Electrical Issue with 4.3L Fuel Pump?

[Jorgy]

Hello all,

Thank you so much for all of the great information on this forum. It has been a great help already.

I have a 1996 Rinker Captiva 192 with the Mercruiser 4.3L (OF824722) with the 2 barrel Mercarb. I seem to be having issues with my electric fuel pump. When I turn the ignition key to the "on" position, the pump does not do it's normal 2-3 second run before starting. Also, I popped the fuel line off the carb, installed a catch cup, and cranked the engine over until I had normal oil pressure. Nothing but air in the cup. Next, I removed the pump and hooked it up to a 12v source and found that it ran fine. I have double/triple checked that the pump does not run when hooked up to the engine. This does not seem to be a blockage problem (although I did already check the in-tank pick-up screen, anti-siphon, water-fuel separator, and lines up to and passed the pump). I have to be missing a fuse, switch, or (cry if it is) some random wire fault. What is the next thing to check "upstream?" I don't know where the heck I put my multi-meter, so I'll have to go grab a new one. In the meanwhile; any suggestions as to what might be killing power to the pump? Heck, I'm relatively new to this whole scene so it's entirely possible I'm operating on some faulty assumptions.

The engine turns over fine, has spark and compression, and ran like a top first time I had it out this season. Second time out it failed. The only thing I've done since then is fill it with fresh gas. I took it to the launch and ran it for about 20 sec before it used up the fuel in the line and died.

Thanks in advance for any advice. I did a bit of searching, but if someone wants to re-direct me onto a previous post, that would be just fine.

Sincerely,

Adam

 

[Bondo]

Re: Electrical Issue with 4.3L Fuel Pump?

When I turn the ignition key to the "on" position, the pump does not do it's normal 2-3 second run before starting.

Ayuh,... It's Not supposed too...

It's wired from the inner small terminal on the Stater to feed fuel only while Cranking,...
And,..
After it Starts,... It gets it's power from the Igntion circuit, going thru the oil pressure switch, mounted down low, mid-way along the portside of the block, down just ahead of the oil filter boss...

 

[Diggerpine]

Re: Electrical Issue with 4.3L Fuel Pump?

Does the fuel pump have a circuit breaker? You might check to see if the breaker has "popped", if so you might want to reset it and try again.

"Keep your Bow into the Wave"
Steven

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

Ayuh,... It's Not supposed too...

It's wired from the inner small terminal on the Stater to feed fuel only while Cranking,...
And,..
After it Starts,... It gets it's power from the Igntion circuit, going thru the oil pressure switch, mounted down low, mid-way along the portside of the block, down just ahead of the oil filter boss...

Thank you for the quick reply.

I'm almost certain that before this situation I would hear the pump cycle for a second or two before I cranked the engine. Maybe this absence of a little mechanical whirring noise is something else entirely. I was under the impression that the fuel pump would only run if the oil pressure switch registered appropriate pressure; resulting in a delay in fuel pumping until said pressure was achieved. Are you saying I need to check the power between the starter and the fuel pump first?

Thanks again,

Adam

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

Does the fuel pump have a circuit breaker? You might check to see if the breaker has "popped", if so you might want to reset it and try again.

"Keep your Bow into the Wave"
Steven

Thank you for your reply.

Not that I know of. I checked the wiring diagram from the engine manual and didn't see any fuses or breakers(again, thank you so much to those responsible for providing all of that literature). Didn't see any in person either, but I've been known to miss things.

Adam

 

[180shabah]

Re: Electrical Issue with 4.3L Fuel Pump?

Are you saying I need to check the power between the starter and the fuel pump first?

Yes.

You manual is available for downlaod in the adults only section - it has a wire diagram of the system.

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

Since I know the engine has good compression and normally operates with solid oil pressure even within the first couple seconds of cranking, can I bypass the oil pressure switch for just long enough to see if it allows the fuel pump to cycle? Just to see if the switch is bad. I know I should be able to just check voltages, but I'll be working on this alone this evening and turning the key while holding the meter might get tricky.

Adam

 

[chrclo]

Re: Electrical Issue with 4.3L Fuel Pump?

Since I know the engine has good compression and normally operates with solid oil pressure even within the first couple seconds of cranking, can I bypass the oil pressure switch for just long enough to see if it allows the fuel pump to cycle? Just to see if the switch is bad. I know I should be able to just check voltages, but I'll be working on this alone this evening and turning the key while holding the meter might get tricky.

Adam

yes you can just to check. I am doing that tomorrow on my 96 regal 4.3

 

[tracyb]

Re: Electrical Issue with 4.3L Fuel Pump?

