1987 Force 85hp Starts + Idles but WILL NOT accelerate

[CaptainHook]

Any ideas? 1987 Force 85hp 3 cylinder. Compression is good. Cleaned engine fuel filter and replaced fuel pump diaphragm. New plugs. New inline fuel filter. Pulled carburetors apart, cleaned out the bowls, jets look good.

The motor will fire right up and idle all day. But you can not accelerate. As soon as you put it in gear it dies. You can not rev it up. But again, will start right up and idle all day.

Thanks in advance for any help.

 

[scottmm73]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

What is the rpm at idle?

Compression numbers?

 

[CaptainHook]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

What is the rpm at idle?

Compression numbers?

I have no idea what the idle is as there is no tachometer on the boat but it is what I would call normal. Compression is 125 125 128.

 

[further]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

Get yourself an inductive type tach. Google tiny tach - very easy to install and use. Very important to know rpm at idle as well as WOT so you can gauge how the motor is running. Did you take carbs all apart as well as the linkage? These carbs are finicky... If so, you probably need to do lync and sync and verify timing is correct, check out the sticky at top of the forum.

 

[tater76]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

Start with the simple stuff first. Is the gas tank vented? Are the mix screws on the front of the carbs turned one full turn out from lightly seated? Floats on the carbs adjusted correctly? The condition you describe sounds like fuel starvation.

 

[Jiggz]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

Well, from your original post it seems the reason it will not accelerate is because IT DIES when put in gear. So that means you need to do the synch and link where it tells you to adjust the idle and fuel/air mixture to ensure it doesn't die when put in gear. Thereafter you can tell us about acceleration problem if there are any. For now your problem is that the engine dies when put in gear not necessarily acceleration.

 

[baldtire]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

I'm having a similar issue with my 1987 125.
It will start fine, and even run at low end. It will even jump into a full plane and then boggs down within 5-10 seconds. I put an inline filter, replaced all the fuel lines, diaphragm doesn't appear to have any holes in it.
The in line filter looks like it only trickles fuel through it. When I floor it it is empty. The bulb doesn't get to a hard point. Checked my tank connectors. Even tried a different fuel tank (SAME result).
Frustrating...

 

[foodfisher]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

If the bulb is collapsing, fuel tank venting is the prob.

 

[baldtire]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

I'm having a similar issue with my 1987 125.
It will start fine, and even run at low end. It will even jump into a full plane and then boggs down within 5-10 seconds. I put an inline filter, replaced all the fuel lines, diaphragm doesn't appear to have any holes in it.
The in line filter looks like it only trickles fuel through it. When I floor it it is empty. The bulb doesn't get to a hard point. Checked my tank connectors. Even tried a different fuel tank (SAME result).
Frustrating...View attachment 209048

INTERESTING: I bought a new gas tank and used non-ethanol gas. It ran fine the entire weekend and that was in saltwater.

 

[Jiggz]

Re: 1987 Force 85hp Starts + Idles but WILL NOT accelerate

INTERESTING: I bought a new gas tank and used non-ethanol gas. It ran fine the entire weekend and that was in saltwater.

I doubt the ethanol has anything to do with it but more likely because of venting problem with the old tank as indicated by the collapsing bulb.