Fuel Pump Relay location on 4.3 Vortec

[GlennR]

My 1994 Chapparal isn't getting fuel and I think I have a faulty fuel pump relay, but I don't know where it's located. The wires to the fuel pump lead into a larger bundle of wires and I don't know exactly what the relay looks like or where to look for it. Can somebody tell me where to look, or even better show a pic?

Thanks,

 

[Mad Props]

I don't think there is a fuel pump relay...

 

[Bt Doctur]

Got a engine serial number?

 

[Scott Danforth]

Post a serial number

The vortec motors came out in 1996

 

[GlennR]

I'm pretty sure it's a 94' 190 SCL. It has a 4.3 Vortec with a carburetor. I'll look for the serial number tomorrow.

I removed the wiring connector from the fuel pump & checked the volts with the ignition turned on. The reading wasn't steady, but was much lower than 12V. I assumed it would have to come from a relay, which I read could be triggered by an oil pressure switch ( I don't know if that's correct). I'd planned to bypass the relay and connect the pump directly to the battery to test the pump. I discovered this forum & figured I'd ask about the relay since I didn't know where to look for it.

I'll get the serial number to confirm what it actually is in the morning.

thanks,

 

[achris]

If it's '94, then it is not a vortec, despite having 'Vortec" cast into the valve covers. No, it's a very standard, non-vortec 4.3L engine. It has no fuel pump relay... The circuitry for the pump consists of 2 parts.

The first part is the 'RUN' part. When the engine is running, the power for the pump is supplied via an oil pressure switch. This switch closes when the oil pressure reaches 4psi, and allows current to flow to the pump. The switch is located on the port side of the engine, on the block, below the rear spark plug. It's on a tee-piece with the oil pressure sender (for the oil pressure gauge). Before the engine starts running and the oil pressure reaches 4psi, the switch stops current flow. This is so that should the engine stall, and the key is not turned off, the pump stops pushing fuel to the carb. Yes, the needle valve in the carb should stop the fuel flow. This is a USCG requirement, and stops you from taking yourself and your boat to the moon. :boom:

The second part is the starting part. When the key is turned to 'START' the starter solenoid's auxiliary connection has 12v put to it. This is the purple/yellow lead, and it applies power to the pump while the engine is cranking, and before the oil pressure reaches 4psi..

All the wiring for the pump is in the harness.

The biggest cause of 'no fuel' with these systems is the oil pressure switch terminals getting wet and corroding. Check the connections for corrosion.

Chris.........

 

[Bondo]

Ayuh,...... Welcome Aboard,...... The name Vortec was used, Before the Vortec heads came out in '96, you Don't have a true Vortec motor,....

I explained how yer fuel pump is wired in This thread,....

 

[Scott Danforth]

I removed the wiring connector from the fuel pump & checked the volts with the ignition turned on. The reading wasn't steady, but was much lower than 12V. I assumed it would have to come from a relay, which I read could be triggered by an oil pressure switch ( I don't know if that's correct).

no relay

non-steady reading of low voltage is one or more poor connections

clean all your connections. start at the battery, work your way to the motor and back with all the cables. then move from the starter up thru the wiring harness to the large circuit breaker to the big connector to the helm, back of ignition switch, etc. back all the way to the motor. then do the same with the ground connection at the back of the motor.

 

[GlennR]

Thanks for all the great info. That looks like what I have and the advice given all makes sense. Going through all the connections doesn't sound like fun though, but at least I have good instructions and drawings to refer to now. The great thing is it doesn't sound like I need to buy or wait for any parts to fix it.

It's raining here on & off this weekend, so I get the pleasure of finishing up a bit of house painting instead of wrenching & probing on the boat.

Thanks again.

 

[GlennR]

I checked all the wiring that I could and decided to pull the fuel pump and test it. It turned out to be a bad pump. Got the new one installed yesterday & she's fixed.

I have another dumb question. Does this engine have an oil filter? I want to change the oil & can't locate the filter.

 

[Bt Doctur]

Yes it does, same place you find it on a automotive motor, port side bottom rear of motor

 

[GlennR]

I knew it must have one somewhere. It must be black and hidden behind black hoses, etc. Too bad they didn't relocate it to an easy place to reach. Hope it isn't too tricky to loosen & snake out without spilling oil. My engine is flanked by seats which makes servicing harder. I can remove them, but would rather not.

I'm really happy that the fuel pump wasn't located in a back corner that was impossible to reach or see.

Thanks,

 

[achris]

You can buy a kit to 'remote' the oil filter. Well worth it, as I did on my previous engine, and the current one came with the remote filter, located just above the steering pump.

Chris........