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88 Supra TS6M Hard start when hot.

Printed From: Discussion Board
Category: Engine Or Boat Troubles
Forum Name: Problems & Solutions
Forum Discription: Please only discuss any troubles or solutions here.
Printed Date: 06 December 2019 at 10:14am

Topic: 88 Supra TS6M Hard start when hot.
Posted By: Suprats6m
Subject: 88 Supra TS6M Hard start when hot.
Date Posted: 31 May 2017 at 3:33am
I have a 1988 Supra Comp TS6M with the 351 Windsor.
It will run fine for 15 - 20 min through our no wake zone and when we get out on to the main lake we run around at 25 - 30 mph for 10 minutes or so. Once we stop and get a skier in the water it will crank and crank what seems like forever. Usually takes cranking 3 separate times for 10 - 20 seconds to start.

The coil gets extremely hot and i think that is the issue but don't know exactly what I need to trouble shoot.

The boat was converted to electronic ignition by the previous owner.
The ignition module has 1904 on it. It also has a purple and black wire that come out of the distributor. The purple wire connects to the positive side of the coil and a pink wire connects to the positive side of the coil also and runs back to the resistor.
The black wire connects to the negative side of the distributor and also has a grey wire that runs into the wire loom I assume to the gauge.
The coil has #903 on it and says use with external resistor.

What voltage reading should I have at the +side of the coil?
Should I be using a different coil?
How many Ohms should the resistor have?
Should I pull the resistor?

If anyone has any trouble shooting ideas I would greatly appreciate it. This is a prestolite distributor and is stamped with a CA im assuming its a california distributor if that makes a difference.


Posted By: tsnichols
Date Posted: 04 June 2018 at 5:49pm
Something to take a look at is the voltage to the coil when it is hot.  I have very similar issues to what you describe.  I chased it for years.  In the end the issues seems to be related to low voltage at the coil.  I have an 87' correct craft with a PCM 351.  The wiring is obviously dated and when I re-seat with the spade connectors behind the dash it often fixes the low voltage issue and it starts fine.  I also have a ballast resistor.  Sometimes in a pinch I jumper the ballast resistor to get it started.  when its low it reads 7 or 8 volts at the coil (hot), after fiddling with the spade connectors it gets closer to 10 volts.

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