1995 135 Mercury idle issues

[Bruce2]

1995 135 carbbed Mercury wants to just shut off at idle while in gear...but starts right back up...would carbs being to lean at idle do that? Also turning about 3500 and stab the throttle and it will hesitate like bad accelerator pumps being bad and then take off..these carbs dont have accelerator pumps.....any ideas thanks..

[rock]

Might need to bump up timing (primary pickup) so it idles about 650 in gear.

Rock

[Bruce2]

When it idles right , idle rpm's is around 650 - 700 rpm's in gear...one time it acts like it's loading up and next minute might idle fine...loaded boat on trailer..drive on..and i leave it in gear at about 1100 rpm to hold boat up against front roller while i hook winch cable up and it just stopped running like someone shut the key off....... you come off plane and once boats settles down if you back off throttle real quick is will die...........Idle stabilizer been removed..new switch boxes, fuel pump rebuilt,plugs changed not long ago..bleeders are all new. replaced ignition switch due to old one feeding a volt to stop wires on switch boxes in run position...compression on all 6 are 105- 110 cold motor...

[Bruce2]

:confused:

[Bruce2]

I found the problem thanks for replies...

[FORBESAUTO]

Wweell, ya gonna keep us hangin? :rolleyes:

[Bruce2]

Wweell, ya gonna keep us hangin? :rolleyes:

I haven't been able to get it in the water yet to be 100% sure that was my problem...but who ever did the link and sync didnt tighten the jam nut on the idle timing adjustment and timing at idle was way off..:rolleyes:

[FORBESAUTO]

Dang knucklehead! Cant find good help anymore:rolleyes:. When you get it on the water set the idle timing to whatever makes her happy in hear and let her roll

[Bruce2]

Well that wasn't the problem...when it starts acting up on the idle you can shut it off and remove engine cowling and start it up and it will idle like it should...any ideas?

[FORBESAUTO]

Are you running with air box on the carbs or without it?

[Bruce2]

Are you running with air box on the carbs or without it?

With air box on carbs.....i think i may have an exhaust leak...when you put cowling back on it wont hardly idle..other wise it runs great..about 5100 rpms (56 mph gps) it starts chine walking, porpoising and doing the trailer whipping thing...lol..this is on a bass boat...lol

[FORBESAUTO]

Check the above water exhaust relief at rear of cowl. If it leaks into cowl they will run like doo doo

[Bruce2]

does this look right??bottom side in between the heads 2 holes on the right side bottom...


385273385275

[FORBESAUTO]

Yes, that's where the divider bolt holes where machined and they go all the way through at that point

[Bruce2]

Yes, that's where the divider bolt holes where machined and they go all the way through at that point

So does that mean block is junk or what?...it's been leaking there because of all the discoloration

[FORBESAUTO]

No, they are all like that. If exhaust is leaking from those holes you have a leaking divider plate gasket.

[Bruce2]

Ok ty...i have the diverter plate off of motor, gasket did look good..but the white residue looks like it maybe coming from the head gasket thats just above those holes... is it possible the head gasket leaking exhaust??...i did compression test on it the other day and they where all even on compression..

[FORBESAUTO]

I wouldn't think so being the cylinder has water all the way around it. If the gasket leaked externally it should leak water

[Bruce2]

I wouldn't think so being the cylinder has water all the way around it. If the gasket leaked externally it should leak water

I didn't think so either but figured i would ask...now to get a divider gasket and seal and put it back together and start over..lol...Thanks..

[W2F a V-King]

While you have it idling with the cowl off and running good try wiggling/pulling on the wiring harness in different places. Might have a wiring issue.

[Bruce2]

I just changed all the mid section gaskets from when i changed motor mounts and they all look still good...it seems to be worst when it is good and hot(up to temp)...

[Bruce2]

What's the chances of a cracked exhaust plate? as it idles pretty good when cold..

[Bruce2]

Another thing i failed to mention until i saw it do it tonight when i fired it up is i have water spitting out of my pee tube on motor when motor cold, so after motor cooled down for about 2 hours i pulled thermostats and they where closed. Put thermostats back in and fired it up and it started peeing right away, right side head got warmer faster than the left side head...any ideas??....Thermostats are about 2 years old..

[Bruce2]

It lives...

https://youtu.be/_RT6k6Qti5c

[pcrussell50]

Might need to bump up timing (primary pickup) so it idles about 650 in gear.

Rock

Not that I would begin to say you're wrong as I'm quite sure you have waaay more experience than me, but I had good luck with my 2.0L by setting the idle timing according to the factory manual, (at about 12 deg while cranking if memory serves), then cracking open the butterflies using the idle speed adjustment screw to get the desired idle in gear.

Although you're not the first experienced boater to advise setting idle by timing adjustments, either.

-Peter

[Bruce2]

Well had boat out today for a test spin finally and idled better but still not right....Question should i be able to feel the fuel pump pulses in the primer bulb when idling??..

[rock]

Peter....I always set timing by the book but there seem to be oddball situations where they just don't respond correctly and a little tweak here and there often compensates for what ever kept them from working correctly in the first place.

Rock

[pcrussell50]

Got it, thanks. I always like to hear from the experts when it's ok to deviate from "the book" in oddball situations.

-Peter

[W2F a V-King]

True that on having to do what you have to do in the out of the ordinary situations.

Fish motors and low pitch props do well with the "stock" idle timing settings..

Hang a large pitch prop on it and sometimes the idle in gear and set the timing to raise idle works best...for me anyway. And in addition to that I take the idle stabilizers off every motor I own. Those things when working are supposed help the low rpm sometimes, so I'm told..I never run one. :thumbsup:

[Bruce2]

I got tired of messing with it so i took it to the boat doctor.. I did bump the timing up to get it to idle at 650- 700 rpms in gear but idle in neutral was like 950 - 1000 sometimes to 1100 rpm's was around 6 degrees ATD and now probably about 2 Degrees ATD...anyway took it to friend who has a marine repair shop.

[Bruce2]

Well boat is ready for pickup, they put timing up to zero and also rebuilt fuel pump which i had just done but they said i had a gasket on wrong, which i put fuel pump kit in as manual describes...oh well only if we where all perfect...lol