91 nautique excel will not throttle up under load

Well thanks for all the hep guys, I finally have a boat. The engine wasnt running right because of a fuel problem, I believe it was the anti siphon valve as it was dirty. But I did also change the fuel filter so it could of been that. The tranny issue was the previous owner had the linkage on the tranny wrong, when it was in gear, the pump was not working. I will create a new thread on how I swapped an 89 truck engine into a reverse rotation boat engine since I know know my problem was only fuel.

Shua4242 wrote: I believe my anti siphon valve is the culprit, I could not blew through it with my mouth, How hard are these supposed to be? I will get a new one tomorrow and take it to water to find out.

I have a new one on the workbench and I couldn't blow hard enough to unseat the ball.

If you take a little screwdriver and push on the ball, it should move very easily and the spring will reseat the ball when you remove the screwdriver.

A little hard to quantify "real easy" but hardly any force is required at all

Yes, I live in Ohio but right on the state line of Fort Wayne, Indiana

Years ago, I worked out a CCFan discount 20% - It may be worth asking. You go directly to WEMA............ If not, at least ask for free shipping.   

Since you'll have the rear bench out and the floor off, It is a good time to switch to a WEMA sender for that tank. (stick, rather than float arm). Measure to the tank bottom through the sender hole. Order a sender 1 inch shorter than the tank (11 inches IIRC for my Excel). They are worry-free and tame that big tank slosh better. Original gauge is 240-33 ohm American Stewart Warner type (Not European, 0-80 ohm).

Shua4242 wrote: I never knew there was a valve in the tank so I will pull the sender and check it. Thanks for the help guys.

Don't pull the sender, the anti siphon valve is external on top of the tank.

The hose to the fuel pump connects to the valve. unhook the hose and unscrew the valve.

Then you can see if it's plugged with debris.

It looks just like a barbed hose fitting, but there's a ball and spring inside of it

I had a professional rebuild the carb while I was rebuilding the engine, he told me how to adjust the air screws, I got the one side to adjust but the other side would not make a difference if I screwed the screw all the way in or out. I will check the coil.

So how's your carburetor?

Idle mixture screw adjustment good ?

Accelerator pump adjustment/clearance as it should be?

How's the anti siphon valve at the gas tank?

Shua4242 wrote: I just did the alignment, and it was already perfect.

I know the cam is correct as it was an original one with the factory motor

Years ago, before this site, when I rebuilt my HM 302 in the Mustang,I bought a reverse rotation cam from Crane. Used the firing order on the cam card and ran it in at 2k at the dock. Went to go for its first drive ran much like yours. Long story short the cam card showed the reverse 302 firing order when in fact they ground the cam to the reverse 351 order which is different. I had to pull the valve covers,turn it over by hand and watch the rockers in order to figure out what they did. Just saying.....

But what is the firing order?

People have screwed up their firing order,cylinder numbering, mixed up a couple of plug wires etc and had those same symptoms trying to accelerate which were magically cured when they realized it and then got it right

Here's a picture

Gary S wrote: Where are our Excel experts?? By that time frame '91 were they using right hand engines? By then most SN were using lefty's

Far from an Excel expert but they had RH engines at that time.

Here's an old thread Gary, complete with pictures

old thread

What's your firing order and have you double checked that the wires are run correctly?

At idle and on the trailer it sounds like it is running just fine, but when I try to set the timing, i cant quite get it to run at 10 degrees before tdc, it isn't happy there but will run if I adjust the idle speed up higher, and I did the rebuild because I bought it In the Fall last year and the previous owner did not winterize it right (the block was cracked) I did not know this until this spring when I took it to the lake and after aout 2 hours it was full of water. I used the block out of an 1989 ford truck with my camshaft and the truck bottom end, the truck motor only had 20,000 miles on it. The crank is drilled both directions so it can run in reverse. This is the same ignition system as last trip on the lake when the engine filled with water. (engine ran fine then)