Poor Man's GT40 Diagnosis

You're welcome. Hope it helped.

I updated the IACV line with the Autozone PN, the Napa one is there too.

Another fuel pump popping a breaker:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=26855&title=circuit-breaker-popping

Engine Missing Solved by ECM Relay:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=23424&title=engine-missing

Hot loping (rolling idle) problem fixed with Idle Speed Control Valve:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=24848&title=gt40-engine-loping

Part found on Rock Auto:
IACV PN: e9se9f715eb (off the original valve)
http://www.rockauto.com/catalog/moreinfo.php?pk=945342
$55.79 + shipping

Updated Spreadsheet

Specifics:

1999 GT-40 EFI. 671 hours. Well maintained since new but never tuned up.

Symptom:

Lumpy idle. Clear raw fuel smell at the exhaust when idling. Obvious miss/skip from idle speed up to around 2100RPM. Occasional miss at cruise speeds if you listen carefully.

Solution:

Replace distributor cap and rotor. The original cap and rotor were clearly worn and pitted. The boat ran great after this. $44.

Also:

New plug wires, new spark plugs, new fuel filter and raw water impeller. Might as well do it all. The boat hasn't run this smooth in years. Total cost was $200 and it took about an hour to replace everything.

Intermitant no start


Sometimes a single click and no start-> faulty starter relay

found relay at advance auto. i believe it was off of a 60's or 70's dodge muscle car   

1994nautique wrote: Can you tell me where the anti siphon valve is located? My 94 does the same stalling out every now and then when pulling up a skier. It acts like it floods out so I put it in neutral and start it with the throttle wide open. Then I can usually pull the skier up. Thanks!

There's a good picture of it in this thread:
http://www.nautiqueowner.com/forum/forum_posts.asp?TID=23090&PID=289854&title=anti-siphon-valve

Water needing to be drained from Fuel Control Cell caused no start condition here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=26185&PID=337102#337102

Distributor causing sporatic cutouts at speed, as described here:
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=23542&title=interruptions-while-running--2001-super-sport

1998 Model GT40- Victim of neglect.
Problem 1: Boat had sat for a while. Would not start at all with proper fuel pressure, spark, and compression, but would run on fuel poured into the intake.
Solution: Replaced all injectors, they were completely plugged. You can pick them up for far below retail on ebay. They are 26lbs blue top injectors. Another good precaution would be to ensure that your fuel rail is clean and that all filters are clean and functioning to avoid the same problem again in the future.

Problem 2: No power to either of the fuel pumps.
Solution: The fuel pump relay (There are two- Ignition and Fuel) located on the rear on the engine had been damaged by moisture. Both ignition and fuel relays are interchangeable and cost about $20 a piece depending on where you purchase them.

Problem 3: Leaking water from around the base of the intake manifold (visible from exterior of engine while being run).
Solution: Removed the intake manifold. The four corners of the intake manifold must be set in silicon (we used high temp permatex) to prevent leakage. You shouldn't have to worry about this unless you have jostled around, or removed the manifold.

New ECM fixed rough running, hesitation, little now power as documented here: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25775&PN=1&title=99-sn-gt40-fuel-supply

Updated Spreadsheet

^^Did you replace the injectors?

Thanks again Joel. I updated the spreadsheet with a column containing a simplified description or the symptoms and added a row for Oil Pressure switch.

The sheet is always the same link, I just update the same one.

Thanks Joel

I updated Spreadsheet

The "IAP" idle motor is 2-1944, the MAP sensor is 2-19002 at NAPA.
Found this on a search