4.3 Mercruiser Problems...Lots of em...

[slshady]

I've got a couple of problems with my 98 4.3 mercruiser. I have just finished installing a new motor, don't know if any of these problems have anything to do with that but here goes...

First problem is with the tach... It goes backwards ( counter clockwise) when you rev it up. Don't know how it got like that.

Second problem is no oil pressure reading on the gauge. I know its got to have oil pressure, its a new engine!! OR it at least better have, i ain't pulling it back out lol!

Third problem is the trim "up" doesn't work. No clicks or anything. The trim "down" and "trailer" work beautifully.

Fourth and problem is that the tilt trim reseivoir has water mixed in with the oil. How did water enter into there??

Also, when you turn the key to on, the position before you crank it, the fuel pump comes on and stays on. I don't remember it doing that before. It could be that i just never noticed it though.

Also, does anyone have a diagram or know which wires plug into each other on top of the intake( beside the drive oil reseivoir). I think i might have one or two mixed up. I have a black wire with a male spade terminal left over and a white and black wire left over.

Thanks in advance!!

 

[Chris1956]

Re: 4.3 Mercruiser Problems...Lots of em...

Slshady, Here goes:

Your tach and oil pressure guage. Check to see that +12V and Ground connections are clean and actually have +12V and ground on them. The sender terminal should connect to the ign coil. If your 12V connection and ground are bad, you will get a bad reading on your oil pressure gauge as well. You can put a mechanical guage into the low oil pressure switch located on the oil filter mounting bracket.

The trim button: You may not have reconnected the wire fro the trim limit switch, or the switch went bad. Look for the two "lamp cord" like wires coming from the outdrive. They power the trim gauge and trim toggle switch.

Trim fluid with water: Water can get past the seals if the trim cylinders. First suck the white stuff out and refill with new fluid. I use 5W-30. It is a bit thicker than ATF, so less water can leak past the seals.

Not sure about your fuel pump operation

The wires near your intake. On my 4.3, they are for the low oil pressure and overheat alarms. If either of those conditions occur, they ground the black wire, setting off the dashboard buzzer.

 

[slshady]

Re: 4.3 Mercruiser Problems...Lots of em...

Thanks chris. I would like to know which color wires plug into each other by drive oil reseivour and carb. I think theres like 4 black wires, one purple, one white, can't think of the rest. They have various connectors on them and i can't remember which one is suppose to plug into each other.

I will check the gauges when i get home. They all move except the oil pressure when i turn the key on.

About the fuel pump, i read somewhere online that it is only suppose to come on after the engine is started and has oil pressure, but mine comes on and stays on as soon as you turn the key. I haven't taken the boat out yet since putting the new engine in, only run it on muffs for about 5 mins. Just trying to get everything in check before i go break 'er in sat.

 

[tommays]

Re: 4.3 Mercruiser Problems...Lots of em...

You have connected the fuel pump wireing wrong

It should not run until you start cranking and then it is kept running buy the oil pressure switch when the motor starts

The trim pump can also suck in a lot of water from the vent hole in the cap i found this out on a rainy week of boat camping



Tommays

 

[slshady]

Re: 4.3 Mercruiser Problems...Lots of em...

I guess i need to reverse the wires on the oil switch?? The fuel pump wires have only one blue connector. I don't think that it can hook up wrong? How about the purple wires going to the oil pressure switch by the oil filter? What if they are reversed??

Any ideas what would cause a tach to go backwards anyone?

 

[tommays]

Re: 4.3 Mercruiser Problems...Lots of em...

I am thinking you really need a service manual to refer to it will have the correct wireing diagram and trouble shooting to get things connected correctly


Tommays

 

[slshady]

Re: 4.3 Mercruiser Problems...Lots of em...

Would the fuel pump run without cranking if the fuel system needed to be primed? Reason i ask is because i had all the fuel lines off when swaping motors and changed the fuel filter/seperator also. Don't know how long it takes the pump to prime the fuel lines though. I never let it run longer than 45 secs before i cranked the boat.

Can anyone look at their 98 & up 4.3 merc and tell me which wire plugs into which one on the top of the motor beside the drive oil reseviour??

 

[vipzach]

Re: 4.3 Mercruiser Problems...Lots of em...

Like tom already suggested, you really need a service manuel. They may not be possible before Saturday though, so here are some links for an online manuel that I got from DonS.

This one is for the wiring diagram
http://www.boatfix.com/merc/Servmanl/18/18E4R2.PDF

This one is for the main page so you can look for your specific motor/drive. Some links don't work.
http://www.boatfix.com/merc/Servmanl/srvcovr.pdf