i know i know, another gt40 idle problem
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=49926
Printed Date: November-22-2024 at 11:20pm
Topic: i know i know, another gt40 idle problem
Posted By: 97superspotBOB
Subject: i know i know, another gt40 idle problem
Date Posted: June-20-2021 at 7:13pm
| i have recently made the switch from my beloved 88' SN to a 97' super sport. but i have a feeling there is someone on here who can point me in the right direction with the problem im having. motor is a gt40. recent tune up included plugs, wires, cap and rotor which made the boat run significantly better and faster. however. i am now experiencing an intermittent problem. boat starts almost instantly with flick of the key everytime regardless of hot or cold and NEVER stalls. but, after the boat has been running for a few minutes, idle rpm reads about 850 (which i believe is high) and then every few minutes rpm will surge up to 3k-4k for a few seconds before dropping back down to 850ish. when it bounces up like this, the engine definitely kicks up a bit but not as much as i think it really would at 3-4k. does this in neutral and in gear. when in gear and idling around it still does it. when i get on it it picks up quick until about 3/4 throttle. between 3/4 and WOT it seems to hesitate on and off and tach reads between 5k and 6k which does not seem right to me. today when i went to the boat, started it up and stayed at a nice 600 rpm idle, went out and opened it up and it was smooth and fast with no hesitation. took it back down to idle and it started bouncing again. i have ordered new tps, new idle air controller, new ecm relay and new fuel filter (plus 3 inch hose inside canister) as the boat is new to me and no idea when it was last changed. im leaning now towards thinking it is the tach that is causing the issue. i checked the back and all connections were tight and secured. i also spun through the cylinder settings on the back a few times with no success in the problem going away. it was set on 8c 4p, should it be on just 8c? also should the manual controlled dial on the back of tach click for each setting? it just spun freely through all settings... any and all input is appreciated |
Replies:
Posted By: JayG80
Date Posted: June-21-2021 at 8:25am
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Pull off the cap and rotor and inspect distributor internals. May be pip related. The plastic parts inside my distributor broke and the internal parts (stator?) behind the vane wobbled. ------------- 2007 Ski 2002 Ski |
Posted By: 97superspotBOB
Date Posted: June-21-2021 at 10:08am
| thanks for the suggestion, will check later today. does anyone have a napa part # for a complete distributor that works |
Posted By: JayG80
Date Posted: June-21-2021 at 10:29am
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https://www.oreillyauto.com/detail/c/spectra-premium/spectra-premium-distributor-new/gtrp/fd14?q=fd14&pos=0
I bought Spectra FD14 at O'Reilly and deleted the cap and rotor in favor of my new PCM parts. Make sure dizzy has cast iron gear. There may be other suggestions and also part numbers on the Poor Man's GT40 thread. https://www.correctcraftfan.com/forum/forum_posts.asp?TID=25584&title=poor-mans-gt40-diagnosis
------------- 2007 Ski 2002 Ski |
Posted By: 97superspotBOB
Date Posted: June-21-2021 at 10:52am
| got it! do you or anyone happen to have cross refrence number for ecm relay? |
Posted By: JayG80
Date Posted: June-21-2021 at 11:40am
------------- 2007 Ski 2002 Ski |
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Posted: April-24-2012 at 1:37amPosted By: KENO
Date Posted: June-21-2021 at 12:24pm
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Since you were asking about NAPA,If you want an Echlin relay, the number is AR-174 like mentioned above Just as good as any of the others mentioned. Here's an old thread with some info http://www.correctcraftfan.com/forum/forum_posts.asp?TID=49000&title=fuel-pump-relay-failed" rel="nofollow - link They come in handy if you have an old Fleetwood Brougham or an Eldorado too  And............if you're replacing one, replace the other too because one bad relay out of the two will keep the engine from running. And .........if the engine starts and stays running, both relays are good.
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Posted By: KENO
Date Posted: June-21-2021 at 12:42pm
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Bob, do you have a copy of the 301 page gt40 diagnostic manual If the answer is NO, click on the link below from the CCF reference section and the answer will be YES |
Posted By: workky
Date Posted: June-21-2021 at 2:46pm
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https://www.napaonline.com/en/p/NRD482891?impressionRank=1&keywordInput=distributor
I think this is the Napa Dizzy, or its the one I used
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Posted By: 97superspotBOB
Date Posted: June-21-2021 at 6:39pm
| replaced idle air control valve today. still no difference. boat starts and runs strong. pulls out of the hole great. but when running over 25-30 mph its almost like after a few seconds it speeds itself up a bit without giving more on the throttle. next step is fuel filter and new 3 inch tube inside fcc canister. starting to definitely seem like a fuel issue. but also still seems a bit electrical since the tach still acts really whacky... anyone know an experienced gt40 mechanic in Massachusetts haha :( |
Posted By: JayG80
Date Posted: June-21-2021 at 6:55pm
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You really need your fuel pressures to see what is happening in that regard. Key on/ Engine Off pressure, Engine Running pressure. This isn’t your issue but while you are changing fcc filter and mini hose, look at the electric wiring on top of canister. Original wire harness is glued in place and will eventually leak. Bad situation, keep routine inspection for fuel leaks. My 2007 ski still has the epoxy instead of metal thru seal. https://skidim.com/kit-fcc-pass-thru-retrofit.html" rel="nofollow - https://skidim.com/kit-fcc-pass-thru-retrofit.html Just ordered this $40 piece of insurance. I installed it in my 2002 about 3 yrs ago after a fuel leak. ------------- 2007 Ski 2002 Ski |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 4:15pm
| installed new fuel filter today. started right up as usual. hooked up fuel pressure gauge and at both key on engine off and key on engine on, pressure guage read spot on for where it should be. the boat only starts "surging"? and almost giving itself throttle after its been runnning for 10-15 minutes. never stalls and never dies. so now im thinking its something getting too hot? bad coil pack? any one have any ideas where to go next. im not thinking its a bad ground somewhere since it only does it after its been running for 10-15 minutes, runs smooth as can be until then |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 4:20pm
| also, when the rpms start jumping and engine kicks up a little, fuel pressure doesnt change and stays spot on. someone mentioned the wire mesh ball filter inside idle air valve... can it be run without this to see if it makes a difference? |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 7:53pm
| new findings. after speaking with vince at skidim, he assures me my fuel pressure is too low. key on, engine on at idle im around 33 psi, giving it throttle to about 3k rpm fuel pressure goes down to about 29. |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 7:55pm
| there is no in line filter from my tank to the pumps. have i read somewhere that there is some sort of screen in the low pressure pump? |
Posted By: Gary S
Date Posted: June-23-2021 at 8:11pm
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Yes there is,it is under the top mounting plate ------------- 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: JayG80
Date Posted: June-23-2021 at 9:08pm
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Did you replace the 2.5" hose inside the FCC? ------------- 2007 Ski 2002 Ski |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 9:13pm
| jayg80 yes, i replaced the small hose today when i put the new fcc filter in. does anyone think that the high pressure pump which is the original for that boat, is dying out and thats why my fuel pressure isnt quite as high as it should be? i was under the impression that it would either work or it wouldn't, but vince from skidim sermed think otherwise and he is certainly more knowledgeable than i am with these motors. |
Posted By: 97superspotBOB
Date Posted: June-23-2021 at 9:15pm
| i also read another post on a different site where someone had the same issue as me. wouldnt happen till 10 minutes after the boat had been started, would idle fine then start sporadically surging up on and off. and he said his fix was the injector connections had gotten corroded and were giving off 30 ohms instead of 12 which makes sense to me because it seems like when im at a certain speed the boat kicks itself up a notch here and there |
Posted By: JayG80
Date Posted: June-24-2021 at 8:00am
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It could either of the fuel pumps. The low pressure one seems to fail more frequentlty. What did Vince advise? ------------- 2007 Ski 2002 Ski |
Posted By: KENO
Date Posted: June-24-2021 at 9:56pm
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Since you're worried about proper fuel pressure, fuel pumps etc, have you looked at the anti siphon valve and the in tank suction line for any restriction/plugging. It's kinda hard for a pump like say the LP fuel pump to put out proper pressure if the suction is restricted That, in turn makes it kinda hard for the HP fuel pump to put out proper pressure as demand/flow required go up as you give it more throttle. Kinda like sucking through a kinked/restricted straw You could also check the fuel pressure regulator to make sure it's functioning properly. The 301 page manual you have will talk about the regulator but not the tank suction or anti siphon valve. Back to your tach selector switch question, you might not be reading those positions right. Most tachs with the selector switch have 8cyl and 4 P at one position and no separate position for just 8 cyl. And if somebody somewhere on some unnamed site cleaned his connections to the injectors, I suppose you should give it a try
