2002 Supra Launch with intermittent starting issue

[morpheusmac]

I’ve been chasing an intermittent starting issue over the last couple of seasons. Engine is an indmar 320 assault with TBI and mefi 4. Boat is a 2002 Supra SL direct drive. I made my own code reader and initially found code 41.

When it first started happening I would turn the ignition on and the pump relay would start making a clicking noise and fail to start the fuel pump to prime the fuel system. After several attempts at starting the batteries would run flat and jump starting the boat would usually fire the pump again.

1st year it happened the batteries were getting old and I replaced them in the off season. I also replaced the fuel pump replay. Neither of this stopped the intermittent starting issue and I continued to chase it. I pulled the cap off the distributor and moved the rotor and with the ignition on it would energize the fuel pump to prime the system.

I traced wiring and ohm rang wiring (without issue) and replaced the ignition control unit in the distributor and the boat ran fine last year.

This year I installed new plugs (MR43LTS gapped to .045) in the off season and tried to fire the boat up on the fake a lake to de-winterize it....no fuel pump prime. Took a lot of swearing and checks until magically the boat started and ran fine.

I dumped the boat in the lake and Ran it from the launch to the lift, let it sit for a couple of weeks and it fired up perfectly. Come back a couple weeks after and now I’m encountering a no start issue that has persisted about a week. I ran codes and got an 81 code. Fuel pump is not firing.

I pulled the ignition control unit and took both the old and new one in for testing at autozone. The new unit failed (Chinese) and the old unit checked out as good. I reinstalled the old unit and still am getting nothing from the fuel pump.

I ran a large ground wire direct from the batteries to the engine block, I’ve swapped relays...only new thing I’ve found is that now I can get the coil to arc under the plug wire at the coil when I move the rotor back and forth.

I’m really starting to lean towards replacing the ecu...anyone have any suggestions for me?

[morpheusmac]

Jumping the fuel pump relay will get the boat to fire briefly then die. Pulls code 81 after jumping the relay.

Signal wire from fuel pump relay trigger wire to ecu has continuity but has no signal from ecu at ignition on.

[morpheusmac]

If I understand this system correctly, the distributor sends off an ignition reference signal that the ecu uses to turn the fuel pump relay on. Anyone see how or why the ecu would fail to prime the system with the checks I have completed above other than a faulty ECU?

[Eurobound]

Ugh... following this thread closely. I have a 2002 Launch DD and have electrical/fuel pump issues. I think my multimeter crapped out on me too!

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[morpheusmac]

Ugh... following this thread closely. I have a 2002 Launch DD and have electrical/fuel pump issues. I think my multimeter crapped out on me too!

Sent from my SM-G900W8 using Tapatalk

I’d love to find someone near Seattle to borrow an ECU to confirm that the ECU is causing the problem and not some other cheaper thing to replace...

[Eurobound]

I’d love to find someone near Seattle to borrow an ECU to confirm that the ECU is causing the problem and not some other cheaper thing to replace...

Unfortunately the cost of gas is prohibitive... I'm just across the border a few hours away...

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[morpheusmac]

Went ahead and bit the bullet, ordered a new MEFI 4 ECU from OBD Diagnostics http://mefiburn.com/. Got a brand new ecu, they had the correct Indmar program for the ECU; they burned and shipped it same day and it was here in two days, just in time for the weekend.

Fixed the starting issue and we are back on the lake just in time. The B.O.A.T. Is living up to its name!