Knock sensor location help and wiring.

I dont know the year of the engine other than the boat is a 1992 so i figure just a early 90's pcm 5.8 with the protec ignition. I have heard people say the knock sensor is on the back of one the heads but when i went to look for ours, it was on the intake manifold. Now about 15 years ago we had water come back up through the exhaust and destroy the heads during some powerslides. So it has two "new" (as in already over 15 years old) heads on the engine. There is more but thats for later.

i really would like to know where the knock sensor is supposed to be located and how its supposed to be wired.

the one labeled as knock sensor should actually be the temp sender to the gauge.

About the knock sensor yes it belongs to the rear of the cylinder head. And its wired with a coated white cable,


looking again I might be wrong...anyway the knock sensor in my case was in the head....

double pumper carb? odd

huh. odd. but anyway. so is the knock sensor supposed to be on one of the heads or intake manifold?? the engine has 2 replacement heads as i have stated before and he brought the boat to a garage for them to replace the heads.

But i have been thinking. From what i have gathered the knock sensor is only used for switching the timing from "performance" mode to a more i guess economy mode. or am i completely off base?

On the back of each head there are two threaded holes. The upper one is too small for the threads to fit into. The lower one the threads fit in but loosely. But it will snug up against the head.


Now as for the carb. Here is another shot for ya.



Its been like this since we have owned the boat. Its a 1992 that we bought in 1994. Its had one previous owner and we bought it up in Sunapee Lake, NH. We the boats second and probably last owner. Almost sold when we acquired the Martinique but thankfully sentimental value and fun factor allowed us to keep it :)

what happened to your coil pack? and should i just leave it on the intake manifold or try using the slightly large threads and try to snug it against one of the heads? also, do i really need it? from what i've heard it only allows the coil pack to switch out of "performance mode"

Actually, the carburetor probably did come with your Supra. I was scouring the web yesterday for a picture of a secondary actuator and stumbled onto a Supra site. I guess PCM used that Edit: 4010 Holley at one point. For Supra only, and only for one or two years according to the poster:
http://www.supraboats.com/bbs/showthread.php?1056-vacum-secondary

You can tell that is indeed Marine (or at least a valiant conversion attempt) because of the J-tubes.

Well, 2010 was the last time the Supra was used as the interior is in tough shape and we acquired the Martinique which is a much more family friendly boat. So the Supra sat in our barn till this spring, now its home. But towards the end of the 2010 summer the ignition pack started to play up. when we would be cruising (at any speed) the alarm would sound and then no spark. Sometimes we would have to let it sit for 15 min before it would fire up again. And when we would be going over 3,000 rpm the spark would cut and then the engine would severely back fire through the carb. So we are going to replace all the sensors as an attempt to fix this. Now this happened to my dad back in 1995. He replaced the smaller oil switch and that fixed the problem. But we did that again and didnt help at all :( So when taking the sensors out I noticed the knock sensor on the intake manifold rather than on one of the heads.

nice catch on that one Brian... I stand corrected... that is a funky carb choice. I don't really know what they were going for there.

seems that all pro-tecs will eventually be converted. Only a matter of time.

Nice carb actually.   I have one on my shelf, when I moved to a 4160.


Some, and me too have had a heat issue after shutoff, supposed to be hot enough to boil gas and create a vapor lock. Don't know if that was my exact problem, but changed it anyway.

Interesting thing about them, they will run with out the top.   Make sure you stop the pump. Some also claim, they give you a real seat of the pants feel of acceleration.

When I first bought my boat it had a 4010, upon researching I found a hot rodders forum, and it is an old out dated carb, NLA.

One of the things they were raving about is the ability to remove the top plate, I think there are 8 torx screws on top, and it will run....as long as the bowls are full. Never tried it, but it is an unusual carb that I had never seen, and read alot about it. Very simple design.

Not sure why anyone would do this, but that is what I read. Seems to me though, the fuel pump would be pumping, so you would have to stop the flow or you would have a mess of fuel.


Not sure what the main differences, they are two different carbs, 4010 the way to access the bowls is to remove the top, a 4160 the bowls mount to the side.

Actually I just found it, well close, designed from the 4010, which was designed from an old autolite.

here is the new design.

According to my information I read awhile back, they were somewhat problematic, vapor lock and some other issues but you'd have to google it, I just cannot remember. Might have been a power valve issue, like they kept blowing out.

Yours looks lots better than mine does, it's black with corrosion and probably junk. I did rebuild mine and I'd have to say it was very easy, compared to a Quadrajet.


Ok, one thing I do remember, if you ever remove the needle and seat, (the two opposite rusty screws on top of yours, under the screws) be very careful, and have a thread chaser handy.   Mine broke, they are brass and corroded together.