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  #1  
Old 04-27-2021, 11:26 AM
going360 going360 is offline
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1999 LTR 330 Idle Surging

Hey Everyone, first post here on TT but iíve been lurking for a couple years and have found all the information I could ever need without posting until now! I have an issue that I have been trying to solve since early November last year. Could really use some help as the local MC said it was the fuel pump but after spending over $1k that is not the case.

1999 Maristar 210 with the LTR 330 motor 800(ish)hrs

Short Story: Towed from Sea level to 5200í now engine dies after starting cold unless I disconnect the TPS then it starts, idles high (1000rpm) but runs great! No backfire and good throttle response.

Long Story: I purchased the boat in WV (Sept. 2020), used it in Maryland for 40 ish hours and all was pretty good. It would die once on a cold start maybe every 10 starts but I really didn't think anything about it as it would start right back up and idle no problem.
The last day we used the boat in Maryland we ran it out of gas not on purpose. I put some fuel in it and it ran the next day no problems.
Then we towed it from Maryland to Denver CO, so sea level to 5200í.
Since then it will NOT START COLD without dying or if iím on the throttle and get the rpms up before it dies then it will stay running at the high rpms. Once the motor is warm it will idle but it surges big time from 500 rpms up to 1100 rpms. Once it is warm (150-160) it will idle more consistently but on hole-shot it bogs for a second or two and sometimes backfires. Once on plane or even just up to surf speed it will have no issues whatsoever and runs like normal.

If I unplug the TPS the idle evens out but at about 1000rpms but everything else is great... throttle response, no backfires.

Here is what iíve done so farÖ in order.

Cleaned intake screen/baffles
Replaced IAC
Tested Fuel Pressure ( Local MC dealer did this and recommended fuel pump replacement due to low fuel pressure)
Replaced fuel pump with new upgraded dual pump unit and harness, gasket and bolts
Replaced Spark Plugs (they were clean and if anything seemed to indicate a lean mixture)
Did not do wires as they usually indicate faulty at high RPMS (from what iíve read)
Replaced TPS
Injectors cleaned and re-build (this was a good thing as the spray patterns were horrible, but did not fix the issue)
Disconnecting the throttle cable
Corrected fuel pressure vent hose kink
Checked Fuel Pressure at rail (59psi)
New Plenum Gasket
Map sensor
Checked throttle body bolts


I have read every thread I could find on this issue here and other forums but have not found a solution. I am posting all the info I can in hopes that it might help me and someone else down the road. At the very least I am going to try and get all of the information I found into one place. I have had it in to the local MC dealer but honestly they donít seem to be up on the older MC boats so I am having to do this myself.

Threads that were useful in my search for a solution

https://teamtalk.mastercraft.com/sho...=49249&t=49249
https://teamtalk.mastercraft.com/arc...p/t-32881.html
https://teamtalk.mastercraft.com/arc...p/t-77268.html
https://teamtalk.mastercraft.com/sho...=76899&t=76899
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  #2  
Old 04-27-2021, 01:25 PM
ewilcox11's Avatar
ewilcox11 ewilcox11 is offline
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Not sure if yours has it, but the PPS caused mine to surge at idle.

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Old 04-27-2021, 01:53 PM
robadele robadele is offline
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You've already done a lot of great work. Sorry you haven't been able to find the cause yet and it must be frustrating.

If the fuel pressure is consistently good, then only spark and air problems are left. It seems like you have already looked for air flow issues like an intake leak, but this would still be my best guess that you are getting air into the intake not detected by the MAP sensor. This would explain both the cold start issue and the surging. Being able to start it with the TPS disconnected seems to confirm this, because this should cause the engine to try and run full rich. If this spark plugs are showing lean, this also points to an intake leak.

I can't think of how a spark issue would cause both the cold start and the surging issue.

Will the engine start with either starting fluid or propane sprayed into the intake? This would also confirm the air leak issue as the extra fuel compensates for the extra air.

Have you tried running the engine with a vacuum gauge attached to measure the intake vacuum?

The LTR and other engines of that same time period operate without a oxygen sensor, so it is somewhat open loop control and the engine doesn't know how much oxygen or hydrocarbons are in the exhaust.

Good luck.
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Old 04-27-2021, 03:45 PM
going360 going360 is offline
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@ewilcox11 - Not sure what a PPS is however I will look into that.

