Engine Surge at WOT |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Posted: August-15-2012 at 9:13am |
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Good morning,
Im having a minor issue at WOT that bothers me a bit on our 96' Ski. Engine is 351w carbed. Boat runs flawlessy throughout power band, except when at WOT after about 30-45 seconds. Engine will loose a little power for a few seconds, like it isnt getting fuel, then it will pick back up to full speed and have no issues. Only time this occurs is when I am footing at WOT, other than that, it runs perfect. Last week I replaced the fuel line, and ASV. Could this be a fuel pump issue at those higher rpms? Appreciat the help guys. Mark |
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levin
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Mark, do you happen to have one of these under the floor panel behind your motorbox?
EFI Inline Fuel Filter Skidim Vince at Skidim said that they are supposed to be a pre-filter for EFI boats, and he hadn't heard of Carb'd boat having one. Mine definitely has one, and I'm curious if they wound up on some later model carbed boats. It would be something to check for, I'd imagine if it got clogged, it could slow the fuel flow. |
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BuffaloBFN
Grand Poobah Joined: June-24-2007 Location: Gainesville,GA Status: Offline Points: 6094 |
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Might be as simple as setting the secondary floats as the bowl may be running dry.
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MI-nick
Gold Member Joined: January-12-2009 Location: Ypsilanti, MI Status: Offline Points: 809 |
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sounds like something on the secondary side is a little jacked...float level, needle & seat, booger in the secondary metering block...could be fuel pump too...easy enough to pull the secondary bowl first and see if anything is amiss...
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As far as I can tell, I'm not quite sure...
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Thanks for the input guys. Brian, I have that exact in-line filter, and that is the only one in the fuel line. I replaced it in the spring and have put a little over 50hrs on it so far, so I am going to replace that first thing and see what happens. If I still have the issue, I will take the carb off and see whats up with the secondary bowl like suggested. Hopefully the new fuel filter solves the problem. I will report back when I get the new one on and tested.
Mark |
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levin
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Well fellas, sort of have an update. Havnt put the nnew inline filter yet, hopefully arives today. Anyway, boat ran flawlessly this weekend till I footed. Again, about 30-40 seconds in, starts to die out, then picks up again. After I pulled me wife slalom, I went and out and ran wot with no slowing down. Im thinking there must be some crud in the secondary needle and seat and got through. So, im thinking of just pulling the secondary bowl and cleaning things up and check the float setting. I was reading last night that the secondary float should be set 3/8" off the bowl when inverted. Does this sound right and is there anything else I should scope out while im in there? Thanks for the help!
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levin
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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O.K., one more update. Got the new inline filter installed after work and pulled the secondary bowl. I adjusted the float to parallel when inverted. I must have misread the 3/8" measurement for the float setting. It would of been sitting lower than it was originally set at. So I put it to parallel like I said. Anyway, I sprayed the heck out of the needle and seat area while working it up and down. Reassembled, hooked up the hose and no leaks. I wont be able to get the boat out till Friday to test it. Hopefully the cleaning, readjustment of float, and new fuel filter will cure this issue. I will post the results as soon as we get her out on the water. Thanks for the help.
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levin
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Final update fellas. We went out after work yesturday for some evening runs and it is good to say that the problem is solved with my surge problem. I ran a couple WOT runs and it ran flawlessly . Thanks for the help with this issue!
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levin
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Good evening everyone, finally had a decent afternoon today and went out for the first ski of the season. As you know from previous posts in this thread, I had surging issues when at WOT, not that I run it that hard much, but I thought I solved the issue, and sure enough at the end of the day, went for a little speed run and it did it again. This what it did. I gave it full throttle and picked up speed just fine, and about 8 seconds into it, surged big time, like almost dying, and then it would pick back up to full speed and surged again like it was dying. It did this a couple times and the last time it did it, it really slowed down and jerked a little and picked back up like a bat out of hell and never slowed down again like it got some debris or something out of the way and had plenty of fuel flow. Before the beginning of the season I took off the secondary float again and readjusted it and cleaned up the needle and seat again, hoping to clean out any debris. I was pretty bummed when it started to surge again. It runs flawless when skiing at 36, just happens at WOT or when footing. I would appreciate any more input and suggestions. If you read previous posts, I replaced the fuel lines, filter, anti syphon vavle, and adjusted floats and cleaned needle and seat previously. Stumped on what to check out next. Thanks for the help.
Mark |
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levin
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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You might want to check the fuel tank vent - an easy way is to leave the cap off for a test. Also - maybe weak fuel pump that can't keep up?
Have you watched the secondary butterfly linkage to make sure it isn't intermittently closing? (pinhole in diaphragm maybe). |
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Chris, next time out I will check the fuel vent with the cap off. I have not watched the secondary butterfly to see if it is closing. The carb was new in 2010 and it did not start doing this till last year. We'll see how the weather is this weekend and hopefully get out to check on things. When I first bought the boat I took it to a dealer near us to check things out and the mechanic said that the fuel pump on the boat was not the right one, but would work fine. I didnt think anything of it till now. Maybe there is an issue with that pump and wore out? I'll check the vent and secondary butterfly first and will be in touch. Thanks for the help
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levin
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TRBenj
Grand Poobah Joined: June-29-2005 Location: NWCT Status: Offline Points: 21138 |
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Check the antisiphon valve... Ive seen that exact issue happen a few times and found it to be pretty well clogged up with junk from the tank.
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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What ignition system is on this motor? And is there an ei conversion on it?
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Brian
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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I'll check the anti syphon valve, the ignition is just a standard distributor with a prestolite coil ( dont know modeloff hand, ill check aftrt work. Do not know if is orginal to boat or not. There is no efi conversion. New carb was put on it in fall of '10.
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levin
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hotboat
Gold Member Joined: March-28-2009 Location: Conn Lake Pa Status: Offline Points: 814 |
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Ei = electronic ignition conversion. If it has one clean it and check the spacing, I had one that gave these symptoms
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Brian
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Brian, I think your right on point with the spacing. I talked with Vince at SkiDim this afternoon and came to the conclusion that I have the electronic ignition with the prestolite distibutor (black and purple wire). He told me to pull the cap and check the spacing between the fins and the rectangular piece and that it is recommended to be set at .010", however they set them up at .006". Afterwork I pulled the cap and sure enough it was way out of adjustment. I should of checked it before moving it but it wasnt even close to .010. So I proceeded to space it at .006" and fired it up. Before the adjustment, I would give the throttle a couple pumps and it would turn over for a 3-5 seconds and fire up. After the adjustment when I turned the key, it fired up instantly. I know that this wasn't my issue to begin with, but what a difference in start-up and idle. Also, how would you go about cleaning up in the distributor cap? Hopefully we'll be able to get out this weekend and give her a run and test it out. Thanks for the input fellas, I'm learning more and more as time goes on. I'll go ahead and clean out the ASV before heading out also, and will take a peak at the secondary butterfly at wot for good measure.
Mark |
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levin
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Just an update, we hit the river this afternoon for some runs and I ran the boat WOT a few times and never had any issues! She ran perfect. Thanks for the advice and help everyone. Mark
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levin
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13512 |
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Great news. Thank you for reporting back so the next victim can search this result.
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MI-nick
Gold Member Joined: January-12-2009 Location: Ypsilanti, MI Status: Offline Points: 809 |
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do you happen to have a photo of this?? |
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As far as I can tell, I'm not quite sure...
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Nick, I did not take any pictures of the distributor. I should have now that I think about it. Basically, when I pulled the cap off the distributor, the center rotor shaft has a splined-like piece about 1" in diameter. These splines are what I am referring to as the fins. To the side of the fins is a little rectangular sensor with a wire attached to it. I simply turned over engine till one of the fins was perpendicular to the sensor and then loosened screw to adjust to .006". Pretty simple fix and made a world of difference. If you need me to, I could pull cap off after work and post a pic.
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levin
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echobravoecho
Groupie Joined: March-14-2011 Location: Kansas City, KS Status: Offline Points: 73 |
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I'll add my experience for the next guy also. 93SN 351W, holley carb, electronic ignition. Same symptoms as the OP, only worse. Slightly different conclusion.
Look under the coil packs for resin on the transmission housing. My electronic ignition system was in the process of melting and the cutting in and out at high speed was the first major symptom. The engine started immediately when cold. Ran perfect at ski and wakeboard speeds, until it was time to haul a**. Open the throttle, and the engine sounded like it has a high and low power switch cutting in and out. Top speed was low 40's. At first I blamed it on clogged filter, alcohol in the gas, clogged check valve, etc. etc. Rebuilt the carb, no change, changed power valve and jets, no change, replaced the carb, no change(the rest of the carb circuit was finely tuned, but the initial problem remained.) I had also replaced the plugs and wires earlier. From the forum research, I knew the only thing left was the ignition module, but the failure symptoms didn't match anything I could find that was previously discussed. I purchased a DUI ignition and called my old-school mechanic to help me swap it out since the old ignition pickup has seized in the block and I couldn't pry it out. The first thing he said when we opened the engine cover was, "What's a GM coil pack doing on a Ford engine?" The second thing he said was, "Look at all that resin that has melted out of the circuit board." as he pointed to the bell housing directly under the coil pack. The third thing he said was, "Do you want me to rebuild the coil pack? They are only 30 bucks at the junkyard. Cadillac modules work best." I allowed that since I had already sprung big bucks for the GM based HEI ignition system that I'd pass on the rebuild offer. That was the problem, no more missing, stumbling or cutting in and out. Top speed is now right around 47 MPH on the speedo. Dunno if it's accurate or not, but it runs great now. Regards, Ed |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Good to hear you got her straightened out. I was getting a little frustrated with the surging, so to finally have the issue resolved is a relief. Sure is nice to have access to the wealth of knowledge available here from everyone.
