1971 1150 Hard Start and Shifting Issues

[tinmanchris]

Hey guys,

I have a 1971 115HP Tower of Power that has a hard time starting and running.

Here are the symptoms:

• The only way I can get it to start is if I spray some fuel directly in to the carbs
• Shifting the motor to forward will cause the engine to sputter and eventually die
• If it dies I have to respray the carbs with fuel again in order for it to restart
• If I'm fast enough to give it more gas in forward, the engine will roar to life and I can go pretty fast with zero issues.
• This is a super weird one but if I have it running in idle on the hose and I put the covers back on, the engine WILL die and it will not start (or it'll start and die instantly) till I remove the cover. I will try to reconfirm this when I get some time.
• When starting, the starter sometimes only turns the flywheel for a second or two before dropping back down.

What I have done
[Last season (barely took it out)]

• Rebuilt fuel pump
• Rebuilt all carbs by professional mechanic
• Replaced all spark plugs
• Rebuilt starter motor
• New fuel filter

05/19/13

• Fresh fuel
• Attempt to adjust idle mixture screw according to service manual

05/26/13

• Found out how my timing works
• Attempted a sync and link from this video since I don't have a timing light
  How to Link and Sync Mercury 1150 Inline 6 - YouTube
• Uploaded pictures of spark plugs as I don't know if they are bad

05/29/13

• Ran power tune in to the system
• Adjusted idle screw to close to all the way in
• See posted results in thread

What I plan to try next:

• Sync and link (with with a timing light)
• Fuel in a separate fuel tank to see if any fuel lines are clogged

Does anyone know what else it could be? Thanks!

 

[Chris1956]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

Sounds like a case of incorrectly adjusted carbs. Did you set the floats to spec? Idle adjustments need to be 1-1/2 open from light seating. In the water with the motor warm and idleing, adjust the carbs until you get fastest, smoothest running. They will likely be too lean to allow acceleration, but test it. If she stumbles or dies, open top carb mixture screw 1/8 turn and retest, follow with mid carb, and then bottom carb, testing after each adjustment. Eventually you will find proper setting to give reasonable idle quality and good smooth acceleration.

Make sure battery cables are clean and tight. Sometimes they can get corroded under the insulation. Starter must spin pretty fast to choke motor properly. Take compression test as well. Low compression causes hard starting.

 

[tinmanchris]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

Sounds like a case of incorrectly adjusted carbs. Did you set the floats to spec? Idle adjustments need to be 1-1/2 open from light seating. In the water with the motor warm and idleing, adjust the carbs until you get fastest, smoothest running. They will likely be too lean to allow acceleration, but test it. If she stumbles or dies, open top carb mixture screw 1/8 turn and retest, follow with mid carb, and then bottom carb, testing after each adjustment. Eventually you will find proper setting to give reasonable idle quality and good smooth acceleration.

Make sure battery cables are clean and tight. Sometimes they can get corroded under the insulation. Starter must spin pretty fast to choke motor properly. Take compression test as well. Low compression causes hard starting.

I had the carbs professional rebuilt by a marine mechanic. Prior to the rebuilt the floats were pretty bad as gas was leaking out of the back of the carbs. Now it seems pretty good as no gas is leaking from the back.

I have tried doing the 1-1/2 open from light seating but still have a hard time starting the boat. I followed the instructions from the mercury service manual and wasn't able to obtain a setting that works well. I can get it to idle but it will die when shifting in to gear.

Battery connections are clean and tight as I checked them this past weekend before heading to the lake. Thanks!

 

[tinmanchris]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues


How are my spark plugs looking? They don't look too bad to me. I wasn't able to get number 6 out because the shell of the engine is in the way. Trying to figure out how to remove it.

 

[Chris1956]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

Plug 6 can be removed using an open end wrench. Your plugs look a bit fouled. Clean them up or replace them. Check for an exhaust leak at the powerhead base gasket.

 

[merc850]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

Those plugs are oil and carbon fouled - the insulator should be white or light tan color, if they are new clean them with Power Tune , what type and ratio of oil are you using? 50/1 is the recommended mix using more will just cause poor performance. I would spray some Power Tune into the engine to cleanup some of the gunk.

 

[tinmanchris]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

Those plugs are oil and carbon fouled - the insulator should be white or light tan color, if they are new clean them with Power Tune , what type and ratio of oil are you using? 50/1 is the recommended mix using more will just cause poor performance. I would spray some Power Tune into the engine to cleanup some of the gunk.

I am using a 50/1 ratio... maybe accidentally a tad bit much but not a bunch more. I think West Marine might have that engine cleaner so I'll swing by the store tomorrow to buy some. Do I spray some in the spark plug holes as well? If not how should I use it to clean the engine.

Thanks.

 

[merc850]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

You warm the engine up then spray into each carb at fast idle then slow the engine down and spray more cleaner until engine stalls. Wait for 15 min. then take boat out for a ride at 3/4 + throttle.

 

[tinmanchris]

Re: 1979 1150 Hard Start and Shifting Issues

Re: 1979 1150 Hard Start and Shifting Issues

You warm the engine up then spray into each carb at fast idle then slow the engine down and spray more cleaner until engine stalls. Wait for 15 min. then take boat out for a ride at 3/4 + throttle.

