2003 Mercury 90hp 2stroke hard to start cold

"In March 2007 my father and I

"In March 2007 my father and I purchased a used 2002 Fisher Freedom 220 DLX Fish pontoon boat with a 2003 Mercury 90hp 2-stroke on it. The engine started fine for the seller when we went to go look at the boat and it started ok when we got it home. Just to play it safe we changed the plugs, water pump impeller and bottom end gear lube. We now have the boat at our favorite lake and had no problems with our first few outings. Our last two outings (mid and late May) have not been as fun. On our second to last outing it started fine, but the primer bulb didn't really want to get firm. After fishing for about four hours the primer bulb wouldn't firm up at all and the motor wouldn't start. It cranks fine, but just will not start. So we replaced the primer bulb, added fresh gas and checked for spark, all is good. But still it cranks without starting. We then asked a local shop to check it. They got it started and said the fuel line was to long. We get the boat back to the lake on our last outing and we still have the same problem. It took about 1 1/2 hours of primer bulb squeezing, cranking with or without primer/choke and adjusting throttle unit a gentleman helping someone else suggested getting the motor as vertial as possible. So with a long primer (key pushed in), engine angle adjusted and almost full throttle it started. It smoked a little, but runs great once running. On the water it will run at full throttle without surging and turn at about 5300rpm. Next morning it is hard to start again, but did start after about eight trys (last try short primer/choke and half throttle). Later in the day and the following morning still hard to start and still playing with engine angle, primer bulb squeezing, primer/choke and throttle position. Once again when it does start it runs fine and starts fine if restarted shortly after shut down. So any suggestions on what to check or insight on starting procedure? Also, engine angle, what is better for starting a little in or a little out? In advance thanks for any info that is shared!"

"Well it looks like we solved

"Well it looks like we solved the problem. We spoke to a senior mechanic at the shop we took the boat to last. We explained everything that their shop did and what we did. The mechanic focused on the issue that the fuel filter would drain and the primer bulb would go soft after a short time. He suggested that the fuel pump may have a check valve problem. So we rebuilt the fuel pump and changed our starting procedure all seems OK now.

For those of you out there that don't know how the enrichment valve works (it replaces the choke on many motors), here is what I learned. It is a valve (not a pump), press the key in and the valve opens, release the key and it will close. When open fuel is allowed to go right into the engine. What moves the fuel? Pressure from the primer bulb (a little) or fuel pump (primary source). So pushing in the key for a long time before cranking the engine (as a mechanic told us to do so) doesn't really do anything. The enrichment valve really doesn't work until the engine is cranking and the fuel pump is moving fuel. Hence bad fuel pump hard to keep primer bulb pressure and hard to start (not enough fuel for carbs and enrichment valve system).

FYI, fuel pump rebuild kit $19, Mercury motor manual $80, time 1 hour, fun on the lake with family priceless!

Hope this helps anyone out there with starting problems, which seem to be fuel system related!"

"Thank you Manuel. You have gi

"Thank you Manuel. You have given me some ideas about my starting problem. I have 150hp Black Max. Previous owner (who I trust) said it always started first time and it started well for me the first few times, but now it is difficult to start - runs great once started. I have noticed primer ball is not very firm and after few attempts to start primer ball is empty. Changed ball - no effect. So I think I may have problem similar to yours - fuel leaking back through fuel pump."