no power

[laganiere]

Hello everyone,

I have a mercury 1150 sn4859218, The problem I am having is I have no hole shot and about 5 seconds after it reaches top speed around 28 mph it will start cutting out, almost like its starving for fuel, if I pull it down to 3/4 throttle it seems to run fine and runs about 24. This motor has a new timing light rebuilt carbs and has been retimed and the link and synch done all in the last 4 monts, i have also checked and all carbs are opening all the way and in perfect time. I did have to open the bottom carb just a smidgen to keep it running at adle it would just keeping dying, this was after we had the boat out. I also tried spraying premix into the carbs but it would flood and die , so I am thinking its getting enough gas, I also have tried moving the idle screws out for a better hole shot, started at 1 3/4 out and turned each one out and 1/8th turn at the same time, turned them out to about 3 out, then it ran really crappy. Any ideas would be much appreciated, hopefully before I decide I need a 300 lb anchor.

 

[Chris1956]

Re: no power

It sounds like two problems. Loss of top speed is usually weak fuel pump or fuel restriction. If primer goes flat, it is restriction. If boat continues to run at max RPM, when you pump primer, rebuild fuel pump.

Hole shot is controlled by idle mixture. Top carb runs leaner then mid carb, which runs leaner than bottom carb. So adjust needles at idle, in the water to get smoothest idle. Now test hole shot, richening top carb 1/8 turn, then mid carb, then bottom carb. Test after each adjustment. You will need to richen the bottom carb the least, if at all.

 

[laganiere]

Re: no power

so shoild start about 1 3/4 turn out. should i test hole shot after adjusting each carb 1/8 out, or do all 3 out then test the hole shot? pump at full throttle to see if it goes flat or not? should it be hard at full throttle when you squeeze it? so if i squeeze it and quits cutting out but is hard,would it be fuel pump? is there any filters besides the pump, that one is clean.

 

[Chris1956]

Re: no power

Adjust each carb individually and then test adjustment for improvement/non-improvement, after each adjustment.

The only factory filter is the screen on the fuel pump. Look in the boat for others.

Pump primer bulb. If motor keeps max RPM, fuel pump is weak. Rebuild kits are cheap and easy.

 

[laganiere]

Re: no power

k I just went ahead and pulled the pump apart figured could use a rebuild regardless. I found what looks to be mineral deposits in there, from water, the filter was clean and no tears in it. How would water be getting in there? there is to hoses running from the bottom of the fuel pump to the block, do you know what they are for? That is where the water appears to be comming from, as it has the most deposits in it, you can see where it was leaking from the underside of the gasket into the main fuel cavity of the pump going to the carbs. My last question is on the rubber diaghram is it supposed to be stretched where it sits over the 3 cavities, it almost looks like it is stretched thinner than the rest of it?

 

[laganiere]

Re: no power

ahha figured it out, number 3 piston is melted around the ring . to lean on the gas maybe, or bad timing, it was off untill recently? anyone know what else could cause this. are these motors worth rebuilding and what would it consist of

 

[laganiere]

Re: no power

anyone?

 

[Blevins]

Re: no power

Ok so the motor isn't junk. I feel that motors can always be rebuilt because swapping is a nightmare between changing gauges and all the parts. That being said you need a good machine shop to check hay cylinder and the sleeve. You need to see if it's rebuildable and feasible for cost. Good mechanics can work magic. Good luck. Seal kits are cheap but boring out the sleeve can get a little costly.

 

[Blevins]

Re: no power

Also the water pump impeller could be slipping and overheated the motor or there is junk in that cylinder that built up

 

[Chris1956]

Re: no power

#3 cylinders tend to be the first to fail. The cause can be over propping, too lean fuel mix, overheating, overadvanced timing, or poor fuel.

To rebuild that motor, you need to tear it down to the bare block, and obtain an oversize piston and have it bored to match the piston. Now hone the other cylinders, and install new rings, gaskets, rebuild the fuel pump, rebuild the carbs, rebuild the water pump, and set the timing properly.

W/O labor the cost is about $100/piston, $30-$50 for boring, $75 gaskets, $10 fuel pump kit, $50-75 for carb kits,$30 for waterpump.

 

[laganiere]

Re: no power

might be a stupid question but I am going to ask anyways. Wouldn't boring out just the one cylinder trow the balance of the crank off? also what about replacing the upper and lower ball bearings and seals is that a good idea? the bearings don't look burnt at all. I found a shop, only one within 100 miles that would work on the old girl, 60 bucks to bore it out, if its just the one cylinder. I noticed some blow by on the other pistons as well. Could this be caused by bad rings or could those cylinders be tore up too?

 

[Chris1956]

Re: no power

Oversize pistons are designed to weigh the same as standard pistons. You can therefore mix and match w/o balance problems.

All motors have blowby. You can lightly hone the other 5 cylinders, and replace with standard rings. it might improve the compression. Replacing the lower and upper crankseals is a good idea. Check the upper and lower main bearings, and replace any that need it. it will usually be the upper bearing that needs it. Don't forget to retain and reinstall any shims that you find.

 

[Blevins]

Re: no power

Ohh I just started having this issue with my 225 carb. Check your fuel tank fume scoop. It should be right below your gunner and face towards the rear. The tubing that was put on mine was coming in from the scoop the straight down towards my tank allowing water to splash in. Check the tube and make sure it comes into the boat and goes straight up and comes back down that way the water has to be forced into to allow water into your tank. The other thing you can try is hold your hand over the carbs and create a vacuum. While running and pull your hand away it should bring out water if water is being pulled into your carbs. Let me k ow if I can be of any other help as I am going through the same problem right now

 

[Chris1956]

Re: no power

Say what?

 

[laganiere]

Re: no power

now you have me confused on the whole water thing. could you explain more please

 

[laganiere]

Re: no power

Do all these motors have shims? I have taken it apart and have not seen any shims on the motor at all.

 

[Chris1956]

Re: no power

I think the CPT was talking about water entering the fuel tank via the vent.

Merc's usually have shims in the gearcase, under the upper endcap, and perhaps under the lower endcap and maybe under the fuel pump base. Simple replace them in their orig. positions.