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Poor Man's GT40 Diagnosis |
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Bri892001 
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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 Posted: May-19-2016 at 9:10am |
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No fuel pumps and no spark (no start) fixed by replacing the fuse in the battery box fuse holder. This is a boat that had no been retrofitted with the fuse elimination:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=38652&PN=1&title=efi-gt40-help-and-opinions Added to next to spreadsheet: Fused Line in Batt Box For EEC Power Updated Spreadsheet: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: June-02-2016 at 11:28pm |
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Fuel pumps not priming/no start caused by three separate items.
-Potentially defective lanyard -Low pressure fuel pump -Wires pulled lose inside of Fuel Control Cell (High Pressure Pump) during filter change. As described here: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=38636&PN=1&title=gt40-fuel-pumps-inoperative Updated spreadsheet: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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workky
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Joined: June-26-2004 Location: Marietta,Ga Status: Offline Points: 206 |
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Posted: July-10-2016 at 11:25am |
Hey i was just reading this because i was having the same issue, I thought he said it was the idle air control motor that he replaced to fix this issue, not the EEC, of course i have no idea what the EEC relay is |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: July-10-2016 at 4:01pm |
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That's a good catch. I think I had meant to link that entry directly to Lewy's particular post within that thread. That's the only thing I can think of. It gets a little tricky to keep track of, when there are multiple boats being talked about within the same thread. Lewy does mention, what we were calling the EEC relay, later on in that thread.
In that instance, I believe I might have been calling that fusible, separate, wire from the battery box the EEC relay. I realized later on that that was a separate thing, and a source of some issues. There is a retrofit that gets rid or that fused wire from the battery box to the engine. As far as the actual EEC relay, I believe that it is one of the two, frequently replaced, relays. One is for the fuel pumps and one is for the engine computer. Sorry for so much confusion, I just try to follow it the best I can myself. Your best bet is to start a new thread, under the engine heading, and include GT-40 in the subject. If you want, you link back to your new thread from here. You'll likely catch the eye of the GT-40 experts. |
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workky
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Joined: June-26-2004 Location: Marietta,Ga Status: Offline Points: 206 |
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Posted: July-10-2016 at 10:32pm |
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No confusion at all, or atleast i dont think
 Issue-Boat idles fine at idle, but when warm it idles erratic and shuts off, but will start right back up just fine Solution for me- replaced Idle Air Control Motor or whatever its called Thanks |
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Bri892001
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Posted: July-14-2016 at 11:36pm |
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Brent, I added your fix to the spreadsheet.
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: July-21-2016 at 9:10am |
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Replacing Idle Air Control fixes loping idle. This post also comes with an updated part number: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=39377&title=gt40-isc
Updated Spreadsheet: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: July-26-2016 at 9:46am |
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Fuel pumps not running = engine not running. Fixed by replacing ECM (ECA is the correct terminology as explained by Paul, AKA the engine computer) Relay. This is one of the two relays in the back of the motor. One of which is for the fuel pumps and one of which is for the ECA:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=39443&title=gt40-fuelpumps-not-running Updated Spreadsheet: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: August-02-2016 at 6:48pm |
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Replacing Fuel Pressure Regulator solves poor idle and eventual stalling.
Ruptured FP Regulator diaphram was allowing gas to leak into vacuum lines. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=39282&title=1997-gt40-efi-poor-idle-eventually-shut-off Column added to spreadsheet for poor idle and stalling. Spreadsheet same link as above. |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: September-18-2016 at 8:59pm |
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Baffle Broken Loose, restricting muffler and causing reduced performance and slow acceleration.
Fix was to repair muffler. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=38572&title=gt-40-slow-acceleration I updated the spreadsheet and added a new row for the broken muffler. I logged it under the reduced top speed column: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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kylake
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Joined: September-07-2007 Location: United States Status: Offline Points: 11 |
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Posted: November-06-2016 at 3:12am |
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GT-40 1998 SNOB warm engine shutting down; problem solved [Low pressure fuel pump]
As in other postings, my Nautique would start when cold and run great until the engine hit regular operating temperature (160 degrees). Then it drops to idle rough for 30 seconds or so and shut down (sometimes with a backfire). Would not re-start. After reading postings here, I replaced the easiest suspected part first: idle speed control valve. Test drove and got up to temp and it shut down again resulting in a 100-yard paddle back to the dock. Installed a new low pressure fuel pump. No problems during the test drive plus a 20-minute in neutral idle at the dock. Issue seems to be fixed. |
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workky
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Joined: June-26-2004 Location: Marietta,Ga Status: Offline Points: 206 |
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Posted: January-24-2017 at 4:19pm |
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Anyone have a motorcraft part number for the MAP sensor, i did not see it int he spreadsheet, surely somebody has replaced it
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lewy2001
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Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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Posted: January-24-2017 at 9:56pm |
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Ford-AA5Z-9F479 Map Sensor base number is 9F479 the prefix varies with revisions.
