1997 4.3 lx testing a fuel pump

[samm835]

I have a 1997 4.3 mercruiser, having what I Believe is a Fuel pump issue. There is no sound/hum from the pump when ignition is turned on. Any good way to test if its good or not?

 

[Bt Doctur]

what type of ignition? carb or injection
Test is usually hooking the pump directly to 12v to see if it runs

 

[samm835]

Its carburetor, hooking the pump to 12v? Im guessing unplug connection to pump and then do what?

 

[Bt Doctur]

the purple or purple/yellow is the hot side, other wire is ground Being carbed the fuel pump does not run with the motor off. It is controlled by a oil pressure switch . No engine oil pressure = no fuel pump The pressure switch is just above the oil filter and has 2 wires. shorting those 2 wires will allow the pump to run with ign on.

 

[samm835]

What do you mean by "short two wires"? So I could possibly have a bad oil pump switch possibly? Can that be tested? I dont want to just throw parts at it especially when the fuel pump seems to be around 200+.

 

[Bt Doctur]

There is a pressure switch just above the oil filter It has 2 wires going to it. unplug the plug and insert a paperclip across the 2 pins in the plug end with the wires..This will by-pass the pressure switch and should make the pump run with the ignition "on"

In most cases the fuel pump tries to draw more current and the contacts cant handel it and go bad.

 

[Bondo]

What do you mean by "short two wires"? So I could possibly have a bad oil pump switch possibly? Can that be tested? I dont want to just throw parts at it especially when the fuel pump seems to be around 200+.

Ayuh,..... What BD is explainin' is how to diagnose it,....

Jumper, or by-pass the oil pressure switch, 'n the pump should run with the key "On",....

Or, unplug the pump's connector, 'n put 12v to the purple wire side, 'n ground to the other, the pump should run,...

 

[samm835]

Thanks for the help, im going to the boat today after work to try this out. With the paper clip in the two wires, I only turn the key to accessories correct? I dont need to try and start correct? If I hear the fuel pump, this could mean the oil pressure switch is bad vs the actual fuel pump. Man do I hope it's the oil pressure switch......my fuel pump at the marina is 318.00, an the oil pressure switch is around 50.00.

 

[Bt Doctur]

Key must be in the "ON" position. Where are you finding these outrageous prices?
Airtex E 84389 is a replacement pump for under $70.00
Standard auto parts PS-64 is a 3 connector $5.00
Standard auto parts PS-126 2 connector $5.00

I can ship you these and charge you marina prices if you like LOL

 

[samm835]

I called the marina shop yesterday so I could prepare myself for $ hit to my wallet, I gave him my engine serial # 0K023103, He told me fuel pump was 318.00. I haven't had a chance to find either parts online, is there another way to find them? Are these two things inter-changable with auto? Btw.....if you know a link send me a pm with what you can find.....even throw u a finders fee lol

 

[Bt Doctur]

this site should have those parts too the merc pump for cool fuel is 300 airtex was 102 .same pump,same wiring, just a different box
http://www.ebay.com/itm/Fuel-Pump-M...432-86115A2-/231433145644?hash=item35e27d8d2c

 

[samm835]

I do appreciate all the help, currently looking on iboats for the parts, but I can't find part# for either

 

[Bondo]

currently looking on iboats for the parts, but I can't find part# for either

Ayuh,..... A replacement electric fuel pump is 18-7326,....

Safety switch, well, can't find it,...
Use the numbers BD posted, ain't nothin' "Marine" 'bout 'em anyways,....

 

[Fun Times]

Here's your parts guide for your engine serial number through iboats,
http://www.iboats.com/4-3LX-GEN-2-BB...iew_id.1682873

iboats is just starting out with selling OEM parts and using an OEM parts guide, it's not fully up-to-date yet and some of the images are still missing, So here's a site to use (for now )

MERCRUISER

1997

4.3LX

Model Number 443LC00KS

4.3 LX/LXH ALPHA AND BRAVO (GEN +)

to "see" what parts you need then search the part number here for both OEM and aftermarket, http://www.iboats.com/

If found to be needed, The Oil Pressure Switch is Merc part number 87-864252A01 but like mentioned by Bondo, iboats don't seem to have it....Yet. Qty Required For Repair: 1
Minimum Order Qty: 1
Supersedes: 87-805024

 

[samm835]

I really appreciate all the help! I went to the boat and by-passed the oil pressure switch. Wooooohoooo, so it worked and the fuel pump works. I was able to get a new pressure switch, while I was trying to take the old one off I stripped it. I am going to go get a needle nose vice grips to help take it off. What happens IF I can't get it off? Can I hook it up and zip tie to the old one? Yes lame cheap, lazy fix.....but am I setting myself up for more issues if I can't get off?

 

[Bt Doctur]

while I was trying to take the old one off I stripped it

It unscrews with normal thread CCW????????????
In most cases coming from the engine block is a short nipple and a T . oil pressure sender is in one end and the fuel pressure switch is in the other end.
If necessary unscrew CAREFULLY the whole assembly and take it to the workbench and vise.

 

[Bondo]

What happens IF I can't get it off? Can I hook it up and zip tie to the old one?

Nope,.... If it ain't screwed into the oil port, it won't see oil pressure, so it won't work,......