Merc 3.0 won't start - but looks like things are workin'

[southkogs]

I've got a head scratcher going here:

'03 - 3.0 - Alpha one.

I crank the engine, and it won't start. I have spark at the wires, but I'm not skilled enough to tell you how much spark/what kind I have. Fuel should be good, but to test the issue I did shoot some starting fluid in the carb. No joy. Haven't tested compression, but I would think even if I somehow blew a gasket - I would at least get a cylinder or two to fire up. Right?

BACK STORY:
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A month or so ago, while towing a family in I caught a line in the prop and the engine shut down. I cleared the line off, and then restarted - everything seemed to be working fine. The next out on the lake, I ran into the problem of the boat not wanting to plane. I could maneuver and move along fine at idle speeds, but try to get it on top of the water and the RPMs would run up, we wouldn't go anywhere. Everything seemed fine otherwise, so I began chasing down a spun hub, thought I confirmed it and put a new hub in the prop.

While I was at it, I decided to change the spark plugs because they hadn't been changed in a while. Had the dude at NAPA cross reference against the AC Delco plugs it was supposed to have, and put a set of NGKs in there. Had 'em gapped at .035 per specs (that I read in one of the Merc manuals). Cranked cranked the engine and it wouldn't start. No stutter, pop or backfire. Just spinning.

After fiddling with it a while, I figured that maybe the plug wires were going bad and I pushed 'em over the edge. So, I just went the full monty: new cap, rotor and plug wires (took forever to get parts). Nope : no change.

Tracked down the correct AC Delco plugs that I think originally came in the engine and found 'em via the local auto parts shop, and also found (in rather large type on the flame arrestor, once I saw it) that the plugs should be gapped at .045. Oops - fixed that. Still nuthin'.

When I test the plug wires, I see spark. But I don't know how to tell how "good" it is (or if I really can).

I'm lost. The boat was running a little rough on occasion before I decided to change the plugs, but never gave me any real trouble. I can't think of anything I've done that would kill the whole starting process.

I could change the coil, it's old enough that changing is probably not a bad idea. But I don't wanna' just start chuckin' parts at it, not knowing what is actually wrong.

Any thoughts before I take it up to the local boat doc (good mechanic, but I don't particularly like the guy)?

 

[achris]

Check, recheck, and check again. Firing order. Check the direction of rotation and that the right wire is going to the right spark plug.

A 'good' spark is fat and blue. If it's yellow and insipid, it's weak.

Did you try putting the old (known good) plugs back in?

Chris...

 

[southkogs]

Yup - Sorry, done those all: Wires are to correct plugs. Firing order is correct. I did try the old plugs. No joy.

I used a test light on the end of the wires to check for spark. I don't have an inline tester, and I didn't try testing with the plug in the wire, but out of the cylinder. I've seen that test, but didn't try that way (don't completely understand it).

The spark I see in the wire boot is not blue, and on one of the wires (#3) I thought looked a little weak. But I am no expert on this at all.

 

[achris]

Occam's razor. It was running before you removed the spark plugs. It won't run after. Therefore something in the process caused the problem. Check you didn't bump something else...

Did you throw a timing light on just to check the spark is fitting at the right time?

 

[southkogs]

Occam's razor is a good way to say it. Kinda' why I'm lost: I thought I back tracked through everything.

I'll check the timing later today. I think I need a new light - haven't used it in a while.

Will the engine still crank with a bad solenoid? I checked wires and things I needed to shift while getting the plugs out, and saw nothing. The breaker up over the valve cover was fine. The solenoid sits just to the left of plug 4, and the coil is kinda' in the middle of everything. Of course I had to pull the wire from the coil, so that's why that one comes to mind. And that solenoid is kinda' close to where I was turning #4, so maybe I bumped it :noidea:

I was also thinking the coil and that solenoid are in the same process, so maybe by fixing one thing I caused something else to break. - - But, the starter is consistently turning, and the engine is cranking.

 

[achris]

EST? (or points)...

Will it crank with a bad solenoid? No..

Chris...

 

[southkogs]

^^^ est

 

[Rick Stephens]

Spark testers are between $10 and $20. Worth having one in your tool box.

Since things were running rough already, pull your water separator and dump contents into a clear container. See if you have some sort of contaminant causing something other than an ignition problem.

 

[southkogs]

Spark testers are between $10 and $20. Worth having one in your tool box.

You must have sent that instruction telepathically. Went and got one after church this morning, along with a timing light.

