1991 150 force won't turn over??

I have replaced the starter, starter soleniod, and the head gasket. I have had the battery tested and even tryed another battery but it will not crank the motor over fast enough to start. If I take the plugs out it will crank over just fine but as soon as I put the plugs in, it cranks reel slow. Does anyone have any ideas what it could be???

Re: 1991 150 force won't turn over??

sounds like a dead battery, I know you said it wasn't but doesn't seem to have the juice under compression load. check to make sure all your batt cables are tight and corrosion free, no breaks or anything, put a meter on your battery while you start it and see if the voltage drops to nothing, or holds pretty well.

Re: 1991 150 force won't turn over??

seems the hold pretty well, drops to 10.5 while cranking

Re: 1991 150 force won't turn over??

Now measure it at the starter.

Re: 1991 150 force won't turn over??

7.5 at starter

Re: 1991 150 force won't turn over??

Take out all the plugs and turn over the engine by hand. It should turn easily withjust a slight pressure when each cylinder compresses the crankcase gases. If not free, check for broken or dragging rings hanging up in the ports then check lower unit for binding ( possible bad bearing or waterpump impeller) Remember: The thee gears in the lower unit (forward, reverse, and pinion) are constantly in mesh and spin around the prop shaft in neutral. Any binding in there will directly affect the drag on the powerhead and will be most noticeable at cranking. Drop lower unit and try to start engine. Check to be sure that there is no corrosion where the starter mounts to the block. The starter is grounded through the block and corrosion will reduce its power even though the battery shows good--Think of it--Voltage and amperage go into the motor but can not go out. Like a hose with a clogged nozzle--plenty of water but you can't use it.

Re: 1991 150 force won't turn over??

i have force 150 with same problem i have changed water pump and head gasket because i had no compression on one cylinder and now it turns over very slow and heats up my battery and goes into a drag it tries to start at first then i loose everything i took out plogs and put marval mystery oil in the plug holes then turned it over to blow out the oil and it does better now but still heats up my battery pretty fast i am looking into my stator now to see if that might be some of my problem too

Re: 1991 150 force won't turn over??

hi maybe i have a solution to ur problem i fixed mine today it was not getting a good ground i ran another ground from my battery to my head turns over great now and starts with no problem what so ever . maybe it will help urs too