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Posted By: Gary S
Date Posted: June-24-2021 at 10:59pm
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FYI the Ford Motorsport injectors I got came with a tube of dielectric grease so if your checking them make sure you get some extra. Also with all this talk about anti siphon valves,even though I've had no trouble,I pulled mine this year to check it. Since the fuel lines are 26 years old I replaced them too ------------- 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: 97superspotBOB
Date Posted: June-25-2021 at 6:10pm
| replaced coil back today and the problem is gone. idles smooth, no hesitation or random kick up while under load anymore. before replacing coil i was just barely at 12 volts on the gauge, at a steady 13.5 now |
Posted By: KENO
Date Posted: June-25-2021 at 7:15pm
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Sounds to me like "you done good" BB Another case of a fuel problem solved by fixing an ignition problem. It happens fairly often
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Posted By: 97superspotBOB
Date Posted: June-29-2021 at 8:26pm
| ugh, i wish. but unfortunately i did NOT solve the problem. when i put the new coil on, i had the battery unplugged for a half hour which i believe allows the computer to reset. connected everything back up and she ran great like she was supposed to, no idle flair, no surging, no missing at high speeds. took it back to the dock and parked it. came back the next day and problem was backed. next i changed the TFI. also unhooked battery for a while while doing this. connected everything back and bam. running great again. perfect in all aspects. for about 35 minutes... problem back. with everything i have done and changed, i have narrowed it down to its got to be the ECM. bit the bullet and ordered a new one from gt40marine.com it will be here thursday. my reasoning is this. everytime i change something and unhook the battery allowing the computer to restart, it runs great like it's supposed to for 30-40 minutes before the problem returns which tells me the computer resets and is good but then goes bad again shortly after. fingers crossed the new ecm does the trick. not sure what else it could be. i was thinking distributor. but it just seems too convenient that it runs great for the first 10-15 mins until something gets hot, and the fact that everytime i disconnect the battery for 20+ minutes it goes back to being good again for a brief while... |
Posted By: JayG80
Date Posted: June-29-2021 at 8:36pm
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You said fuel pressures are too low. I think that is the proper vector to resolution and cheaper than ECM. ------------- 2007 Ski 2002 Ski |
Posted By: KENO
Date Posted: June-29-2021 at 8:44pm
OK, I'm taking that back then Figured maybe it wasn't fixed since you probably surfed through every gt40 thread on CCF during the last couple of days.You probably know it already but it's a 30 or so year old ECM that's been reprogrammed for the gt40 that you're buying. Since a bunch of signals feed into the ECM, so that it can figure out what to output, there's always that chance that the new one will do the same thing after the same amount of time if one of those inputs is really the culprit.. Good luck with the "new to you ECM" , |
KENO wrote:Posted By: 97superspotBOB
Date Posted: July-01-2021 at 8:23pm
| @keno i am cryinggg right now haha. "new" ecm came today. went and installed... boat wouldn't even fire up with it! jist kept turning over. put the old one back in, fired right up. i called the people i bought it from and they are sending another one. they said it may have gotten damaged during shipping... either way, after opening the ecm cover today to take the old one out, i certainly do believe it is the problem considering how much corrosion was all around it. wish me luck when the next "new" one gets here |
Posted By: Gary S
Date Posted: July-01-2021 at 9:00pm
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I've always wondered for $780 what refurbishing and testing steps are done to the used ECM's by this company. Don't be too anxious to send your original back for the core ------------- 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: KENO
Date Posted: July-01-2021 at 9:13pm
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Whatever you do, don't send your old one to them for the core charge unless you're totally happy. Since you're convinced it's the issue, I'd like JayG80 said, make sure your fuel system is "right" while you're waiting on the next one Have you checked the tank suction and the antisiphon vale to both be clear and unrestricted since your fuel pressure drops as load goes up. An alternative would be to hook a temporary tank to the LP pump suction and see if pressure is any better under load. Make sure the tank is vented. A hose from the pump suction into a 5 gallon gas can would work. And.............my dear sweet old long departed Irish granny used to say..............if you don't have anything good to say, then keep your trap shut. You don't see me saying anything about gt40.com Good luck when the next one gets there There are other ECM solutions that you'll spend a lot less on that people here and on Planet Nautique have had good experiences with. Here's a link to a little reading http://www.google.com/search?q=correctcraftfan+Franscioni&oq=correctcraftfan+Franscioni&aqs=chrome..69i57.17958j0j4&sourceid=chrome&ie=UTF-8" rel="nofollow - link .
