2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

[Pupek]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

I am having the same problem on my merc 3.0, and have replaced all ignition stuff (coil, point, cap, rotor), retimed, etc. I think I have it narrowed to a fuel problem as many have mentioned here. Some testing I did to verify this - you may want to try as well:
1. Eliminate bad fuel, fuel tank, pickup, checkvalve, 'sock filter', by running a clear hose from an external gas can to the input side of the filter.
2. Eliminate fuel pump, by running a hose durectly to the carb, and holding it high in the air, attached to a funnel - this guarantees gas gets to the needle valve - there is no pressure needed beyond that needed to ensure gas gets to the needle valve. When you do this make sure the input side of the fuel pump is still disconnected from step 1.
3. Run a compression test - Autozone will let you use their compression tester for free - it's very easy to do. This eliminates bad valvetrain, pistons, rings. You should get over 100psi without adding oil.
4. Back to the fuel - try this experiment - put some gas in a water bottle, and poke a small hole in the top. run the engine up to the RPM where it starts popping and squirt a stream of gas into the carb. Try to keep the same RPM, and even go higher, and see if the popping goes away - I did this, and it eliminated the popping in my engine.

I tried all of the above (and more - replaced carb, new manifold, new heads last year), and still can't find the root cause. If you have the same results, I think it's safe to say we have the same problem. If not, hopefully this gives you more ideas. Good luck!

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

i have also elimated bad fuel as you did in step one... i eliminated the fuel pump differently by check fuel pressure and volume flow .....my compression is also 180 per cylinder without oil.... the only test i did not do is the water bottle with fuel because i am afriad my bachfire will come back at me .... my problem only occurs under load (on the water) so it is also hard to do this ..... i just dont know where to go next

 

[TowRoper]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

have you checked your springs in your advance under the distributer cap? i had this problem a long time ago and it ended up being one of the springs, its a long shot but an easy thing to check?

 

[RichSmall]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

I just entered a new thread above (RichSmall - 4.3 Mercruiser) and have about the same challenges. I keep going back to the shop, pay for more part replacements and still have the same pinging, etc. We have done about everything you did, except replacing the electronic module. Did you ever resolve your issue?

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

my issue is still ongoing and my ditributor is electronic and believe it does not have wieghts or springs......... but as an update i have noticed my tach works normally from idle to about 1500-1800 rpms after that it goes a little crazy but to describe it at about 2000 engine speed my tach will float between 3500-4000 gradually rising and sinking sometimes fast sometimes slow..... for a second it make come back and read the right rpm then goes crazy again ........... at wide open throttle or close to my tach will do the same behavior except its reads from 5k-7.2k .......... the tah is not broke does it with my autometer pro comp tach sunpro tach and my faria tach............. i think maybe i have a electrical issue ...................... update on my noise i will get my pinging and backfiring at a lower rpm now maybe at anything about 3k used to be above 4k the pinging is going to be defined by me as a spark knock from a rogue spark or some sort of electrical short and the backfiring from a misfire .................................... any help????

 

[futz]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

tach problem try this: lay on your back locate the back of the tach there should be a switch for 4-6-8 cylinder cycle back and forth the switch maybe that will fix your problem. Also make sure the wires are good back there.

To the pinging, seems you tried ALMOST everything. Want to try one more thing?

Yank off the valve cover, and with the motor running re-adjust the valves, seems to me they may be to tight.

And to the other people who jumped on the thread i just don't understand why you don't start your own thread, i got very confused, and didn't know who to reply to first.

 

[RichSmall]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

Not yet! My certified Mercruiser mechanic is going to take it out on Puget Sound on Wednesday so they can test it under load. One thing we haven't done is change the plug wires. I learned yesterday that bad plug wires can crack the tower on the coil and in the last month I have had two cracked coil towers. The mechanic did not think it was relevant and just chance that the new coil cracked right away. I have a notion to buy a new set of wires and stick them on myself and see if that makes a difference. The trouble is, if I muck in it, it gives them a way out. Please let me know what luck you might be having. I will keep you informed.

 

[RichSmall]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

Sorry, I will stick to the thread I started.

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

please keep my thread in mine as will i can we can give each other ideas...... the tachs are set for 4 cylinder motors .... its is not in the tach ..........i have a hard time seeing it being in the valves since my motor does not do it every time or constant it will do it for a few seconds then not for anywhere from 10 seocnds to 5 minutes.........some times it does it more than others .... i feel if a valve was tight it would be constant and the same amount ...... compression test is 180 on all cylinders

 

[Bondo]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

i did notice today that the outdrive only lets water out the right side when facing the drive and more exhaust gas on the left. Is this normal when being ran on muffs??

Ayuh,... You might have a burnt up Shutter blocking the exhaust flow....

