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5.7GS wont shut off

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Uncle Rick

New member
1997 5.7 Volvo GSPLKD, CARB, MECHANICAL FUEL PUMP, Will not shut off from the key switch. Disconnected all 5 wires to alternator, fires right up, runs in on position, no shut off from key. Disconnect battery while running, no shut off from key. There is a box on Grey wire in Grey out with black to ground, but can't get a part number to look it up. Have service manual on order, but won't be here for two weeks. Connect Alternator back up, getting 14.1 v running. Switch is 3 prong B I S. Running out of ideas.
 
Uncle Rick said:
1997 5.7 Volvo GSPLKD, CARB, MECHANICAL FUEL PUMP, Will not shut off from the key switch. Disconnected all 5 wires to alternator, fires right up, runs in on position, no shut off from key. Disconnect battery while running, no shut off from key. There is a box on Grey wire in Grey out with black to ground, but can't get a part number to look it up. Have service manual on order, but won't be here for two weeks. Connect Alternator back up, getting 14.1 v running. Switch is 3 prong B I S. Running out of ideas.
Click to expand...
Does the boat have more than one Bat?
With the ALT and Bat disconnected there is no way the motor "can" run

It's normal for many VP to run and not shut off if the diode coming from the ALT to FP relay shorts out. This causes the ALT to back feed the ignition.
 
There is no fuel pump relay. MECHANICAL FUEL PUMP.
Disconnect alternator, engine will not shut off with key.
RECONNECT Alternator and disconnect battery. Engine will not shut off at key.
Either way, power continues to the coil.
 
ok, mechanical fuel pump
Have a wiring diagram for GS 3.0 with Mech pump

First you said
Disconnected all 5 wires to alternator, fires right up, runs in on position, no shut off from key. Disconnect battery while running, no shut off from key.
Click to expand...

Now you say
Disconnect alternator, engine will not shut off with key.
RECONNECT Alternator and disconnect battery. Engine will not shut off at key. Either way, power continues to the coil.
Click to expand...

So you don't have both the ALT and Bat disconnected at the same time, correct???

The ALT can back feed the coil (purple wire) but don't see how this can happen with the Bat disconnected (meaning Positive cable disconnected)

In drawing note the purple wire does not go to the coil, but drawing is missing that connection which should be there. The purple wire is there to excite the ALT so it will produce a charge voltage. The ALT direct powers the choke pot on the carb.

The only conclusion without another Bat supplying power, the ALT is producing it's own power and that doesn't happen

VP wiring GS 3_0 abc.jpg
 
FIXED!!!!!
The wiring diagram shows a start solenoid and a relay for power bypass to the coil in start.
mode. The starter for the 5,7 GS SHOWS TWO CABLE STUDS and two energizer studs. The solenoid has yellow to supply switching for the solenoid, and the other side of the solenoid has start bypass to energize the coil in start mode.
A wiring diagram for an OMC installation 5,7 1997 carbed and mechanical fuel pump showed everything exactly the same, but with w 3 stud starter and different configuration for the bypass function of the relay. I pulled a large hose up and the battery cable was a bit loose. What was happening was that the battery cable was touching the energizer circuit for the starter, but because the start side of the switching relay to apply voltage to turn the starter, wasn't being activated, the battery was applying power TO the ignition circuit bypass but NOT the start circuit unless the start switch was activated. Basically, the engine was hot wired thru the starter.
 
AllDodge said:
ok, mechanical fuel pump
Have a wiring diagram for GS 3.0 with Mech pump

First you said


Now you say


So you don't have both the ALT and Bat disconnected at the same time, correct???

The ALT can back feed the coil (purple wire) but don't see how this can happen with the Bat disconnected (meaning Positive cable disconnected)

In drawing note the purple wire does not go to the coil, but drawing is missing that connection which should be there. The purple wire is there to excite the ALT so it will produce a charge voltage. The ALT direct powers the choke pot on the carb.

The only conclusion without another Bat supplying power, the ALT is producing it's own power and that doesn't happen

View attachment 36847
Click to expand...
No. I disconnected the alternator and no joy. Shut it off by pulling the coil wire, reconnected the alternator and restarted and then disconnected the battery. Still no joy. The process eliminated any issue with the alternator, (all alternator outputs met spec) but still had the problem. Still showed voltage at the key switch ign terminal with the key off. Knew I had a back feed SOMEWHERE, but couldn't be thru the fuel pump relay because I HAVE NO FP RELAY with a mechanical fuel pump and Holly carb. 5.7GSPLKD. Both the 3 stud and 4 stud starter solenoids have a start BYPASS relay, but are wired differently for either the 3 stud or 4 stud solenoid. What had actually happened is explained below. Got a bit anal with the explanation, but what was wrong mimicked an issue for a Electric fuel pump, but was something so simple, I wanted to show what else could be the issue.
 
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