97 Sport Runs for awhile then dies, starts again next day, repeat

[TG3]

I’m having some trouble with my ’97 Sport Nautique. PCM GT-40 engine. I replaced the fuel filter when I got it out of storage as I usually do, and this year I gave it new plugs, wires, cap and rotor too.

First time out I noticed my fuel consumption has increased. On our 4th outing this summer, we ran the boat off and on all day. On our last run of the evening, I left the dock, gave it moderate throttle to get to about 20 miles an hour and it died. No drama, no coughing, just stopped. It would not restart. It would turn over fine, sometimes “catch” like it was starting but as soon as i released the key and the starter quit turning it would die.

I got towed to the dock where it sat until the next day, roughly 24 hours. I was going to be towed to the marina by a friend, but I tried to start it before we left, it started fine. So we made it to the marina under our own power with no problems. I took it in to the our local Nautique dealer as we were about to leave town for vacation. 4 weeks later they got to it and the first thing they found was a faulty starter, so they replaced that along with the battery cables/ends. After that they ran it and tried to diagnose it but it ran “like a top, nothing we can find wrong with it at this time.”

So this past Saturday we took it out for the day. It was a bit more difficult to start when I first put it in the water, but then it ran fine. We tubed and skied in several sessions that day, with an hour or so break between each session. with the exception of one time early in the day where it took a few turns of the key to start, it cranked fine and ran great (though still burning more fuel than last summer). Third session out, idled for a few minutes while a kid got situated on the kneeboard, and it died. No warning, just died and would not restart. We got towed to the dock where it sat for a few hours, then I tried starting again, no luck, so towed back to the marina.

The next evening, so roughly 24 hours after it died, I hooked up the water hose and it fired right up and ran smoothly.

It seems that whatever the problem is, either time or heat is causing the shut down.

I have some videos of trying to start it right after it died, several hours later when I tried again, and a video of when it cranked right up after 24 hours. I can post these if they would be helpful.

Any suggestions would be helpful, I’m am hoping I can get it fixed myself this time and not have to wait in line another month at the dealership.

[gary s]

Your going to have to do sometrouble shooting first- it can get you no where fast randomly changing parts. When this happens you should check to see if you have spark. Down load the service manual here- https://www.planetnautique.com/Corre...e%20Manual.pdf and join the GT40 Marine Engines page on FB. A wild wild guess with what you have provided would be the Thick film Ignition module, Ford part number F1PZ-12A297-A but you should verfiy no spark first

[TG3]

Ok, I will do some checking on the spark. I have a daughter about to go to college, so once I get that done in the next few weeks I will have some time to troubleshoot and report back. Thanks!

[bturner]

Sounds like fuel due to the increased fuel usage but electrical due to that way it's shutting down. Here's 2 that I worked on with somewhat similar symptoms.....

Fuel..... Is this EFI or a carb? If EFI I'd start at the fuel rail and check the pressure. Malibu's had a problem with the fuel pressure regulator that we've had to replace on the BIL's boat twice now. With that one the regulator basically stopped regulating and was pushing fuel past the injectors flooding out the engine. Once flooded it wouldn't start for 20 - 30 minutes. Sometimes it would run well other times it would miss really bad. With this boat we got black smoke briefly on startup and you could see it building on the around the exhaust ports and on the transom.

On a carb, I'd be looking real close at the float which may be sticking or is staring to leak. A bad power valve would give you a rich condition and issues associated with harder starting or flooding.

Electrical... I had a 89 ProStar that ran great but would randomly shut off. At first it would start right back up but later got difficult to restart at times. The ah-ha moment came when it stopped after hitting a boat wake. Got it back to the dock and started jiggling the key while it was running and had it die. Turned out the ignition switch had gone bad. The switch pretty much started coming apart as I was disconnecting the wires on the terminals. Fast forward to about 2019. Had a friend ask me to look at their 2005 Malibu with intermittent starting and cutting out issues. Boat would just die for seemingly no reason. Sometimes it would start right back up sometimes they had to be towed in. Had it at the dealer twice and it never failed at the dealer, or at least that was the story from the dealer. He fired the parts cannon at the fuel system and even drained the tank thinking it was a water issue. Told him my story above, he replaced the ignition switch and all the problems went away. He's still driving it today. He was so happy that I got an unsolicited fifth of Crown Royal the next day.

