1990 Merc. 115 Hard to start

Bought this unit last year. Power head has about 10 hrs since rebuild. I have tried every imaginable combonation to start this engine cold (no starting fluid) and I still have problems. This is one of the idle on two run on four units. During starting it does not seem to matter how long the choke is held, override throttle position, pump bubble, nothing seems to help. It's gonna start when it's ready. Once running, all seems to be good. Accelerates good, transitions good. I usually make about a 10 min. run then fish about one hour then move. Starts great the rest of the day. The last boat I had was 14 ft. with a 85 HP Chrysler Charger and yes it had a combonation to start, but it worked every time. I am a technical person and rebuilt this Chrysler power head myself and it worked well. I am not sure if this "drip choke" solenoid system is working or not. When engine does start it does not smoke excessively or act like it is flooded. I have checked the timing per the crappy Clymer manual I have and have it set dead on. Bubble pumps up hard, fuel filter is clean, fuel is good. What am I missing? Thanks in advance.

Re: 1990 Merc. 115 Hard to start

Have you tested the enrichner to see if it is in fact pumping fuel to the carbs?

Re: 1990 Merc. 115 Hard to start

Enricher ? Are you refering to what I am calling the "drip choke"? If so, I can hear it click, when I use the override button on top it seems to override. I have not removed or tested it I guess. Suggest to me the best way to test. It has two fuel lines attached. One seems to be a main fuel line and one disappears behind the oil injection tank. Thanks for your help.

Re: 1990 Merc. 115 Hard to start

Disconnect the output line. Rig a hose up so gas can be put in a can or something, then test it. It should spit fuel out sort a like in pulses.

Re: 1990 Merc. 115 Hard to start

I removed oil injection tank to gain access to the fuel lines from enricher to carb 1 and 3 (from bottom to top) First thing I noticed was the tubes have no clamps. I removed the tubes and checked for blockage and found none. Pumped up bubble and fired enricher with ignition key. Found good fuel flow from enricher. Compared this to using the override button and found to be the same. With engine spining over I do get pulsing fuel as you described. I installed fuel tubes with clamps (small wire ties) and installed oil tank. Replaced spark plugs. (these have about 5 total hours run time) I was there what the heck. Pumped up bubble, key on fired enricher 3 seconds, spun engine started right up. (go figure) Plugs looked like new. Maybe no clamps on tubes was letting fuel escape before it could reach throttle body. I will be fishing on Thursday evening so will wait till then to see. On another note what is the best way to set timing? I have the idle set at 1100 free idle, 700 in gear, timing on a timing light at 1100 is about 15 degrees btdc free idle up to 3000 total timing is set at 23 degrees btdc. This is using a timing light and hull in the lake tied tight to the trailer and dock. I ask this because the CLYMER manual is a little hard to follow on this procedure. Thanks in advance.

Re: 1990 Merc. 115 Hard to start

Hard starting on these engines is usually due to a lack of fuel pressure or air in the fuel lines. These problems normally stem from bad check valves in the fuel pump. You can't rely on the primer bulb check valve to keep fuel from being sucked back into the tank if your tank is lower than your engine. The choke will not flow fuel into the manifold if there's not enough pressure (1-3 lbs) in the line. Pumping the bulb with the choke held in should make it start if this is the problem.

Procedure: Remove the stbd side cover, pump the primer bulb, push down the black manual choke button on top of the primer solenoid located to the right of carb #1. for 5 seconds. Start engine. Engine should false fire once then with a slightly advanced throttle in the neutral run position it should fire and run. That would be the normal scenario for these engines.

Re: 1990 Merc. 115 Hard to start

Gotcha. Thanks for this info. Never thought of fuel pressure. You know I had a guy tell me when he gets back to dock he always disconnects fuel line and allows unit to run out of fuel. I don't do this. I don't like leaning out engines. Ever heard this?

Re: 1990 Merc. 115 Hard to start

Yes, you do this so the carbs don't leak fuel out the throats when it's tilted up for trailering. Not all engines do it but the 4 bangers with 4 1 barrels seem to make it a habbit even after a fresh rebuild.

Re: 1990 Merc. 115 Hard to start

Try to trim the motor all the way in when starting.I have the same motor and always had a hard time starting after sitting for awhile.The wife said try it with the motor all the way down and it has started perfect ever since.How embarassing.

Re: 1990 Merc. 115 Hard to start

Yep that's in the manual believe it or not. Actually it say's level but trimmed down does seem to work better. I have 2+2 Mariner same/same.

Re: 1990 Merc. 115 Hard to start

Wow. Thanks guys. Yes it does leak fuel out when trailered for a short period of time, which makes sense. No I have never tried to start engine trimmed all the way in. I usually lower unit just enough to insure water intake is in water sufficiently to pick up properly. Trim down more when in motion, down a little more before take off, then trim out after full RPM achieved. You can bet I am going to try starting the next time with unit trimmed all the way in. That's funny.
Again, any suggestions for adjusting timing properly?