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

thats new and been replaced also

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

i have an update while moving wires i hit the distributor and it cause my motor to back fire...... any ideas

 

[fat fanny]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

My Faria tach is speratic as well on my 96 3.0 LX and it drives me nuts but I believe it all revolves back to one thing and that is an electrical issue! Try this.In the dark open your engine hatch and start her up and look real close for a blue arc @ all electrical connections and components especially the coil wiggle all plug wires and check and clean all grounds. Also did you replace the module with the oem GM or after market? the after market mods are a waste of money learned that from experience the extra 30.00 is worth it. Another thing you may try is readjusting your valves the higher octane doesn't always react well with the older engines valves (just a shot). And as for the carb you could of had the wrong climate jets installed on your rebuild and or new carb the 3.0 mercarb has I believe 3 to 4 intercangable jet and veturi possiblities which could definately result in a lean condition depending on your climate. And one last thing is your oil level correct if to high it could cause your lifters to colapse. Just remember try the most inexspensive issues 1st and trouble shoot them until there proven out and then replace suspect parts one @ a time but to me it sounds electrical. Good luck and post back with results. Just noticed something on the last post of yours take the distributor off and flex it a bit and see if there is any cracks in it that definatly will cause this pining issue that pretty much narrows most of you issue to electrical sort misfire and or lose connection.

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

carb is set up correctly and the boat has had 93 since new ..... used a oem module

 

[jtybt]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

I seem to have missed it, but did you read your spark plugs?

Your 'pinging' may not be pinging/detonation. Keep the symptoms coming.

Do you by any chance have a vacuum hose from the carb base to the valve cover?

 

[bigbrownbuku]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

thats new and been replaced also

did you find all the old pieces though...

 

[garyr]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

i have also elimated bad fuel as you did in step one... i eliminated the fuel pump differently by check fuel pressure and volume flow .....my compression is also 180 per cylinder without oil.... the only test i did not do is the water bottle with fuel because i am afriad my bachfire will come back at me .... my problem only occurs under load (on the water) so it is also hard to do this ..... i just dont know where to go next

a problem you may have is a live wire grounding out when you get to full speed ,because of vibrasion ,as for pinging ?

 

[garyr]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

it's sounds to me like you do have a electrical problem. i would be looking for a live wire that has been rubbing from vibration and causing it to short out, this would cause the back firing.

 

[benz660r]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

im going to try to reply to everyone here so bare with me .... the exhaust shutter was in one piece actually in good condition but replaces anyways so there was no pieces.... as for reading the plugs they look perfect in color and are correctly gaped......... the entire motor has no vacuum hoses at all .... valve cover breather is not block and works so its not coming from there


Now for my update to everyone here..... i was looking for a bad wire or connection and was shaking wires and fiddling connection to try and get some sort of clue to where it is coming from ..... well long story short after getting nothing for about an hour i got a little angry and began to lightly and i mean lightly tap on the distributor ..... my motor sputtered and stalled, and would not restart after a little bit i got it to re fire and i began to tap the distributor less than running into someones wake would and what do you know the problem i get on the water were occurring in my drive way...... i went to bay liner and the mechanic there said that the pickup is possible to be changed if you rebuild the distributor so i bought the necessary parts and will be trying this...... i asked him if this was a common problem and he said not common but not uncommon either, he further said it is a bunch of very thin spun wire that can break down or start to fail from corrosion. He also stated that he would recommend trying this next because a failing part like this will causes my issue and "reek havoc on a motor" ...... if any one has nay other ideas let me know and i will also let you know what my conclusion is

 

[fat fanny]

Re: 2004 bayliner Mercruiser 3.0l pings above 3800 with backfire

im going to try to reply to everyone here so bare with me .... the exhaust shutter was in one piece actually in good condition but replaces anyways so there was no pieces.... as for reading the plugs they look perfect in color and are correctly gaped......... the entire motor has no vacuum hoses at all .... valve cover breather is not block and works so its not coming from there


Now for my update to everyone here..... i was looking for a bad wire or connection and was shaking wires and fiddling connection to try and get some sort of clue to where it is coming from ..... well long story short after getting nothing for about an hour i got a little angry and began to lightly and i mean lightly tap on the distributor ..... my motor sputtered and stalled, and would not restart after a little bit i got it to re fire and i began to tap the distributor less than running into someones wake would and what do you know the problem i get on the water were occurring in my drive way...... i went to bay liner and the mechanic there said that the pickup is possible to be changed if you rebuild the distributor so i bought the necessary parts and will be trying this...... i asked him if this was a common problem and he said not common but not uncommon either, he further said it is a bunch of very thin spun wire that can break down or start to fail from corrosion. He also stated that he would recommend trying this next because a failing part like this will causes my issue and "reek havoc on a motor" ...... if any one has nay other ideas let me know and i will also let you know what my conclusion is

Did you look @ the distributor cap for cracks? if you didn't it's worth a shot before you dive into the distributor rebuild. Post back on results and price of distributor rebuild. Good luck!