1996 Ski Nautique 176 with GT-40
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=48630
Printed Date: November-27-2024 at 5:44am
Topic: 1996 Ski Nautique 176 with GT-40
Posted By: browningskir7
Subject: 1996 Ski Nautique 176 with GT-40
Date Posted: May-02-2020 at 12:20am
|
I recently bought at 1996 ski nautique 176 with a GT-40. There is a long story behind the boat but in short it set with the motor dissassembled for 10 years. I have put the motor back together complete rering kit with all new gaskets. Lots of new parts due to corrosion, Besides building the motor from the beginning , I put the following in new. New carter low pressure pump, New walbro high pressure pump new plugs new wires new fuel injectors, new fuel and ecm relays new vacuum lines new hoses new impeller new battery new map senso new IAC censor new fuel regulator most of temp sensors and other sensors Once all this was done, I touch the key and it fired right up-But it lopes RPMs go from about 800 to 1050. I have pretty much tried everything in all the forums I have put in on the lake and it will only run about 34 mph and about 3800 rpm and it it will get up and run but as it goes down the lake it starts to lose power. It starts very easily but just lopes and does not get up to the RPM's it should. Anyone have suggestions? Ted ------------- Browningskir |
Replies:
Posted By: Gary S
Date Posted: May-02-2020 at 12:48am
|
Have you checked fuel pressure while this is happening? If you haven't get a gauge and see what your running while this is going on. I would have guessed a fuel pressure regulator if you hadn't already changed it. A 176 with a gt40 is quite a nice find ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: browningskir7
Date Posted: May-02-2020 at 12:52am
|
I have check pressure and it is as shop manual states, while idling it is in the 31 range which is what the shop manual says. if you pull the vacuum line off, it goes up to 39 which is what the shop manual also says. It has a brand new ford fuel regulator. ------------- Browningskir |
Posted By: MrMcD
Date Posted: May-02-2020 at 4:23am
|
This may seem like a dumb question but did you install new fuel in the tank? The boat sat for 10 years. The old fuel will not work and could cause major engine damage. If you have fresh fuel, sorry but it had to be mentioned. Many classic car owners have caused engine damage by not using new fuel after the car restore is done. How about some pictures of your new toy. Glad you are getting it back on the water. Once sorted out I bet you will see top speeds of 50+ in that boat with a GT 40. ------------- |
Posted By: SNobsessed
Date Posted: May-02-2020 at 9:23am
|
Maybe there is a nest in the exhaust hose That would slow down an engine. I remember a guy at Green Lake telling me that happened to him.. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: KENO
Date Posted: May-02-2020 at 9:36am
I don't think you've quite answered Gary's question about fuel pressure.  If you leave the gauge hooked up and drive it down the lake, does pressure die off when it running at higher speeds under load? Did you look at the anti siphon valve and the pickup line in the fuel tank to make sure nothing is restricting either of them causing fuel flow/pressure to die off? |
Gary S wrote:Posted By: bigwavedave
Date Posted: May-02-2020 at 10:13am
|
Just got through working on a 97 GT 40 it was the fuel injectors I had three that were bad I have five good ones left thanks Dave 815-953-1823 ------------- bigwavedave |
Posted By: browningskir7
Date Posted: May-03-2020 at 11:32am
|
Thanks for all the suggestions. The gas tank was taken completely out of boat, all the old gas drained, the tank then had nuts and bolts dropped in it, a half gallon of drain cleaner and shaken many times over three or 4 days, Then all of that dumped, the tank rinsed with water several times, all nuts and bolts removed, then flushed with new gas, a gallon 3 times and then dumped and then new gas put in it. The lines all the way to the fuel pumps were replaced and the screen at the bottom of pick and anti shipon valve were blown our wihile the tank was apart. Pressure gauge was left hooked up to boat and passed down the lake. Fuel pressure under load stayed very consistent at 31psi. To answer the question about exhaust, just about every place you could image had dirt dobber nests and wasp nest in it. Even the vent for the tank. Before I put the engine In I flushed and was everything-heat hose lines, shower lines, exhaust, new fuel lines, even the intake plenum had nests in them and had to be washed and cleaned. It was a disaster. I put probably 30 hours just cleanning everything up before I put the engine back in. BTW this boat only had 114 hours on it when I got it. It is in really good shape. I will try to get a picture in. ------------- Browningskir |
