Engine Popping/Backfiring

[bagzzz]

thank you bell

[chpthril]

Ok, my computer has for some reason uninstalled the audio driver, so I cant hear the audio in the video, but I do have one question about how you checked the timing: Did you disable the ecm control and put the module at base timing before hitting it with the light?

Also, did you watch the timing light while duplicating the problem? If the light misses a beat, change to a different plug wire and try again. If the light still acts erratic, it's probably a bad pickup or module.

[da.bell]

If this help Chpthril, the video sounds like he is rev'ing the engine and 80% into the video, the rev'ing is reduced and you hear a definite backfire.

[chpthril]

If this help Chpthril, the video sounds like he is rev'ing the engine and 80% into the video, the rev'ing is reduced and you hear a definite backfire.

ok, got it know. did a restart and the audio drivers reinstalled.

man, i'm still feeling secondary ignition, only thing left are plug wires, right?

[AdaminMN]

600 RPM - at the T in BTDC
800 RPM - 12 degrees
1000 RPM - 12 degrees
1500 RPM - at the B
2000 RPM - at the D

A couple things....

"Idle timing should be set below 900 RPM. After initial timing, the advance starts approx at 1000RPM and increases to a maximum of 14 deg BTDC. Plus the initial setting of 8 deg, for a total of 22 deg BTDC. This advance occurs between 1100 and 2500 RPM." ~Seloc Service manual

A weak valve spring may not "slam" shut at high Rpm's either.

Good luck.

[bagzzz]

Ok. I am going to do the wires. I am going to be gone the rest of the weekend, but as soon as I get back, I will order the wires and replace those. I will post an update next week. Thanks again for everyone's help.

[bagzzz]

Plug wires are ordered. Should be here Wednesday.

[bagzzz]

Ok, so I received and installed the wires and nothing changed...

Here are a few more things I noticed that may help:
Every once in a while, you can barely hear (more like feel) a deep explosion when the boat is idling. It is not very noticeable, but when it happens the engine hesitates for a very quick amount of time.

There was some pretty rich white smoke coming from the exhaust and the port side exhaust manifold was much warmer than the starboard side.

Not sure if this is going to help at all. I am about to take the boat into the local mercruiser dealer but they will not be able to even look at it for another couple of weeks. It is 85 degrees and sunny here...

[chpthril]

Ok, so I received and installed the wires and nothing changed...

Here are a few more things I noticed that may help:
Every once in a while, you can barely hear (more like feel) a deep explosion when the boat is idling. It is not very noticeable, but when it happens the engine hesitates for a very quick amount of time.

There was some pretty rich white smoke coming from the exhaust and the port side exhaust manifold was much warmer than the starboard side.

Not sure if this is going to help at all. I am about to take the boat into the local mercruiser dealer but they will not be able to even look at it for another couple of weeks. It is 85 degrees and sunny here...

How quicaly did the white smoke disapate? if it was actaul smoke, such as oil smoke, it would linger like a good fart. If it was steam, such as from a blown headgasted or cracked block, it would be gone rather quickely.

Have you put a timing light on the coil wire? if the light misses a beat when the probelm happens, you are looking at a module or pickup.

[bagzzz]

From what I remember, the smoke I was referring to was actually steam. It did not linger around. I will put the light on the coil wire tomorrow.

[bagzzz]

The light did not show any hiccups when lighting via the coil wire. There is a really rich fuel smell when the engine is running. I am now on the waiting list for the local marina here, but it is a 2 week minimum wait. Is there anything else I can do in the mean time?

I am thinking about rebuilding the carb (I am coming from 7,000ft to 1,000ft), but I think that is a little beyond my mechanical ability. Does anyone know of where to find a good step-by-step manual for rebuilding these older Weber carbs?

[Paublo]

bagzzz, you will get better advise on the engine problems from others, than what I would suggest. But I wanted to say sorry about the ankle. I assume that you are a pilot, so that has got to really suck. I love Lake Amistad and what a great place for a skier to be stationed. My daughter and son-in-law were there until last year. Did you ever see a '95 Ski Nautique in the storage yard? It was theirs. Good luck.

[bagzzz]

bagzzz, you will get better advise on the engine problems from others, than what I would suggest. But I wanted to say sorry about the ankle. I assume that you are a pilot, so that has got to really suck. I love Lake Amistad and what a great place for a skier to be stationed. My daughter and son-in-law were there until last year. Did you ever see a '95 Ski Nautique in the storage yard? It was theirs. Good luck.

Thank you for your condolences. You would be correct, I am currently in pilot training so this ankle thing has put me on hold. This is the best lake for watersports I have ever seen. It is one of the largest lakes in Texas and the ONLY other waterski/wakeboarding boats I ever see are my friend's boats. It is not out of the ordinary to go out on a Saturday or Sunday afternoon and literally see miles of untouched glass. Plus, it is already in the 90's here!