I have a 4.3 gxi. mine has a circuit braker in the back of the motor about were the distributer is. It is hard to see you just have to feel for it. when the braker trips it shuts down the fuel pump and the hydrolics for the drive. hope this helps

<((((((><

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

I have a 4.3 gxi. mine has a circuit braker in the back of the motor about were the distributer is. It is hard to see you just have to feel for it. when the braker trips it shuts down the fuel pump and the hydrolics for the drive. hope this helps

<((((((><

Thanks for the suggestion. In the Rinker, the engine sits pretty far into the cockpit/seating. This makes for lots of room to get at the engine and the breaker that sits right next to the distributor. That's the only one I know to check in the engine compartment and it would have been sweet if that was the fix. No luck there though.

Adam

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

yes you can just to check. I am doing that tomorrow on my 96 regal 4.3

How do you do this safely? Do you just pop the two purple leads off the switch and connect them? Or do you have to do a more complex jump? I plan to do this simply to check to see if the switch is my problem. I've heard that depending on which unit I have it can be as cheap as 15 bucks or as high as 50-60. Hoping I just find a fragged wire while I'm in there.

Thanks,

Adam

 

[180shabah]

Re: Electrical Issue with 4.3L Fuel Pump?

A quick simple jumper is perfectly acceptable.
Just hook them together, turn the key on and listen for the pump.

Did you ever verify that you have power coming from the starter?

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

A quick simple jumper is perfectly acceptable.
Just hook them together, turn the key on and listen for the pump.

Did you ever verify that you have power coming from the starter?

I got home this afternoon and jumped the oil pressure sensor and, what do ya know, all of a sudden my fuel pump runs when I turn the key on. Not well though... It might be that I didn't get a super good connection with the alligator clip leads I used to make the jump. But, it worked well enough to let the thing idle on muffs for 5+mins. Tomorrow I'll replace the switch and take it back to the boat ramp to put it through its paces. Then I'll decide if I need to buy a pump as well. Too late to call local shops to see if they have the switch in stock. Thanks all for the input and I'll try to let you know how it works out. I'm just excited I found the gremlin.

Adam

 

[cooter2506]

Re: Electrical Issue with 4.3L Fuel Pump?

Replacing that switch will not solve the pump not running during cranking though. Pump draws power from the starter to get it running while cranking then the switch takes over to run pump when it is running. Check power to it while cranking like 180 shabah said. Might simply be the wire is burnt of the starter terminal.

 

[180shabah]

Re: Electrical Issue with 4.3L Fuel Pump?

Yep, still need to verify that the pump is getting power while cranking.

 

[Bondo]

Re: Electrical Issue with 4.3L Fuel Pump?

Ayuh,.... You've only found 1/2 of your Problems...

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

Replacing that switch will not solve the pump not running during cranking though. Pump draws power from the starter to get it running while cranking then the switch takes over to run pump when it is running. Check power to it while cranking like 180 shabah said. Might simply be the wire is burnt of the starter terminal.

Ah, gotcha. Will do tomorrow when I have an extra set of hands around. I did do a visual of the starter and associated connections and nothing seemed out of the ordinary or excessively corroded. The connections (tabs and clips) of the oil pressure switch were in pretty rough shape but i got an ok connection with the jumper. Also, once i got the engine running, I stopped and replaced the wiring to the switch. I immediately restarted the engine and it will run for a good 15 sec or so off the gas in the carb bowl. This is plenty of time to build adequate oil pressure and it registers good (40+) on the dash gauge. But it still dies due to the pump not running. I'm not saying I shouldn't verify the power coming from the starter, but isn't this a pretty good indication that the switch is bad?

Thanks guys,

Adam

 

[cooter2506]

Re: Electrical Issue with 4.3L Fuel Pump?

Yes the switch is bad. Put it on and see what happens after that. I would still check that cranking voltage

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

Yes the switch is bad. Put it on and see what happens after that. I would still check that cranking voltage

Thanks for the reply.

I did check the cranking voltage and it was good. I'm back to thinking it's a bad fuel pump. I ran it today both with the switch jumpered and with it hooked up. When the switch is jumpered the fuel pump runs continuously. Seemed to point to the switch. I turned the key on to do a restart after it had ran for awhile and the pump didn't kick on... Hmmm, I thought, and pulled the plug from the fuel pump and tested the voltage at the plug; 12v. I plugged the pump back in and as soon as the contacts touched, the pump started running. I kinda thought these stupid pumps just go, or at least require a tap or to to unstick them. I wish something in the system would just give up and stop working permanently so I could pinpoint this better...

Adam

 

[Jorgy]

Re: Electrical Issue with 4.3L Fuel Pump?

double post