Sputter - Pop - Fart - Go like Heck and Back

[flashback]

Re: Sputter - Pop - Fart - Go like Heck and Back

I had very much the same problem with a 305 in my boat, first start up and it ran fine, 20 mins into the run it started acting up just as you describe.. I changed the fuel pump and all was well again........good luck

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

Outboardguy- I still don’t think its vapor lock. However, your point about the vacuum line between the tank and pump is very insightful. It would seem that I could eliminate the tank, anti-siphon, vent, and lines all the way to the pump with one test. Or am I reading too much into this?<br /><br />Merc 140 Pontoon – I have through-hull exhaust, so that takes care of the flappers. As for the obstruction in the tank, it would seam that outboardguy’s suggestion would help identify/eliminate that possibility. I do have the old components, and have in fact tried placing the old coil back on. No Help. I bought the fuel at Shell for what its worth. Paid Special attention to the ground. No problem there. Keep posting, your ideas are valuable. It would be helpful if you took a look at the diagrams above and let me know about this resistor wire (#8). <br /><br />Sammy 805 – I replaced all the valve springs when I did the heads. Also, looking at figure #2 above, components # 2, #3, #11, #5, #27, #22, and #21 are all new. That covers the ignition, except for #7 & #8 in figure 1. Good thinking on the jumped timing idea; however, this can be eliminated by the fact that it is running well again after a good cool down. If it jumped timing, it wouldn’t be jumping back.<br /><br />Lube Dude – You are spot on! I was concerned about vacuum leaks too. I found the carb was a little loose and tightened it up. I thought for sure I’d found the gremlin, but 20 minutes later…. sputter-pop fart again. Maybe I should just change the name of the boat to 20 minutes, or take 19 minute trips... but the gasket is original. Hmmmm…..<br /><br />Flashback – Waiting each night for my fuel pump. I pray that fixes it. <br /><br />All – I have found new hope in seeing all this activity. I hope that this thread will solve my problem, and I hope that it may help others too. Thank you to each and every one of you. BP

 

[outboardguy]

Re: Sputter - Pop - Fart - Go like Heck and Back

Actually I think I misworded my previous post.You should tee in a vacuum gauge to the fuel line between the tank and the pump.This would eliminate the tank as being a source of restriction. But the easiest way to eliminate the tank altogether is to remove the fuel line at the fuel pump and hook up a known good outboard tank (properly vented) and go for a spin. If the problem goes away look into the tank. If problem persists try and pump the bulb and see if it picks up.Could be fuel pump or carb problem.<br /><br /> I'm really glad to see the persistance that you have at finding the problem. It's in there somewhere, You'll find it. Good Luck and don't give up

 

[merc 140 pontoon]

Re: Sputter - Pop - Fart - Go like Heck and Back

BP212 -<br /><br />I don't know enough about that ignition to know where the resistor is in the circuit. I think your coil positive post voltage experiment eliminated the resistor as the problem. Do you have the Mercury manuals?<br /><br />Also, I don't remember if you mentioned this (and I don't want to re-read the whole thread)--can you run with your engine compartment open as a test? I found that helpful in confirming that my problem was heat-related.<br /><br />M140P

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

I got the pump, tomorrow will be the big day. I'll let you know how it goes. Are there any tips on changing the pump? I'll read my manual, but sometimes there are tips not documented there.

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

I got the pump in and ran it on the muffs, then went to cut the grass while the engine ran. I checked it every couple of laps to see how she was doing (160 degrees at around 800 rpm) ran great. After about 20 minutes. That son of a gun started acting up again, even after the new fuel pump! <br /><br />I tried again at the timing too. This can't be that freaking hard! The timing mark is no where near the indicator. And, if I turn the distributer to get it (the line on the crank) where it should be, it runs like crap. I'm starting to wonder if the timing has jumped a tooth or two in a prior life and this is causing pre-ignition after about 20 due to bazaar valve train heating. I wanted to check the alignment of the timing gears to see if they had jumped. But of course this will require pulling the entire engine. Shouldn't it start hard and idle rough if this was the case? I swear if it's the last thing I do I'm going to figure this stupid motor out even if I have to pull it, and start over!

 

[DJ]

Re: Sputter - Pop - Fart - Go like Heck and Back

Boiling Point 212,<br /><br />Forget the timing jumping a tooth. That is permanent, not itermittant.<br /><br />You may have something with a valve or two hanging up.<br /><br />You mentioned-"top end rebuild" in your original post----BINGO!!

