84 V150 hard start and loading at idle

[Doug57]

Some of you have helped me through my first rebuild. The rebuild is done and I have finished with the break in. I thought that the hard to start and loading at idle would go away as my mix got back to ratio got back to normal, but that hasn't happened. I am thinking the problem is improper float adjustment, primary timing or my not changing all the needles and seats in the carbs.

I plan to pull the carbs back off Saturday and install new needles and seats, also check the float adjustments, and install new plugs. I have already removed the stabilization mod. and have WOT timing set at 23 BTDC. The Selco book I have said to set the primary timing at 11 ATDC. Is that correct? I have checked the entire ignition system and everything checks good.

The motor try's to start when cold but wont stay running. I have to push the throttle to about 3/4 and it will clear out, then I pull back to around 1500 RPM and hit the choke 3 or 4 times. I can then go to idle which is at around 850 RPM. If I shut it down even after warm and it sits for a while is becomes hard to start again but not as hard as when completely cold.

Is that primary timing right at 11 ATDC and is there anything else I should check before I take it back to the lake?

 

[j_martin]

Re: 84 V150 hard start and loading at idle

Do all your basic troubleshooting, concentrating on the fuel system as a whole, and also intake integrity. (vacuum leaks) The fault you're looking for is probably what grenaded it in the first place, so it's important to get it resolved.

hope it helps.
John

 

[Dukedog]

Re: 84 V150 hard start and loading at idle

11 ATDC sucks. Through tha book away (especially Sel.) when it comes ta idle timing. Never seen a Merc that would idle worth is weight at that setting. If all tha other stuff is set right (linkages, throttle cam ta roller, stops and etc.) start at at least 0. maybe up ta 5 ta 8 degrees advance. But like I say, everything else has ta be right. Set it where its happy and starts easily on tha hose. Now ya got ta put it in tha water, in gear and make sure its happy there. If not put some more (advance) in or take it out. Till your BOTH happy with it........JMO

 

[j_martin]

Re: 84 V150 hard start and loading at idle

I'm afraid the mutt is on the pipe again.

Most of em idle between 7-12 degrees ATDC. The throttles on the carbs are totally closed at idle, so the only thing that determines idle speed is idle timing, and of course mixture which is fixed. If it weren't within reason, it either wouldn't start, or it would run out of control.

What I recommend is that you go at it logically. Be sure you have proper fuel delivery and pressure. Then, because it's a very low cost item, spray a little water mist around the intake gasket joints while it's idling, looking for leaks. Then go after the carbs, setting them up carefully according to the book.

If you're not sure about basic health, do a compression test. If you tear down the carbs and they look real good before you work with them, then pull the reed plate while the carbs are off and inspect them.

By the way, simple quick check. If the throttles are not all fully closed, either out of sync, or being held slightly open by the cam, and you retard it enough to idle, it'll do just what yer saying.

Long story short, step by step, by the book, and it SHALL run well. I do recommend the factory manual, though.

hope it helps
John.

 

[Dukedog]

Re: 84 V150 hard start and loading at idle

No pipe here! Not any of my motors or anyone I know have idle timing atdc...........It sucks, loads tha motor terribly and makes tha responce terrible. But I guess thats just me..............

 

[j_martin]

Re: 84 V150 hard start and loading at idle

No pipe here! Not any of my motors or anyone I know have idle timing atdc...........It sucks, loads tha motor terribly and makes tha responce terrible. But I guess thats just me..............

Let me guess. Your WOT timing works best about 40*

 

[Dukedog]

Re: 84 V150 hard start and loading at idle

Some of tha so called BIG boys told me 30 degrees but I still opt out for 23 ta 25 crankin'. Guess I got no balz

Might have something ta do with their junk blowin' up and mine don't huh.......

 

[Doug57]

Re: 84 V150 hard start and loading at idle

J

The stabilizer module shorted out and I'm sure that's what caused my problem. I put in two new pistons and all new rings, seals, needle bering's and everything in the cooling system. Did away with the oil injection and went to pre mix. Boiled and rebuilt carbs except for the needles and seats. Re built fuel pump and installed a large water separator. Compression was at 124 to 127 across all six cylinders before I completed break in. I will recheck this weekend. All the reed's looked to be in very good condition. I think I want to go ahead and put the new needles and seats in the carbs now that I have them. I'll check for the vacuum leaks first, that's a real possibility because I had planed to re-torque every thing this week end after the engine has gone through some heat cycles. I'm not comfortable with the sync on everything. Because I know how critical that is. I went through it three times and made only a couple of slight changes. The biggest head scratchier I had was the position or the throttle lever that engages the carb linkage roller. The diagram I have looks different that my motor. This whole rebuild project has been a great learning experience and I you guys have been great in helping me through it. The most important thing I have learned is there's a lot more to taking care of an out board than water pumps, lower unit oil and stabil. I let ya know what I find.

 

[j_martin]

Re: 84 V150 hard start and loading at idle

Ouch. Shorting the bias circuit to ground geatly advances the timing, like about 25 degrees (from the 19 it already is). That's probably why they're NLA from Mercury. I removed mine prophylactically.

If you have to guess on the carb cam timing, leave a bit of a gap when the throttle is closed. They like to have the timing advancing a bit before the carbs start to open. There's a sweet spot that can be found by experimentation once you have it idling nicely.

hope it helps
John

 

[Dukedog]

Re: 84 V150 hard start and loading at idle

Like John says. Leave a gap (how much is your choice, just a hair is fine for what your doing) between tha cam and roller. There is a mark on tha cam that should line up directly to tha center of tha roller no mater how much gap you leave in between tha two parts.................

 

[Doug57]

Re: 84 V150 hard start and loading at idle

John & DukeDog

Just wanted to follow up and let you know what I found on my motor today.

I went ahead and put in the new seats & needles. I had one of the floats set too high. But the biggie was one of the seats was loose, I'm sure it had fuel coming by. Re torqued everything front to back and went through sync procedure again. I set the cam as you said Duke.Also did another compression check, ranged from 127 to 132. Started it up on muffs, it turned over about 5 times and fired up and didn't die. Let it warm up and idle was at 1150 RPM. I did leave a gap between the roller and cam so I adjusted timing and brought idle down to 950. Have a smooth idle with no sneezing or excessive smoke. Just tapped the carb linkage with my finger and it sounded crisp and quick. Checked the timing with motor at idle and it's at 12 ATDC. Ready to get it in the water and get some back pressure on it and start looking for that sweet spot.

Thanks for your help! You guys are the best.

Oh yea, if you run across anybody who needs it I have the complete oil injection system and a brand new time bomb (I mean stabilizer module)

 

[sschefer]

Re: 84 V150 hard start and loading at idle

Oh yea, if you run across anybody who needs it I have the complete oil injection system and a brand new time bomb (I mean stabilizer module)

Shoot just when I thought I found a home for the box of em I have.. Need any alarm modules.. I get rid of them too!

 

[Doug57]

Re: 84 V150 hard start and loading at idle

LOL Maybe I can figure out a way to use it to make the Christmas lights blink faster next Christmas.

 

[j_martin]

Re: 84 V150 hard start and loading at idle

Shoot just when I thought I found a home for the box of em I have.. Need any alarm modules.. I get rid of them too!

I could use an alarm module. Used my spare last summer.

Doug, The devil's in the details on those carbs fer sure.

 

[Doug57]

Re: 84 V150 hard start and loading at idle

John

If you're serious about the alarm module tell me where to send it and it's yours.