so the sterndrive will come out of gear easier. To set ignition timing you do have to put the ignition system into a service mode as described in your service manual but the only reason you would need to do that would be if the distributor was turned or removed and then reinstalled. Otherwise the ignition timing should be the same as it was when the engine ran correctly.

Note your engine MAY not have a choke plate. In recent years MerCruiser has introduced TKS engines (Turn Key Start) they do not use a choke like older engines. Instead they use an enrichment module that does basically what the choke did and it is controlled by the ignition control module. If your engine makes a sucking noise like it has a vacuum leak when you first start it up cold and that noise goes away after the engine warms up you have a TKS engine. It should also say TKS on the plastic carburetor cover.

Why the engine has always run bad.

First if you changed anything set it back to what it was originally set at.

Second when you start the engine if it is a TKS engine DO NOT advance the throttle leave it in the neutral position. The TKS is designed to operate with the throttle plates in the idle position. Advancing the throttle will make the engine hard to start. You might pump the throttle one time to wide open throttle and then back to idle if the engine sat unused for three months or more other wise just turn the key with the throttle/shifter handle in the neutral position.

Third if the engine runs rough after it is warmed up it may need the idle mixture adjusted. All MerCarbs have an idle mixture adjustment but in recent years you do have to have a special tool in order to make that adjustment. If the engine shakes violently the carburetor may be misadjusted. Correcting this adjustment will make a big difference in how the engine runs. I have seen many new 3.0L engines come from the factory with the idle mixture misadjusted.

Fourth don?t forget to make sure the emergency lanyard switch is in the ?RUN? not ?OFF? position.

Try these items first.

Attached is a picture of a TKS MerCarb notice the round tube on the side with the two wires coming out of it. A carburetor with a choke will have two metal plates one in the bottom of the carb bore (throttle plate) and one at the top of the carb bore (choke plate). A TKS MerCarb will only have one metal plate (throttle plate).

View attachment 134092
 

fat fanny

Lieutenant Commander
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1,935
Re: Mercruiser 3.0 Delco EST wont start

I would also highly suggest getting a freee download of a merc service manual those seloc's are only worth in Don S's words "to kneel on" and then completely going through your wiring harness and doing a thorough continuity test and then cleaning,lubing and tightening every single connection after sitting as long as you said it could have numerous corroded connections also go to the top of the this page and open the adults only sticky and read it completely it has a large amount of very usefull maintenance information including answer to some of your issues. And if you do have the TKS good luck hope this helps but I would strongly urg you to read the sticky I suggested and check all those connections. My Ray suffered this once and a loose connection solved it.
 

cyclops2

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Apr 19, 2011
Messages
1,237
Re: Mercruiser 3.0 Delco EST wont start

I do not like the hard restart after a a well heated up engine.
That to me, smells like a fuel pump diaphram or electrical ignition module dying a SLOW death. Had one just like that on a outboard. For a year. After a FULL cool down. Instant start.

50 hours ??? ALMOST ALWAYS a electronic part that is a reject. Bad luck
 

achris

More fish than mountain goat
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May 19, 2004
Messages
27,468
Re: Mercruiser 3.0 Delco EST wont start

... the SELOC Mercruiser manual....

:facepalm: seloc is not a manual. It's a knee pad, hand wipe or fire starter...

You need the GENUINE manuals

Engine -> http://www.4shared.com/document/xEKlzP-s/Service_Manual_26.html
Drive -> http://www.4shared.com/document/dPQUcyn_/Service_Manual_14.html
TKS carb -> http://www.4shared.com/document/SNqPsoNI/Service_Manual_41.html

I would look at the timing curve. Check the base timing is correct and that the system is advancing on throttle up...

Here's a link to a very good explanation of the shift interrupt system -> http://forums.iboats.com/showthread.php?p=1930449#post1930449

On the EST 3 litres once the white wires (on the distributor) are linked, connect the shift interrupt wires together. The linking of the white wires will stop the linking of the shift interrupt wires from stopping the engine. Page 9 in section 4B of the engine manual I gave you the link to...

