1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

[fickesd]

I own a 1987 force 50hp that I use on my pontoon. It starts every time right away when cold. After stopping to swim for 15 - 30 minutes we try to start it and it will only start if we throw it into gear while engaging the starter. Any ideas? I took the carburator apart and the only thing I needed to do was adjust the float per the recommendation in the manual. I also checked the fuel pump and there wasn't any torn diaphrams. That's the first issue. Then once I put it back together I still have that problem but now the engine jerks randomly and feels like I'm hitting the bottom of the lake. I talked to a marina and they suspected the second issue was tied to fuel somehow and suggested that the ethanol in the gas is causing problems and suggested I use some sort of gas stabilizer and also said I may have some gumming up in my gas line since the fuel line is exposed to the sun all day. Does that sound likely? Any help on both of these problems would be appreciated.

 

[Frank Acampora]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

It id difficult to tell from your description but it SOUNDS like the idle speed is too low. Thus when you hit the starter and throw it into gear, the RPM is higher when it starts and it will not stall. Try cleaning or replacing the plugs then check the warm idle speed in forward gear in the water. It must be 700-750.

As far as randomly jumping and feeling like it is hitting bottom--that may be the drive dogs in the lower unit wearing or it may be shift linkage mis-adjusted. This will cause jumping out of gear and slamming back in while running. Bias the shift linkage slightly more toward forward (down).

Many things are possible but if the engine runs well at high speed I doubt that it is a fuel problem. BTW: Ethanol gets blamed for a lot of problems--it is a popular myth.

 

[Jiggz]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

Oh yes! The ethanol myth and also the Octane myth! They basically go hand in hand. Presented very well with all the tech terms depending which one the customer will buy into. The only thing real about ethanol is that with older engines combustion is not as complete thus resulting in release of nitrogen oxide but only if the mix is more than 15% ethanol.

 

[fickesd]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

Hey Frank and Jiggz, thanks for the input. It sounds like you have given me a great place to start and it all makes sense given more information that I didn't share in the first post (trying to avoid writing a novel). Here's the rest of the story: As far as the low idle, that's quite possible since as I bring it back into the dock at low idle it will stall. I don't have a tachometer to know where it's running at. Do I just adjust the idle mixture screw a little at at time until it stops stalling and also improves the warm start issue? If so, which direction do I turn it? As far a the jumping while driving: I've been in the market to replace the lower unit for about 2 months. Over the winter the housing had cracked so I assume I had water in it and failed to check it before it sat out on the lawn for the winter. I tried to do a make shift fix job and also replaced the shift seal since it was leaking when I air tested it. That fix didn't last and I know the gear lube was bad since I checked it about a week ago. Being a rookie, I didn't know how long it would last if I didn't drive it hard. I'm guessing you are right on with the drive dogs being worn. I purchased a lower unit off of ebay last night so I'll see if that fixed that problem (got my fingers crossed that I don't get a piece of junk). As far as the ethanol: I need to replace the fuel bulb anyway since it only lasted a year before I starting seeing major cracks so it's just a matter of time. Based on your comments I assume adding some sort of stabilizer every tank full might be over kill. Would you suggest a couple times a summer? Any suggestions on what type to add? I've used seafoam in the past based on other recommendations. The only last comment is I also noticed the water coming out of the pee hole has gotten weaker over the last week. It has always been weaker than I expected but when I took the lower unit apart 1 month ago, the water propeller looked good without any pits or bends. I'm hoping the lower unit purchased off of ebay has a good one, if not I'll replace it before I put it back together.

Thanks again for your help.
I'm hoping to have it up and running soon.

 

[Jiggz]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

Not having a tach makes it hard to set the idle speed. I recommend investing in a tach even if it's only a non-contact tach for troubleshooting or better yet get one of those tiny tachs. High idle RPM can be detrimental to clutch dogs. I highly recommend troubleshooting the idle setting after you get a tach to prevent future damage to the new LU. But yes, the adjustment for the idle setting can be done using Frank's Link & Synch method which is in the stickypost.

 

[Frank Acampora]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

DO NOT adjust idle speed by adjusting the mixture screw. That is a recipe for disaster. On the timing tower there will be a stop screw and locknut that keeps the tower from returning all the way. Moving this screw in or out will raise or lower the idle speed. If you have a question, go to a marine site that sells parts and has diagrams. It will be called the idle stop screw.

While a tach is necessary to correctly set the idle speed (700-750 in forward gear, in the water) you can set it roughly without one. With a new or correctly functioning lower unit, increase the idle speed slowly in increments until a reliable idle is acheived. However, do not go too high. The lower unit should "Clunk" audibly when put in gear but not be loud or harsh. The drive dogs should not rattle over each other due to a too high idle speed. Remember though, that you need to quickly snap the control handle into gear. Do not "ease" it thinking this is good. It will actually accelerate drive dog wear.

 

[fickesd]

Re: 1987 Force 50 hp - trouble starting when warm. need to throw into gear to start

update on the progress: (but more questions)
I received the used replacement lower unit that I purchased off of ebay and of course it couldn't be as easy as unbolting mine and bolting on the new one. I've confirmed the housings are the same and then leak tested the new assembly with only very tiny bubbles coming from the shift rod seal area so I'm guessing it's ok. I could replace the shift rod seal if I had to since I did on my previous lower unit without problems. The problem I have is the shaft on the new lower unit is about 1/2 the diameter of my existing lower unit and a few inches shorter. The question I have is: Can I take the lower part of the unit off of my new Lower unit and put in a new pinion gear that matches my old shaft and put it on my old unit. So the basic question is why are the shafts different and is everything else the same between the two that would allow me to mix and match to make one good one. I know everything the shafts go through would need to be the same as my old unit. Another thing. I couldn't get my old shaft out of my Lower unit. Had no problem getting the new shaft out of its unit but for some reason something is hitting inside where I can't see and not allowing me to pull it out. I followed the instructions in the repair manual.

As always, any help would be appreciated.