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Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14500
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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2001 Mariah 212 tbi 305. Will start and run at idle, but will

Customer Question

2001 Mariah 212 tbi 305. Will start and run at idle, but will not take throttle. Fluids are up.
Submitted: 9 months ago.
Category: Boat
Expert:  Jason replied 9 months ago.

Hi George, my name is Jason.

Is the engine a Mercrusier, Indmar, PCM or something else?

Have you ever seen the engine make full power? If yes, when was the last time?

How old is the fuel?

Have you done any testing on your own yet, if yes, what have you done?

What kinds of questions did you have for me?

Customer: replied 9 months ago.
Mercruiser, full power just used the week before all day. Fuel one month old, marina ethanol free. No testing other than checking all fluid levels.
Expert:  Jason replied 9 months ago.

Have you done any testing on your own yet, if yes, what have you done?

Expert:  Jason replied 9 months ago.
Got it. The positive battery cable connects to the right side of the starter relay. I'm attaching a picture, see attachment.
Expert:  Jason replied 9 months ago.

Are you still with me?

Customer: replied 9 months ago.
Got the picture. Motor starts and runs but only at slightly above Idle speed.
Expert:  Jason replied 9 months ago.

I'm sorry I don't understand, I didn't send you a picture. I was waiting for a response for 2 question that I had asked you. Those questions were;

1 Have you done any testing on your own yet, if yes, what have you done?

2 What kinds of questions did you have for me?

Customer: replied 9 months ago.
The reason for the delay was because the bank called.
Customer: replied 9 months ago.
Engine will start and boat will operate in gear but will not accept any throttle. I answered you question about testing.
Expert:  Jason replied 9 months ago.

I don't see any response to testing. I need to know if you have done any testing on your own yet, and if yes, what have you done.

Customer: replied 9 months ago.
2 recent batteries, all fluids topped, 2 week old ethanol free fuel.
Customer: replied 9 months ago.
Checked for loose connections.
Expert:  Jason replied 9 months ago.

Got it. I know what needs to be done in order to troubleshoot the problem. Did you have any specific questions for me on the engine or did you want me to explain how we trouble shoot this in the shop, covering all bases?

Customer: replied 9 months ago.
Troubleshoot please.
Expert:  Jason replied 9 months ago.

Okay give me about 10 minutes to get you an answer typed up.

Expert:  Jason replied 9 months ago.

When I get engines in the shop that do not make full power, this is what I do to troubleshoot them, I also do it in this order to keep from making mistakes. There is a method to this and if you follow the method then you can't make mistakes, and you won't throw unneeded parts at it.

1. Compression test. Your results need be 100 psi or better, all cylinders should be within 10-15% of eachother. If any cylinder is under 100 psi it is either worn out, or has a valve problem, and the heads will need to come off and the valves inspected next. A healthy engine will read in the 140 to 160 psi range. I know the engine ran well just a week ago but this really should be checked, all it takes is 1 burnt intake valve to cause the engine not to make full power.

2. Spark test. The easiest thing to do here is to hook up a timing light to each plug wire one at a time and see if the light flashes or not. Flash means spark, no flash means no spark. No spark can be something as simple as a bad spark plug, that was dropped on the floor before you got it. Also make sure the timing is advancing when the engine is throttled up, if the timing is not advancing there is an ignition module issue. You also want to pull the distro cap off and see if there is a lot of burning or pitting or erosion on the inside of the cap or on the tip of the rotor. To much corrosion will cause the engine to misfire. To much erosion can cause cylinders not to fire at all.

3. If compression and spark are good, make sure the fuel filters are all changed. Some engines will have up to 3 fuel filters on them. With 1 large canister filter in the front, followed by paper filters in the carb and fuel pump. The serial number on your engine would need to be run to see exactly how many filters it as. If any one of the filters are clogged the engine will starve for fuel.

4. Next is to get a small outboard tank (like a 3 gallon) and fill it up with known new fresh gas and try it. If the engine runs better on the portable tank there is an issue with the boats tank, this can be a blockage, air leak in the fuel pickup and related hardware, or simply bad gas.

5. If no change, next is to hook up a fuel pressure gauge between the pump and the throttle body. Fuel pressure needs to be 30 psi always. If it's not, the fuel pump is weak and needs to be changed out.

6. Lastly, if you got this far and the engine STILL is not running correctly, it will have to go on the scan tool. If you get to this point everything that can be checked without a scan tool has been checked. If it still does not run correctly the engine has a bad sensor on it.

If the troubleshooting is done in that order, and no steps are skipped, the root cause will ultimately be found.

Does that all make sense to you?

Expert:  Jason replied 9 months ago.

Do you have any other questions on the issue?

Expert:  Jason replied 9 months ago.

I think that should do it. 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 you

Jason

Expert:  Jason replied 9 months ago.

Was there anything else?

Expert:  Jason replied 9 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.

Thanks

Jason

Expert:  Jason replied 9 months ago.

Hi George, Jason here. How are you making out?

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