According to the tester, I'm getting spark on all four. After all of my fiddling, I've got to charge the battery up enough to get turns to read the timing. Tried doing that with the box set to START, but wasn't getting a consistent turn. So, I've got it charging up for a while.

 

[southkogs]

Well ... talkin' with a bud, the battery gave me a question. So, we load tested it. It was weak, but tested okay. Kind of on the edge, so since it was older I decided to go ahead and replace it.

No effect. Still won't start.

 

[achris]

You're getting spark, so it can only be a couple of other things. No compression, no fuel, spark at the wrong time.

Check you have the right plugs. Pull the cap off the dissy and make sure it's turning, and the right way, and with the plugs out, turn the engine until you feel pressure build in #1 cylinder, check the rotor is pointed at the post for #1. I know you may have already done this, just checking... This is a weird problem, so will require some thinking 'out of the box'...

If that all checks out, then with the plugs still out, put your timing light on lead #1 and check it's flashing at the timing marks at the right time (close to TDC).

Chris...........

 

[southkogs]

Haven't done the gig with the dizzy yet: will see if I can get into it tonight.

Firing order is dead on (I've checked that about six times)

I've now got AC-MR43LTS plugs in there. I had NGKs, but they had been cross referenced for me so I wasn't sure if I had the exact right thing ... Now I have an extra set

I can see active spark on all for wires.

Haven't checked compression - I guess I can put that on the list.

Checked the battery, it registered as "okay" but getting toward weak/bad; so I replaced that

I've got fuel flow, but just to see if I can get a chug outta' the thing, I've hit it with some starting fluid a few times. No change.

Slave solenoid sits right up by the #4 plug. I bumped it when I was pulling the spark plug - and I do mean "bumped" not hit, bang or slammed - the system turns, so I'm ruling that out. Unless I should just replace it.

I had replaced the stereo while I was waiting for the plug wires. But it is currently unplugged from the harness just to eliminate another variable.

Any fuses that I should be looking at? The breaker on top of the engine seems fine.

Thanks for the help Chris.

 

[achris]

The only thing electric is the spark, and you have that... Mechanical fuel pump, carb... Nothing electric in those...

 

[Rick Stephens]

What did the fuel look like when you dumped the separator?

 

[southkogs]

Oh - sorry Rick. It looked fine to me. Maybe not as clean as would come out of the pump noidea but not much different.

Typically I let the tank run down to 1/4, and then fill up (not quite topping the tank). The boat gets towed about 20 min immediately after every filling. Effectively the tank gets "turned" rather regularly (at least, that's what I think).

 

[Scott Danforth]

if your battery is weak and it wont spin the motor fast enough, it wont start.

minimum cranking RPM is about 200 RPM

 

[southkogs]

Batt is good. I was probably doing okay until it ran down on Saturday, but the one that was in the boat was weak and getting old. So, I put a new one in yesterday. Crankin' like a champ last night.

 

[southkogs]

Well ... I'm simultaneously happy and embarrassed: the answer did turn out to be firing order, but I'm going to illustrate why in the event that any other mediocre mechanics like me get caught the same way.

I had been checking the firing order against this diagram (see the original up in post #11). I've redrawn it here to add the red marker to indicate the position of cylinder 1:


What got me, was that the connection to the plug wire for number one seemed to be illustrated as being in the forward half of the distributor, closest to the engine block (that's what it looks like, right?). BUT, as it turns out firing point for #1 would actually be one over clockwise in relation to the engine block:



Chris had suggested checking the timing, and I was trying to figure out how to do that on a motor that wouldn't run. So, I was doing a little YouTubin'. Came across a video where the dude had his distributor numbered (I couldn't find a #1 marking on the one I got from Quicksliver ... still don't see it), but noticed it was not where I had been pluggin' in.

Ran out ... swapped wires ... and she cranked right up. eace::doh::rant::embarassed:

I had actually swapped orders once before, but must not have had anything close enough. I didn't want to get too crazy there so not to damage anything.

Thanks for the suggestions y'all. Ultimately it cost me a couple of days boatin', a battery I didn't quite need just yet and a little pride. But hey! ... maintenance is done for a little bit. :lol:

 

[achris]

So, someone in the past has installed the distributor with the shaft 90 degrees out. That's easy to fix.

Chris...

(And I would recommend you do fix it. It bit you in the *** this time, it could easily do it again in the future.)

 

[southkogs]

Okay - didn't know you could do that. I'll look into it. Thanks!