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Posted By: JayG80
Date Posted: July-02-2021 at 9:32pm
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Of the 1994 to 2002 Ski Nautiques on our lake, all have replaced a low pressure fuel pump and none an ECM. Not a big sampling but I suspect it would hold up if we had a poll on CCF. ------------- 2007 Ski 2002 Ski |
Posted By: 97superspotBOB
Date Posted: July-02-2021 at 9:39pm
| jayg80. that is very interesting. but the fuel pressure stays steady always, even when it starts to act up. i wish that was the case for me |
Posted By: bwinn
Date Posted: July-02-2021 at 11:00pm
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If you haven’t already I would clean the battery connections and fully charge/test the battery. While your in the battery box take a look at the inline fuse and pull it out and clean up the connections. If it were me I would probably by-pass the kill switch for now also. Curious, does it have perfect pass? -Burton |
Posted By: 97superspotBOB
Date Posted: July-06-2021 at 9:26pm
| just to be clear, i was never talking bad about any business. in fact, the guy at gt40marine.com in my opinion gets a gold star. after realizing the ecm got sent with a chip that was never programmed, he did everything in his power to get me a new one for the next day knowing it was the holiday weekend. and he did! i got it in less than 24 hours. put it in, boat cranked right over and has been running like a dream! finally got to ski behind my new boat for the first time and burned through 2 tanks of gas the past few days pulling others with zero problems what so ever. i am so happy and relieved to finally be able to enjoy it! thanks so everyone for their input and possible solutions. you guys are what makes me love correct craft boats so much! |
Posted By: KENO
Date Posted: July-07-2021 at 6:09am
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Just to be clear I don't think you were ever talking bad about gt40 marine.com, but I was and your experience does little to change my thinking, but I'm glad it worked out for you.
Time for another "you done good" Can't say much about Mike's "rigorous" testing of the first dead ECU he sent to you.
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Posted By: agetech
Date Posted: September-01-2021 at 12:39am
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I know that this post is kinda old. I just wanted to let everyone know that you can buy a used computer on Ebay for a 91 to 93 4 cylinder Mustang 12A650-BB coded D1L1 and then get in touch with https://www.planetnautique.com/vb5/member/18335-t-franscioni" rel="nofollow - t.franscioni at Planet Nautique to program a chip for you. I gave $50 for the computer $25 to t.franscioni for programming, and I believe $75 for the chip a from Moates. The chip card can be used on another computer if this one fails. I was having hot start problems with my old computer, and after checking fuel pressures and complete ignition tune-up, I was able to verify the computer was not firing the injectors when hot, with a noid light. Recently took the boat to the lake for a week and the grandkids skied and tubed for hours each day, never had a hot start problem. My son started the boat clear across the cove while I was sitting on the dock, I was looking around to see where that good sounding boat was, then I realized it was mine, cool!
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Posted By: KENO
Date Posted: September-01-2021 at 6:46am
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That's pretty old news, but good to see it get reposted every once in a while. There have been a number of people here on CCF that took that route with good results. Tom is a member here too Sounds like one more satisfied customer.
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Posted By: agetech
Date Posted: September-01-2021 at 10:47am
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Posted By: KENO
Date Posted: September-01-2021 at 11:38am
So it sounds like we agree SuperspotBob bought his from the other place before asking any questions or saying he needed an ECM and he had to pay. You might say that the guy selling them for 600 or more just pirated what Tom and some others did all the legwork on.
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