Thunder Jet fuses?

[MattPark]

A buddy has a 96 TJ with a fuel injected 351, the fuel pump isn't coming on, and we can't find the fuse box. The engine cranks just fine, but there's no fuel pressure. Before I spend a bunch of time chasing the problem, can anyone tell me where the fuses are?

Also, two of the circuit breaker buttons are stuck, you can't push them in. I assume that's not normal.

[freedrift]

If i remember right, mine had fuses on top of the motor behind the carb. That was on a carb 305 though.

[Redneck]

a friend of mine had a non working fuel pump last august at the hammond boat ramp at 5:00am. it turned out his fuel pump relay was full of water. fuses were all intact. bad day.
redneck

[MattPark]

I can't find, and have no clue where any relays are. On the back of the engine there's the ECU, and 3 circuit breakers.

I could throw power to the fuel pump, but I'd like to know where the power comes from. That's where the lack of fuses and relays come in to the dilemma.

[freedrift]

I would call siglers marine and talk to Scott. He rigs all the boats and should be able to explain it.

[wwjetboater]

the 2 circut breakers just take a voltage reading in both sides of them see if you have 12vdc

[MattPark]

Time to make some calls.

One circuit breaker has 12V on each side, and continuity. Easy. The other 2 have continuity, but no volts on either side, ignition on or off.

The fuel pump turns on with power wire from the battery. Found out at this point that it still won't start (it cranks fine), there's no spark.

Either the computer isn't getting power, or there's something wrong with it. I'm leaning towards a power supply issue with the 2 breakers having no power on either side.

I have a OMC Ford EFI diagnostic manual, I guess I'll go through and see what I can find there. The engine isn't an OMC, but it's a Ford with the same diagnostic setup.

[MattPark]

Put power to the circuit breakers that had none, and it barked off. Must be some kind of relay issue.

[Redneck]

If the relays check out OK it might be the ECU. The ECU grounds the solenoid in the fuel pump relay that closes the circuit to provide power to the fuel pump. You can check to see if the ECU is grounding the relay's solenoid with a multimeter. During the first 2 or 3 seconds when the ignition is turned on the fuel pump is energized to prime the fuel system. Find the relay and check to see if the grounding wire from the ECU is getting continuity to ground. Also check for ground continuity during cranking.

[MattPark]

Relays checked out OK.

The thing I noticed was that everything was actually getting power, but only 3-4 volts. That pointed me to the battery switch/batteries. Battery 1 was borderline and the connections weren't the best they could be.

Always check the simple things first :cheers: