1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

[grock425]

Hello every one! My engine starts and idles fine but bogs down and dies after a little bit. When this happens i can pump the primer bulb and it powers back up. I had the carbs rebuilt and the problem got worse. I have also replaced the fuel lines. What do I do next. Also, the white/black trigger wire casing is flaking of and the wire has started turning green and brittle. Obviously I need to replace the trigger but what causes this. Are there other parts I need to look at replacing. Thank you for your help.

 

[Yepblaze]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

I would rebuild the fuel pump, probably with a check valve kit, while paying close attention to getting the check valves correctly replaced with new gaskets on a clean gasket surface.

 

[Laddies]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

If the people that rebuilt the carbs made the problem worst there is a good chance that they are not a reliable service place but I do agree that fuel pump needs attention.

 

[grock425]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

Thanks for the advice on the fuel pump. I'll do it myself this time to make sure its done correctly. How about the trigger wires. Does anyone have any advice about that.

 

[crazyskier]

1983 50 hp mercury thunderbolt- wont accelerate

1983 50 hp mercury thunderbolt- wont accelerate

hi everyone, im have problems with my motor, its a 1983 50 hp mercury thunderbolt. It wont accelerate. i checked to see if all plugs are sparking, and found out the the second one is not, what are some other things i can check?

 

[verado7]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

the green is corrosion -clean that up first and re-check - fuel pump needs rebuild for sure .

 

[ajgraz]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

White/black insulation on the trigger bias wire must have been a crappy rubber formulation. That insulation on my 1978 70hp trigger flaked off and the wire corroded away to nothing. I bought a new-old-stock that was in an unopened box for 30 yrs, and the bias wire insulation on that was crumbly, too. I replaced that wire on the new trigger and insulated the whole thing with heat shrink and plasti-dip...good news is that it made my symptoms--which were the same as yours--go away.

As I understand it, if the trigger bias shorts out, the timing gets all fluttery. Idle can be OK one moment, flaky the next, and forget getting any power trying to throttle up. And because it didn't run steadily, the fuel didn't pump steady and it had many symptoms of a bad fuel pump (like soft bulb).

So don't discount trigger problems.

 

[Markeb63]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

I am experienceing the same problem with the same type engine and have been throught the exact same steps. It seemed like a fuel pump issue but I see no fuel pump between the gas tank and the carbs. Am I missing something? Where is the fuel pump?

Thanks for any help.

 

[Markeb63]

Re: 1980 50hp 4 cyl. Mercury thunderbolt power loss and trigger ?

White/black insulation on the trigger bias wire must have been a crappy rubber formulation. That insulation on my 1978 70hp trigger flaked off and the wire corroded away to nothing. I bought a new-old-stock that was in an unopened box for 30 yrs, and the bias wire insulation on that was crumbly, too. I replaced that wire on the new trigger and insulated the whole thing with heat shrink and plasti-dip...good news is that it made my symptoms--which were the same as yours--go away.

As I understand it, if the trigger bias shorts out, the timing gets all fluttery. Idle can be OK one moment, flaky the next, and forget getting any power trying to throttle up. And because it didn't run steadily, the fuel didn't pump steady and it had many symptoms of a bad fuel pump (like soft bulb).

So don't discount trigger problems.

Interesting. When I got my boat two years a go, it would start and idle fine but when I throttled it up it would not come up to speed and would sputter. I eventually discovered a very corroded wire coming from the trigger to my switch box. It was so corroded that it fell apart when I touched it. I was able to graft in a good wire and problem solved. Now I read that your trigger was causing symptoms like a fuel pump problem. I'm wondering if I should replace the trigger.

As a side note, while trying to get my carbs out to have them rebuilt, I discovered two more corroded wires (yellow/red) coming from the stator to the rectifier. I have grafted good ones on like I did my trigger problem. So, what is the difference in function of the trigger and the stator? I just assumed that the trigger was related to the firing of the cylinders but no clue on the stator.