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wakeboard1964

MEFI-4 (J1-6) pin no longer sending voltage for fuel pump relay

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wakeboard1964

2002 Malibu Wakesetter VLX w/5.7 fuel injected. About a month ago I diagnosed that my ECM is no longer sending a signal to the fuel pump relay. Its been intermittent of going in and out (quick pause) while running every once in awhile for the past year but now it's permanent with the pump relay not receiving a signal to keep the pump running. 6 months ago I replaced the HP fuel pump but it did not change this problem. To get the engine started, last week I put a oil pressure switch to bypass the relay and it starts and idles fine but does not run well at faster speeds almost like it's in limp mode but it's not overheating. I purchased a CodeMate Tester (Wink, blink) to read the codes for my MEFI -4 unit and followed the directions (plug unit in, turn key on with engine off, switch CodeMate to ON) with every variation and the red light stays on solid. I found a forum that says to disconnect the oil pressure sending unit, which I did and it did not change anything (still solid light with no blinking) . 

I originally thought that one of the sensors was going bad and the ECM was shutting the fuel  pump  relay off but checked the Temp, pressure, ETS sensors all checked out. 3 fuses near ECM are good, battery 12.3V.  That's why I wanted to see what codes may be available. Any suggestion on getting the CodeMate to work? 

I noticed in the past when I had trouble of the intermittent engine pause while running that the problem would not happen as much when everything was wet after a rain.  The engine has not run in over a month and after fiddling with connections after a big rain the ECM fuel pump relay worked again and the engine ran NORMAL for a couple hours and then shut down again. Im wondering if this could it be a short somewhere? 

How do I check if my ECM is bad? I found the pinouts for the MEFI-4 and all values that I could measure show good except no voltage from J1-6 (fuel pump relay control) when I initially turn the key on (HP fuel pump prime).  I'm not really wanting to spent $2K to try this if it's not the problem. Any suggestions? 

 

 

 

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JasonK

Check for corrosion in any plugs/fuses/relays you can disconnect. I just had a fuse in a suburban that had a pin corrode off. You couldn't see it until we pulled the fuse.

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98sportsterlx

Just throwing this out there but I have a brand new MEFI-4b I would like to get rid of. I’m not completely sure on difference between mefi 4 and 4b, but if it would work I’ll make you a good deal on it

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Steve B.

Watching this thread. I developed an alarm last year. 2002. New oil switch, temp ok, new knock sensor.

Steve B.

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Sixball

I had a friends boat doing what sounds very much the same. It was the oil pressure switch that sends the signal to the ECU not the gauge.  Its down near the oil filter. If its the same .  All we had to do is pull the unit and flush the unit ( plunger)  and its worked fine since. The signal not being seen will shut the fuel pump off.

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tvano

Take a close look at the pins in the relay socket w a magnifying glass 

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boardjnky4

Check all fuses near the ECU. Wiggle them to make sure they're making good connections.

Check the fuel pump relays. As stated above, sometimes the female end wears out and doesn't make solid contact.

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wakeboard1964

Thanks for all the responses. I checked the continuity from the ECU plug on J1-6 to the relay and shows good. When I apply 12V to the same wire the relay and pump work. When I put a voltmeter on J1-6 wire with everything connected it does not work but for the short time when it started working again I got 12V. I'm almost 100% the MEFI is just not allowing voltage on key up.  The book says the codes may tell you if a sensor is bad so I was trying to get it to work with no luck. 

I tested the Oil Pressure Switch which is grounded with the engine off and open with engine on with about 5psi or greater but I did not check the wire continuity from the switch to the ECU plug so I'm going to try that next. 

Is there anyone else who had any problems with a CodeMate (Wink, blink) code reader with the red light staying on and not sending codes? Any resolutions. 

 

 

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electricjohn

The ECU only grounds (completes) the circuit for the fuel pump relay's coil.  Make sure you have an uninterrupted +12 volts to the contact and the coil in the relay when the key is on.  Wires will be red, orange, or pink. One thicker than the other.

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electricjohn

The oil pressure switch has nothing to due with fuel delivery on EFI engines.  Do not (I repeat) do not apply 12 volts to any wire going to the ECM.

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electricjohn

The red light is staying on because you have no oil pressure.

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