How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tan Your Own Question
Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11073
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
25721800
Type Your Boat Question Here...
Tan is online now
A new question is answered every 9 seconds

I have Merc 60 HP 4 stroke, big foot my friend se owned since

Customer Question

I have Merc 60 HP 4 stroke, big foot my friend se owned since new. I can't get above 3000 RPM, motor is running fine, oil level good, fuel pumps replaced 12 months ago, same prop since new, done around 3300 hours, my friend seems to think, the throttle body has a build up of carbon
JA: Thanks. Can you give me any more details about your issue?
Customer: Jason, my issue is I can't top end speed, RPM gets up to 3000 tops, I use to get 5000, motor does surge or stall, just no top end speed
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: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with? Can start by getting the serial number on the engine please. I need to run that to see which version of the 60 that you have.
Customer: replied 1 year ago.
Jason its Don Beer, Model 1C095822, March 2009, 60ELPT BF
Customer: replied 1 year ago.
Jason are you there???
Expert:  Jason replied 1 year ago.
Hi Don,Got the serial. The engine will need some troubleshooting in order to try and figure out the problem(s). That would start with checking engine compression, checking spark output, and checking fuel pressure with the boat at maximum speed. Are you able to do those checks?
Customer: replied 1 year ago.
Jason, I will to take to a mechanic, as I can't perform these functions, as I need a pump to test fuel pressure.
Customer: replied 1 year ago.
Jason, I had a diagnostic report done 2 months, nothing showed in the report, so it could fuel related, have you had any experience with throttle body issues with build of carbon, common with Honda's
Customer: replied 1 year ago.
Jason, I take it this is a difficult for you to answer,
Expert:  Jason replied 1 year ago.
I'm sorry I don't understand what you mean. The engine needs troubleshooting in order to figure out the problem/problems. That troubleshooting starts with checking compression with a compression gauge, checking spark output with a timing light or adjustable gap spark tester, and finally checking fuel pressure with a fuel pressure gauge. Are you able to do those checks and report back with your findings? If not, how is it I can help you?
Customer: replied 1 year ago.
Thanks Jason, got that, my question, I have had any problems with the throttle body on these motors, pretty simple, I have the the service manuel, and I took the details from this. Cheers ***** *****
Expert:  Jason replied 1 year ago.
I'm sorry I still do not understand you. Can you please type out your question with a "?" mark at the end of it.
Customer: replied 1 year ago.
Sorry Jason, the throttle body is located on page 3C-22 of the Mercury Service Manuel, it is shown as figure 2, along side the intake manifold assy. My question to you, is that, have you had experience of carbon build up, resulting in lost of top end power, its a common problem with Honda's. I trust this is clear to you.
Cheers ***** *****
Expert:  Jason replied 1 year ago.
The only way carbon buildup would effect engine performance is if there was so much carbon on the valves causing them to not seat and seal correctly. This would lead to low compression and when this happens the engine will typically spit and backfire through the intake manifold. Does that make sense?
Customer: replied 1 year ago.
Thanks Jason, this answers this problem, the motor does not backfire. I will get the local mechanic to check these and will get back to you.
Expert:  Jason replied 1 year ago.
Sounds good. Keep me posted.
Customer: replied 1 year ago.
Hello Jason, all checks were carried out yesterday, but motor still will not go above 3000 RPM.Cheers ***** *****
Expert:  Jason replied 1 year ago.
Next step is to hook it up to a scan tool and both check for codes, and read the live data. If your mechanic uses "Diacom" scan tool I can read those printouts.
Customer: replied 1 year ago.
Jason, the mechanic hooked the motor to a diagnostic computer, and no fault was found
Expert:  Jason replied 1 year ago.
What was his opinion or the engine not making full power?
Customer: replied 1 year ago.
He does not know, and will have to talk to an expert, I guess that's you
Expert:  Jason replied 1 year ago.
Was fuel pressure and spark output checked under a load? That is checked with the boat in the water and at maximum speed?
Customer: replied 1 year ago.
Yes he did as well, with the boat tied to wharf, and boat in the water
Expert:  Jason replied 1 year ago.
Are you near the motor now by chance?
Customer: replied 1 year ago.
Yes the boat is at home on my trailer
Expert:  Jason replied 1 year ago.
Pop the engine cover off and follow the shift cable into the engine and have a look at the shift linkage where the shift cable connects. Some engines have neutral switches on them. See if you see a little switch on the shift linkage or not. If it's there it would have 2 small black wires that come off of the switch.
Customer: replied 1 year ago.
Jason, just had a look, and the shift linkage has no wires.
Expert:  Jason replied 1 year ago.
Well, i'm out of ideas. I will opt out, if one of the other guys wants to take a shot at this they will jump in. good luck.
Customer: replied 1 year ago.
Ok Jason, this is a really hard one, Cheers ***** *****
Expert:  Tan replied 1 year ago.
Hello Don. My name is***** go at this a different way. Has the boat been sitting unused for a long time? Did this just start happening? Have you tried squeezing the primer bulb when you get to full throttle?
Customer: replied 1 year ago.
Nice to hear from you Tan, motor done 3300 hours, I go fishing 3-4 times a week, 4-5 hour trips, trolling, speed range 1500-3000rpm, last trip as on Sunday, problem is that I can't get past 3000rpm, there is no surging, or back fire, engine runs fine, but no top end speed. Last year, we replaced the low pressure mechanical pump, fuel pressure regulator, and high pressure fuel pump, I am at lost my, we removed the manifold yesterday, and checked it, including the throttle body
Expert:  Tan replied 1 year ago.
Is there a possibility you could have some trash in the fuel; tank causing a fuel restriction? Have you tried squeezing the primer bulb when engine hits full throttle?
Customer: replied 1 year ago.
Thanks I clean the tanks periodically, replaced the house and primer bulb, and installed new fuel filters, I checked the VSP which houses the high pressure fuel pump, all clean as well. Cheers ***** *****
Expert:  Tan replied 1 year ago.
Have you tried squeezing the primer bulb when engine hits full throttle?Do a compression test. 3300 hours are allot of hours.
Customer: replied 1 year ago.
Okay Tan will try this out, Cheers ***** *****
Expert:  Tan replied 1 year ago.
Ok Don keep me posted. If the engine has low or no compression this will be the problem. With one cylinder down it won't turn up to full power.If the engine runs better when squeezing the primer bulb you have a fuel restriction or a failing fuel pump. To eliminate the boat side fuel system run the engine on a different fuel tank. If engine runs the same you have a failing fuel pump.If engine runs better then you have a fuel restriction in the boat side fuel system.
Customer: replied 1 year ago.
Appreciate the feedback Tan, will let you know, Cheers ***** *****
Expert:  Tan replied 1 year ago.
Ok Thank you.