Go Back  Offshoreonly.com > Technical > General Q & A
Idle problem >

Idle problem

Notices

Idle problem

Old 06-28-2020, 12:21 AM
  #1  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default Idle problem

I have just bought a 1998 Maxum 2300 with 5.7 TBI mercruiser. It always starts easily but sometimes it imediatly cuts out, if i keep it running on the throttle it will rev fine but then wont idle most of the time .
It had code 21, 22 and 34 TPI high voltage, TBI low voltage and Map sensor low voltage . when I got it the idle was very high and rough , I found the ground and signal wires to the TPI were cut . after repairing it now has this slow idle cutting out problem.
I have cleared the fault codes and they have not come back, the previous owner fitted a new TPI and IAC .
When it does idle ok after a while the IAC starts to hiss loudly and with the flame arrestor off it can be seen to be opening up more, Is this the ECM trying to save the engine stopping because of another fault ? there is a steady spray from the injectors at all times , I picks up very well with no hesitation when the throttle is snapped open.

Any ideas please ?
nickwad is offline  
Old 06-30-2020, 06:40 AM
  #2  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default

Originally Posted by nickwad View Post
I have just bought a 1998 Maxum 2300 with 5.7 TBI mercruiser. It always starts easily but sometimes it imediatly cuts out, if i keep it running on the throttle it will rev fine but then wont idle most of the time .
It had code 21, 22 and 34 TPI high voltage, TBI low voltage and Map sensor low voltage . when I got it the idle was very high and rough , I found the ground and signal wires to the TPI were cut . after repairing it now has this slow idle cutting out problem.
I have cleared the fault codes and they have not come back, the previous owner fitted a new TPI and IAC .
When it does idle ok after a while the IAC starts to hiss loudly and with the flame arrestor off it can be seen to be opening up more, Is this the ECM trying to save the engine stopping because of another fault ? there is a steady spray from the injectors at all times , I picks up very well with no hesitation when the throttle is snapped open.

Any ideas please ?
I forgot to mention my rev counter is reading roughly 2.5 times the rpm , Could this be connected to the idling problem , any help would be much appreciated .
nickwad is offline  
Old 06-30-2020, 07:11 AM
  #3  
Registered
iTrader: (1)
 
Join Date: Nov 2009
Location: KY
Posts: 2,819
Received 61 Likes on 52 Posts
Default

What is the motor serial number?
When idling what is battery voltage measured and don't use the boat gauge?
What is the IAC count reading?
AllDodge is offline  
Old 06-30-2020, 05:50 PM
  #4  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default

Originally Posted by AllDodge View Post
What is the motor serial number?
When idling what is battery voltage measured and don't use the boat gauge?
What is the IAC count reading?
The serial number is L09691.
The battery voltage was 12.5 not running and 12.8 idling using a meter direct on the battery
I cant check the IAC count reading as i dont have a scanner.

One more thing to mention is that the engine wont idle at all unless the throttle is opened very slightly after initial start, if the throttle is not touched it starts for a few seconds then stops. sometimes it idles slower and slower until stopping but sometimes just cuts ( the flow of fuel stops from the injectors) and the alarm sounds. But no codes are thown up
nickwad is offline  
Old 06-30-2020, 05:55 PM
  #5  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 10,456
Received 167 Likes on 95 Posts
Default

Originally Posted by nickwad View Post
The serial number is L09691.
Seams to be invalid. Missing a # or ?

"Rev Counter" ? As in tach on dash or rpm on scanner ? Or crank sensor ? or cam sensor ? or
SB is offline  
Old 06-30-2020, 06:04 PM
  #6  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default

Originally Posted by SB View Post
Seams to be invalid. Missing a # or ?

"Rev Counter" ? As in tach on dash or rpm on scanner ? Or crank sensor ? or cam sensor ? or
That is definatly all the serial number on the engine plate close to the starter motor. strange?
I was refering to the rev counter on the dash reading much higher than the actual engine rpm . Unfortunatly no one has a scanner for this engine in thailand.

one more thing to mention is that the boat came over from the US with a non servicable engine so a 'complete' second hand replacement engine was fitted here. apparently no parts from the original engine were used, but this may be incorrect.

Last edited by nickwad; 06-30-2020 at 06:07 PM.
nickwad is offline  
Old 06-30-2020, 06:12 PM
  #7  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 10,456
Received 167 Likes on 95 Posts
Default

Okay, as far as the tach, it may be switched on 4 or 6 cyl. Take a look at the back of it, there will be a timy dial with 4,6,8 settings. Put to 8 cyl.
SB is offline  
Old 06-30-2020, 06:30 PM
  #8  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default

Originally Posted by SB View Post
Okay, as far as the tach, it may be switched on 4 or 6 cyl. Take a look at the back of it, there will be a timy dial with 4,6,8 settings. Put to 8 cyl.
Thank you, The switch is set to number 3, that is correct for 8 cyl .
nickwad is offline  
Old 06-30-2020, 06:41 PM
  #9  
Registered
iTrader: (1)
 
Join Date: Nov 2009
Location: KY
Posts: 2,819
Received 61 Likes on 52 Posts
Default

The battery voltage was 12.5 not running and 12.8 idling using a meter direct on the battery
This could be your problem. The alternator should be producing around 14.5V running. Some of your errors are low voltage, this would cause it to happen.

There should be a 90amp fuse on the starter, so check voltage at the alternator output lead which is orange.
AllDodge is offline  
The following 2 users liked this post by AllDodge:
nickwad (07-01-2020), PA.WOODCHUCK (06-30-2020)
Old 07-01-2020, 03:09 AM
  #10  
Registered
Thread Starter
 
Join Date: Jun 2020
Location: Thailand
Posts: 17
Received 0 Likes on 0 Posts
Default

Originally Posted by AllDodge View Post
This could be your problem. The alternator should be producing around 14.5V running. Some of your errors are low voltage, this would cause it to happen.

There should be a 90amp fuse on the starter, so check voltage at the alternator output lead which is orange.
Thankyou for your help .
I have checked the voltage on the orange lead from the alternator , I have 14.4 v at 1000 rpm up , also i checked on the battery it is the same. ( i only checked at the battery before ) I have taken appart many connections cleaned and reassembled also charged the battery since checking before. My cutting out problem is still there.
nickwad is offline  

OSO Sponsor
OSO Advertiser
OSO Advertiser

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

OSO Advertiser