 

[boaterntexas]

Re: Sputter - Pop - Fart - Go like Heck and Back

I had the same problem. Turns out my fuel filter wasn't installed properly (upside down), and was cuasing fuel starvation at topend speeds. would pull the plugs and see what they look like. but I'm sure you have already checked these two things. <br /> move past timming problems, and concentrate on the fuel system, if that all checks out good.. next thing is preignition, or some other sort of electrical problem.<br /><br />good luck

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

Update - The timing has not jumped. However if you bring #1 to TDC on the compression stroke the line on the harmonic balancer is off almost 45 degrees to the indicator on the block! The steel of outer housing of the balancer has rotated somehow on the internal rubber part of the balancer. I have made a new mark for TDC and I'm putting a timing tape on the balancer with 0 degrees at my new mark. This will set the foundation for exact timing going forward. Will keep you posted - BP

 

[Northern Eclipse]

Re: Sputter - Pop - Fart - Go like Heck and Back

If that is the case I would want to replace that harmonic balancer before it comes apart and cleans out the entire motor, That thing is rotational mass and becomes alot heavier when its turning 4600 rpm. I'd seen one come off a VW Jetta ..lots of damage

 

[BinLurkin]

Re: Sputter - Pop - Fart - Go like Heck and Back

For whatever this is worth it seems that when I used to come across an engine that was put back together by it's owner & the timing gears were not properly lined up I would just pull the distributor up & move it over the right direction a tooth or two & nobody knew the difference anymore. Everything lined up again, timing mark wise, & ran just fine. We didn't have to pull an engine or timing cover to line up the gears again. Everybody was happy.

 

[Dunaruna]

Re: Sputter - Pop - Fart - Go like Heck and Back

I'm not familiar with the Petronics ignition, but I've seen plenty of faulty modules over the years.<br /><br />Its probably the most difficult ignition conponent to accuratly diagnose, but its usually always heat related, and often comes good when cooling off. Unfortunatly it sometimes requires a 'change and see' approach.<br /><br />IMO I'd refit the old pick up, if no change - new module (or maybe borrow a mates distributor). And definetly new balancer. Aldo

 

[cobra 3.0]

Re: Sputter - Pop - Fart - Go like Heck and Back

I too would second guess the Pertronix ingitor's reliablity. I would try your old points and condensor(or get some to try).

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

It's fixed! I set the timing as I said I would. Then Friday night I picked up an infrared thermometer at Sears. I used it to keep track of manifold and ignition components as they ran through a 20 minute test cycle. The manifold was between 180 and 185 fore to aft and port to starboard. My mechanics stethoscope picked up nothing but a steady werrrrrr fore to aft and port to starboard. The hottest ignition component was the distributor. It started out at 65 degrees Fahrenheit but through the 20 minute test cycle it rose to 110 just before the event. After that Sputter - Pop - Fart.<br /><br />I let the engine cool off. After lunch I took out the Pertronics Ignition Pick-up (#11 from fig 2 above) from the distributer and compared it to my old one. I did not try putting the old one back in because it was clearly in rough shape (rust), but I did do some comparison work between the old one and the new one. The old one had all of its circuitry covered by silicone. The new one's electronics were exposed to the heat. I applied a generous dose of silicone all over the circuit board and put it back into the distributer. <br /><br />I ran it through another 20 minute cycle, no event. I continued on for 40 minutes, no event, 60 minutes no event. Then I shut it down for 20, And ran it again for another 20, no event. Today I took her down to the ramp and ran her on the trailer (but in the water)for 60 minutes under load at 2k rpm, no event. It seems hard to believe but that tiny squirt of silicone over the top of the circuitry must have been just enough to protect it from the heat. From what I have learned in this forum, circuits change properties when exposed to heat. I now have the confidence to take her for a lake trail.

 

[Boomyal]

Re: Sputter - Pop - Fart - Go like Heck and Back

Boiling Point 212, I'd be calling Pertronix about that. It doesn't seem right that there would be exposed circuitry.

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

I'm just glad it's fixed

 

[Dunaruna]

Re: Sputter - Pop - Fart - Go like Heck and Back

Just a thought, if you used an acetic based silicone, it will damage the wiring & curcuitry in a short time. Probably want to do a proper fix before next outing. Aldo

 

[jlshields]

Re: Sputter - Pop - Fart - Go like Heck and Back

BinLurkin, did what?? The valve timing would still be out and it would run like sh--, if it would run at all!!!

 

[outboardguy]

Re: Sputter - Pop - Fart - Go like Heck and Back

Agree with jlshields,binlurkin.All you did was straighten out ignition timing.If valve timing was off then you definitely have to tear into timing cover and get gears to line up.

 

[cjflanagan]

Re: Sputter - Pop - Fart - Go like Heck and Back

Take your issue with Binlurking to another thread. My problem ended up being a heat related ignition problem in the Pertronix ignition pick up, and an alignment mark on the harmonic balancer being off from true TDC, thats it. Both of these issues have resolved. Case closed. All done. Party over. <br />BP