Posted By: KENO
Date Posted: May-03-2020 at 11:55am
If your quote is true, then you have a problem with your regulator. At idle (lots of engine vacuum) you should have about 31 psi and as engine load goes up your vacuum starts getting worse and the regulator compensates by increasing fuel pressure to maintain the same driving force across the injectors. At full throttle/load, engine vacuum is essentially zero and you should have about 39 psi to give the same driving force In between idle and full load you'll have numbers that are in between the 31 and 39 ish values. If you have the 310 page manual in the reference section here on CCF, look at pages 2B2 and 2B3 for some info. A steady 31 like you say you have will give you running issues You can ignore the words about the fuel vapor separator, that's not a PCM thing, it was used by Volvo/OMC with their version of this engine. |
Posted By: Gary S
Date Posted: May-03-2020 at 12:35pm
|
Can’t remember the details but wasn’t loping idle one of the symptoms of our very own “colorful” Joe had that was solved with an adjustable regulator? Can’t recall if he had higher rpm issues though. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: browningskir7
Date Posted: May-27-2020 at 12:37am
|
Ok, here is one for the books and not sure ever heard of this before. Everything done as described above. Ended up talking to the mechanic who worked for PCM and built the first 10 GT 40's ever built. He first asked about the IAC as many of you had suggested.I told him I had changed it so then he asked if the timing had been set to which I replied yes. He stated again was the timing set correctly to which again I answered yes. He said just for kicks and giggles check it again. So I was using a friends timing light and he happened to be out of town so went to Yes you guessed it Harbor Freight and got a 30 buck timing light. Took it home and the timing was way off. Reset the timing and the hit the start, it starts right up and the loping disappeared. Friend came home and got his timing light ( a very expensive one) and by it the timing is way off so it appears a bad timing light caused much of this. But still got a slight problem. After fixing the loping the boat fired right up and in the driveway hooked to water hose RPM's went up over 5000. Put boat in water and it would only turn about 3200 RPMs under load and by the old airguide speedometer was running about 32 mph wide open. Did not appear to open up. Suggestions? Fuel related? Maybe a bad injector? Taking a break so looking for suggestions when I go back to work on it. ------------- Browningskir |
Posted By: KENO
Date Posted: May-27-2020 at 9:13am
|
Maybe it's the way I'm reading it but from the first post till now, you've fixed the lope and made the engine run a little slower if anything. I'd ask the PCM guy why your fuel pressure stays at 31 psi and doesn't change with engine vacuum like it should. Deep philosophical question here.............if you have 2 timing lights, how do you know which one to believe ? |
Posted By: browningskir7
Date Posted: May-29-2020 at 1:39am
|
The one I used, made the loping go away and the mechanic I talked to state that the timing being not correct would make one lope. So with the new light it made the lope go away, but to satisfy your deep philosophical question after the I got rid of the lope and blamed it on the timing light, just for kicks and giggles, I hooked the bad light up to my 1977 ford bronco which runs like a top and check the timing. Again i could not even see the timing marks. So now I have the old light doing the same thing on 2 vehicles one which run great and had never given me any trouble. I am pretty sure the old light is not good. I haven't been able to get in touch with the PCM guy to ask the question, so I through it up here. But I do intend to ask him the same questions I have here once I can get in touch with him. Looked at plugs again and 2 of the plugs look to be running real lean (nos 2 and 4)-wondering about 2 of the injector. ------------- Browningskir |