99 SN GT40 Fuel Supply

I went back out and put the Test Connector and STO back together, and saw how the small gray lead had to be put into the Test Connector. the pumps would not prime, even with wiggling. I swapped out the relay, as I have two extras and so I think my problem seems to be the Test Connector. I jumped the STO again, and the pump ran fine.

I would have liked to run the boat with the STO jumped, but it was raining and getting late.

Gordon - I couldn't see if the smaller gray plug actually plugged into any clips or anything, but there are two different shaped grooves on the exterior of it, and one way it went on like it was going to stay in there, and the other way was pretty loose. There is an exposed metal female type fitting, so I figured it was probably good to at least stick it up in the housing to keep it out of the elements.

I will call around tomorrow for the Test Connector. Seems like that is not getting the signal crossed over from the STO connector.

Does this sound right?

Thanks

AMB wrote: I do have a question though, there was a smaller gray plug at the top of the pic above, that looks like it just popped out of the STO, and it is sort of hard to see if it should snap in or just rest in there with no purpose. There is another dead end looking larger gray plug, which is a the bottom of the pic above. Do I need to do something with the smaller connector?

That smaller grey plug just may be your SPOUT Connector.

Did it's being in place or not in place have any effect on your loping? It's related to distributor timing.

Well I am really bummed now. I took off the EEC Test Connector, thinking that there was series of connectors in there that the STO plugged into, and zilch. It is just a housing to keep the STO out of the weather. Might as well put duct tape over the STO.

Why did my fuel pumps prime when I jiggled the STO? It ran when jumping the STO, so that tells me the pumps work and put pressure out consistently when power gets to them.

The only thing I think I can do next to make sure the pumps are okay is to start the boat in the driveway with the STO jumped. If it runs like a champ, then fuel pumps should be okay.

Leaving what? A bum wire somewhere before the pump? Does the STO utilize the same wires to the pumps? What is it bypassing?

Next steps??

From the wiring schematic, going backward from the low pressure pump, there is a fuel relay, a 20Amp fuse, tied in with the 60Amp fuse, then goes through a 10-way connector, and then a 20Amp fuse, then to the ignition switch.

The Service Manual says that if I ground the STO and the pump works, it says to service the open circuit between the fuel pump relay and the ECA. What? The only thing between the ECA and the Relay is a green yellow wire leaving the relay and attaching to the ECA. Is the manual saying that this is probably a bad connection?

UNCLE!

Bri892001 wrote: That smaller grey plug just may be your SPOUT Connector.

The spout connector is near the distributor (actually near the oil fill cap (I pulled my distributor recently so used the spout connector when setting my timing). The one you're talking about looks the same but it is something else (I just can't remember what).

Al like Gordon said you are getting closer to a resolution.

Need to confirm some of your symptoms.

1. You said that the pumps run every time you jump the STO connector to ground?

2. The fuel pumps run intermittently but mostly do not go through the prime cycle when the ignition is switched on?

If the answer to the above is yes in both cases. Then the computer is not providing the earth that is required to start the fuel pumps for prime cycle. All jumpering the STO connector to earth does is provide the earth that the computer normally supplies from pin 52 of ECA 60 pin connector to turn on the pumps.(see Self Test Circuit diagram on page 279 of GT40 manual)

The problem is either a broken wire in the harness, bad connection at 60 pin connector or fuel pump relay connector "86". The bad news is it could also be the computer itself. But we hope it is the previous.

Disconnect the battery terminal. Remove the 60 pin connector from ECA and clean all pins with contact cleaner paying special attention to pin 52 make sure there is no pushed in or damaged pins. There is a 10mm 3/8" bolt seating that connector to the computer housing. Page 285 of GT40 manual has the pin out for this 60 pin connector.

Check for continuity of wire from fuel pump relay connector "86" to pin 52 of ECA connector. Diagram states it as blue/orange wire. I will confirm colour tomorrow in daylight on my relay and STO connector as some of the colours seem to vary from the diagram to what I have on my engine. Check that pin 40 and 60 of the ECA connector are short to ground.

Continuity or short is zero ohms or close to it. If you put both leads of your meter together that is short. Take note of that reading as it is the reading you want when testing. (have meter on lowest ohms range)

I am looking at the ECA. Do I need to cut the tie strap on the rubber boot to reveal the 60 pin locations or is there another way?

