Temp light won’t go off

[bigbeard]

Hey Supra land I am new to the forum and new to Supra, but I have a 1989 supra saltare with a pleasure caft 454, I have a temperature light that comes on immediately when you start the boat from a coldstart temperature gauge is reading about 160, not only is the alarm pretty new annoying I’m wondering if it is throwing the boat in limp mode if they even had that technology in 1989 the boat runs great to 2400 RPMs and then after that it starts to backfire, Timing and carburetors or set and has a new carburetor new fuel pump in the distributor was converted to electronic distributor new plugs plug wires and rotor cap. Please help

[etktryd]

Welcome to the family!
Ok I,m going to ask a lot of questions. I would unhook the temp sensor at the motor and see if the alarm stops and see if the temp gauge stops working. If they both stop they are hooked together. If not the alarm and gauge have there own sensors.

What distributor are you running? Internal or external coil... Mechanical or vacuum advance.
What carb? Q-jet, Holley, and so on.
Is it backfiring out the intake or exhaust?

You will need a friend or two to do this. One to drive. One to hold the engine cover open. And you the tune on the engine while you are flying down the lake.
I would take the engine cover off... but I have done it both ways. Take the air cleaner off. Run her up to where she starts to backfiring. Hold the RPMs at that point.
loosen up the distributor just enough that you can turn it. ( you can loosen the dist. bolt before you take off. Should be a 9/16'' bolt. ) Don't loosen it up too much or the distributor can move while the engine is running !!!!
At the point of backfire start to turn the distributor SLOWLY !!!!! You pick the direction you want to go. I would start to retard it fist.... ( Thats clockwise looking at the dist. from the front of the motor. ) If it gets better keep going.... if it gets worse turn it the other way... If nothing changes set the dist. close to where it was at the start.
Move to the carb. take something and start to close the choke plate ( SLOWLY ) It should start to run rich. If it starts it run better we have a fuel issue or a vacuum leak.
Lets start with that. ( Can you get a compression check? )
Good luck !!!!!

[etktryd]

Make sure your plug wires are right. 1-8-4-3-6-5-7-2.
5 and 7 can be crossed and a chevy will still run.

[bigbeard]

Etkryd thanks so much I going to give it a try the temp tonight, the dis is a Mallory with a conversation to electronic dis, and it a holly carb, and the back fire is coming out the carb. And I will also try to get a compression check tonight as well thanks again will be back soon

[etktryd]

Ok... Holley is a great carb. It has one major issue. If you backfire out the carb. and it only takes one. 9 times out of 10 you will blow the power valve and you will have a lean condition.( not enough fuel ). How does the engine idle? Often an engine will surge at idle with a blown power valve but not always.

[bigbeard]

It idle great just when it gets to 2500 rpm’s is when it backfires I did a little tweaking over the week I’m going to take it out in the morning see how it runs!

[bigbeard]

Water test went great, had the timing not set right. Does any one know what the time is supposed to be for a 1989 Supra with a pleasure craft 454?

[etktryd]

OK Ill try and make this as simple as I can. Most boats run a lower engine temp than cars do because you are pulling cold water from the lake. With lower water temps. you should be able to run the timing a little higher than normal. Better performance and better economy. You and a friend take the boat out, let it get to operating temp. Here we go !!! Run at full throttle. start to retard the timing. Rotate the distributor clockwise from the front of the engine until the RPMs start to drop off. Stop at this point and start advancing the timing. ( counter clockwise ) The RPMs should start rising and the boat should get faster. Keep going until the RPMs stop rising. Bring the boat to an idle and snug the distributor bolt. Idle RPMs may be high. Adjust at the carb. OK almost done... Depending on what type of fuel you are running ( regular, premium, ethanol free etc. and what heat range spark plugs you have, all play a factor in this ) Some marinas sell ethanol free. I highly recommend it !!!!! From an idle, in drive... hammer the throttle. listen for spark knock as you reach max RPMs. It will sound like a ball peen hammer smacking the block. To a slight pinging sound. If you have spark knock retard the timing just a small amount. ( clockwise ) Repeat the last step until no spark knock is heard. Tighten distributor and adjust carb.

[etktryd]

What did you fine out on the temp light ?????