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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14288
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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JA: Thanks. Can you give me any more details

Customer Question

***** *****,
JA: Thanks. Can you give me any more details about your issue?
Customer: I have a 1995 Johnson 40 hp. The fly wheel key sheered off. I replaced it and it cranked right up. It has recently started acting like it isn't getting any spark. Fresh gas, new plugs, plugs passed spark test. I couldn't get it to sputter by using a gas oil mixture sprayed straight into cylinder. I was told to check timing. I thought it would back fire if timing was off...I switched my spark plug wire. Bottom to top and top to bottom. It started back firing. I switched the wires back and and engine started for approx 2 min and died. I had to repeat the above process with wires to get it to even sputter. Any ideas?
JA: OK got it. Last thing — Marine Mechanics generally expect a deposit of about $26 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 7 months ago.
Category: Boat
Customer: replied 7 months ago.
Going to check compression . What about timing could be out of time? If so how would I adjust it
Expert:  Jason replied 7 months ago.
Hello my name is ***** ***** am I speaking with? Do you have a timing light in order to check spark output? Also, will the engine hit or run on some starting fluid?
Customer: replied 7 months ago.
I do have a timing light but never used it before. The motor wasn't hitting on starter fluid. Whatever reversing the plug wires to make it back made it run for a few minutes when plug wires were put back correctly.Any idea why that would be?Reason I did this was thinking the plug wires were hooked up wrong. I also had to had some increase throttle at carb while priming it from the key to make it start. I know this sounds confusing cause I was there and it confuses me
Customer: replied 7 months ago.
It was acting as if spark wasn't working but it was passing all spark tests. Spark tester as well as grounded plug to engine block.
Expert:  Jason replied 7 months ago.
You might have a blown head gasket. Check the compression first and write down your numbers. Next, hook up the timing light to each plug wire, crank the engine over, and see if the light flashes evenly with engine rpm or not. Let me know what happens.
Customer: replied 7 months ago.
Haven't checked timing yet. Top cyl was at 117 and bottom 120 compression.Not really understanding the timing concept. Also is there a way to time it without a light?
Expert:  Jason replied 7 months ago.
You are not checking timing with the light, what you are checking is spark output with the light. If the light flashes there is spark, if there is no spark it will not flash.
Customer: replied 7 months ago.
There is spark.
Expert:  Jason replied 7 months ago.
There is a right way and a wrong way to check for spark, tell me exactly how you are checking it.
Customer: replied 7 months ago.
I used an inline tester and removed the plug and grounded it block to check for a spark. Both showed positive results
Expert:  Jason replied 7 months ago.
What kind of inline tester? Was it a neon type, or does it have an adjustable gap on it that the spark can jump? If it is the adjustable gap type, what did you have the gap set to?
Customer: replied 7 months ago.
Not adjustable
Expert:  Jason replied 7 months ago.
What you would need to do is get an adjustable type, set the gap to 7/16ths on an inch. And see if the spark jumps that gap or not. Click this link to get to a youtube video that shows the correct way to do it. https://www.youtube.com/watch?v=eSmNMWTDtZE While you are out getting a proper spark tester get yourself a can of starting fluid as well.
Customer: replied 7 months ago.
It's sputtering and back firing when hooked everything back up after compression test
Expert:  Jason replied 7 months ago.
Alright.... Lets do something else. Pull the plugs, stick a screwdriver down the top plug hole, slowly turn the flywheel clockwise until you can feel the piston come up to the top of it's stroke. When the piston is at the very top, does the 0 mark on the flywheel line up with the timing pointer?
Customer: replied 7 months ago.
No it's at 12 at TDC
Expert:  Jason replied 7 months ago.
Is your pointer adjustable or is it fixed on the engine?
Customer: replied 7 months ago.
Fixed on engine
Expert:  Jason replied 7 months ago.
Do you have any idea why the flywheel key sheared in the first place? They typically do not shear for no reason. Did the prop hit something? Was somebody jumping waves with the boat? Was the lower unit shifted into gear at a high speed? What is the story there?
Expert:  Jason replied 7 months ago.
It looks like you read my last reply. Are you able to answer any of those questions?
Customer: replied 7 months ago.
It was shifted with a high idle. I'm gonna need to adjust the idle once I can get it to start
Expert:  Jason replied 7 months ago.
If it was shifted at a high idle the problem is going to be a bent crankshaft. With the piston at top dead center, the 0 mark on the flywheel must line up with timing pointer on the engine. If it does not line up, it can only be a couple things. One thing is the connecting rod for the #1 piston can be bent (which would not happen with a high idle shift). The flywheel key can shear, which has been corrected, and lastly, the crankshaft can bend. Basically what happens is the engine is spinning at a high rpm, the propeller acts like a brake and wants to slow everything down when shifted into gear, but when that happens the flywheel wants to keep spinning because of all of that inertia. The end result is either the driveshaft in the lower unit twists and splits, or the crankshaft bends, in your case here, the crank has bent. I do realize that is not the best of news but I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.Thank youJason
Expert:  Jason replied 7 months ago.
It looks like you read my reply without putting through a rating for me. Please keep in mind the website does charge you to speak with me, but they will hold your money and not credit me for helping you out if no rating is put through. If you have a problem with the ratings box or can not see it please let me know.ThanksJason
Customer: replied 7 months ago.
I got a marine mechanic coming to
Look at my boat. If he diagnosis it the same I'll credit you
Expert:  Jason replied 7 months ago.
The pointer can not be 12 degrees out for no reason. So let me know what happens.

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