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-   -   Prostar 205 engine surge issue (http://www.mastercraft.com/teamtalk/showthread.php?t=49308)

jmhjgh 07-13-2012 11:21 PM

Prostar 205 engine surge issue
 
I posted last year about our 96 PS205 having issues with surging. The boat is up north and is not used much. We had codes for TPS sensor and that has been replaced. The boat now does not throw any codes. Last year the boat would run perfect up to 3200 rpm and then surge. We could pull the kids skiing and tubing but not adults who wanted to ski faster than 30. Now, the boat will rev up to full throttle, but will cough for a second before it settles down (almost like turning engine switch off/on). Pulling a skier, the boat will cough every 10-15 seconds in an irregular pattern. The fuel pump inlet is clean, and I replaced the fuel filter today. I am wondering about a fuel line leak or sucking air somewhere (I will check the intake manifold tomorrow). The shut-off valve on the top of the tank does not feel good opening or closing and I wonder if it should be removed/cleaned/replaced?
Also, coming off plane, the engine does not immediately go to idle speeds. It wants to rev at 1500-2000 before settling down to idle in 15 seconds. What else should I check?

mikeg205 07-14-2012 10:45 AM

Check the fuel vent in back to make sure its clear...friend had a cocoon in there... and was causing a suction issue. Is the spark(flame) arrestor clean?

How old is the gas? What do the plugs look like? Take a look at the distributor and rotor to make sure it's not fouled...

my .02....

jmhjgh 07-15-2012 01:08 PM

fuel vent is clear and we ran without flame arrestor. Watched both fuel injectors cut out when it coughs. I think I need to buy a fuel pressure gauge.

mikeg205 07-15-2012 01:15 PM

TBI? maybe fuel pump connection is loose...or fuel pump starting to give you warning signals. Not a tough replacement... just a thought. TBI pressure is low... fuel cutting out is a different issue...could be also a bad ECT - does it do it when it's cold? JimN and Jmcrieght would have better insight than I.

jmhjgh 07-15-2012 11:42 PM

Yes, TBI. Pump connection looks good. I tried to put my meter on the pump leads to see if the pump voltage is also cutting out, but there isn't much room. I might need to make an extension. ECT should be good, and if it wasn't, the limp mode should only be cutting out one injector not both. It seems like I am missing something easy. I checked the distributor voltage (purple/white wire) and it stayed around 1.5-1.7VDC and when it coughed, it looked like the voltage went up to around 2 VDC, but it never went away.

Double D 07-16-2012 12:25 AM

My only addition to this is do not ignore the ECM or computer. My Engine surged a bunch after 20 minutes of use and viewing the injectors the fuel would sputter on one. It proved out to be the injector driver in the computer was bad. I currently run both injectors off one driver and it's fine. If this ends up being the problem and both injectors are sputtering, then a computer replacement would be in order.

My $0.02....


Sent from my wife's old iPad using Tapatalk....

jmhjgh 07-16-2012 10:54 AM

I remember reading your post a while ago. I would like to be able to confirm the ECM is bad before replacing. I was able to borrow a marine scanner and all seems to be in order electrically, but I am not sure what is happening when the injectors cut-out. It does seem to be changing because last fall, the engine would run perfect to around 3000 rpm, and now we get the injectors cutting out anywhere in the power band.

Double D 07-16-2012 11:22 AM

Quote:

Originally Posted by jmhjgh (Post 858588)
I remember reading your post a while ago. I would like to be able to confirm the ECM is bad before replacing. I was able to borrow a marine scanner and all seems to be in order electrically, but I am not sure what is happening when the injectors cut-out. It does seem to be changing because last fall, the engine would run perfect to around 3000 rpm, and now we get the injectors cutting out anywhere in the power band.

Agree 100% about confirming computer is bad before you drop ~$800 on a new one. However, I am not sure how you do that since both your injectors are sputtering. My advantage was only one was sputtering and I could switch the lines to confirm it wasn't an injector, etc. Good Luck!!

jmhjgh 07-17-2012 01:24 PM

Do you think a bad fuel line could stop both injectors temporarily? I would think bad lines would slowly slow the boat, and not behave like someone is turning the ignition off and on. I need to tow the boat home so we can run some more tests.

Stx221 07-17-2012 02:38 PM

Another thing to look into:
What does the oil pressure gauge look like when under way? Is it all over the place, or does it get up to about 30psi at idle and 55-60psi under load?
If it bounces all over the place, I recommend a new oil pressure sending unit. I know I was having a similar issue with the fuel pump power being cut on and off and it was due to the ECM "seeing" low oil pressure due to a faulty sending unit.


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