SN GT-40 won't stay running. HELP?

[Wish]

So, walked down to the lake to ski, turned the key, motor started, ran for 4 sec and stopped. Turned key again, same thing - 4 second run time and stops. What I did not hear when turning the key to just start all electrical systems was the click and buzz of the fuel pump doing it's thing at startup. I'm assuming the pump primes the system before it starts. That sound did not happen. Checked wiring to fuel pump - disconnected then reconnected - same response - 4 sec then stops. Is there a breaker somewhere or do I have a dead fuel pump. It ran flawlessly 4 days ago. Worst part - fellow Baller Sully was here to ski a set in warmer conditions than what he's used to. Was going to be a great day. Extremely disappointing. Any thoughts ideas suggestions welcome. Plan to have a buddy come over with an electric meter at some point.

[A_B]

There is a relay on the back of the motor that controls power to the pumps. The low pressure pump is visible in front of the engine and it shoots fuel into the Fuel Control Cell, where a high pressure pump is located that shoots it up to the fuel rail.

The relays are a high probability, there are two, and you cant swap them to see if one works and the other one doesnt. I replaced mine a while ago, and I think there is a purple lead on the fuel pump relay. The other relay I think controls the power to ECM, maybe Jody knows for sure.

 

Also, as I just found out this past season, the 12.5 circuit breaker also controls power to the pumps. Mine went bad, and I thought I had the whole relay things all over again. There are no computer error readings on this issue, so the dealer typically troubleshoots it.

 

I have an extra relay, but they are pretty cheap from SKIDIM or White Lake, or Jody can hook you up.

 

A way to test the low pressure pump is to put leads from a battery or battery charger on it, and it will whine if good. Do in a ventilated area though!

 

You are correct in listeining for the prime. Another possible is the battery cables may have a fuse in the circuit, older GT40 had it. My 1999 did not.

[Wish]

@AB you said

The relays are a high probability, there are two, and you cant swap them to see if one works and the other one doesnt.

 

Did you mean that I "can" or "can't" swap them?? Just checking. And thank you. We will run down some of those possible causes this week.

 

Will still take any and all thoughts or confermation of ABs thoughts. Thanks.

[A_B]

Can't. I don't think you can swap them, as a mechanic told me that you need the non-fuel pump relay to get power through the ECM. Never tried, just going by what he told me.

 

The pumps prime every time you turn the key on, even if full, so if you turn the key on and no prime, that is a problem. The fuel pump relay does not just normally quit, mine was intermittent for a while, seeming like someone pulled the kill switch. It would start and run, then repeat. Eventually, it stalled and wouldn't start at all.

 

This is a very common maintenance item for a GT40.

 

http://www.skidim.com/prodinfo.asp?number=R130011

 

 

 

 

[Wish]

@AB thanks. The pics and web pg is perfect. Next question, can I isolate the offending relay via line tester? If so how? Ooops, that's 2 questions. Thanks.

[Jody_Seal]

If it is running for 4 seconds I think I would first take a look at your ECO (emergency cut off)switch/ circuit. Either stick a dime under the button on the lanyard or pull the switch out and jumper the female spade connectors on the back, the two purple wires.

[Jody_Seal]

You can also jumper the relay by jumpering the green wire pin with the red wire pin in the relay receptacle. that will make the pumps run provided your ECO circuit is good.

[A_B]

What Jody suggests with the Kill switch was the first thing I did, as it seemed like it just cut out when we were under power. We taped the 2 lines together and it started and ran, so we assumed problem solved. Wrong. Even with a new kill switch, the next time on the lake, it cut out again, and again, until we replaced the relay. It was intermittent and would just cut power to the pumps with no warning or pattern.

 

I just went through a similar issue thinking it was the relay, which was only a year old, but it turned out to be the circuit breaker. That is about $40. This was odd in that it would idle all day, but when I gave it gas, it would starve the engine off and fuel pump pressure would drop to zero. It would restart and do the same thing over again. Then finally, it wouldn't start and the pumps weren't priming. I bought a new relay, no fix. Then traced back to circuit breaker. Put a new one in and fired right up and revved in the driveway fine. Will have to wait to next Spring for a real water test.

[Wish]

@Jody Seal- what of the fact that I do not hear the boat fuel pump prime at startup? Is that tied to the ECO as well?

[Nick Sullivan]

Wish, What Jodi is saying makes perfect sense and so does what AB is talking about. The fact that the boat would rev when you put it in neutral and applied a little throttle would indicate its getting fuel. Try the neutral safety switch, I'll bet thats it.

[Jody_Seal]

Could be, I like to start my diagnostics from the key switch or battery back to the engine. The Emergency cut off switch is a real common failure. I see many of them fail every summer, have only replaced a couple of relays in the six years of business . I keep a couple new ones in stock, and a relay or two.

[Wish]

Neutral safety switch?? ECO switch? Are these the same thing and is that the switch with the lanyard next to drivers seat? Does that switch cut power to the fuel pump?

[A_B]

Wish -'easy enough to rule cutoff out. Just pull the wires off the back and connect them direct. You could take a wire and jump the terminals but mine had rubber coating on them, so had to remove them to get a good contact surface.

 

I fashioned a wire with two ends that mimicked the terminals in the back of the kill switch while I waited for the new one to come in. Turned out to be a waste of money for my problem.

 

 

 

 

 

[A_B]

Try tapping the circuit breaker with 12.5 on it. Mine was froze in but I tapped on it with the butt end of my screwdriver and the pumps primed. Could be an easy find if you have a similar issue.

[A_B]

Now that I am thinking about it, I think the kill switch shuts down everything, so no ignition or pumps. I am not sure your boat would run for a few seconds then shutdown..

 

If you mess with the relays, here is some info I posted on Planet Nautique a while ago:

 

There are 2 relays, one for the fuel pumps and the other one controls the ECA, which could cause other problems.

 

The way to tell which is which, is by looking at the wires going into the relay (which is the half that is bolted to the bracket that holds them). Both relays have several wires going into them, but the fuel pump relay has a green/yellow wire and blue/orange wire. My fuel relay was the relay farthest away from the motor, as they are side by side, and looks like unless there is a technical spec to mount one in a specific location, they could be mounted in either location.

 

Good luck.

 

 

[Jody_Seal]

Neutral safety switch and emergency cut off switch are two separate devices . The Emergency cut off switch shuts down power to the fuel pumps and ignition while the key switch is in the on position, however when cranking the motor (key switch in start position) power is supplied to both the fuel pumps and ignition for the time the start relay is engaged (about 4 seconds). the neutral safety switch is on the transmission and makes sure the throttle control is in a neutral to allow for starter engagement.

[A_B]

Jody, wouldn't the pumps prime then if there is a 4 second delay? Just trying to learn, not bashing your post. God knows I've spent a fair amount of time chasing through the fuel delivery system, and I actually sort of enjoy it. Weird I know.

Thanks

[jhughes]

Don't discount the LPP as the source of the problem, assuming it is not the ECO switch. The LP pump is a very common failure point on the GT40, and is one of the handful of things that ever goes wrong with them. Diagnosis can be sneaky because they can partially fail- for example, when mine went out, it would still whirr to life but after a few seconds of running the breaker would pop above the ECU, so although it ran, it was drawing too much load due to a fault. I wouldn't be afraid to pull off the LP output hose and put it into a gas can and make sure it's doing its job, assuming it is getting power. HP pump failures can be diagnosed with a pressure gauge on the fuel rail, although they seem to be less common.

 

Relays can be switched with one another, but I only do it to see if something else happens. If something else happens, (for example now the ECU does not get power) then you know a relay is bad.

 

Take it one step at a time and keep it simple. 1. is LP pump getting power. Yes? Good. No? Relay, ECO, inline fuse on battery lead (older GT40s). 2. Is it pumping out fuel? Yes. Good. No? Replace LP pump. Is the HP pump pressurizing the fuel rail? Yes? Great. No? Inspect HP pump hose in FCC, inspect wiring connections on HPP, ensure FP regulator working correctly, etc.

[A_B]

Be very careful with the wires on the FCC. They are set in epoxy to seal the unit, and after pulling my HPP, I sprang a major gas leak through the wire seal. This is a $475 part to replace, you can JB Weld the wires in place, but I didn't want to go cheap inside the motor box with gasoline. I suspect I had a small leak there anyway, as I would occassionally smell gas in the garage and never find a leak anywhere.

 

Jhughes hit on the breaker on older PCM boats, mine didn't have it, but that also kills power to pumps I am told, as I mentioned above. I think it is a red lead with a fuse in it.

 

If you don't mind posting what you find it to be I would appreciate it. Can never have too much knowledge about boats and motors!

[Wish]

@ AB, you and others postings have been invaluable. I won't get to it until later in the week. I have a friend who is very mechanically inclined and understands and interprets what is said here far better than I ever could. I have no doubt that through this thread and his skills, it will be diagnoses in short order. I have emailed him the link. I most definitely will share the findings and solutions. My gut tells me whatever causes the HP fuel pump to not receive electrical power at all is the culprit. Not hearing that click--buzz of that pump when I turn the key full or half way to me says no power to it and no continuous fuel to the rail. But what do I know. I come here begging for help and count on a knowledgeable friend. Like I said in my other post about tranny fluid leak (resolved thanks to BOS) I should know just about everything on a GT40. Ill be close to a dirt nap by then but I'm learning.

[Jody_Seal]

Brian if you have my cell number call me if you get into a jam when you start looking into the problem and are at the boat. See if you can round up a fuel pressure gauge in the meantime.

[jhughes]

@ AB,The wires that power the HP pump in the FCC, and the associated epoxy plug are about a 50.00 part, max. The plug screws out, with the wires in it, totally separate from the FCC assembly! I'd ask for a refund. Mine developed a leak in this same area from the gas eating away at it. I was able to order that plug/wire set as a separate part directly from the dealer.

[Wish]

@Jody Seal. I may have had it. I looked back at the emails re tranny but it wasn't there. I believe you and I spoke through the business line. You can PM me the # if you'd like. Also, my buddy showed me (I believe) where you set the fuel pressure gauge. It's on the top of the motor and small yes?? He mentioned it can be tested with a tire pressure gauge. Maybe I heard him wrong. Odds are good he has a fuel gauage.

[Jody_Seal]

Yea!!! PM sent. The fuel pressure fitting is the same "as" a tire pressure gauge it is called a shradder valve, looks like a tire valve but dont use a tire gauge you will get fuel everywhere...

[Dirt]

This probably has nothing to do with your problem but we had 96 MC that was delivered with no fuel filter. We didn't know it of course but when it started acting up it would run and then shut off. It would start up again and then shut off sometimes while skiing. The screen on the HP pump would get clogged as fuel flowed to it.

[A_B]

@JHughes, no one carries the part you refer to anymore. I called around and PCM sells the complete FCC only. I thought about JB Welding it, but thought if I blew my boat up on the lake it could wreck a great day of skiing someday.... IF you know where I can get one, let me know, as I could fix my old FCC and sell it or have it as a spare for someone..

 

The pumps should prime regardless of a plugged filter or fuel injector, so this sounds more like an electical supply or bad LPP. You can hear the LPP and normally will have to "feel" the FCC to get the HPP vibrating, as it is hard to hear inside the FCC.

 

If you have an old style FCC, all black, the middle port on top is the supply line so follow that up to the fuel rail and you will find the shrader valve on that side of the engine. The other port on top is a return line and returns fuel from the fuel rail. If you have a newer all brushed aluminum FCC, there are different options for the ports and I am not sure the middle is the supply line.

 

The shrader valve is covered with a black fitting that looks like a tire valve cap. I am not sure I would invest in a fuel pressure gauge yet, as it sure sound like an electrical problem to me (power to the pump) vs pump. The pump could be bad, but I would trouble shoot power to it first. My bet is on the relay. Too bad you aren't close to Ohio, as I have 2 good relays sitting on my transom. Had a LPP but sold it. That is pretty easy to replace, as it is outside the FCC. I think that was around $120.

[Wish]

BOAT IS FIXED!!!! and it only took about 30 seconds. So... Who won the "what the ..... is wrong with my boat" contest. That would be Mr Jody Seal !!!!! He is the man. Turns out he was right on with the emergency cut off switch being falty. In fact, it was so sensitive that when my buddy and I went down to analyze the problem, and turned the key for the first time, the damn thing started and ran. Total head scratcher. Spoke with Jody, who said check ECO switch and I barely had to touch the switch and it killed the boat. I owe Jody ski sets whenever he wants .... period. Many thanks to those that posted. I know a great deal more than I did two days ago. That will come in very handy if something falters again. Worth book marking for GT-40 owners.

[A_B]

That's good to hear. Nothing worse than a boat with no go.

[Jody_Seal]

Yea it is just way to common after boats are more then 5 years old. take a look at your lanyard clip and see if it has turned a milky white and is oxidized, that is a good indication that the switch and especially the lanyard is prone to fail. In the industry we try not to call them Kill switches, kinda leaves a bad impression. Emergency cut off switch or ECO is a more relaxed word. kill just sounds so.... hurtful and hateful......... Funny stuff!

Brian glad you are back up and running will take you up on a ski ride in the near future.

[Wish]

My lanyard could not be more white and chalky. Anytime Jody.