1974 (200) 20HP Timing or Fuel problem?

[ShaneC]

I got my 1974 Thunderbolt running a few weeks ago. I placed it in a 30gal barrel this weekend to run an extended test on it. I had a couple of problems pop up. So going to tackle the 1rst problem and then the second.

1. The problem I am going to explain in detail in this post
2. No pee stream (Impeller, clogged tube, or thermostat)

So when I start the motor I have the throttle set to the start position and the motor will start. But it pulses in a very distinct pattern. It revs then idles then revs then idle and continues in this pattern when in start position. When I go to shift position it will hardly idle (When cold) once the motor warms up a bit it starts to idle better in the shift position but same result in the start position.

I noticed when out of the bucket (no back pressure) the motor will run more smoothly in the start position.(no pulsing)

When in gear the motor would rev up in forward and reverse gears and run smootly.

Where do I start on this problem or is it even a problem?

Shane

 

[ShaneC]

Re: 1974 (200) 20HP Timing or Fuel problem?

Well I ran this guy on the muffs last night. After cleaning out the Telltale pee hole I had a nice stream of water flowing. But I am still left with this weird pulsing even at open throttle while in gear it still puleses.

I think I had mis-spoke in my last post. Anything above idle the motor will rev and then it drops to idle and then revs and drops to idle. It is like it is getting intermitten fuel but in a distinct pattern.

Ideas?

Shane

 

[ShaneC]

Re: 1974 (200) 20HP Timing or Fuel problem?

Bump!

 

[7920hpMercury]

Re: 1974 (200) 20HP Timing or Fuel problem?

I think I would first try and clean the carbs and replace the fuel pump diaphram. Also make sure your fuel tank screen is not clogged up and your hose is good.

Good luck and great motors!