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My 85 force was running great until this weekend then my son took it out and now it only goes idle s

deanr6761

New member
My 1984 85 force was running great until this weekend then my son took it out and now it only goes idle speed and when you try to accelerate it stalls out, gas is good, primer & plugs new this season, rebuilt engine in 95, i'm thinking its something easy, someone said maybe high speed screw problem, or diaphragm in fuel pump, how do i check these easy things before i take it to shop?
thanks for any help on this
 
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I'd start with new fuel filters and the fuel pump kit. These are replace vs inspect items though it never hurts to inspect the old parts once the new ones are installed.

BTW, the stuff they sell as gasoline nowadays, is notorious for ensuring a short service life on the fuel pump diaphragm - buying the OEM kit usually gets you better materials.
 
Did he add oil to the fuel at the proper ratio I would start from the beginning test the compression and spark gap with a spark gap tester.

i appreciate your reply,

you may be right he did not add oil when he topped off tank, is this the result of poor mix ? no high speed? does the engine have shut down precautions when this happens?
 
thanks for your your input,

found out he did not add oil when he topped off tank, would this result in stalling when throttle is increased? does the engine have shut down precautions when this happens? do you think it hurt the engine? it still idles, should i just remix new tank first before i start replacing fuel pump kits etc?
 
Don't get too pessimistic yet. It depends on how much "topping off" was done and how hard it was run with too little oil in the mixture. The engine will shut down when it overheats, which may have been caused by too rich of a gas mixture, or any number of other things. What is needed is a good and accurate compression test. Have a fully charged battery, remove all the plugs, use a screw-in compression gauge, and crank the engine over at least ten full rotations for each cylinder. Write down the compression on each cylinder. Compression needs to be in the proper range (which you will need to look up) and all cylinders must be within +/- 10%.

If that passes, then your rings are good, and about anything else is fixable. If the compression test is marginal, then run a concentration of SeaFoam or Yamalube Ring Free through the engine IAW instructions.

If you try the SeaFoam, in a separate small tank, mix the 3 parts gas/oil mixture with 1 part SeaFoam. Warm up engine, then connect the mixture tank to the gas line. Run engine until is burns out the gas in the carbs and starts drawing in the mixture. Let it run for about a minute. It may stall out. Let it sit for 15 - 20 minutes, then repeat the whole process. Expect to see a bunch of smoke and black soot being blown out the exhaust. That process will de-carbonize the rings and top end, and will also clean up the carbs.
 
so for the compression check i remove all wires only and then one plug at a time with gauge is this correct?


Don't get too pessimistic yet. It depends on how much "topping off" was done and how hard it was run with too little oil in the mixture. The engine will shut down when it overheats, which may have been caused by too rich of a gas mixture, or any number of other things. What is needed is a good and accurate compression test. Have a fully charged battery, remove all the plugs, use a screw-in compression gauge, and crank the engine over at least ten full rotations for each cylinder. Write down the compression on each cylinder. Compression needs to be in the proper range (which you will need to look up) and all cylinders must be within +/- 10%.

If that passes, then your rings are good, and about anything else is fixable. If the compression test is marginal, then run a concentration of SeaFoam or Yamalube Ring Free through the engine IAW instructions.

If you try the SeaFoam, in a separate small tank, mix the 3 parts gas/oil mixture with 1 part SeaFoam. Warm up engine, then connect the mixture tank to the gas line. Run engine until is burns out the gas in the carbs and starts drawing in the mixture. Let it run for about a minute. It may stall out. Let it sit for 15 - 20 minutes, then repeat the whole process. Expect to see a bunch of smoke and black soot being blown out the exhaust. That process will de-carbonize the rings and top end, and will also clean up the carbs.
 
fuel filter looked ok, the fuel pump diaphram looks a little more intricate for the average do it your selfer, i will test each of the three cylynders with gauge and go from there, if they test ok then i will take in for fuel pump overhaul...
thanks for your input.
 
Fuel pumps are not hard to inspect / repair , not at all.-------Once you do one the rest are easy, sort of like toilet paper " once you rip off the first piece the rest are easy "
 
Just to be clear - when you do the compression test, first remove all three plugs and mark which wires came off of which plugs.
 