Chris.....
 

dingdongs

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May 29, 2009
Messages
649
Re: Mercruiser 3.0 Delco EST wont start

Do you have spark?
on my v8 the pick up went inside the dizzy cap.there is a test for it but mine over a season started breaking down and left me stranded on the water a couple of times thankfully only a few hundred metres from the shore on a tidal river.there is a method for testing it which someone may be able to post and a spark tester was all i had to purchase to test but it proved the point of what the fault was and was only a case of striking a wire to earth.
this may be of help and i had a thunderbolt v ignition system.
 

cyclops2

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Re: Mercruiser 3.0 Delco EST wont start

Here are the basic parts for a BOAT or CAR tool kit.

used or new 1/2" drive sized rachet, 6" extension or whatever length you need, 1/2" drive spark plug socket.....that HAS A RUBBER BOOT INSIDE TO HOLD THE PLUG SO IT DOES NOT FALL OUT during removal or installing the sparkplug. 1 roll of plastic electrical tape

1 FULL SET of spark plugs.

Use 1 of the NEW plugs to test for a good spark. Use the tape to hold the plug AGAINST the metal part of the engine.......WITH THE PLUG GAP FACING YOU........You will need a BLACK OR DARK CLOTH to block out sun light. That allows you to see & hear the spark.
 

Maxum2006

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Feb 24, 2012
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Re: Mercruiser 3.0 Delco EST wont start

Ok, thank you all for your replies, I would just like to give an update to the situation;

Last night I was able to take another look at the boat and 'take on board' (excuse the pun) what some of you had advised.

I connected a freshly charged battery to the boat, ensured the master isolator switch was on, gave one pump of the throttle, turned the key and the boat engine just turned and turned.

I then decided to use a 'spark tester' that I had bought (basically a small lamp that connectes in series, and when a current passes through it lights up, and saves any messing about with removing spark plugs), I disconnected one spark plug lead from number 1 cyclinder spark plug, plugged my tester in series with the plug lead and the spark lead and cranked the engine over again. There should have been a flashing / flickering light in the tester but there was none, indicating that there was no spark.

Next I decided to put back the plug lead onto the spark plug on no. 1 cylinder and now place my 'spark tester' between the lead coming from the ignition coil and the centre point on the distributor cap (run in series of the main HT lead), again I cranked the engine but no light, i.e. no spark!!!

Ok, my next logical step was to test that when I turned the ignition key to the first position that I had 12V (live at the power feed to the coil). On my wiring harness it is the purple wire, and when I tested this I indeed have a live of around 13V (due to my fully charged battery). Ok this was one good thing, at least I had power to the coil pack!!

Ok, my next step was to follow the Ignition Coil Testing procedures as explained in both my Seloc manual and the Mercruiser manual kindle supplied by 'ahris' above. The both manuals described exactly the same test. The Ignition Coil results for resistance where exactly what they should be according to both manual, i.e. when the resistance should have been between 0.35 Ohms and 0.45 Ohms, my actual resistance was 0.4 Ohms. Ok, so this proved that my Ignition Coil does not have to be replaced.

Ok, my next logical step was to follow the Pickup Coil Testing procedures again from both Seloc and Mercruiser manual, this involved labelling all of the plug wires before removing from the distributor cap, unscrewing the two small holding screws on the distributor cap, and removing the distributor cap and then removing the rotor arm (just pulls off snug fit). After unclipping the pickup coil and running through the tests, once again the tests indicated that the pickup coil was in compliance.

In both manuals, it states that if the Ignition Coil and the Pickup Coil are in compliance and still no spark then you must replace the ignition module, as apparently this has two failure modes, 'it either produces a spark, or doesnt produce a spark!!!'

Ok, not having the parts available I decided to inspect the rotor arm and distributor cap. Within the distributor cap, the four contact points for each cyclinder looked rather green and scaley, hence I used a fine piece of emery cloth, and lightly sanded the contacts to get a clean finish, also, right in the centre of the distributor cap I noticed a carbon point, the carbon point seemed to be spring loaded, however when I pushed the Carbon Point inwards, it stayed inwards and didnt spring back, hence I turned the cap upside down and gentle tapped the cap, the carbon tip then protruded back out like it had done, I washed the distributor cap in petrol, and blew dry with an air compressor. Next step was the rotor arm, on the top of the rotor arm, where the carbon brush makes contact, the silver connect looked a bit dirty, hence I gently wiped the connection and made it a lot more shiny and cleaner. I wiped the tip of the rotor arm with a piece of rubber hose. I replaced the rotor arm and distributor cap and replaced the plug leads.

Having done all of this I thought it best to give it one more try, I connected the spark tester again in the same manner as before, and low and behold the light appreared and the engine started.

I removed the tester, and started the engine up again, no problem stopping and staring it. Left run for 30 mins again, and started no problem. Just for a test while the engine was running I clicked the Laynard Switch by the trottle arm to the OFF / STOP position and the engine stalled as expected, I tried to start the engine with the switch off but I wouldnt start as expected, I turned the switch to the RUN position and the engine fired up completely.