I took the 4 screws out that hold the ECM on the frame, and by the way, with the key on, the Son of a Gun pumps are priming.

Al you must of been posting as I was out checking wiring colour. You don't need to remove the computer housing from bracket. But you do have to cut that cable tie on bottom and push the rubber boot back to reveal the 10mm 3/8 retaining bolt I mentioned previously. Undo this bolt and the 60pin connector will come off.

Sure sounds like a bad wiring connection problem as you have now disturbed the harness and connectors and it is supplying earth for prime cycle again.

If still having problems let me know and I will go out to boat and snap a picture of 60 pin connector removal.

Here is the 60-Pin and I will try to post a pic of the female connector as well.

The whitish substance is a grease or lube.

Basically, looks ok to me..??

Joel sort of but really just semantics. The computer grounds pin 52 if it does not get a PIP signal in 1-2 secs it will shut down the pumps. So it is really part of the computer program.

Al, hard to tell from picture but it does look OK assuming that the white substance is dielectric grease and not oxidisation.

Earth, ground and negative (-ve) are the same thing in a 12 volt DC (direct current) negative ground system.

While you have it apart I would clean with contact cleaner and reapply dielectric grease. Do the continuity tests first though.

Ok, tested continuity from relay to 52 and no problems. Meter went to 0. Then checked 60 and 40, each going to a ground and they went to 0. Was that the correct way to test?

I am just wondering if one of the breakers is having a bad connection.
It seemed like jiggling stuff around back there and I started the pumps.

I replaced the lowest amp breaker weeks ago, (I think it is 12.5) as the original was sort of stuck. When I tapped on it, the pump primed. So maybe somthing else on the panel? All connections including the one I replaced have liquid rubber sealer on them, so hard to tell if the connections are bad.

Where is the 20 amp and 60 amp breakers, along with 10-way switch? Then there is a 20 amp after ignition switch. I have a 15 and 50 amp breaker mounted above the 12.5 amp breaker, is the book referring to those, but I have different amp breakers? These are the red buttons mounted on the plate at back of engine.

Thanks!
AB

My helper is in bed already, so I guess I will call it a night.
I understand what you are saying, so need to wrestle up another meter, as I have 3 but only one seems to be working. Maybe I blew the fuse in them or they have a loose wire too!

I am looking over the manual and there are quite a few tests to make, but first I will have to figure out how to use the meter. There are a few good youtube vids out there, but they are slightly different than my meter, and my multi purpose meter, which is new, doesn't seem to be working (or more likely I am not using the right plug ins and settings).

Sure glad the weather is still not so hot!
thanks for all the help. I feel like I am getting somewhere, even though your signature tagline sums it up.

No, I didn't wiggle anything when I had the STO jumped. That sounds like something I maybe shoulda tried... Well, the ECM is apart and I will continue testing tomorrow.

What you say about the power side makes sense when I stop and think about it. It may say 60, it is getting late! I know it is not 20 though, so I must have one of the newer FCC setups.. Mine is real new, in like 2 months old! Springing that leak is still getting me ticked, as that was no where near the problem, and $450!!

Thanks
AB

Yes, that price included the high pump and filter. They don't make the old black screw on style. One of the fittings on the new FCC was not fitted to the older fuel line going up the rail, but you can take out one from the old style and change it out.

I will chase some more wires tonight.

Thanks
AB

AMB wrote: Yes, that price included the high pump and filter. They don't make the old black screw on style. One of the fittings on the new FCC was not fitted to the older fuel line going up the rail, but you can take out one from the old style and change it out. I will chase some more wires tonight. Thanks AB

Oh- it's YOU! AB from TWSF? Nice to see you here!

That really sucks about the old FCC parts not being offered anymore, but it must prove that the old design was flawed with that epoxy wire plug thing and not worth making parts for.

Yep its AB from the WSF etc...

Texas, at the onset of the problem, the pumps primed, so I thought of that antisiphon valve, filter, high pressue pump, etc.. I swapped out the asv with my spare. I take them off and blow electrical parts cleaner in there or braker cleaner, and no impact on the problem, which appears to be a loose wire or bad ground on something at this point.
Any pump priming is just random.