Poor Man's GT40 Diagnosis

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

Brent, I added your fix to the spreadsheet.

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.

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

Tim is correct, '95 Correct Crafts did not have a FCC. In talking to a PCM rep I was under the assumption that the low pressure pumps were added to help cure the problem as he was telling me how hard it was installing them. I wonder if there was a recall to add them to early boats? My low pressure pump does not have a plug but instead is hard wired with shrink wrap crimp fittings. Knock on wood I have never experienced it. I wonder with the larger engine compartment and venting that a V Drive does not have the same trouble?

Hi EJ - We have a '95 Nautique GT40 that experienced similar problems last summer.   Did you resolve your issues ?   Our boat starts and runs great under most conditions but we regularly see hesitation, missing, rough idle on hot days. We could pull a few skiers just fine but by the 3rd or 4th skier (or if the boat sat at dock for an hour after use) then we would regularly experience rough idle,missing and hesitation during the hole shot.

Any thoughts ?

If possible, please start a new thread to hash out the individual GT-40 issues. Include "GT-40" in the title of your new thread so people know to weigh in.

I'd like to keep this thread as a place to post the results and the links back to the full thread. Working out the individual problems here will ultimately make this thread too messy to read through.

Maybe pull one wire at a time at 2000 rpm to see if running changes at all. If you pull one and nothing changes that's a bad wire. Reply to EJNautique

That's something I could do if people posted those cross referenced part numbers. I'd have to look at it closer, but I could either add a column to what I have, or maybe a new tab in the workbook, with a spreadsheet just for that.

Yes, spark advance was adjusted, which improved the performance. I am still left with a noticable hesistation and rough running at around 2k rpm. Cap and rotor were replaced. New spark plug wires too. Appreciate any thoughts on causes.

New ignition switch solves mysterious starter engagement when shifting into neutral
On approach to dock.

Sorry, just getting back to my previous post. It turned out to be electrical. Replaced the distributor and spark plug wires. I still have a slight hesitation at 2k RPM, but it is running much better. Top end speed has gone down a few MPH too. Any ideas on remaining issues

It was another relay issue. Apparently one of the "new" relays went bad.

Thanks Lewy,

I've heard of that retrofit before, but that was somehow the first time it's been documented on this thread.

I've corrected my post and the spreadsheet.

Thanks for the input Tim. I logged your 30 amp inline fuse fix in the spreadsheet under:

EDIT: Per Lewy's correction below
I have now added a new row to the spreadsheet and put the entry under:


Fused Line in Batt
Box for EEC Power


Updated spreadsheet:
https://docs.google.com/spreadsheets/d/17VemuIOaa9i8kEply-ZmFOSyjyzz8rd7B0WEuIT_6S0/edit?usp=sharing