Boat only starts when trim is up?!?

Willbillboatin

Recruit
Joined
Jun 30, 2018
Messages
3
Hey guys
4.3 liter mercruiser only turns over when trim is up. Although, the engine will crank when an any position it's will only start when the trim is up for the most part the further and further I put it down the more trouble the engine has starting. But once I get the engine started in the up position it can be lowered slowly while cruising without it dieing. I don't know what the problem is I was thinking it could be the trim limit switches but I don't know if they have any direct correlation. Any input would be useful!

thanks in advance guys!
 

Willbillboatin

Recruit
Joined
Jun 30, 2018
Messages
3
Hey guys

4.3 liter mercruiser only turns over when trim is up. Although, the engine will crank when an any position it's will only start when the trim is up for the most part the further and further I put it down the more trouble the engine has starting. But once I get the engine started in the up position it can be lowered slowly while cruising without it dieing. I don't know what the problem is I was thinking it could be the trim limit switches but I don't know if they have any direct correlation. Any input would be useful!

thanks in advance guys!
 

Willbillboatin

Recruit
Joined
Jun 30, 2018
Messages
3
Boat only starts with trim up?!

Hey guys

4.3 liter mercruiser only turns over when trim is up. Although, the engine will crank when an any position it's will only start when the trim is up for the most part the further and further I put it down the more trouble the engine has starting. But once I get the engine started in the up position it can be lowered slowly while cruising without it dieing. I don't know what the problem is I was thinking it could be the trim limit switches but I don't know if they have any direct correlation. Any input would be useful!

thanks in advance guys!
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
trim controls have nothing to do with starting. Running with the tyrim full up is even worse
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
Agree, trim has nothing to do with your issue.

might have some bad corrosion on your cables/wires

What year 4.3 and is it carb or EFI?
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,438
I normally don't answer unless I have experienced, and resolved a posted issue.
So I'm guessing your trim limit switch may be a factor. Your helm control has a dead man switch that is supposed to be connected to a wrist lanyard if you are operating alone. If the toggle is down (lanyard pulled out) the engine will crank and start, but dies when the key is returned to run. (I did experience this by accidentally flipping that toggle). I think the kill switch grounds or opens the run circuit. Anyway, maybe there is a wiring issue in your control, or the trim switch wiring that is interfering with the run circuit. The trim limit switch opens the 'Up' trim circuit, to force the operator to use the trailer button. It closes that circuit when the out drive is down enough.
Try disconnecting the trim limit switch and see if anything changes. Then jump the engine side of the connection and try it. Some boats have the trim switches wired into the multi-pin engine electrical connector that includes the key switch wires.
If you are competent and/or ballsy, make up an alligator clip jumper between battery + and the + side of your coil, and see if things run normally. IMPORTANT: Don't operate with the jumper. The engine won't shut off until you remove the jumper, and it will start in gear. Diagnostic only. If it operates normally, something is messing with the run circuit.
Check for water or bare wires. Trim and engine wiring diagram attached to help you chase it down.
 

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