73 merc 1150

[ssm]

I have 1968 15' Horizon flat bottom that I restored about 15 years ago. I put a rebuilt 1150 on it about 13 years ago. Top speed is around 53-55 depending on load. The last two seasons have been very frustrating. The motor will die intermittently out of the hole. Top end is still there. I have been through the carbs, fuel pumps, new wire harness under the cowl, new cap, new timing belt cannot get to the issue. any help would be great.

[Robby321]

Die or just bog? Try a lower carb jet size.

[Ira Tindale]

open idle jet screw a little till the bog is gone

[Robby321]

open idle jet screw a little till the bog is gone

Also did you replace all motor fuel lines if orig? They gotta go. Have info house puter the easy way. Got a 15.6 Flatty myself, crank up rebuild "Frankenmerc"

Yep, thats a start. Has to be in the carbs from idle jets, to intermediate, then mains. BUT! Have you replaced ALL the motor fuel lines? If orig, need to go. I have all "what to do that the house puter". Have a 15.6 Flatty myself, crank up rebuilt Merc Il 6 ass end too.

[ssm]

Yes I have changed all the fuel lines, squeeze bulb, check to make sure all the bleed restricters were still there, compression is good. It doesn't bog it just dies like I turned off the key. Sometimes I can work the throttle and recover it. I have taken the boat to Neheilem Bay OR and it ran great. Seems to like sea level. That leads me to believe its running rich at home or the spark is week and cant handle the fuel load.I have been through the carbs a couple times and have tried adjusting them on the water. I should not have to mess with the jets as it ran great for 13 + years up until two years ago with the current jets. I try to run non-ethanol. It runs and idles great at home in the test barrel, just doesn't like a load. I am starting to wonder if the motor is just tiered and needs to be gone through again. The shop I had rebuild it is no longer, would like to find someone capable of doing the job close by.

[W2F a V-King]

"Usually" when fuel issues are present, the motor doesn't shut off that quick, and gives notice in some way. Try running without the cowl and have someone drive the boat, and spray a short burst of carb cleaner at the carbs ( Be sure it's a flammable type, as some are "green" friendly and useless ) as it is bogging or shutting off. If it helps, you know it's fuel related.

Going through the carbs can mean a lot of things. Not just drain/spray out and blow out. Have the original foam type floats been replaced with newer plastic ones? These disintegrate and can leave small pieces to wreck havoc in the carb. There are a lot of very small passages that need to be soaked in carb cleaning solution and or ultrasonically cleaned to get it really clean. These carbs have a funky needle and seat arrangement that can cause issues as well.

That engine has a distributor that moves to advance/retard the timing. And old Mercs are notorious for wiring issues. I'm restoring a 1975 1500 right now, and there wasn't hardly a good wire on it. Insulation falling apart, and the wire inside corroded badly. I know you replaced the engine harness, how about the distributor wiring?

So if running it on the hose or barrel won't duplicate the problem, maybe because you can't run it hard in a barrel in gear. Try moving the distributor harnesses while it's running in the barrel. See if you can get it to hick up. Disconnect the distributor from the throttle linkage and rotate the distributor while running and wiggle the harness to it.

If it runs well up top, wot. Then the power head sounds like it is in pretty good condition. Lots of basics to check first. Compression, leak down, etc.


James

[Robby321]

Yes I have changed all the fuel lines, squeeze bulb, check to make sure all the bleed restricters were still there, compression is good. It doesn't bog it just dies like I turned off the key. Sometimes I can work the throttle and recover it. I have taken the boat to Neheilem Bay OR and it ran great. Seems to like sea level. That leads me to believe its running rich at home or the spark is week and cant handle the fuel load.I have been through the carbs a couple times and have tried adjusting them on the water. I should not have to mess with the jets as it ran great for 13 + years up until two years ago with the current jets. I try to run non-ethanol. It runs and idles great at home in the test barrel, just doesn't like a load. I am starting to wonder if the motor is just tiered and needs to be gone through again. The shop I had rebuild it is no longer, would like to find someone capable of doing the job close by.

If runs better at sea level, jetting would be leaner with altitude, not richer. What are the plugs telling ya? If ya want it refreshed, got a friend here (Dr, Frankenmerc, this side the bumps 5 hour ride, Outside Olympia ) but be a total split the case, total new what needed. Not cheap, but done right.

[Robby321]

"Usually" when fuel issues are present, the motor doesn't shut off that quick, and gives notice in some way. Try running without the cowl and have someone drive the boat, and spray a short burst of carb cleaner at the carbs ( Be sure it's a flammable type, as some are "green" friendly and useless ) as it is bogging or shutting off. If it helps, you know it's fuel related.

Going through the carbs can mean a lot of things. Not just drain/spray out and blow out. Have the original foam type floats been replaced with newer plastic ones? These disintegrate and can leave small pieces to wreck havoc in the carb. There are a lot of very small passages that need to be soaked in carb cleaning solution and or ultrasonically cleaned to get it really clean. These carbs have a funky needle and seat arrangement that can cause issues as well.

That engine has a distributor that moves to advance/retard the timing. And old Mercs are notorious for wiring issues. I'm restoring a 1975 1500 right now, and there wasn't hardly a good wire on it. Insulation falling apart, and the wire inside corroded badly. I know you replaced the engine harness, how about the distributor wiring?

So if running it on the hose or barrel won't duplicate the problem, maybe because you can't run it hard in a barrel in gear. Try moving the distributor harnesses while it's running in the barrel. See if you can get it to hick up. Disconnect the distributor from the throttle linkage and rotate the distributor while running and wiggle the harness to it.

