3.0L not running right when hot. help!

[kart74]

Well the saga contines with the 3.0l serial number starting in 497. It is a 1983 and has the Rochester 2gc carb, and Mallory distributor. I have gone through the carb many times and it is spot less every time. I have replaced points, condenser, cap, rotor, wires, coil all this year. Last weekend we were out and tried sking and when we went to pull up the skier after being out for awhile, it just fell on its face when going to WOT. I assumed a dirty carb so I took it all apart again, cleaned the carb (was clean), and replaced the fuel filter. We went out today and the boat was great... for awhile. All of a sudden while going WOT it started breaking up a little. We lowed down and went to take off again and the same thing. It falls on it face and sputters, wont get on plane, no power. We parked for awhile and I let the blower rung the whole time. Went to take off and it was better for a little bit again and then same thing. Just starts sputtering at WOT and not power. Eventually it gets to the point where idle is about all it will do. Apply throttle and it starts missing. I am wondering now if it is ignition, but it is all new! Before we left today I check compression and all were around 140. Checked dwell and timing and was right on. Any ideas? Thanks in advance.

 

[kart74]

I also forgot to mention that the plugs all look good. Nice brown in color. The number 2 plug was a bit oily, but not too bad. I am lost at what to look at next...

 

[stonyloam]

Check to make sure that the fuel tank vent is not plugged. When it acts up, take the cap off the tank to vent it, see if it runs better after.

 

[Starcraft5834]

water fuel separation filter system installed? Ive got a 1987 3.0.. I've noticed better operation this season since it's installation........

 

[kart74]

I do not have a water separation unit installed. The gas tank vent line is open. Last time I filled the boat full the gas shot out of it at the gas station lol. So I am thinking it is open.

 

[kart74]

I am thinking about getting the electronic ignition upgrade and the new coil to go with it. My engine has the Mallory yl673av distributor in it. Does anyone know if there is a conversion kit for that?

 

[airshot]

Sounds like a fuel flow problem, could be anywhere between carb and pickup inside tank. Add water/filter separator unit inline, has the carb inlet filter been replaced? Any kinks in the fuel line, check inside tank to be sure pickup is connected and not clogged and as suggested vent hose. Be sure vent hose has an upward loop to prevent water from backing into fuel tank.

 

[kart74]

Update! So I ended up ordering a Peronix kit and coil for the Mallory distributor I have. Got it all installed and headed to the lake over the weekend with the family. I ran the boat in the drive and got it timed and everything. The boat has never started so good! On the lake it continued to impress. Seems to have a lot more power! was running about 400 more RPM than before. Shut it off and started right back up. So it was awesome... until it wasn't. All of a sudden it was like someone shut the ignition switch off. Just died and would not restart. I played around for awhile and didn't find anything wrong. Tried it one more time before looking for someone to pull me in, and it started right up like nothing ever happened. Well we headed for the launch and again everything was great... until it died again about 100 yards from the launch. Same thing. Loaded it up and started it in the drive as soon as we got there and again starts right up. Contacted the company today and they gave me some tests to run. Turns out that I only have 6.2v at the coil. I talked to them again and they said with the resistance wire that I am thinking it has, when it gets hot the voltage drops even lower and the electronic ignition stops. SO now I am looking to replace the resistance wire. There are 2 wires that go to the positive side of the coil. A purple-ish\red and the same with a yellow stripe. Does any one know if I need to replace both or just one? I think one if from the ignition switch and the other is from the alternator? I am guessing it is just the ignition one, but if anyone knows what I need to replace or has done this before I would appreciate it. Save me a bit of time of tracing wires. Thanks in advance. Hopefully once this is resolved everything will be good.

 

[stonyloam]

I do, you leave the the yellow one, that comes up from the start solenoid and provides voltage during starting. You replace the purple one. You can just remove it, tape the end and coil it up out of the way (or cut it off). Replace it with a stranded copper wire (12 ga). You can splice into the choke wire near the connector. It is best to use a solder splice and coat with liquid tape for a water tight seal.

 

[kart74]

Thank you!