@robadele - thanks for the comments and ideas. I am thinking the same as you concerning the air intake. Since it runs perfectly with the tps disconnected, I have pretty much ruled out spark or compression issues. Just wish I knew where the leak was. When I took off the plenum there was no gasket! I thought for sure I had figured it out! After new gasket, no luck. I did check the MAP sensor seal and it sure seam like its in there very tightly. Where else could it be leaking?

To be clear, the engine starts right up per normal operations for about 3-4 seconds. Thats when it acts like its going to go down to 600 rpms and start to idle but then just dies.

I have not tried the intake vacuum gauge but will ad that to the list of diagnostic items. Will need to buy one of those.

Another thing that I have read is that there was one, possibly two, firmware upgrades for the ecm. I have an email in to indmar to see if I can send it in and have it checked out. If anyone has more info on this I would greatly appreciate anything you have to offer.
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Old 04-27-2021, 04:34 PM
robadele robadele is offline
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On one of the prior threads you listed there were multiple posts about the fuel pressure. In that post it was noted that this year of LTR may or may not have a functioning fuel pressure regulator. In the early 99 versions where there is no return line from the fuel pressure regulator to the tank, the fuel pump was stated to be what controlled the fuel pressure and the maximum fuel pressure was supposed to be 45 psi. Your first post seems to indicate that you have fuel pressure of 59 psi? I could be mis-reading that previous thread, but something to consider.
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Old 04-27-2021, 05:38 PM
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bret bret is offline
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Did you do an IAC reset for the pintle?
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Old 04-27-2021, 06:39 PM
going360 going360 is offline
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Quote:
Originally Posted by robadele View Post
On one of the prior threads you listed there were multiple posts about the fuel pressure. In that post it was noted that this year of LTR may or may not have a functioning fuel pressure regulator.....
Hmmmm. Thats what I remember reading as well, 45psi however the dealer told me it was supposed to be 60 psi so I just though it was good when I saw 59 psi and not the 35 that the dealer told me it was prior to the new pump. The funny thing is that it runs exactly the same as it did before I put in the new fuel pump. Could indicate a pressure regulator issue I suppose.

Quote:
Originally Posted by bret View Post
Did you do an IAC reset for the pintle?
I did do the reset but it has always been in the back of my mind that I didnt do it correctly. I did the procedure that was posted by Jimn (?) I believe. I will try that again for sure.
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Old 04-27-2021, 07:18 PM
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ewilcox11 ewilcox11 is offline
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If yours does have one, it's a pedal position sensor attached to throttle lever. Several boats have had this issue. Surging RPMs is a symptom. There a big thread here somewhere

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  #9  
Old 04-28-2021, 10:55 AM
going360 going360 is offline
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Concerning the fuel pressure. I did some more searching and there are conflicting reports. Some say 40 psi and some say 60 psi. I wonder if the 40 is with the old single pump assembly and the 60psi is with the new dual pump assembly. I don't know but these are the threads I read concerning that.

https://teamtalk.mastercraft.com/sho...t=77268&page=5

https://teamtalk.mastercraft.com/sho...=42438&t=42438

https://teamtalk.mastercraft.com/showthread.php?t=37431
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  #10  
Old 04-29-2021, 08:31 PM
Mark rsa2au's Avatar
Mark rsa2au Mark rsa2au is offline
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Quote:
Originally Posted by going360 View Post
Concerning the fuel pressure. I did some more searching and there are conflicting reports. Some say 40 psi and some say 60 psi. I wonder if the 40 is with the old single pump assembly and the 60psi is with the new dual pump assembly. I don't know but these are the threads I read concerning that.
I have also found this to be somewhat confusing. The manual for my 99 LTR-330 suggests 35-44psi is the operating pressure. I replaced my previous pump when it failed so I don't know what it was at before, but after much research, I went with a 60psi pump as a replacement and it is running great. I also assumed the pressure regulator would keep pressures in check, and taking readings from the fuel rail it holds a consistent 55-63psi across the rev range.

There does not seem to be any black smoke or evidence of over-fueling other than the guy at the fuel station now knowing my name.. but then we did do 115 hours this year and at about 20L per hour on average we visited often...

I plan to replace the plugs soon so will check their condition but they were fine last year after the pump replacement.
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'99 Mastercraft ProStar 205 330-LTR
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