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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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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: March-16-2017 at 5:35pm |
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Unclogging clogged fuel pickup screen, solves runs&dies fuel starve problem as discussed here: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=40597&title=98-gt40-rpms-drop-when-engine-warms-up
Updated Spreadsheet added in Clogged Fuel Pickup Row, Runs and Dies Fuel Starve Column: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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workky
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Joined: June-26-2004 Location: Marietta,Ga Status: Offline Points: 206 |
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Posted: June-11-2017 at 1:39pm |
I google that PN, my map looks nothing like that, it's more of a rectangular box with a hose nipple on it. Has anyone here replaced there MAP sensor I did not see it on the spreadsheet, just curious of symptoms Thanks |
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lewy2001
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Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234 |
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Posted: June-11-2017 at 10:05pm |
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The MAP sensor on the GT40 is shown in picture below just above the ACT with the vacuum line running to it. Look through all the google images that the search found, you will find one that looks the same.
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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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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: June-12-2017 at 5:19pm |
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Brent, what symptoms are you trying to remedy with the MAP sensor, also what have you tried to fix said symptoms. I haven't seen that particular part come up in the time I've been paying attention, but that doesn't mean it never has.
If you start a fresh thread with GT-40 somewhere in the title, you'll get a good amount of GT-40s weighing in. Hopefully a solution will be found and I can post it back here and add it to the spreadsheet. |
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Bri892001
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Posted: June-20-2017 at 1:31pm |
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Fuel Pump (FCC) not priming because of loose battery connections.
As described here: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41292&title=fcc-issue-where-to-start I added a new row in the spreadsheet for: Tightened Loose Battery Connections |
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Bri892001
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Posted: June-21-2017 at 6:47pm |
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A second/separate issue solved in the same thread as above.
Replacing a low pressure fuel pump solves a hot restart issue as described in this specific post by by mtguy: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41292&PID=531631#531631 Spreadsheet Updated: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Posted: June-21-2017 at 6:53pm |
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Low RPM misfire fixed by replacing broken/damaged spark plug as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=40837&PID=526898#526898 Added broken spark plug rows to spreadsheet. Same spreadsheet link. |
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Bri892001
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Posted: August-01-2017 at 11:41pm |
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Bogging under full throttle solved by replacing anti-siphon valve and braided fuel line between Low Pressure Fuel Pump and FCC.
As described here: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41488&title=2001-gt40-bogging-under-full-throttle Updated spreadsheet under "Reduced Top Speed" column. Gave half credit to anti-siphon and braided fuel line: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Posted: August-16-2017 at 1:18pm |
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Lack of power after overheat fixed by replacing fouled/damaged spark plugs as discussed here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41631&title=need-some-gt40-help-gents Logged on spreadsheet in broken spark plug row and split in the columns for Hesitation and Reduced Top Speed: https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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Posted: August-16-2017 at 1:27pm |
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Skip/hesitation on acceleration solved by replacing spark plugs and TFI module Edit; TFI module was the fix as mentioned below as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41734&title=gt-40-slight-skip-on-acceleration I logged in the spreadsheet (same link as above) under the hesitation column. I attributed half to spark plugs and half to TFI module. Edit: Logged just under TFI |
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fgroce
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Joined: July-05-2016 Location: Georgia Status: Offline Points: 350 |
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Posted: August-16-2017 at 6:09pm |
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On the skip on acceleration the plugs were Platinum and looked brand new, I really think the module fixed the problem. Just my opinion.
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FGroce
88 Ski Nautique For 28 years Now 2002 Ski Nautique |
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Bri892001
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Posted: August-17-2017 at 11:08am |
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Ok, I'll amend my post and the spreadsheet.
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Bri892001
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Posted: September-20-2017 at 12:09pm |
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No power in gear fixed by replacing faulty fuel injectors as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41742&PID=537812#537812 Logged in the Hesitation column in the Fuel Injectors row on the spreadsheet https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing |
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Bri892001
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Posted: September-20-2017 at 12:15pm |
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Engine surging solved by properly installing the correct spark plugs as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41778&PID=537476#537476 Logged in Rolling Idle column on Full Ignition Tuneup row. |
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Bri892001
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Posted: November-30-2017 at 2:18pm |
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I never got around to logging this one. Intermittent loss of power at speed fixed by replacing distributor. The base problem was a loose/dislodged PIP Hall Effect Sensor.
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=41558&PID=538985#538985 I logged it under the Distributor Complete Rebuilt Row and split between the Hesitation and Reduced Top Speed Columns Updated Spreadsheet |
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Bri892001
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Posted: December-20-2017 at 11:23pm |
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No start condition solved by cleaning/repairing engine 10 way harness as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=42231&PN=1&title=diagnosing-no-start-gt40 Edited: I added in the No Start column and created a new row Corroded 10 (or 8?) Way Engine Electrical Harness Updated Spreadsheet |
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KENO
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Joined: June-06-2004 Location: United States Status: Offline Points: 11112 |
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Posted: December-21-2017 at 12:18am |
That 10 way connector is really an 8 way connector and it seems like putting something in the spreadsheet about the manual being wrong in reference to the connector would be a good idea too. |
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Bri892001 wrote: