351w Miss Under Load When Hot
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=36695
Printed Date: October-07-2024 at 6:22pm
Topic: 351w Miss Under Load When Hot
Posted By: LeftFieldEngineering
Subject: 351w Miss Under Load When Hot
Date Posted: July-09-2015 at 8:50am
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Well I’m defiantly getting use out of the boat, I’m now up to 3 days a week driving for the ski club and it’s a blast. It's been 30+ hrs with no issues, but she developed a miss under load condition. I don’t have much for data yet, but I wanted to get the ball rolling as I need the boat back up and running properly ASAP. Cold Observations: - Will fire up with 1 pump of the handle - Idle fine - Run up to 48mph WOT with no missing or any problems Hot observations (2+ of constant driving): - Miss @ WOT / coming out of the hole - Occasional it smells a bit like unburned fuel. - No dripping from boosters, no excessive fuel smell in carb - Will run fine up to 40-45 under medium acceleration - Doesn't feel like fuel starvation because there's no bog or hesitation, just missing - Back off to 3/4 throttle and it'll go away - Coil was 160-180 degrees when we called it a night yesterday (tho the intake was 160 so it may just be radiant heat. I’ve had some new ignition parts on the bench waiting to be installed so I replaced the cap, rotor & points (not the condenser) on the 4th of July. Overall the boat started and ran better, but it didn't change the miss @ WOT Now that she’s home and I have all the proper tools I plan on: Pulling the plugs to see if they show anything Tripple-million check the plug wires / firing order Check voltage at coil Swapping out the condenser Rechecking / resetting the dwell (24° - 29°) Rechecking / resetting the timing (10°-12°@ 600, 34°-36°@ 3000) I'm typically not a "just throw parts at it guy", but seeing as I replaced the other 90% of the ignition system when I did the motor swap I may just pick up a coil on my way home. |
Replies:
Posted By: TRBenj
Date Posted: July-09-2015 at 9:51am
| The carb was dumping gas before right? I'd throw some fresh plugs at it before anything. Dwell and timing checked after the ignition tuneup right? |
Posted By: LeftFieldEngineering
Date Posted: July-09-2015 at 10:04am
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The old carb dumped fuel, but had a vac leak so I got lean plugs (over a month ago). The new carb also dripped fuel for a little while until I adjusted the floats and it’s been running drip free for at least 3 weeks now. Yes I checked the dwell & timing after installing the points, cap & rotor. Only unsettling fact is it did this Before the tune-up as well. |
Posted By: GottaSki
Date Posted: July-09-2015 at 10:13am
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I concur with Tim. Plugs brand and model? Friends don't let friends run champions ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: phatsat67
Date Posted: July-09-2015 at 10:48am
Hey now, Champions are Mopar plugs so it makes sense they get cranky when they get put into something inferior like a ford  .But really, I hate when people run plugs that didn't come in an engine. I stuck champions back in my Hemi because they were less than half the cost of the NGK set that was in it but the previous year they used these Champions with no other changes. My fords get Autolite, Chevy's Delco, and Mopar champion. Small engines get NGK. ------------- |
GottaSki wrote:Posted By: LeftFieldEngineering
Date Posted: July-09-2015 at 11:28am
| Autolite 24's They have apx 40 hrs on them. |
Posted By: TRBenj
Date Posted: July-09-2015 at 12:29pm
| Change em. Stick with the autolites. |
Posted By: LeftFieldEngineering
Date Posted: July-12-2015 at 8:59pm
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Update (and possible solution): I installed the condenser, triple checked the firing order, rechecked & reset the timing / dewell and installed new plugs. All the plugs looked fine except 1 and 6 which were a little darker then the rest. I'll run it with the new ignition parts & new carb before I worry about the dark plugs. I also picked up a new coil, but didn't install it as I wanted to see if the problem would still show up with the new plugs & condenser. On the water the boat ran great for the first 2 hrs then started to miss just like it did before. I swapped the coil out at the dock and the problem vanished. We only skied for another hr so I didn't get to really test the new coil, but I'll run it through its paces tomorrow at ski club. |
Posted By: LeftFieldEngineering
Date Posted: July-14-2015 at 10:10am
| Over 2.5 hours yesterday at ski club with no missing. Looks like the coil solved the problem. |
Posted By: GottaSki
Date Posted: July-14-2015 at 10:18am
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Good to hear! ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |