1985 Mariner 150 HP Magnum won't idle

[LannyF]

Being a newbie ... I started out by checking compression, all cylinders seem to be around the 105 to 110 max area. I've replaced fuel tank lines and bulb to make sure I wasn't getting any air leaks, as well as a new Mercury style fuel adapter at the engine. I've pulled the Carbs and soaked those ... not much to them, replaced needle and seats & gasket set ... floats set to level w/ fuel bowl edge, turned upside down to have slight pressure on needle was how I checked the height. These Carbs have no idle adjusting screws, so jets pre-determine fuel quantity. I haven't done anything with the fuel pump. Spark plugs have been replaced and don't have any carbon build up. Not familiar with checking the timing on this - being an ex-car mechanic, this is a bit different. This Mariner is on a 21' Misty Harbor (square pontoons) and will push it wide open about 22 - 24 MPH per Lowrance Speed. But I haven't been able to get it to idle and I don't want to tear my lower unit out with having to put it into gear at a faster idle. Thanks for any advice anyone may have! Lanny

 

[j_martin]

Re: 1985 Mariner 150 HP Magnum won't idle

Carb float setting is 1/16" below the bowl edge, carb inverted, measured at the edge away from the needle. You might be a bit lean.

If you have any spitting from the carbs at idle, pull the reed plate while the carbs are off and inspect the reeds. Bad reeds don't lower compression, but they do screw up idle.

Another thing to check at that time is bleed hose condition, routing, and check valves.

hope it helps
john

 

[LannyF]

Re: 1985 Mariner 150 HP Magnum won't idle

Thanks John, I may be a "smidge" low on the float than. When I had the carbs off, I did look at the reeds, but didn't pull the plate. The carb side looked clean and shiny ... so didn't give them an extra thought. Any fuel related hoses around the carbs, I replaced; if in question replace the hose - hair line checks or cracks are hard to see and cause vacuum leaks. Sure appreciate your info and I'll post what I see.
Lanny

 

[LannyF]

Re: 1985 Mariner 150 HP Magnum won't idle

An update (7/19/2011) on this won't idle ... Having rebuilt the carbs, float levels to correct height of 1/16", rebuilt the fuel pump, and replaced fuel lines, bulbs and connectors; we've moved on to the ignition side now. I'm losing spark on 1 and 3 and 5 until I hit the throttle lever to rev up slightly. Then all cylinders are hitting according to my timing light flashing (using it as a spark tester). Once it drops to idle no spark flashing. This is also after replacing the trigger switch ($175), which an old Merc mechanic suggested. Tonight I flipped the 5 and 6 cylinder coil packs and 5 fires just fine in #6 spot, so leading to the inner switch box. The best Ohm'd out coils per specs are the ones not firing. The stator physically looked OK - meaning no burnt or wore spots. Still pulling my hair out on this one! Wife's also getting frustrated with me and the motor now!! Any other hints? Thanks all, Lanny

 

[Coloradolakeboy]

Re: 1985 Mariner 150 HP Magnum won't idle

Sounds like you need to test the ignition with a DVA. Do you have the Merc Tech Service manual?

 

[CharlieB]

Re: 1985 Mariner 150 HP Magnum won't idle

Download the Ignition Troubleshooting Guide from the Support pages at CDIElectronics.com

DVA testing your stator may reveal a low output on one the speed winding for the 1,3,5

PROVE this as there is NO RETURN on electrical parts.

 

[LannyF]

Re: 1985 Mariner 150 HP Magnum won't idle

I have purchased the Merc/Mariner Serv Manual. I've replaced the inner switch box for the odd # bank w/ a new one. If I can get the idle up to 800 the odd side all fires, but I can't keep it at 800. It's either 550 -600 or 1250 and higher. Just no happy medium. I'm going to check out the CDI troubleshooting. I was hoping not to hear the stator, but why not ... more money. Change the name to "Money Pit" Ha!

 

[LannyF]

Re: 1985 Mariner 150 HP Magnum won't idle

Sat 7/23 - got into a local marine shop and we ran the DVA test - CharlieB hit it that the 1, 3, 5 read low. Blu/Wht to Gnd (outer) was 25 VDA Red/Wht was 3 VDA / Blu to Gnd (inner) was 3 VDA and Red was 3 VDA. So the low speed is trying to suck the juice out of the Hi speed once above that 800 to 1000 RPM range. So now I'm getting a stator!
Thanks guys for your help - I liked the CDI site for troubleshooting as well.