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levin
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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I searched the 'net for 15 minutes & this is the only picture I could find of the sensor (kit, not assembled). You just loosen the retaining screw & move the pickup until you get the proper gap between sensor & the fin. In the instructions it warns to use a non-magnetic feeler gage. |
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Good morning guys,
Unfortunately I am still fighting this darn problem and It seems to be getting worse. The other day the engine started to cut out when I was making a 36mph run through a course which it has never done before. Yesturday I was footing and it was cutting in and out at about 40 and it was way worse than before. Weird thing is that when I hopped back in the boat and took it for a spin (4 people) at WOT, it did not miss a beat the entire length of the lake. Now as soon as there is a load on it (footing, skiing at 36) the darn thing starts acting up. There are no issues what so ever out of the hole, it gets up and goes like crazy. I hear people talking about their coils heating up and causing issues, and was wondering if this might be my problem? After a ski run, I felt the coil and it was definetly hot to touch. I am really getting frustrated with this as you can imagine. Just to recap 96' ski with 351 carb'd, electronic ignition (carb was replaced in fall of '10, new anti-syphon vave, new fuel lines, new filter last fall, new fuel pump) Both primary and secondary floats have been adjusted, needles and seats cleaned out. The one thing I havnt done is pull the dog house and make a footing run with someone looking down the carb to see if fuel is being delivered. The weird thing is that this is occuring when under a heavy load. Once agian, I appreciate the input and advice from all of you, and hopefully we can figure this thing out. Mark |
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levin
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echobravoecho
Groupie Joined: March-14-2011 Location: Kansas City, KS Status: Offline Points: 73 |
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Do you have the original electronic ignition, with the separate coil packs? If so, check underneath them for resin dripping out of the bottom of the box and/or onto the transmission housing. That was the symptom on my boat that indicated that they were overheating. The resin looked like amber colored sticky grease by the time it had melted and dripped out. Replaced the electronic ignition with a DUI and my cut-out/hesitation problem was solved.
Unfortunately I haven't read of an inexpensive way to test the OEM electronic ignition system, apparently a swap out is the preferred test method. Could get pricey if it didn't fix the problem. I'd guess that an old 351W distributor and coil from the pull-a-part junk yard would be the cheapest way to test the ignition, if you had the time to pull one out. If that fixed the cut-out, you could then decide which type of ignition would suit your needs. Compare the two cam gears and re-use the cam gear at the end of the boat's distributor pickup on the junk yard distributor, it reverses the direction. With the DUI unit, I removed the OEM distributor pickup, and the electronic module with the coil packs on the top, along with the plug wires. The DUI has the coil inside the distributor, so it's self contained. |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Take a footing run in the early evening, preferably a damp evening. With the doghouse removed. (Actually don't know how you'd do this without risking the rope getting caught in the belts, maybe use rear tow point?)
Anyway, look for sparks jumping from your wires etc. I'm starting to think ignition on this. |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Thanks for the replies, I believe the post before Brians was referring to a pro-tec ignition, which I do not have. Here are a few pics. Im getting pretty frustrated. When I foot, I usually go off the fly high pole, so it shouldnt be an issue. Where exactly should I be looking for sparks. My wires and plugs are 3 years old, so they are probly ready for replacement this winter?
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levin
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echobravoecho
Groupie Joined: March-14-2011 Location: Kansas City, KS Status: Offline Points: 73 |
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Much clearer now with the photo. Suspect the coil/wires/rotor/cap. as this is one symptom for overheated/damaged coils. If you inspect the inside of the cap and don't see a lot of arc damage at the pins and rotor, (sooty black dust and pits/bumps in the metal parts), then change out the coil. If there is evidence of arcing inside the cap and it can't be cleaned up and polished away, change that also.
Ed |
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levinmark
Senior Member Joined: November-11-2010 Location: illinois Status: Offline Points: 375 |
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Thanks for the reply Ed, watching da Bears at the moment, I'll go dig into it at halftime and see what it looks like under the cap.
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levin
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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The problem is obvious--Jay Cutler. ...sorry |
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