Go Back  The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > The Boating Forum
Reload this Page >

Tohatsu 70 tldi MD70B mid range issues

Notices
The Boating Forum

Tohatsu 70 tldi MD70B mid range issues

Old 08-06-2016, 05:32 AM
  #1  
Junior Member
Thread Starter
 
Join Date: Aug 2016
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Default Tohatsu 70 tldi MD70B mid range issues

Hi I have a 2003 Tohatsu MD70B (70 tldi), it always starts easily & runs nicely above 4500 rpm & at tick over 800 rpm. In between that it it's like it misses I can stay at 1500 rpm & every so often ( could be 20 seconds or 2 minutes) the revs will drop to 1000 rpm for a second then return back to 1500 & run smooth again until the next time, the time beetween varies between seconds & minutes, if I increase the the revs to 4000 it will drop to 3000 for a second then return to 4000. Has anyone got any ideas, my mechanic is at a loss as to what could be causing it. The injectors are clean & ok.
Many Thanks

Last edited by Dunky75; 08-06-2016 at 06:13 AM.
Old 08-06-2016, 08:07 AM
  #2  
Senior Member
 
Join Date: Aug 2005
Location: Sturgis, Michigan
Posts: 921
Likes: 0
Received 3 Likes on 3 Posts
Default

that is a three cylinder, my bet is a bad plug or wire. This is classic bad plug wire symptom.

So do two things:

1. Put new plugs and wires on all three cylinders. Just change them all.

2. Find a new mechanic if this guy is "at a loss" this is pretty basic stuff.

Jerry
Old 08-06-2016, 10:26 AM
  #3  
Junior Member
Thread Starter
 
Join Date: Aug 2016
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Default

Thanks Jerry, I have replaced the plugs & no change, I have also run it with an injector unplugged changing through all 3 cylinders & it ran the same at 1500 rpm, sorry I forgot to include that in the post. Wouldn't it of run smooth when I isolated the cylinder with the broken lead? Cheers
Old 08-07-2016, 03:36 AM
  #4  
Junior Member
Thread Starter
 
Join Date: Aug 2016
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Default

I think we've located the problem following reading a post on here from 2008 where Tohatsu Guru mentioned some early 90 tldi had issues with rfi from the rectifier, so disconnected the rectifier & it ran perfectly. Hopefully a new one will sort the problem.
Old 08-07-2016, 06:00 AM
  #5  
Senior Member
 
Join Date: Aug 2005
Location: Sturgis, Michigan
Posts: 921
Likes: 0
Received 3 Likes on 3 Posts
Default

The 70 and the 90 are the same block and same basic set up. I hope that does it, if not change the plug wires.

A bad plug wire will misfire under load cutting in and out randomly, very common problem. 13 year old plug wires might be time.

Cheers,
Jerry

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

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.