5.0 GXi-J fuel pump relay keeps tripping

kevinmongar · Sunday at 1:54 PM

VP 3869399 S/N A112833
It seems to happen when the motor has been idling for awhile. (I leave the motor on when bottom fishing in the ocean.) There are 2 alarm beeps and then the motor dies. Usually the relay will be HOT (i.e., cannot leave my finger on it.) I replace the relay and the motor starts back up...and runs fine...until the next time it trips (like on the next trip out). It actually started to melt the plastic in the fuse box the 2nd to last time it happened. I noticed then that the connection to the low pressure pump was loose...it pulled right off. Apparently the 'snap' part of the connector is vibrating loose. I used zip ties to hold it in tight. Coul this loose connector cause excess heat at the relay? Note the 20A fuse for the fuel pump did not blow.

The relay tripped again the next time out...and the relay was not even hot...just warm (normal)(could have been a bad relay?).

-The alternator (only a few years old) runs at 13.5 V (unless I turn on a water pump and then it drops to about 12.6)
-The fuel pump has been replaced...and runs fine with no whine or noise.
-The electrical connections on the fuel pump look fine...not corroded or burned.

Does anybody have any troubleshooting advice on this?
I bought an infrared temp guage and am going to start taking temps of the fuel pumps and relay next time out.

Scott Danforth · Sunday at 2:32 PM

Crimp the terminals in the relay mount. You have a bad connection causing heat

alldodge · Sunday at 3:05 PM

^^^ Agree
With it not blowing the fuse it's a bad connection

kevinmongar · Sunday at 4:06 PM

OK thanks for the response. On this GXi-J the fuse and box may be different...see the pics. The box is part of the wiring harness and I don't really see a way to take it apart to check the terminals in the relay mount.

Scott Danforth · Sunday at 4:30 PM

go in from the back side where the terminals are snapped into the plastic bit.

you need access from both sides, you also need a small pick or small jewelers screw driver to release the tang to pull the terminals out.

kevinmongar · Sunday at 5:57 PM

OK I got the box apart and can see the 4 wires going in from the bottom. Do I access the tang from the bottom or the top? Is it visible in the picture I attached?

Scott Danforth · Monday at 3:17 AM

kevinmongar · Monday at 11:20 AM

Thanks for the help.
Apparently this box is made so that there is no slot from the top to access and push the tang down ...to pull the connector out. I pushed the sides together from the bottom side as best I could with a very small screw driver. I could see where the lead/wire to the fuel pump was discolored (burned color).
I ran the engine up to operating temp and measured the temp of relay with an infrared temp gauge...and it was about 130 degrees (seems high). It did not feel overly warm to the touch though.

Question: how would I measure the voltage to/from the relay?

alldodge · Monday at 11:55 AM

The relay should no more than the temp of the air. The relay can handle more current than what's called for by the fuel pumps

Place voltmeter probes between Red/purple and yell/red wires on the relay pins. You should see close to zero volts. The more resistance the higher the voltage

Scott Danforth · Monday at 1:12 PM

based on the pic, your contacts were well over 200F at some point because the plastic is melted around the terminals. I would replace the terminals

kevinmongar · Monday at 2:28 PM

First of all...thanks for the help guys.

Voltage across Red/purple and yell/red wires on the relay pins:
Battery switch ON: 13.2 V
Ign switch to acc: 13.0 V
Turn batt switch to off: 1.0 and drops to 0 V in about 30 sec.

"I would replace the terminals"...
Apparently this box is made so that there is no slot from the top to access and push the tang down ...to pull the terminals out from the bottom. I tried but wouold not be able to reach where the tang would be without forcing something down in there and probably breaking the plastic housing.

And apparently this fuse box is "not sold separately"...have to get the entire wiring harness.

alldodge · Monday at 2:49 PM

I meant to say with motor running

Red meter probe on Red/yell and black meter probe on red/purple

You can replace the connector by cutting the wires and solder splice to new connector.

Having issue trying to find the connector, but could always replace it with the standard square type

kevinmongar · Monday at 3:38 PM

Red meter probe on Red/yell and black meter probe on red/purple:
with motor running: 0.02 V

I also looked but did not find that type of base/connector for the stock relay.

Are you referring to the following relay?

Do you know where I would find the base with wires for that?

alldodge · Monday at 4:22 PM

My guess is the voltage will increase as it heats up

Yes, and HERE is a set of 2

Scott Danforth · Monday at 4:31 PM

Standard VF4 relay. Every electrical house has sockets and terminals.

kevinmongar · Monday at 5:52 PM

OK sounds good. Hopefully the last questions.
The 'skinny' stock relay was a 5-pin and was wired as follows:
-red/purple to 87 (from battery?)
-red/yellow to 30 (to FP?)
-purple to 85 (ignition/alternator?)
-Lt blue/white to 86 (?)
- no wire to 87a

Is there any reason that I would need to replace the original 5-pin with another 5 pin (square) relay? Or would the 4-pin work as well using the same connections as above?

alldodge · Tuesday at 4:59 AM

Both types of relays have the 5th pin on 87a and it's not used

Grub54891 · Tuesday at 6:05 AM

If you have way to much trouble getting the pins out, how about getting another relay socket from the local parts store, snip your wires off the ones in the box and splice them into the new one. Fasten the new one to the area with good zip ties? I may be barking up a different tree but I did do a similar repair on my camper several years ago and it’s been fine.

kevinmongar · Tuesday at 1:37 PM

FYI-update
I spliced in a new square type relay connector and the motor started and ran fine. After letting it run for quite a while I found:
-the temp of the new relay also gradually got up to about 130 degrees (depending on exactly where the temp was measured on the top of the relay, ranged from 87 to 130)
-the empty relay connector area (where the old relay was), with wires cut, got to about 120 degrees (this area is next to the 40 A fuse, see pic); this seems not right
-the wiring diagram for the 5.0 GXi-J that I have shows purple to 85 and Lt blue/white to 86; the motor was wired the reverse purple to 86 and Lt blue/white to 85; I put the new relay in the same as was found on the motor. I don't know if it matters...see pic

I will have to take the boat out and try it and see what happens

alldodge · Tuesday at 3:06 PM

this area is next to the 40 A fuse, see pic); this seems not right

We went in to the problem assuming the fuses were the correct size, and this seams we should have asked that question first. The FP fuse should be no larger then 20Amp

If fuse is larger then one or both of the pumps is drawing to much current

5.0 GXi-J fuel pump relay keeps tripping

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