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GT40 won't start cold |
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TigerDyne 
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 Topic: GT40 won't start coldPosted: July-05-2022 at 4:05pm |
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1996 GT 40 EFI
We use boat almost every day. Over the past several weeks it became difficult to start cold. Use in evening it starts ok next morning. Skip a day or two and hard to start. Advencing the throttle usually required to get it going. We went away for 5 days and upon return it won't start at all. Starter runs. Fuel pumps are not turning on. Here's what I've determined so far: No power to fuel pumps - either when key on or starter running. THere is power on both sides of all 3 circuit breakers. connections at circuit breakers are tight. I do have constant on power at the ECM (red wire #1 pin) THere is constant on power at the relays but the relays do not click when key on. I did replace both relays. Ignition power (purple wire) is present at the connector from the gague cluster.
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TigerDyne
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Posted: July-05-2022 at 4:11pm |
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What is the frequency of ECM failure?
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Gary S
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Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Posted: July-05-2022 at 4:49pm |
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They don't go out that often but like anything it does happen. What you can do is read through this- you don't have to read the whole thing but just enough to get an idea. http://www.planetnautique.com/vb5/forum/nautique-topics/maintenance-technical-discussion/510361-hope-for-gt40-efi-ecu
If you think you need one then get one of these, there are only 2 models that will work,they are listed in above thread. Prices vary http://www.ebay.com/itm/154554035521?fits=Year%3A1991%7CModel%3AMustang%7CMake%3AFord&hash=item23fc236d41:g:YWkAAOSw~sZg-viG and one of these http://support.moates.net/f3v2/ and have one of the guys on PN program it for you,you'll be in for about 200 bucks. Or there are people who have done exactly that and resell to you for around 700 |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 10641 |
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Posted: July-05-2022 at 5:49pm |
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You could click on the link below for some reading about ways to power your pumps with the STO connector or just jumping power directly to the pumps.
link
You could power up the pumps and turn the key and it should start. It'll help you decide if a new ECM is what's needed. FSTS2K in the linked thread needed an ECM...........maybe you will, maybe you won't  |
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TigerDyne
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Posted: July-07-2022 at 4:29pm |
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I read the thread in the link KENO provided.
Grounded the specified pin on the test plug and got the fuel pumps to run. I did not attempt to start the boat. Am i correct that the fuel pumps should run for 3 or 4 seconds when the ignition is turned on? This isn't happening. But with the test plug grounded the fuel pumps did turn on with ignition circuit turned on. Whet turns on the ECM? Is there a crankshaft sensor that confirms that the crank is turning? |
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lewy2001
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Posted: July-07-2022 at 7:40pm |
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Starting to sound like a ECM have a look through this thread for some more info.
https://www.correctcraftfan.com/forum/forum_posts.asp?TID=25775&KW=&title=99-sn-gt40-fuel-supply |
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If you're going through hell, keep going
89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
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KENO
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Posted: July-07-2022 at 9:12pm |
You should have turned the key the rest of the way to Start and see if it started. The pumps will run for a few seconds when you turn the key to Run or Start and if the ECM doesn't get a signal from the PIP in the distributor to tell it that the engine is running, the pumps turn off. The PIP on the gt40 does basically the same thing as a crankshaft position sensor. You don't get the pumps to run at all so it's not due to the PIP. When you have the jumper installed and the key in Run (or Start), the jumper grounds the fuel pump relay (which would normally be done by the computer but in your case it's not happening) When the relay is grounded, power goes to the pumps and in your case they ran. This all suggests that the ECM is not performing it's grounding function for the fuel pump relay. So..........try starting the engine when you have the STO jumper installed...........if it runs you know the ECM isn't grounding the relay and the STO jumper is doing that function instead. If it doesn't run you may have other ECM related issues You could run the boat that way, but you'd be defeating a safety feature. That would be a fire situation from say a fuel line leak where the engine quits and you don't turn the key to OFF in all the fire excitement, the pumps will keep on pumping fuel to feed the fire Normally the PIP would see the engine not rotating and tell the ECM to open the ground for the fuel pump relay and the pumps would quit Things you could check would be the ground wire connection to the engine for the ECM and you could unplug the 60 pin connector and make sure you don't have a bunch of corrosion on the pins Pin 52 is the ground path from the fuel pump relay into the ECM and the ground wire from the ECM to the engine completes the path to ground through some electronic wizardry in the ECM
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TigerDyne
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Posted: July-08-2022 at 10:56am |
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THank you KENO.
