80hp Merc stalling when throttled up

[Big Bill]

I have a 1979 Mercury 80hp outboard and when I throttle all the way up it dies. When I restart it and it is in neutral it will rev high if I push the control forward but when I have it in forward the engine stalls. It will start right back up. I recently removed the engine to install a new steering cable. NOT FUN. When I took her out on the lake she was working fine but after fishing she started to do this. Thank you

 

[dctucker]

Re: 80hp Merc stalling when throttled up

When was the last time the carbs were removed and cleaned? Fresh gas?

 

[Big Bill]

Re: 80hp Merc stalling when throttled up

I just purchased the boat 20 days ago. It was running fine before. Just the steering was real stiff. now this. I start it up and on neutral warm up lever will rev it up real high.

 

[tashasdaddy]

Re: 80hp Merc stalling when throttled up

does it stall as soon as you puy iy in gear. does it do the same if you put it in reverse. should be idling around 650-750 rpm's in gear. you may have to adjusst your idle speed screw.

 

[Big Bill]

Re: 80hp Merc stalling when throttled up

I was going to install a tach next and adjust the idle screw. right now I just leave the warm up lever up a 1/4 of the way up or so and keep it running like that. Is the Idle screw and Idle speed screw two different things?

 

[tashasdaddy]

Re: 80hp Merc stalling when throttled up

bill take your cowling off, have someone move the throttle lever, watch the linkage on the port side of the motor. at the upper front part of the motor there is a bolt usually with a rubber end. when the throttle is all the way back the linkage should hit the stop. most have a lock nut on them adjust this bolt so that the engine idles when in gear. should be done in the water as the engine doesn't have exhaust back pressure on muffs. just takes a little tinkering. you are doing the same thing by keeping the ldle lever up.

 

[Clams Canino]

Re: 80hp Merc stalling when throttled up

Originally posted by Big Bill:<br /> I just purchased the boat 20 days ago. It was running fine before. Just the steering was real stiff. now this. I start it up and on neutral warm up lever will rev it up real high.

Could be crap in the carbs that moved when you laid the engine down. DON'T rev it up real high in neutral - that won't take that. 2000 MAX<br /><br />-W

 

[PuckHog]

Re: 80hp Merc stalling when throttled up

I have a '78 80HP I just put on my boat and am having a very similar issue. I removed and thoroughly cleaned the carbs and installed new check valves, diaphragm, etc. for the fuel pump. The tach says I'm idling at about 900 rpm in neutral and 800-850 rpm in gear. It won't stall initially, just won't 'spool up' most of the time. When it does, it really goes. After extended cruising at 3000 rpm (10-15 minutes) or shutting the motor off and restarting, hit the throttle and instead of taking off, it dies.

 

[Big Bill]

Re: 80hp Merc stalling when throttled up

bump

 

[Clams Canino]

Re: 80hp Merc stalling when throttled up

Originally posted by PuckHog:<br /> I have a '78 80HP I just put on my boat and am having a very similar issue. I removed and thoroughly cleaned the carbs and installed new check valves, diaphragm, etc. for the fuel pump. The tach says I'm idling at about 900 rpm in neutral and 800-850 rpm in gear. It won't stall initially, just won't 'spool up' most of the time. When it does, it really goes. After extended cruising at 3000 rpm (10-15 minutes) or shutting the motor off and restarting, hit the throttle and instead of taking off, it dies.

In your case it sounds like the idle mix is a bit lean. Also... what's WOT rpm? It outta be at LEAST 5000 or it's overpropped.<br /><br />-W

 

[grew14ft]

Re: 80hp Merc stalling when throttled up

Hi Big Bill and PuckHog, I have a '79 80HP that is doing exactly the same thing. Idles ruff but excellerates fine until engine is warm, after that it just bogs (around 2000rpm) when throttling up. So far I have replaced plugs, cleaned out carbs, replaced leaky fuel lines, rebuilt fuel pump, replaced primer bulb, and played with link&sync adjustments. Followed the procedure in book to check stator and trigger. Got proper readings for both but found a coroded wire (black/white) coming from trigger to switch box. Cut out the bad section of wire and replaced with new but still same prob. Suspect next course of action is to remove flywheel and check for loose magnets or damaged stator/trigger. Anyone agree?

 

[no spark]

Re: 80hp Merc stalling when throttled up

I have a 70hp that is doing the exact same thing. I tried all the above and still doing it. If you guys get it resolved please let me know how to fix.<br />Thanks

 

[Big Bill]

Re: 80hp Merc stalling when throttled up

Any other Ideas?

 

[horsefly38425]

Re: 80hp Merc stalling when throttled up

i'm going through the same thing. i ordered a new stator/ it would ck good one time and i would go to the water and it ran like crap don't know where else too start/ good luck

 

[PuckHog]

Re: 80hp Merc stalling when throttled up

Thanks Clams- My WOT is 5400 until a few seconds after the boat planes, then it drops to ~5200 and won't come up again 'til I throttle down and run it up and get 5400 then 5200.<br /> I richened the idle some and the motor has been behaving much better.

 

[nagel88]

Re: 80hp Merc stalling when throttled up

This looks like a good place to add my two cents. I have a '77 70hp 3-cyl. with the same trouble. It can be fussy starting and above 1800 rpm in the water it simply dies, but restarts easily. After one disappointing trial, I cranked the wheel to head back to the dock and it took off like a rocket! I took it back home to recheck the timing and sync, and next time out, it ran poorly again. I've been through the carbs, fuel pump, hose, spark plugs, etc. Today I started checking ignition. Coils OK. Stator gave me "funny" readings, too little resistance according to the book, and when I wiggled the harness, the meter started dancing around. I'm guessing at a bad stator and/or wiring.

 

[Kevin W]

Re: 80hp Merc stalling when throttled up

if i had a guess it would be gas related.<br />i am also from MA and we just started with ethanol based gas.<br />Ethanol cleans junk from everywhere in your fuel system and clogs fuel filters and deposits junk in the carb float valves.<br />i have cleaned my carbs twiceon my 79 70hp this year b4 adding a better inline fuel filter b4 the carb.<br />it may not be a bad idea to replace the fuel lines if they look original.<br />check for overflowing carbs when you shut it down.

 

[horsefly38425]

Re: 80hp Merc stalling when throttled up

don't bet on it being the stator got my new one on today now i have worse problems than before it won't idle/spits,misses,rough,rpm's go up and down and it does not won't too rev up /pickup r's unless you go to w.o.t. before it would go too 4000r's then the poop would hit the fan.

 

[jasunderland]

Re: 80hp Merc stalling when throttled up

To revive an old and lost thread... any previous posters get it figured out? I have the same problem with my 79 80HP. I replaced the stator but did not help. did not get worse, but did not help at all. it seems that about the 1800 rpm range it wants to die but if it does stay alive, it finally takes off and jumps all the way to 3100-3200 RPM's. I don't think I could ever run it at 2500 RPM's because it just dies.