maddening mercury-HELP

[jmg]

Hi! I was wondering if someone might have some ideas as to why my merc. 18 hp. short shaft man. start 1982 model motor is not opening up upon full throttle. I had it out Sat. and it started hard, as usual, on about the 18th pull, seemed to idle ok but when put into fwd and opened up, it would only go 5 mph(as per my locator and GPS). If I tried to put it into neutral too quickly, it would kill, but would re-start fairly easily. This happened last Fall, even after putting on a new fuel line assembly with new fittings. I put in fresh gas and stabilizer right before the opener last month, along with new plugs. I don't want to be dry-docked for the rest of the season. No $'s for anything different this year. Any ideas?

[BoxMN]

Are you sure that the tank vent is open? I believe mercs of that style and vintage need vented fuel tanks, I know our '82 50hp does. It will sort of do as you describe if the vents rattles shut on us. Good luck.

Other thing is check for leak in hose/bulb (I had two that were bad, right out of the box - that was last time I bought the big box store fuel assembly. Now I pay for the good merc/evinrude brand stuff at a dealer) or even cleaning the carb.

[boatfixer]

Start with the basics. Spark Fuel and Compression.

If you have spark on both cylinders and good comprerssion, then look at something wrong with the fuel sytem.

[jmg]

Thanks for the input. Yes, the vent is open-first thing I check(ed). I agree with you about the fuel line assemblies and I will double check mine, since sometimes the bulb will pump up till it's hard and sometimes it won't get hard, as though there is a leak somewhere, but I checked everywhere and can't find anything. In fact, that's why I replaced the last one. Do you think it could be one of the receptacle fittings in the motor or the tank? They seem ok, but who knows? There seems to be good spark in both plugs. I haven't had the compression checked yet, but I think it's something in the fuel delivery system. Very aggravating!! I can still picture,in my mind,the kid I bought the motor from, laughing all the way to the bank! Wish I could get something else, but not this year. Will check the fuel line again and start loosening up my arm before pulling on the rope again.

[whitebassman]

Last year the same thing happen to my '88 evinrude 9.9 hp. It was a halfway cracked throttle valve that broke. So it wouldnt throttle up as i revved it.

[FM_Mike]

If you have a portable tank, try a different tank and see if that makes a difference. I have had to feeder hose in the tank go bad. Would Idle but nothing at higher speeds. Found that the feeder line in the tank its self had rotted away. New tank line I was back in buisness.

Mike

[Valv]

I would do a compression test first. Walmart sells gauges for $ 20 or $ 30

[tunrevir]

One thing that I have had happen is the fuel line off the tank is bad. The main line can collapse onto itself when under full throttle and trying to suck fuel and starves the motor for gas but when you move it back to idle or below plane the motor runs fine.

Tunrevir~

[jmg]

Just a brief update to all of you who have been kind enough to lend some thoughts and ideas regarding my maddening Merc. I took the "cover" off the tank that houses the fitting that the hose connector fits into. Seems fine. Screen at bottom of tube is free of debris, etc. I put a new bulb on the fuel line, but I'm still not certain that that was the problem. However, I was able to get the motor started with only about 14-15 pulls, but it ran better and I was able to open up the throttle with appropriate response from the motor. Of course I didn't open it up that much with the leaky "ear muffs" on the motor. Hopefully, I'll have a chance to try it out tomorrow, if I can rouse mama out of bed early enough. Will report after I have a chance to use the motor. Thanks, again to all who have responded to my "pleas" for help. A Happy Father's Day tomorrow to all you Papas!