If the engine will run with the STO Jumper are you saying that we could use the boat? I think I understand the safety concern.... And if the Engine runs with the STO Jumper is this a definitive that I need to buy new ECM? I'd be inclined to use the boat short term while I wait for new ECM to arrive.
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KENO
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Posted: July-08-2022 at 11:48am |
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People have run it with the jumper installed, just one of those personal decision you'll have to make.
You could call it continued troubleshooting
I don't think there's ever anything definitive when it comes to ECMs, but it sounds like that would be the problem. Just a reminder that the "new" ECM will be a 30 plus year old one that's been reprogrammed unless you know some more about getting a replacement.
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MrMcD
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Posted: July-08-2022 at 12:58pm |
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If the ground wire gets your boat up and running again you can purchase an Oil Pressure Shut off switch and wire it in to protect your family from fire. Oil Pressure shut off switches are very popular with Hot Rodders when they add a modern fuel injected engine to an old car. The fuel pump won’t run if the engine loses oil pressure. Just an option to replacing the ECM in your boat.
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TigerDyne
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Posted: July-08-2022 at 5:23pm |
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Per KENO suggestion I grounded pin 1 on the test plug and started the motor. Fired right up. However runs erratically and will only run while holding starter on. Release the key and it turns off.
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MrMcD
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Posted: July-08-2022 at 6:23pm |
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That could be just a bad key switch, when they go out they can supply power to your ignition while cranking but as soon as you release the key to the run position the engine dies. Worth a check.
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KENO
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Posted: July-08-2022 at 7:50pm |
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Did you check the ground wire connection to the engine from the ECM to be sure it's clean and tight?
And did you unplug the 60 pin connector and make sure there's no corrosion there and plug it back in. Nothing to lose by doing these 2 things I'd probably unplug the lanyard/kill switch and jumper the wires together just to rule out that possibility also.
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TigerDyne
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Posted: July-09-2022 at 3:50pm |
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Lanyard switch bypassed
ECM plug clean Disconnected grounds and verified continuity With test plug pin grounded the fuel pumps turn on and the engine will start and will run if throttle advanced. It won't idle. At idle the engine starts runs for seconds and turns off. Looks like the key switch is functioning properly.
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KENO
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Posted: July-09-2022 at 8:31pm |
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I guess you're at a point where you know the ground isn't being made in the ECM and the idle issues could be ECM related like not sending the proper signal to the IAC bypass valve or could be due to a bad IAC bypass valve for example, but it sure seems like you have ECM issues that developed over a period of time.
Now am I gonna tell you to go out and get another ECM? Hell no, I don't like spending other people's money especially when it's not a sure fix and it's expensive, but that might be the solution here.
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TigerDyne
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Posted: July-10-2022 at 1:13pm |
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OK I think I'm to the point of ordering an ECM. I'm a bit leery of buying a used one and the modification chip. This is getting past my knoledge base.....
Are ECM available new? Or is it a remanufactured part. Any suggestions where to buy? |
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Gary S
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Posted: July-10-2022 at 2:06pm |
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No new ones are available. All replacement ones are of a used early 90's 4 cylinder Ford Mustang source with a chip programed using the PCM spec's and installed. V8 ecm's from those same vintage Mustangs do not work. Read through PN thread in my original post. Some have had luck having theirs repaired. As a spare I have one I bought off ebay for under 100 and had the 75 dollar chip programed. It runs fine when I tested it. Roughly have 200 total invested. There is a person who does exactly what some of us have done and charges around 700. Don't know if they are gone through or not but I guess you do get a guarantee for the 500 difference. Up to you,PCM's fix is to install a new engine.
Nautique parts I believe sources them from the person with even some more markup-http://www.nautiqueparts.com/product/gt-40-engine-control-module-ecm/
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TigerDyne
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Posted: July-13-2022 at 9:54pm |
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New ECM and all good!
Ordered it from GT40 Marine in Washington. Prompt ship. Thanks to the Academy and all of you who commented on this thread. Now I'll have a war story to recite at Greg Fossett's next reunion! (Although I'll probably show up with my Flightcraft......)
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KENO
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Posted: July-14-2022 at 8:28am |
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Wallet is a little lighter, you're a lot happier, good job
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TigerDyne wrote: