99 SN GT40 Fuel Supply

Al did you complete the "wiggle" continuity test of the fuel pump relay earth wire?

Remove valve from fuel rail schrader valve before reconnecting pressure gauge?

I can almost feel your frustration. I know you are not comfortable with multi meter. Wish I was closer would like to see the resolution to this problem first hand. Do you know anyone who has some experience with electrics and can handle a meter?

Maybe there is some CCfan's close by who can help you. Randy-in-Ohio is a great bloke that I met at GL in 2009. He would be able to help you but not sure how far Canton Ohio is away from you.

The dealer maybe the last resort but I would make sure they are familiar with the GT40 before I wasted money paying for them to learn.

AMB wrote: Could the ECM be bad? This just isnt making sense.. I guess the low pressure pump could be bad too. I am rally wondering if I have more than one problem..

I feel just like Lewey; I'd be happy to help do electrical troubleshooting. If you want to trailer it to the San Francisco area, just let me know.

Boy, you are obviously stressed/frustrated when you think you should buy a MC.

My quick low pressure test is to listen for the fuel return splashing, but if you haven't done the flow test into a container, that would be a good idea. My old pump was okay, but the flow was a bit low (I didn't have a low pressure test gauge to see what the PSI was). However, my problem wasn't at idle, it was under load when the low pressure pump couldn't keep up.

One thing telling to me is that even when you jump the pumps to the STO, you still had the problem. With the engine off, you have continual pumping and pressure when jumping. However, when running, the pressure goes all over the place (per your previous video) even when jumped. So it could be a ground connection (same symptoms when jumped and not jumped when the engine is running (and things are vibrating)), an intermittent short that seems to happen due to the vibration when running, or something with the computer.

However, what still bugs me is (I just watched the video again):
1. PSI dropping to zero and staying at zero but the engine keeps running. No logical explanation for that.    When you tested this evening, did the engine die when it hit zero PSI, or did it still run for a while?

2. I noticed that the loud hissing sound we here is happening while the pressure is going up. If that is the sound of the pump sucking air, the pressure would not be going up. So something different is going on there. Have you been able to get a better idea of where that sound is coming from? If you watch from 0:29, the engine is running fine from about 0:05 up to that point. Then you hear a click, the pressure drops, and engine starts dropping. The hissing then "changes" to a different hissing, the pressure goes back up, the hissing stops, and then the pressure drops.

I think you need to go back to the hissing sounds and the action of the pressure gauge (while still considering a short or other wiring issue). First, the sound seems to be coming from the spark arrester area (throttle body) since it was the loudest in the video at 0:15 just when you were passing the spark arrester and the hissing started and the engine smoothed out and ran normal until 0:30. Also, note at 030, there seems to be a "click" (like a big relay or something else), followed by the first type of soft hiss, then, the loud hiss starts, PSI goes up, etc.

Also, the loping from 0:30 to about 0:45 is very uneven, but the loping stabilized at a frequency from 0:45 on (and then it sounds like my hot restart loping--the difference being that when my engine is loping, my PS fluctuates between 32 and 40psi, which is caused by the different manifold vacuum pressure during the peaks and valleys of the loping RPM). Your PSI goes to zero (again, don't see how that is possible).

I certainly agree that if you are going to take it in, that you confirm that the dealer has a lot of experience with a GT40 first. If it was me, I'd go back to the hissing, clicking, and other noises we hear on the video and I'd find the absolute source of each. Again, this could all be a ground/short or computer issue, but since there are other things going on besides the loping, I'd want to trace back these noises to their source, and assuming there is something electrical that is causing these noises to happen, I'd then trace them.

Also, one other test I'd do is to go ahead and confirm the + and - terminals on both pumps, and I'd actually jump them directly to the battery, and then start and run it. That bypasses everything. Then see if it runs good, or if you get the clicking/hissing, drop in pressure, or loping. If so, it is NOT an electrical connection to the pumps.

So my two cents. Bypass everything and run it with the pumps both connected to the battery, and then if you still have the problem (including dropping PSI), find out for sure where those noises are coming from.

Then let us know. We don't want you to have to take it in if we can help it!! But I understand the frustration (maybe I'd get frustrated enough to buy a Malibu, but never a MC). :-)

AMB wrote: You are correct on the Malibu vs MC, but at the moment, I was on the dark side.. AB

   Really!! I'm LOL! That's a good one. I'll have to use that one on some of the MC owners in our club!

I believe Harbor Freight has a mechanic's stethoscope for cheap. Haven't picked one up yet, but I'm finding the hose bit doesn't work as well (as I'm getting older too).

Hope the pump jump to battery tells you a lot and the noises can be isolated. I'm getting frustrated with the electrical stuff (so you must really be frustrated), so focusing on some mechanical stuff that doesn't make sense for me is a good diversion (even if it just eliminates some stuff).

Al it could be a bad computer. But my guess is still a bad connection. With the pumps priming and not priming intermittently after disturbing wires it really points to that.

Just need to back track a bit. You may be over it so disregard following if so.

If the Fuel pump relay earth wire to ECA continuity tested OK with jiggling of wiring harness. We can rule out that hopefully.

How did you end up getting the meter leads connected while moving wiring loom? You need to make sure the connection of leads is good so you can see if the wiggling was causing the high resistance reading on meter or it was just the meter leads having a bad connection at test points.

With the STO jumper installed and fuel pressure gauge connected. Without valve inside Schrader housing. I dont trust the readings on your pressure gauge until you do that. The fuel pumps kept running while wiggling wiring loom, relay connectors and tapping circuit breaker terminals.
And the fuel pressure stayed around 40psi. Correct???
This will confirm that pumps are running and there is fuel available in the rail.

The flat battery could just be a combination of the age of battery combined with the loss of charge over winter layup period.

Cranking without starting is another issue especially if you have 40 psi fuel pressure at rail. I chased a intermittent hot start problem all summer. I purchased a Ford Code Reader (this is what the STO connector is really for) to help isolate the problem. They are inexpensive and may be useful in the future. With the help of the code reader I was finally able to fix my problem.

Just confirm the above points to yourself to make sure you are not missing or misinterpreting the symptoms.

I asked my local dealer about cleaning out the asv and reusing it. He says he has tried it several times, but that once they get sticky, even with cleaning, they tend to get sticky more easily. He hasn't had any luck getting them cleaned and back into service.

I'm at the point where I will be changing them out like an impeller, if only to avoid the seemingly regular issues with it on the water.

My boat sits more than I would like, which certainly doesn't help the problem.

Shot in the dark, but I wonder if there is some debris/clog in the fuel rail that is intermittantly blocking the schrader valve and that part of the rail. Is there a schrader valve on the opposite rail that you could test pressure from?

I also noticed a retro kit at White Lake Marine (Nautiqueparts)
http://www.nautiqueparts.com/kitfccpassthruretrofit.aspx

Is that the same thing you are talking about?[/QUOTE]





Yes! Too bad they didn't have the kit available last year !! I bought my FCC from White Lake. They even called PCM on it.. maybe I got something started? You all can thank me!! Send donations my way!!

At least I can get an adaptor for my old FCC and it might be worth something on Ebay or Ski it Again..

I think the fuel lines are braded, so collapsing one would be hard. I have thought of a line collapsing, but don't see or feel any soft lines.

My anti syphon valve was a year old last year when the problem started.

I may check the ground on the ECM and wiggle test, but we have mid-80's today and I should be skiing vs wrenching in the garage!!!!

AMB wrote: but we have mid-80's today and I should be skiing vs wrenching in the garage!!!!

I feel you here, Its supposed to be nice all week/weekend and my boats at FFM for a transmission rebuild. I guess I should have got it up there sooner. Who knew.

I took the ECM stem out again.

Tested the relay and 60 and 40 to ground with wiggle test. No breaks.   Also wiggled the main ground on back of block.

Tested relay purple/red and is over 10 volts like manual sates.   So does that mean all the in lime breakers are good tool?

What is the breaker box that the manual alludes to? It says to install breaker box and then test.

I havent checked the output of the low pressure pump. I think I should do that test outside the garage, and that won't happen tonight.
Mabye late Saturday or Sunday. I am tied up until then...

Should I try to start the engine and test the schrader pressure with the valve out or just jump the STO? When I jump the STO, with valve in, I see 40 psi continuous. Only with engine running does it jump around..

I spoke to the dealer in WA tonight, and they said to check the fuse off positive battery, which I don't have, and check the kill switch. I can jump the kill switch, but it is only 2 years old. I have wiggled it around some while the pumps don't prime, and didn't seem to change anything. They also gave Silver Spray high marks for working on GT40's, so if I don't figure this out over the weekend, it seems like they could be a final sanity measure..

FYI, if the engine is off and the pumps go on and off (wiggling wires, etc.), the PSI is going to stay the same since the bleed down is slow. Pressure should never drop fast if the engine isn't running.

What is the power assist relay? Sorry.

Here are some pics of the panel, Schrader, and my home made lake setup.
The STO and 60 PIN coupler are not in place.

AMB wrote: What color line is postive on the low pump? I imagine that getting that crossed wouldn't be a good idea! Thanks

I don't know without testing. Fastest way is to unplug the connector. Then with your multi-meter on Ohms, first make absolutely sure the power is off on the boat. Touch the two leads together to make sure you are getting zero or nearly zero resistance. Then put the one lead somewhere on the engine (ground), and the other lead to one of the connector pins from the relay. If it is zero or almost zero resistance, that is the ground side and the other side comes from the battery.

You can then see how the plug from the relay plugs into the plug to the pump, and therefore tell which side of the pump side plug needs to go to ground, and which side needs to go to the battery.