poorly blue band

baffled · 06 December 2007, 19:16

i have a 50 hp mercury blue band that since i brought it has caused nothing but trouble. the main problem is that when it runs it will run fairly well on tick over but when i accelerate it just dies. i put it in to a marine garage to be fixed as they said that they were experts (how wrong they turned out to be)
they told me that the problem was the carbs so they said that they were now reconditioned i put it on the water and it still had the same problem after many visits to them they admitted defeat(but would not refund any money) as i can not afford any more money on the engine at the moment a friend suggested that it might be the coils breaking down under load could any one tell me the correct impedance for the coils.
any help would be much appreciated

Nos4r2 · 06 December 2007, 20:00

Have you got compression figures for it?

What have they billed you for (or...what have they done to it?)

davej · 06 December 2007, 20:13

Sorry to hear about your troubles. The best place to start would be with an OEM manual, not cheap but worth their weight in gold. With this and some simple tools you can sort out most problems or get a good idea of the issues before you go to a dealer. For parts I either get a mate in the states to bring the odd thing over, mail order them myself from west marine or use Key parts in Watford, who are very helpful and fairly cheap particularly on sierra parts and the like.

While you wait for your new manual go on (iboats.com) and use the mercury forum and search for an answer to your problem. One thing to bear in mind is that a blue band classic 50 is probably a 70s engine, so its been around the black a few times but if the compression is ok with some tlc it can hopefully be sorted out. Fuel pump diaphram kit could also be a required but get a manual and just trouble shoot it stage by stage. Those engines are great very smooth, pre mix at 50:1

Good luck DJ

9D280 · 07 December 2007, 10:27

Baffled,

A few quick checks might get you going again. An engine needs 3 things in the right proporions and at the right moments to work: Fuel, air and a spark.

Does it die instantly, or do you get a few seconds of power before it slowly fades out? Instant death might hint at electrics as you say, but the other likely cause is fuel starvation. Here's a couple of very simple & free checks:

Not wishing to insult, but is your hose on the right way round between tank & engine? The non return valves in the primer bulb will usually flow enough "wrong way" to allow an engine to idle, but will close up when you open the throttle & start "seriously" moving fuel. There will be an arrow on the primer bulb - it should point to the engine. Most of us have put the hose on backwards at some point...... Also if it's got the Merc "bayonet" type connectors try to make sure you are going metal to metal or plastic to plastic types. Although they all physically connect I've discovered some mixed combos don't open the valves properly when connected, resulting in much fuel restriction.

If it's on OK, Follow the hoses round the engine from the connector to the carb. Check all the clips are tight and the hose hasn't perished (i.e. it's sucking air instead of fuel) . Might even be worth pulling them out & flushing through (with fuel or WD40 - NOT water!) to check for blockages & leaks. Then check the fuel filter (if fitted) for crud, & clean that.

Somewhere in line you'll find the pump - a small(ish) metal lump somewhere on the side of the block, usually near the carbs. Undo the 3 or 4 (that's a guess, there may be more!) bolts holding the top on & again check for crud etc. inside Also check the rubber diagphram. You don't need much of a hole in that for it to become useless. They are dirt cheap so might be worth just replacing it anyway unless your garage has done dso already. (It should be obvious if it's new).

If all seems well, another free test of your carb setup (if you can get afloat) is as you open the throttle, blip the choke. (pointles to test in a bucket or flush muffs- the engine needs to be under load) If it takes off like the proverbial scalded cat then your midrange mix is too lean and chances are someone doesn't know how to set a carb & I'd go get your money back......

Hope this helps a bit.

Nos4r2 · 07 December 2007, 13:16

Quote:

Originally Posted by 9D280

Somewhere in line you'll find the pump - a small(ish) metal lump somewhere on the side of the block, usually near the carbs. Undo the 3 or 4 (that's a guess, there may be more!) bolts holding the top on & again check for crud etc. inside Also check the rubber diagphram. You don't need much of a hole in that for it to become useless. They are dirt cheap so might be worth just replacing it anyway unless your garage has done dso already. (It should be obvious if it's new).

Fuel pumps on these are part of the carbs-on the left side as you face it sat in the boat. They are powered by crankcase pressure differential via a small hole in the gasket face between the carbs and crankcase. Make sure that hole isn't blocked-it's quite easy to block up.

Quote:

Originally Posted by 9D280

If all seems well, another free test of your carb setup (if you can get afloat) is as you open the throttle, blip the choke. (pointles to test in a bucket or flush muffs- the engine needs to be under load) If it takes off like the proverbial scalded cat then your midrange mix is too lean and chances are someone doesn't know how to set a carb & I'd go get your money back......

Good point. I'll have a look at t' book of words for it and see if the mixture screw settings are in it. It might take a couple of days to find though.

jyasaki · 07 December 2007, 16:38

Quote:

Originally Posted by 9D280

Not wishing to insult, but is your hose on the right way round between tank & engine? The non return valves in the primer bulb will usually flow enough "wrong way" to allow an engine to idle, but will close up when you open the throttle & start "seriously" moving fuel.

Should be able to overcome (temporarily) a fuel pump problem by running the motor and squeezing the primer bulb. Forces fuel into the motor, in the same manner that the pump does. If the motor runs while pumping, and doesn't on it's own, you can be pretty sure it's a fuel delivery problem. It's not a spot-on indication, as the problem could still be the pump(s), a blocked or leaking hose, a packed up fuel filter, etc. Still, it gives you a place to start.

jky