 

[kart74]

Well I got the wiring changed and still have issues. As soon as the boat gets hot it breaks up a bit and then shuts off. If I shut the engine off when it is hot it wont restart. Let it cool down for a bit and then like nothing was ever wrong it fires right back up and runs great. I have talked to pertronix about it twice now, and I think I am going to send them the module for testing. What I don't get is why with points I had issues when the engine got hot, and although the boat runs much better with the electronic ignition, I basically still have the same issue. I ran all of the tests pertronixs gave me while on the lake and having the issue and everything checked out perfect. At least with the points I could always get it started it just didn't run good. I don't know what else to look at. It really seems like an ignition issue to me. It is just like you take the coil wire off when this happens. Doesn't put or try to start... nothing. Any one have any ideas? I am at wits end with this thing...

 

[nola mike]

Did you verify that you have no spark when it isn't starting?

 

[Fastatv]

Did you verify that you have no spark when it isn't starting?

Good point here^^^^^^^^. You could have a mechanical fuel pump that when it becomes very hot, fails, then works again once cooled down for a bit. Do as nola mike is asking.....and if you still have good blue spark when it dies, then its a fuel issue. Have you changed all of your fuel system filters this year?

 

[kart74]

I haven't checked that. I thought of it when we were out on the lake but didn't have a spark plug wrench with me. I have replaced all of the filters right after this started happening. I have the carter fuel pump that the manual says is rebuildable. I haven't found a rebuild kit for this. Does anyone know where to get one?

 

[kart74]

Also when it wont start if I pump the throttle a couple times I can smell gas. So I am guessing that the carb is still full or the accelerator pump would be dry?

 

[kart74]

Anyone have any ideas on this? Looking over other posts I found 2 other recent posts of others having the exact same issue. Older Mercruiser 140 and when it gets hot it either dies or sputters. It is for sure an electrical issue on all 3, and all of us have replaced just about everything. One post suggests putting in a delco EST. Has anyone done this with good results? Is that any different that running the Pertronix electronic ignition? I have the Mallory dist. and the other two guys have the delco. I am getting new battery cables this weekend to eliminate that as well. I also have my Pertronix unit being tested by them right now, but I think it will came back with no issues. Any help would be great...

 

[philbullet]

Seem like iam have the same isue's too and curious.

 

[crunch1]

I am having the same type of problem with my 86 170 HP inline 4. It runs about 2 hours and then starts having the same problem as yours. The only thing that showed on the dash gauges was the tach showed 4200 rpm and I was doing about 10MPH. This makes me wonder about the wires coming from the distributor.I'm very curious as to what you find on yours.Mine runs strong and well for those first 2 hours , after that just plain grief.

 

[kart74]

Well I got my ignition tested from pertronix and everything was good. They sent me a new one, so I was a little confused by that but whatever. I got a new battery and new battery cables. All of the connections for the battery cables were nice and clean. Started it in the drive and got it all timed again. Seemed to run fine. Took it out on the lake today, and it started right up. Ran it around the lake a few times and it ran great. Had good power and everything was fine until we idled down to go swimming. As soon as I was coming to a stop it started missing a bit and eventually just shut off. Tried to restart it and again its like there is no spark. I checked things over, made sure fuel was spraying into the carb, everything connected. The coil felt hot to the touch. Could only have my hand on it a second or two. The coil mount right to the head so I assume it is normal to be hot. The coil is the flamethrower model that pertronix recommended. We swam for awhile and I tried to restart it. In the past letting it sit for about 10 minutes and it would restart. Well not this time. Never made a single put again. Eventually the battery was drained and I had to get towed in. I am completely at a loss with this thing. I have been trying to figure this out pretty much all summer, and nothing has changed. Actually today it was worse because it has always restarted in the past. The odd thing is that if I try to restart now that it is back in the drive I guarantee it will fire up and run like nothing was ever wrong. Compression is all around 140, carb has been clean (issue is for sure not fuel related), and every ignition part has been replaced (some several times), except for the distributor itself. Anyone have any ideas? I dont even know if taking it somewhere would help at this point.

 

[jaa241]

If your coil is that hot to touch you are cooking your coil. What pertronix unit did you get. Pertronix 1 or petronix 2. Also which flamethrower did you get. I run a petronix 2 and msd coil 8222 and it doesn't get hot at all.