If it runs well up top, wot. Then the power head sounds like it is in pretty good condition. Lots of basics to check first. Compression, leak down, etc.


James

Yep, I'd look long and hard distributor.

[ssm]

Yes I have changed the floats to new style. The only old wire left under the hood is the leads from the trigger and spark plug wires. i have thought about changing the trigger in the distributor but was not sure what special tools are need if any. I am also thinking about a new harness from motor to control box. What would be "not cheep" as far as a rebuild from Dr. Frankinmerc? I am starting to lean that way. I will have to pull the plugs and take a look again. last time I looked they where to clean like there being washed, to much fuel or not enough spark. I appreciate all the input my head starting to get sore where I keep banging it against the wall.

[25ss]

Had one run like that found the coil wire was not all the way in the coil.
It goes in alot further than you think.
Dale

[Robby321]

Yes I have changed the floats to new style. The only old wire left under the hood is the leads from the trigger and spark plug wires. i have thought about changing the trigger in the distributor but was not sure what special tools are need if any. I am also thinking about a new harness from motor to control box. What would be "not cheep" as far as a rebuild from Dr. Frankinmerc? I am starting to lean that way. I will have to pull the plugs and take a look again. last time I looked they where to clean like there being washed, to much fuel or not enough spark. I appreciate all the input my head starting to get sore where I keep banging it against the wall.

I'll send ya (Doc Frankenmerc) his info a PM. Many options you 2 can discuss. Pic winter builds going on now..

[Robby321]

Ok SSM...this?

I am starting to lean that way. I will have to pull the plugs and take a look again. last time I looked they where to clean like there being washed, to much fuel or not enough spark.

Oh man yer running way lean! OR, ya got a leaking water jacket the block (known IL's where the second, pic Doc doing water jackets. But I'd suggest like in the PM, cheapest and best way is to pull yer power head complete. Then ship or drive the five hours here (seeing the Merc stuff him ALONE worth the trip!). Then best bet would be let him take yer old block, and get a ya a fresh rebuild IL6 with more HP if wanted. Thom a hell off a nice guy, retired LEO, BS none, but simple "knows his stuff"

Also running lean, and still running at 23 degrees timing? Fast looking for a "hole in one"..(did it twice my 70's XS). Run the crap gas now at 21 degrees timing.

More on IL6 carb jets a bit..(gotta find it)

[Robby321]

SSM? Doc built me crank up rebuild, and heres some info on jetting.

I plan on installing the .0785 mains and will be setting the WOT timing at 21 degrees and expect you to run 89 octane without alcohol additives at 50:1 using Quicksilver Premium 2 stroke oil with the TCW-3 additive and don't run her over 5500 RPMs once she is properly broke in.
Lots of people say the 1350 will run up to 5800-6000 okay,...But I would prefer going by the book until she is well broke in.
If she runs out real well and you want to try .080 mains after she is broke in,..No problem & I'll either install 'em or walk ya through it.
I don't want to initially install .080 mains and discover the thing is too rich and "blats" and won't run out well, but if you insist,...I will initially install .080 mains. Let me know your decision.


Thom. the LAST thing I want to do is tell you want to do with this motor...you know a HELL of a lot more than I do...heres a little more of the Forum jet controversy

""What's always bothered me about the 1350 jetting is that the 1250 before it and the 1400 after it both used .082 as the default main jets. The later 1500 defaults to .080 Most experts advise against going smaller than .080 on a 1350 - especially with todays gas.

So we are at sea level here, and my Flatty still has the .80's, and simple (2B ss) prop spin up, grab water and go. Lotta fun my little "Pocket rocket"! Pix motor build...

[W2F a V-King]

Interesting Reading this.

I have just gone through the carbs on this 1975 150 J block I am restoring, and it had .082 mains. Doc Frankenmerc suggests .080?
Wonder what redline he suggests after break in ( small light boat..79 Vector ).....never did like that terminology...."break" in for a new motor...

Thank you,

James

[Robby321]

Interesting Reading this.

I have just gone through the carbs on this 1975 150 J block I am restoring, and it had .082 mains. Doc Frankenmerc suggests .080?
Wonder what redline he suggests after break in ( small light boat..79 Vector ).....never did like that terminology...."break" in for a new motor...

Thank you,

James

.080's? NO WAY...run the.082's. Keep it fat! I had the new 74 J block (friend bought it new, I bought in 76 back Illinois Fox Chain). Bobby Switzer built the boat, Ralph Kozan massaged the motor, Jim Moulis rigged it. Was a real beast! And I beat the hell out it, "foot to the stop" across the lakes to the next channel. Well, I finally did a "hole in one" and into "Uncle Ralph". Replaced #3 and wet again! For about 1/2 hour until another meltdown! Back to Ralph and he had the timing up over stock, as thought I was racing it and using the best gas. Nope, ran the reg (way better gas than now too). Timing back, fixed again and never a problem until sold (still kicking my self in the ass for that).

Anyway, run the .082's. keep the timing at .21, not .23 degrees, run at LEAST mid grade gas, Premium best.
Redline? No prob 5800-6200 me.
On break in? Stuck it in a barrel for a couple hours first. Some say run 50-1 oil and idle only, heat sink and let the parts get to know each other. Other say run 25-1. I'd rather go heavy myself. First 10 hours then easy use, etc, and run 25-1. I only go to 40-1 now both my OB's and zero prob.

Did a couple hours B/I in a barrel, then more boat at the launch under load. Keep the J block alive! They are getting scarce! Wish the best!