Cool. I'll give that a go on Wednesday.

 

[Moody Blue]

Re: 1971 1150 Hard Start and Shifting Issues

I'll throw this out there for consideration since I went through this same symptoms with my 1971 Merc 800.

Poor idle and stalled whenever put into gear. If I goosed the throttle quick enough as I changed gears it would run great. I tore the motor apart this past winter and found the lower crankshaft seals were shot (as were the main upper and lower main bearings). With bad seals, the motor can't create enough vacuum to draw fuel through the carbs when needed when going into gear. A fairly common failure on the old Mercs.

Food for thought.

 

[tinmanchris]

Re: 1971 1150 Hard Start and Shifting Issues

I'll throw this out there for consideration since I went through this same symptoms with my 1971 Merc 800.

Poor idle and stalled whenever put into gear. If I goosed the throttle quick enough as I changed gears it would run great. I tore the motor apart this past winter and found the lower crankshaft seals were shot (as were the main upper and lower main bearings). With bad seals, the motor can't create enough vacuum to draw fuel through the carbs when needed when going into gear. A fairly common failure on the old Mercs.

Food for thought.

Yikes I hope that's not the case. I'm going to the lake tomorrow for a test run with the new sync and link, clean plugs, and power tune changes. I don't have a garage so taking apart an engine is out of the question. :\

 

[Chris1956]

Re: 1971 1150 Hard Start and Shifting Issues

Normally bad lower crankcase seals will let water into at least cylinder #6. If that spark plug is real clean, the OP may have that issue. Surely the other cylinders do not have that issue, as the plugs are filthy.

 

[tinmanchris]

Re: 1971 1150 Hard Start and Shifting Issues

Normally bad lower crankcase seals will let water into at least cylinder #6. If that spark plug is real clean, the OP may have that issue. Surely the other cylinders do not have that issue, as the plugs are filthy.

Well spark plug #1 was cleaner than the rest. Hopefully that doesn't pose an issue.

 

[Chris1956]

Re: 1971 1150 Hard Start and Shifting Issues

It looked OK to me. When you see a plug that looks like it came out of the package, that is an issue

 

[Moody Blue]

Re: 1971 1150 Hard Start and Shifting Issues

Normally bad lower crankcase seals will let water into at least cylinder #6. If that spark plug is real clean, the OP may have that issue. Surely the other cylinders do not have that issue, as the plugs are filthy.

Good point. I overlooked that. I did have water in #4 cyl (only have 4 cyl on the 80hp). PLugs were not super-cleaned but they were rusted. That was the deciding factor in me taking the motor apart.

 

[tinmanchris]

Re: 1971 1150 Hard Start and Shifting Issues

Test run was better but still use some more work. I didn't get to spend too much time on the lake as the clouds were coming in. I managed to get the motor to start up in my driveway before I headed out (first time without spraying fuel in carbs) so I know the sync and link process helped a bunch. I did the power tune spray and let sit for 15 minutes before starting it up again.

After most of the power tune spray was smoked out I took the boat to the lake for a quick run. It was hard to start again but with the throttle level up I was able to get it started without spraying fuel in to the carbs. I struggled hard for the first 15 minutes to get the engine to shift without dying but in the end I managed to pull it off by screwing in the idle speed screw close to all the way in. Even close to all the way in and in neutral the engine wasn't idling that fast so maybe I need to do a spark test on all plugs to make sure they are all working correctly or see if that is normal.

I sadly ran out of time due to the rain but I know I need to still make some adjustments to the idle mixture as there is hesitation if I do a hole shot; It struggles for a bit when I gas it to the max but then it takes off after a few seconds.

Any other tips will be welcomed. Thanks!

OH and another thing I notice is that the fuel line squeeze ball goes soft. It does not stay firm. Is that normal?

 

[Chris1956]

Re: 1971 1150 Hard Start and Shifting Issues

fuel primer getting soft is not bad in itself. If it collapses, that is bad. Normally the idle mixture needs to be quite rich to accelerate smoothly.

 

[tinmanchris]

Re: 1971 1150 Hard Start and Shifting Issues

fuel primer getting soft is not bad in itself. If it collapses, that is bad. Normally the idle mixture needs to be quite rich to accelerate smoothly.

I'll rich up the idle mixture screws on my next outing and let everyone know what happens.

 

[CWKboat]

Re: 1971 1150 Hard Start and Shifting Issues

This may already have been mentioned, but these old inlines are notoriously cold-blooded and hard to start. They are virtually impossible to flood. Pump the primer bulb until hard, and then pump a few more times to push fuel past the floats before choking and starting. You can't flood it. It will start best with an oil slick surrounding the motor in the water, and I'm only half-joking! You get the idea.. I bet that will cure your hard starting assuming that your carbs and everything is synched up correctly.

Set those idle screws on each carb about 2-2.5 CCW turns from a lightly seated position and it should take off like a scalded dog.

 

[tinmanchris]

Re: 1971 1150 Hard Start and Shifting Issues

Well I just realized that I messed up on my timing. I though my primary pick up was at 5 degress when it is suppose to be at 2 degrees. I guess I need to do some more adjusting again.