Hard knocking sound 85HP Chrysler Force OUtboard

[Karla45]

Just purchased a boat with 85HP Chrysler Force Outboard i think is 1989, it had been sitting for 4 years without use. Motor cranked up after disconnecting kill switch. The boat was in shop for 2 weeks. I took the boat out for a drive and when started to speed up I heard a loud (hard)knock coming from motor, it was like a sound if you hit something. Took it out again, and started doing same thing just some loud knocks sometimes when sped up,this is not a constant knocking sound, just Second time out right when I put it into idle it made two hard knocking sounds and died. Then got it started and headed in but not far drive at all and it felt a little like I was dragging bottome some, I know for sure I was not hitting anything or had not hit anything becasue in 26ft of water. I checked the prop and nothing wrapped around it or anything. On the day that the mechanic was bringing the boat over the horn went off, so he replaced something to keep it from overheating. Another problem is that when I trim the motor up while it is docked the motor slowly falls back down. Bill shows that compression was checked and okay. It also makes a spitting sound when trying to start up when cold but mechanic told me it will do that when cold. Amazingly the carbs where in good condition. Another thing is that my dad put gas in the boat mixed in with gas that had been in boat for four years.

 

[john from md]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

You may be hearing detonation but usually that sounds more like a rattling noise. Is the engine jerking when it is making these noises? It could be a miss caused by electrical or fuel issues. Then again, it can be a rod knock and if that is the case, it needs a major teardown.

How does it run at idle? Does it sit and spit and jerk or does it run smooth? What RPM does the knocking start at? It may be a case of the engine running too lean in which case you need to fix it pronto before you burn up a piston.

John

 

[Karla45]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

It does jerk a little when spitting but not knocking sound when first try to start. I called the mechanice at first because i could not get it started when i first got it back, he told me to adjust carbs slightly and then it fired off & was not spitting. When it died on me when I slow down and put in idle it knocked twice and then died and had hard time starting it again. Once when I really started to speed up and go faster it made a loud knocking sound and it kind of felt like it was having a hard time getting into gear and then sped up(almost like a sudden acceleration issue) it was more like a skip. I do not know what RPM it is doing it at and I really do not want to drive it anymore because I do not want to cause any further damage. The mechanic says he is coming over monday morning to look over but i am worried he will make it worse. He told me that it did not do this when he was running it. He replaced the impellar, would this cause problem if it is faulty or not installed right? It runs pretty smooth in idle. When it died on me from deceleration and putting in idle I started going about 10 miles an hour and went about 150yards and starting getting vibration and it felt like it was dragging a little. By the way when it is spitting at first start, it smokes really bad, the mechanic told me my dad may have put too much oil in. I know that on other boats he always puts a little more than called for but i read the manual for this engine and it said to make sure you do exact mix. I had warned him about this. By the way after adjusting the carbs and it starting just fine the first time I tryed to start it later in the day and it started spitting and hard to start but finally got it too start.. I am not sure that I could say there is knocking after the spit as much as it makes a sound like what you would hear when you first try to put air in a tire. I also would like to add that they had to replace the feul pump.

 

[john from md]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

As it was sitting for four years, have the carburetors been taken apart and cleaned? Your problem seems to be fuel related to me. The bad fuel in the tank does not help matters. Auto fuel will decompose pretty bad in four years. I suggest that you drain the tank and get fresh fuel before doing anything else.

John

 

[Karla45]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

I think i may have possibly identified the problem as far as the starting problem. The feul pump was not replace but the feul line with bulb was replaced. When first got boat had to go buy feul hose and pump bulb, when we got back my friend said that the hose was wrong size and did not fit so he too the hose and looked at size and brought back hose the same size. By this time my father gave to a mechanic shop, I went down to boat and looked at installation. On the side the hose is almost 3 inches in diameter, on the other side is the hose that we purchased at walmart and it measures at just below two inches. I do not know much about this but would like to know if the hose is supposed to be bigger on opposite sides of the bulb.

 

[john from md]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

If the fuel pump has not been replaced, it needs to be. This is an easy job and they only cost about $20.

You are confusing me about the fuel line size. This engine either uses 5/16 or 3/8 fuel line. Can you carify what you are talking about? You lost me with the two and three inch diameters.

John

 

[Karla45]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

sorry i am talking about the diameter in inches, on one side of bulb going to motor the diameter of the line(hose) is less than 2 inches round and on the other side of the bulb(Pump) it is 3 inches in diameter or round. In other words they left one side with the new hose we purchased that was wrong and we told them and the other side they put some of their hose. we also gave them some other used hose that was 5/16 which would be right but they did not use it. I am talking about the hose on the outside of the engine where you can squeeze the bulb to pump more gas into the hose, that is what i mean by bulb or pump

 

[john from md]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

Karla,

I am still confused. The fuel line from the tank to the engine is either 5/16 diameter or 3/8 diameter. This is the line on both sides of the primer bulb.

Maybe we are having a language problem with defining terms. Are you located outside of the US?

John

 

[Karla45]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

Yes I am now aware that it should be 5/16 and what i am trying to say is that they cut some hose for one side and attached to the bulb(hand pump) and when you measure how round it is with tape measure it is 3 inches around or round, then on the other side of the black bulb(hand pump) they have attached a different size hose which is a little under 2 inches around. I would imagine that this would cause motor to not get enough fuel, but i could be wrong. On alot of the bulbs you can reattach hose with clamp on each side and this is what i am talking about. Here is picture of pump kit i am talking about, the mechanic changed the hose from original on one side but not the other and they are now two diffferent sizes

 

[john from md]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

It doesn't matter how long or short the hoses are. I had one with a bulb to reach the helm when I was having fuel pump problems. That way whenever the engine started to die I would manually pump it.

I think you need to replace the fuel pump before doing anything else. If you are handy with a screwdriver, it will only take about an hour to change.

Let me know if you want the particulars.

John

 

[Karla45]

Re: Hard knocking sound 85HP Chrysler Force OUtboard

i am not talking about the length of the hose i am talking about the width of the hose. i am aware that it should be 5/16 width on the inside but I measured the width on outside with tape measure and you can also tell by looking the one is much larger than the other. I was told for a 85HP force that it should be 5/16 only. Imagine holding up one finger, if you wanted to see how fat your finger is then you would wrap a tape measure around your finger and that would tell you how fat your finger was in inches, this is what i mean by diameter or how many inches round.