MerCruiser 165 250 c.i. GM Motor Starting Problems

[NetMatrix]

I have a 1971 Tom Sawyer that has a MerCruiser 165 250 c.i. GM Motor in it. Now with the gear lever when I have it in the locked position (neutral) it will not start at all. The motor will attempt to turn over, but that's about it. Now if I take the lever out of neutral slide it either barely forward or reverse it will start and run with out any problems. Now if I go to put the lever in reverse or just to put it in neutral the motor will stop running. Then I will have to put it in reverse or forward and start it up again. I don't have any idea on what the problem could be, but hopefully a answer could be found on this.

Thank you for the help everyone.

 

[Don S]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

YOu probably have a bad lower shift and holding the shift interrupt switch closed. My guess is its probaby stiff to move the shifter too. With a binding cable, everything gets pushed out of adjustment.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

YOu probably have a bad lower shift and holding the shift interrupt switch closed. My guess is its probaby stiff to move the shifter too. With a binding cable, everything gets pushed out of adjustment.

The shifter moves without any problems. I push the button in and she moves with no problems at all. So could possibly putting a new shifter handle in the boat be a good place to start at?

 

[Don S]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

No it doesn't need a new shifter. You need to find what the problem is.
IF you push the button it, and it runs, you are in throttle only mode. if you pull it back to idle does it keep running?

 

[Bondo]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

So could possibly putting a new shifter handle in the boat be a good place to start at?

Ayuh,... You can always Start there, or about Anywhere else....
'course,... The Finish will Still be replacin' the Lower Shift Cable....

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

If I have the lever slightly out of neutral the motor will start and keep running, but if I put it in neutral the motor will die. I'll call the boat shop and get a price on the lower shift cable and give that a start. I'll probably replace the shift lever as well cause I can get a new one for about $25.00 and I don't like the one that is in it.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Well the good news is that I adjusted the idle screw on the carb, and the motor will fire up while it is locked in the neutral position. The cable is still needing to be replaced, but I'll get to that probably next month when I will actually have time to tear into it.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Ok we have a new problem with the boat's motor now. I can start it in the water, but it will only run for about 10 seconds then it will die. Now if I have it in my back yard with the hose on the outer drive it will run till I shut it off. I changed the fuel filter, and got looking at the fuel line going from the pump to the filter, and it's a 3/8" fuel line. Could that cause some of the problems with it not running in water a restriction on fuel. The carb has been cleaned inside/out. Now I'm not sure on what is going on with it, but I still need to change the spark plugs. I haven't even pulled those off the boat to see the condition of them just yet.

 

[Don S]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

3/8" fuel line is what should be there, and it works on 7.4 BBC engines with no problem.

but I still need to change the spark plugs

Did you do a tuneup except for the spark plugs???? Maybe new points? Did you move the distributor?
Sounds a lot like dwell or timing problems. Engine sounds ok on land, won't run with a little back pressure.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

3/8" fuel line is what should be there, and it works on 7.4 BBC engines with no problem.



Did you do a tuneup except for the spark plugs???? Maybe new points? Did you move the distributor?
Sounds a lot like dwell or timing problems. Engine sounds ok on land, won't run with a little back pressure.

All I did was removed the distributor cap. Took the 2 screws off and put it back the way I found it. All I did was changed the oil, oil filter, and installed a fuel filter and that was it. I don't know what would cause it to die like it is in the water. I can check the timing on it in a few days and see if that's in the correct spot.

 

[ziggy]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

just do the tune up thing to it like Don S says.

i do it every spring.

new points, cond. rotor and cap. (this year i'm poor so may not do the cap, i will observe it first though and make my decision then. if i wern't feeling poor, it get replaced for sure too) spark plugs, fuel filter. dwell, then time it. adj. idle speed if necessary. i also go through as many wire connections i can find to take apart and do take them apart. cleaning all contacts with emery to a nice shine. you'd be amazed what ya get off them with just one seasons use.

i'll also do a compression test to be sure i'm still in the game at some point in there..

then go from there. but it's a starting point.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

just do the tune up thing to it like Don S says.

i do it every spring.

new points, cond. rotor and cap. (this year i'm poor so may not do the cap, i will observe it first though and make my decision then. if i wern't feeling poor, it get replaced for sure too) spark plugs, fuel filter. dwell, then time it. adj. idle speed if necessary. i also go through as many wire connections i can find to take apart and do take them apart. cleaning all contacts with emery to a nice shine. you'd be amazed what ya get off them with just one seasons use.

i'll also do a compression test to be sure i'm still in the game at some point in there..

then go from there. but it's a starting point.

Ok I do want to play dumb right now. What is the dwell? I don't know anything about boats so I'm just completely lost at this point in time. lol

 

[bigskiohio]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

you cant just turn the idle screw you will put a bind in throttle. you have to adjust the cable too.

 

[ziggy]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

dwell angle is the distance, in degrees of distributor cam rotation that the cam revolves from the time the points close until they open again. the dwell for any given cam is controlled by point gap.

that's why the spec many times is givin in a point gap distance. and as an angle. you set the dwell angle with a dwell meter. you can set it either way. generally setting with a dwell meter is best (more accurate). but a feeler gauge and measuring the gap will suffice too.

from the adults only sticky.
http://forums.iboats.com/showthread.php?t=288430
look at 16.

oh, forgot to say. dwell affects timing. so if dwells changes, so does timing. the reverse is not true. timing does not affect dwell.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

you cant just turn the idle screw you will put a bind in throttle. you have to adjust the cable too.

I had to give the idle screw just the slightest little turn. Only about a 1/8th of a turn so it will idle at the right spot. When it fires up now it idles at about 1000 RPM. If it's any lower then that it will die. NOW that 1000RPM is when it first starts up it will settle down at 800 after the warm up and everything. I'm going to take a look at everything else and start getting to the point of what is going on. I'm looking at it not being in the water again till the middle of April,a nd sadly it is a 18 mile drive to the closest lake I can put this boat in so I have to basically fix all the little things first and hope when I take it to the water again it will run.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Ok I got to reading some of the information in the adult section. Now on the fuel line part could it be a problem with the length of the vent hose I have going from the tank to the hull being a bit longer than it should be? It's not a straight shot from the tank to the hull. It makes a full circle loop then goes to the hull. It's probably 2 1/2 inches in the inner dimensions of the circle. It does have more dropping than that. I'll have to cut that hose and get it to just be a straight shot from the tank to the hull and see what happens.

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Now could having to think of oil cause problems with this as well? The previous owner told me they ran 10W30 in it, and I put 25W40 or whatever it is they sell at Wal-Mart for a inboard motor. I didn't know if that was something to possibly look at as well.

 

[Bondo]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Now on the fuel line part could it be a problem with the length of the vent hose I have going from the tank to the hull being a bit longer than it should be? It's not a straight shot from the tank to the hull. It makes a full circle loop then goes to the hull. It's probably 2 1/2 inches in the inner dimensions of the circle. It does have more dropping than that. I'll have to cut that hose and get it to just be a straight shot from the tank to the hull and see what happens.

Ayuh,... That Loop keeps Water out of the tank,...
Go to a Straight shot,+ you'll get Water...
Unless the loop is holding liquid, it's Not your problem...

Now could having to think of oil cause problems with this as well? The previous owner told me they ran 10W30 in it, and I put 25W40 or whatever it is they sell at Wal-Mart for a inboard motor.

Nope,... I highly Doubt it...

 

[dirtyoldman]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

You need to buy a book on tuning old engines. Seriously - your boat will run like crap otherwise. You can maybe take it to a good OLD mechanic who will let you watch and see what he does.

You need to set the timing and dwell angle. You need a timing gun and dwell meter to do those. You also need to set the point gap. Now, with that done you need to rebuild the carburetor. You said you cleaned it inside and out, but I assume you didn't rebuild it? It probably needs rebuilt. Seriously - if you set it up too lean you'll burn a hole in a piston. I have a 165 engine with that problem sitting on the stand. Idle should be around 600 RPM, and if you can't get it to idle at 600 you have a problem with the carburetor or ignition system. You just need to figure it out. To set up the carburetor you will likely need a tachometer, but that may be part of the dwell meter.

I'll say it again. You need a rebuilt carb or a kit, a timing gun, a dwell meter, a feeler gauge, a tachometer, and a good book of you shouldn't be messing with these things.

You have one of the best and easiest to tune marine engines out there. Set up properly it will be reliable and run great!

 

[NetMatrix]

Re: MerCruiser 165 250 c.i. GM Motor Starting Problems

Well here is what is on the to do list right now with the motor.

• Spark Plugs
• Spark Plug Wires
• Mercruiser Tune Up Kits
• Carburetor Gasket
• Carburetor Kit
  
• Fuel Line from Fuel Pump to Carburetor.
• Dwell Meter
• Timing Light
• Feeler Gauge

Thankfully all of these items aren't all that expensive. I'm going to download the book for this motor off the site, and give it a good read. I have a lot of knowledge on motors, but not a marine motor. I know they are the same thing as a vehicle motor to a point, but some slight differences in them. Lets see if we can get this motor running in the water correctly.