My compression tested 120 on each cylynder, which i hope is ok,when i started to call around for fuel kit they suggest the below before buying anything,
do you concur?
Test #1 Start put in gear and take off until it starts to bog down, then
pump bulb rapidly

if it continues to stall then u have fuel pump diapram problem,


Test #2 Start put in gear and take off until it starts to bog down, thenpush
in choke if

it does not die then you have carborator problems,


Don't get too pessimistic yet. It depends on how much "topping off" was done and how hard it was run with too little oil in the mixture. The engine will shut down when it overheats, which may have been caused by too rich of a gas mixture, or any number of other things. What is needed is a good and accurate compression test. Have a fully charged battery, remove all the plugs, use a screw-in compression gauge, and crank the engine over at least ten full rotations for each cylinder. Write down the compression on each cylinder. Compression needs to be in the proper range (which you will need to look up) and all cylinders must be within +/- 10%.

If that passes, then your rings are good, and about anything else is fixable. If the compression test is marginal, then run a concentration of SeaFoam or Yamalube Ring Free through the engine IAW instructions.

If you try the SeaFoam, in a separate small tank, mix the 3 parts gas/oil mixture with 1 part SeaFoam. Warm up engine, then connect the mixture tank to the gas line. Run engine until is burns out the gas in the carbs and starts drawing in the mixture. Let it run for about a minute. It may stall out. Let it sit for 15 - 20 minutes, then repeat the whole process. Expect to see a bunch of smoke and black soot being blown out the exhaust. That process will de-carbonize the rings and top end, and will also clean up the carbs.
 
My compression tested 120 on each cylynder, which i hope is ok,when i started to call around for fuel kit they suggest the below before buying anything,
do you concur?
Test #1 Start put in gear and take off until it starts to bog down, then
pump bulb rapidly

if it continues to stall then u have fuel pump diapram problem,

No, squeezing the bulb emulates a 'good' pump which would mean if the "bog down" disappears, you have a pump issue - if the bog remains (and the tank is vented) continue diagnosising ...



Test #2 Start put in gear and take off until it starts to bog down, thenpush
in choke if

it does not die then you have carborator problems,

the idea here is engaging the choke will richen the mixture and offset a lean condition (bog goes away)...Enrichment of a 'proper' air/fuel mixture can stall an engine real fast if rich enough and doesn't indicate any malfunction.
 
120 psi sounds about right. See http://forums.iboats.com/showthread.php?t=509194 . And if they are all within +/- 10%, to are in good shape. The advice you received about testing the fuel pump and carbs is good as far as it goes and Makomark knows his stuff.

At this point follow his advice. I always like to start with the simple things first. Given your description, I suspect a problem with the fuel feed. So, first make sure your fuel tank is breathing and the breather tube is not clogged. The easiest way to do that is to simply run the engine with the filler cap off and see if it runs better. If so, clean out the breather tube to the tank. Secondly, when the engine starts to bog down, check the pump-up bulb. If it is partially collapsed, then the pick up tube in your fuel tank is clogged. Blow low pressure compressed air back through the hose to the tank and see if that temporarily clears the blockage.

If you have an external fuel/water separator (e.g. Racor), either bypass it temporarily, or drain and clean it. If it hasn't been changed out recently, put in a new element. They do get clogged up. I assume you have a low pressure fuel filer on the engine. Remove it, drain bowl well, clean it, inspect the rubber bowl seal thoroughly, and put it back together making sure bowl seal and the hose connections are air tight. Next, run a clear plastic hose from the pump up bulb to the fuel filter. When the engine bogs down, inspect the plastic fuel line for air bubbles. If so, replace the pump up bulb assembly and the hoses.

If all that checks out, then start diagnosing the fuel lines and connections from the fuel filter to the carbs. Then do the tests that Makomark suggested.
 
Hello,
thanks for the info, i have replaced the fuel hoses, ball pump and rebuilt the carborators, and replaced the diaphram, and then tried to start up motor to tune the idle screws but now it does not start at all, i sprayed engine start into the carbs and it started up few a few seconds, i then took the fuel line coming into the engine and pumped the ball and gas is coming into the fule pump, then i took the fuel line coming off the fuel filter line going to the carbs and tried starting but nothing coming out there, is there supposed to be flow?

my question is why all of a sudden no engine start at all after all i did to it? when the original problem was no high speed when i started? any insight??
 
I'm not sure how the fuel pump is set up on that engine, but generally it is drawing fuel through the filters and pushing it into the carbs. The carbs have one or more needle valves that regulate the fuel flow into the venturis. If you disconnect the line coming out of the fuel filter, pump on the pumpup bulb, and fuel should flow out. If not, then you have a blockage in your fuel filter.

As for not starting, I suspect that your carb rebuilt has gone wrong. First thing I would do is pull the fuel bowl and make sure the float valve is operating correctly. Make sure it is not stuck closed, or accidently fell out and make sure your float is operating freely.

Using engine start/ether on an outboard is generally a bad idea. It can harm the top-end and dilute the fuel. Use SeaFoam instead to clean it well.
 
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