Engine Missing? |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Posted: September-08-2011 at 1:08am |
97 SN GT 40 EFI
I had the boat in the water of the weekend and noticed my tach was reading a bit high. Tach was reading over 1100 at idle but was actually aroung 700-800. At full throttle, tach was reading around 6500. Boat redlines at 5800 normally. It was not a big deal deal to me at first. The RPMs seemeed to clear up over time. She started "missing" every couple of minutes. When the boat would stumble, it was very bad. The boat would slow so fast, my buddy hit his head off of the windshield. It felt similiar to hitting the speed limiter in a car. Im not sure if the tach and the miss are releated or not. My initial thought was bad gas. Also, do these engines have a rev limiter? Thanks Shawn |
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LaurelLakeSkier
Senior Member Joined: February-12-2007 Location: Wisconsin Status: Offline Points: 485 |
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The 5800rpm "normal redline" you mention seems pretty high.....if the engine is stock, peak rpm should be closer to 4800 or so. In any case, the 6500 reading is way up there and I doubt the engine would stay together long if you were actually turning that kind of speed.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Check your plugs could be detonation causing the knock sensor to retard the timing. (I just went through similar symptoms)
As for the 5,800 redline what MPH are you running at that RPM. I'm thinking your tach is reading incorrectly, the GT-40 has a rev limiter set at 5,200. |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Im sorry, the engine redlines at 4800 not 5800. The engine is running fine, except when the 1/2 second miss occurs. Also, the boat did stall twice. I will change the plugs, but it will probably be next year.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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I didn't mean change them, I meant check them as in look at them for symptoms of what could be causing the miss.
I had some plugs get the electrode ruined during detonation from bad fuel. After I got rid of the fuel it ran OK but not quite right I pulled the plugs and that’s when I found the bad electrode. |
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Well, could it be bad gas? |
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kapla
Grand Poobah Joined: March-27-2008 Location: BA, Argentina Status: Offline Points: 6148 |
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lots of problem with gas lately, or this boats sit during long periods with untreated gas?
Poor quality gas pump, ethanol? I´m surprised with the low quality fuel down here, I have never experienced bad fuel symptoms in my engine! my boat is used year round at least twice a month so i´m always adding new fuel...thats probably the reason though... |
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<a href="">1992 ski nautique
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13513 |
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Exactly!
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Its time to change the plugs anyways. Im hoping it is just bad gas. There is definetly something wrong with the tach though.
Thanks for your input. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Shawn,
Where do you run your boat. I'm just outside Butler and hit Bradys a lot. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Kap My boat sat in the garage for only about 3 weeks or so but I have no idea how old the fuel was when I bought it. The last fill-up was at the lake and could have been the bottom of the tank. So much for Star-tron put it in when I filled up and it didn't do sh!t I think I'm going back to Sta-bil marine never had a problem with that. |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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We ski/camp at Tionesta Dam. Its only about 20 minute drive for us, but it is usually busy. We rarly go anywhere else. I am always looking for good skiing and camping. Do you know of any good spots?
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89Martinique
Senior Member Joined: September-05-2011 Location: Binghamton Status: Offline Points: 457 |
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TRY REPLACING THE DISTRIBUTOR cap our friends boat had a hairline crack in their cap and #7 fired with every other plug so we put the old one on and it ran beautifully
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Current Boats:
1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Will this item read possible codes off of ECC?
http://cgi.ebay.com/ebaymotors/FORD-EEC-IV-DIAGNOSTIC-ANALYZER-MADE-USA-KASTAR-/290462605457?pt=Motors_Automotive_Tools&hash=item43a0eba091 Since the tach is acting up, I am gonna check all wiring in the tach circuit. When the boat cut out, it felt like rev limiter kicking in. Also gonna check for water in gas and possibly drain fuel tank. |
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Luchog
Grand Poobah Joined: April-17-2007 Location: Argentina Status: Offline Points: 2135 |
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The tach issue could be as simple as some bad isulation on the plug wires or a bad cap.
Does the tach behave if you poke on it? |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I did not poke on the tack, but the rpm seemed to correct itself over time. I probably wont be able to troubleshoot until next spring so I will have all winter to think about it :(
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89Martinique
Senior Member Joined: September-05-2011 Location: Binghamton Status: Offline Points: 457 |
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I hate that you have a problem and have to wait to work on it. It makes time crawl by.
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Current Boats:
1992 Supra Comp-TS6M PCM 351w HO Pro Boss Pro-Tec Ignition - Full Composite (no wood stingers!) 1989 (3rd Gen) Correct Craft Martinique B/R PCM 351w Power Plus 1984 E-Scow Keuka Lake, |
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eric lavine
Grand Poobah Joined: August-13-2006 Location: United States Status: Offline Points: 13413 |
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pull the tach wire off of the coil and run, a shorted tach will also short the coil. got me once, should be the gray wire
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"the things you own will start to own you"
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I had the boat out for the first time this year. The water is already 73 deg!! I believe I fixed the tach issue...bad connection on back of tach.
The boat seems to be running good, but its still stumbling once in awhile. It usually occurs after WOT after the boat gets down to 30-35 MPH. I filled her up with 93 octane and added injector cleaner and fuel cleaner. I ran for about an hour and only about 5 "misfires". Im gonna check the plugs this week. I will also pull the tach wire off of coil. Ill report back with plug conditions. |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Where did you have it that the water was that warm?? Where do you usually go? Maybe we'll run into you some time.
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I had the boat at Tionesta Dam. I couldnt believe the temp. I also heard Pymatuning Reservoir was 74 over the weekend, but it is a very shallow lake.
We pretty much stay a Tionesta even though its not good sking on the weekends. Do you have good camping on Brady? |
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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Used to... a lot of the area got sold at the end of last year planning on building houses.
Hoping to get up there soon and see what the impact will be. As for your tach I think 5,800 could be a little inaccurate, I was under the impression that they have a rev limiter that kicks in around 5,200. I may be wrong but mine runs pretty dang strong and won't pass the 5200/5300 mark. |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Boat has been running about 4900.
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gun-driver
Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4127 |
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That sounds a little more like it should be.
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I removed and inspected the spark plus. The color looked good on all of them, but the ground electrode on one of the plugs was slightly bent to the side. Im not sure if it was put in this way or if it could bend while running???
Anyways, i got some Autolite AP103 to try out; its a platinum plug. I wanted 764s, but they were out of stock. We'll she how she runs this weekend. Still betting its bad gas, but Im usually not right. |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I put on about 4 hours this weekend and still have problems with the boat stalling\cutting out. Occurs more randomly than I originally thought. She was even stalling while ideling back to pick up skiers. I going to start by checking fuel pressure.
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eric lavine
Grand Poobah Joined: August-13-2006 Location: United States Status: Offline Points: 13413 |
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where does the tach wire feed from?
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"the things you own will start to own you"
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Eric, Im not sure where the tach wire originates. I looked for the gray wire on the coil and found nothing.
thanks shawn |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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I forgot I replied to this thread last year. Sounds very similiar to my issues.
Similiar Issue Where is the distributor stator located and is there a way to test? |
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harriss28
Senior Member Joined: July-24-2010 Location: Titusville PA Status: Offline Points: 128 |
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Solved - ECM relay went bad.
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