Home › Forum › Ask A Member › 80 merc 1984 dies out after 1/2 throttle
- This topic has 24 replies, 8 voices, and was last updated 9 years, 8 months ago by
jerry-ahrens.
-
AuthorPosts
-
May 25, 2016 at 7:36 pm #4358
This is a puzzler .Runs great with ears on driveway sputters out after 1/2 throttle on lake . Fuel pump rebuilt sounds like gas problem last time wouldn’t restart siphon bulb tight . ??? Any you Merc guys have idea to check
May 25, 2016 at 9:03 pm #37165Try another tank and line, as a troubleshooting tool. The lines are well known for collapsing inside; and if using a plastic Quicksilver tank, the pick ups in the tank get loose and suck air, even kink themselves off. If you have two Quicksilver tanks, be suspect of both of them. I see that all the time, lately, with the ethanol.
Long live American manufacturing!
May 26, 2016 at 12:56 am #37176I’ve run into the collapsed fuel line also, many many times. If it has the Quicksilver [Mercury] hose with the red print on it, throw it away because it will go bad. Another way to identify this older generation fuel line is that it’s very flexible, and easily slides over a fitting or barb. The new Merc hose has blue print on it, and is much less flexible than the earlier generation hose. Both the old and current hose are silver/grey in color.
Hopefully you aren’t using the Sierra hose that’s white in color. Toss it out too, as I’ve found it’s even worse.May 26, 2016 at 7:03 am #37180A friends 80 Merc had a similar problem. It would idle great warming up at the dock but when he punched it to pull a skier out of the water, it would die and refuse to start. After sitting for a while, it would start and repeat the process all over again. The dealer said it was the reed valves acting up and wanted to tear it down but I found the problem right away when he brought it over. It was the choke shutters. They weren’t opening all the way so the motor would flood itself when the throttle was opened. A few seconds with a pair of needle nose pliers and the bent piece of linkage was straightened out letting the chokes open fully again. Problem solved. The only other problem was when he got the estimate from the dealer for a tear down, he figured he could buy a good used motor for the same amount of money, which he did. It was a barely used 115 Johnson lake motor.
May 27, 2016 at 3:07 pm #37221Interesting theory on possible . I will check out each item . does anyone think about fire power? I don’t get the part of tight squeeze bulb for fuel yet wont restart after dying out .
May 28, 2016 at 12:09 am #37229The problem is you pay good money for this fuel line, and you end up with junk. Where do you buy quality fuel line.?, auto parts stores,? What about the fuel injected fuel line, too stiff?, that’s supposed to be more heavy duty than the carb version.
May 28, 2016 at 2:08 am #37235So my learned friend what are you suggesting . Buying quality fuel line that is supposedly better than most not the answer ? What are u suggesting is the answer to the dying out problem . Or is it just a statement your making . Thanks
May 28, 2016 at 2:21 am #37237Frank,
the fuel bulb should be soft when running. Have you checked your blow & suck lines? They will cause havic! Also vacuum leaks & fuel pumps. The Mercury pumps hardly keep up when functioning. You checked your pumps for no crud in the check valves & some forget to replace the seating gaskets.
Oh BE careful with the lines with the check valves on 3 & 4 cylinders, the check valve could be put in backwards or not at all. They keep the reed plates from flooding unburned fuel!May 28, 2016 at 9:30 am #37246Most problems like that are fuel related but maybe not. You might want to invest in a good quality squirt oiler can. You can put two-stroke gas mix in it. Run the engine until it dies and won’t start. Immediately, go back to the engine with your squirt can of gas and spray a few strokes in the carbs. Try to start. If the engine fires off briefly, your problem may be gas delivery or carbs. If not, you may either have a spark problem or it flooded out, somehow. If it doesn’t fire on the squirt gas, pull the plugs out and check for whether they are soaked with gas (or even water.) If soaked with gas, you might want to do a spark check. Put the plugs back in first, so you don’t blow yourself up. If there is spark, and it still won’t start, try disconnecting the fuel hose from the engine, give it lots of throttle in neutral, NO choke and see if it will start. I doubt it is flooding at higher speeds, yet will idle well; but you have to rule it out anyway.
Mercurys have a high and low speed ignition system. Once in great awhile, it can be tricky to catch it. But let’s not go there yet. Try the gas things first.
Long live American manufacturing!
May 28, 2016 at 3:02 pm #37255Bill,
I would bet money it is some of the fuel delivery. EVERYONE forgets the reed blocks are horizontal & that makes for a huge problem if that system is not functioning. If a guy ran a tank overhead & fuel delivery was perfect it still would either run rich or lean without the scavaging system!
Unburned fuel is a problem with any 2 stroke. With Merc’s the reed blocks lay flat & require the scavaging system to remove the excess fuel. It is a system only Mercury has & EVERYONE is overlooking it. If the hoses are rotted or the check valves are dirty or reversed it will not run after a few minutes. It is timed with crankcase vacuum & pressures hence the check valves. I would bet it is flooding internally. It’s in the book for all to read.
Why this is not discussed is few even know it’s present. Just my opinion. -
AuthorPosts
- You must be logged in to reply to this topic.