Are either of these your problem? Don't know, hard to say without looking at the boat in the non-running state. With the fuel issue above you could smell it in the air when it was running but it was by no means easy to find until I put a gauge on the fuel rail and saw something like 97lbs on the rail (it's supposed to be around 58). That was a dead bang and had the boat back in service a day later.

The electrical issue was pretty straight forward as well. On both you could jiggle the key and have the engine die.

[TG3]

I have fuel injection so I have ordered a fuel pressure tester. I will check the pressure at the rails while I'm checking the other pressures. The ignition switch is nice and tight, but I will double check.

[Jonny Quest]

Sounds like a low pressure fuel pump is failing. Also, the short fuel line inside the FCC that is attached to the high press pump can get micro-cracks (hard to see). You can change both out for under $100 (using non PCM parts).

JQ

[TG3]

I have the spark checker and a fuel pressure gauge kit on hand. A couple questions:


1. Where do i connect the gauge to test pressures? Are there more multiple places to connect?

2. Weather isn’t looking great for being on the water in a stalled boat and doing diagnostics. Anybody have any thoughts on if running it in the driveway will get it hot enough to make it quit? It would be a whole lot easier to let it run at 2500 rpm or something for awhile in the driveway then have to be stalled on the lake diagnosing and then have get towed in! Plus my shop full of tools is at the end of my drive, not out at the lake.....

[FMSKI]

Assuming you have confirmed fuel supply & pressure, the instant quit and no restart would point toward electrical.

The GT40 is self-contained package electrically. It receives the command to start and keep ON (12V) from the 8 way plug that is connected back to the dash /key sw.
My buddies boat had corrosion on that connection.

the 12V key ON energizes the two relays at the back there, one for the EEC power and one for the fuel pump.
Also for good spark the distributor needs to be grounded at the block, through the mechanical connection.
The coil should have 12V on one terminal, then the TFI drops the other side (pulse) to create a spark. That -ve side of the coil also is spliced off to the tach.

The distributor provides a pulse signal to the ECU to control the spark timing. You can bypass the ECU control by removing the SPOUT connector, and the distributor signal is used directly by the TFI module.

My bud's boat is still dying on the water. Haven't come up with the troubleshoot plan, although I would have an LED spliced in on the 12V key-on signal to confirm that stays lit. A new distributor is a good thing too, but mine still ran fine it just sputtered over 2500RPM when that failed.

[TG3]

We went to the lake today and tried to simulate the same conditions as the previous times. We ran out of daylight before i could get it to die and not restart.

However, at one point we were running at approximately 30 mph and it started losing power and then running ok, then losing power again. I pulled it back to neutral and it died. Thinking that his was typical, i pulled out my spark checker first, attached it and then cranked. The boat started right back up, spark checker showed good (of course it would it was running again).

It ran fine the rest of the evening, so we headed back to the marina. Once on the trailer, i hooked up the fuel pressure gauge, just to see. Engine temp showed 160 degrees on the gauge. Fuel pressure at Key On Engine Off showed 20 Ibs. I could hear the high pressure pump when the key came on.

It cranked right up and the pressure gauge showed 30 lbs at idle.

Based on what happened today, and fuel pressure readings, sounds like a fuel problem to me. What do you guys think?

[FMSKI]

How many hours on it? The check valve at the tank, the small screens on the pickup and primary pump could compromise fuel flow/supply

[TG3]

It has 838 hours. How do you check those screens and check valve?

[FMSKI]

You have to get at the top of the fuel tank. The check valve is at the top in line. My buddy's 97 the check valve worked but was resistant. Wasn't until I PB blasted it (lube) that it worked ok. The boat ran great when the check valve was removed at first.

The pickup pump is at the lower engine front, 3 nuts hold it on. Small screen on the inlet of that.