Ok - so all seems good at the moment, but this boat has a habbit of doing this, (starting fine one minuite and not the next), so I will be testing again in a few days and post the result.

Just a few questions, why did it not spark between the Ignition Coil Pack and the centre HD Lead point on the Distributor when I first tried the test, the only reason I can suggest is that I cleaned the top of the rotor arm connection and the carbon point, and the corosion before was stopping a contact to be made for the earth between the carbon and the rotor. But to me this sounds strange? Why would the boat suddenly start one minute and not the other, surely either it makes contact or doesnt, it cant sometimes make the contact and others not?

Thank you for taking you time to read.

Please let me know you thoughts on the issues, anything I have missed???
 

Technorunner

Petty Officer 3rd Class
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Re: Mercruiser 3.0 Delco EST wont start

When you connected the lamp on the wire from the coil to Dist. Since the spark dident go the flash did not appear. It would be if you took the wire and just lket it hang in the air, The coil produces the spark but it cant go any where since not grounded.
If you would have taken a sparkplug and connected it directly to the wire from the coil you would have seen the spark.
 

BRG25

Chief Petty Officer
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Jul 13, 2001
Messages
528
Re: Mercruiser 3.0 Delco EST wont start

Time for a tune up. You have new plugs (did you gap them?). Now a new cap (with gasket), rotor and spark plug wires would be next. Perhaps check your timing and your idle mixture.
 

fishrdan

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Re: Mercruiser 3.0 Delco EST wont start

The only thing that would have stopped the ignition (from what I read/remember) is the cap's coil button being stuck up in the cap housing. If the rotor's spring arm was too far away from the cap's button, spark might not have jumped to it..

BTW, I use a timing light to test to see if spark is present. It's easy to use as you just clip it onto a wire, and can move it to other wires easily. IT won't show how good the spark is though....

I agree with a tune-up, plugs, wires, cap, rotor. Might as well do the fuel filter(s), oil filter and oil while you are at it, if it hasn't been done recently. Along those lines, when was the last time the impeller and drive oil was changed? Bellows??? A 2006 is due for bellows (unless you want to replace more expensive parts).
 

Don S

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Re: Mercruiser 3.0 Delco EST wont start

See if you have power on the coils purple wire while the engine is cranking. Could be nothing more than a bad ignition switch.
 

fat fanny

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Re: Mercruiser 3.0 Delco EST wont start

Good point Don I had the same issue 2 seasons ago intermittant start new switch solved that!
 

Maxum2006

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Re: Mercruiser 3.0 Delco EST wont start

Ok all. An update.

Thanks again for all posts but I have some news. The boat has been sitting in my garage for about 2 weeks. Today I managed to clamber in and give her a start.

I connected a freshly charged battery, secured properly, gave 1 pump on throttle. Turned the master switch on, then the ignition switch, on comes the buzzer for oil pressure, all as it should be. I connect my spark plug tester (100% working and tested) between plug lead 1 and number 1 spark plug, turn the key, and the engine just turn and turns with no spark!!

Try plug lead between coil and centre of distributor and still no spark (light)

So, check purple wire to coil with meter, and yest 12-13v when key ignition on!!

So next step- remove all plug wires, remove distributor cap like ladt time, ensure all metallic contacts are clean and shiny (they are) ensure carbon billet is fully extended (it was) cleaned rotor arm and contact point and re-assembled.

Put plug lead tester as before and still no spark either between coil and distributor or distributor and spark plug. I even tries the tested between the coil and used a sparkplug grounded to the negative terminal of the battery and still no spark (light on tester).

Please can you advice, PLEASE READ ABOVE FOR FULL SCENARIOS ABOVE.

P.S I really dont think this has anything to do with fuel, carb etc but I could be wrong unless someone knows if the TKS carb could effect spark (doubtful though), the engine has no spark, like I said it starts when it wants to sometimes? And when it does start it once its fine, it doesnt like to sit for more than a few days by the sound of it. What could cause a soark to be there somedays and not others. Sounds electrical but what is the key???

Many thanks
 

Maxum2006

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Re: Mercruiser 3.0 Delco EST wont start

Thanks, please read my latest post, I will try if the purple wire still remains live when I crank, it definately say 12v when idle, but will check when cranking and post back.
 

Don S

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Re: Mercruiser 3.0 Delco EST wont start

So, check purple wire to coil with meter, and yest 12-13v when key ignition on!!

I asked this before, will ask again. Do you have voltage to the purple wire on the coil WHILE the engine is cranking over with the starter. That is what you must answer at this point.


EDIT you posted while I was typing.
 
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