engine lacking power
 

I've got an issue with one of my engines, they are 330's in my 89 Formula. One of the engines is lacking in power and I'm at a loss as to what the problem is. The issue is that the port engine is 200 rpms lower that the starboard engine from 2000 rpms up to about 3500, from 3500+ it gets wider up to about 400 rpms less at WTO. Some times I get a popping sound out of the carb and sometime the engine will surge 1000 RPMs up and down until I bring the throttles back. Today I had an issue where the above symptoms happened, then the engine stalled and I couldn't get it to run from more than a few seconds and that took some effort. I have a new cap and rotor and have rebuilt the carb. I'm at a loss here, what should I be looking at?

It could be a number of things or a combination of a few.

Ignition module, pick up module in the distributor, weak coil and a number of other things.
Do both engines pull fuel from the same tank????

I've swapped coils, so I know the coil is fine. As to the fuel it comes from one tank with two pick ups.

My 454 is doing similar, except it runs great untill i want to go wot, it will sometimes run to wot or it will get stock about 700-1000 rpm below then seem to get fuel and sprint to wot run there for various times then decide it wants to run slow again. Im goig to checkif its holding 7 psi at wot or if float bowls are going down, i run 3/8 id hose with a 750 holly

Endeavour32...did you have this problem before you rebuilt the carb ? Did the motor run good after you rebuilt the carb...and now this is happening out of the blue ? How old is your fuel pump ? Do you have a pressure gauge on it ? Change the water seperator lately ? Plug wires are in good shape, tied up nice and neat and all tight ? Just some ideas. :drink:

Pantera232...yours sounds like a fuel delivery problem. How old is your pump ? Did you get a chance to check the pressure ? Water seperator ? Fuel filter/filters ? 3/8th's line is plenty to keep those bowls full...if you are getting the fuel TO them. :drink:

I have a feeling the fuel pump may be bad but I want to make sure before I buy a new pump. I'm running the stock qjet carb and I can't figure a good way to check fuel pressue. On my Holley its easy.

The problem has been there since the first time I put the boat in the water. The carb rebuild didn't improve much. One carb was quite dirty the other not so much. I've not replaced the plug wires, I may try that today and see what happens. I change the water seperator/filter and nothing changed. I think it has to be either, fuel pump, wires, module. Its really all I have left to check.

Ok some additional tests today. Here are the results and what I think the problem is. swaped out ignition sensor in distributor-result: better spark! Tested another Tbolt ignition module- result: no change! Put in water boat ran great for 7-10 minutes. Hit 61 MPH backed off throttles and then the other engine started acting up. Same issue no power, engine would rev 2000-3000-2000. It did this for about 1-2 minutes then stalled and would not start... I checked carb and it was out of fuel. Fuel filter was fine. Tank vent, fine. Tank to filter hose- fine. I'm thinking its the fuel pumps. Both engines do the same thing but never at the same time, thank God! Is it possible for the fuel pumps to work intermittently? If so I think the pumps are bad. Opinions?

This is just my way of thinking....but when I got my boat...I changed everything I could. Thermostats...impellers...plugs..wires...fluids... coils...FUEL PUMPS...filters...etc. I didnt do it all at once, but had it all changed within a couple weeks. I keep a file on my computer of what I changed, part numbers, and when it was done. My point being..NOW I KNOW WHEN EVERYTHING WAS CHANGED, AND HOW NEW IT IS.

Just an example...those fuel pumps could be original...or if the motors were rebuilt, the shop coulda put some used ones back on (you might never know). You truthfully have no idea how many hours are on things unless you replace items yourself. Just my thinking. :drink:

After i change the entire distributer, im going out to test... I have two fuel pumps one electric and one belt driven.. I still had problem when i turned electric one on as well... But ill try running with no air filter.. and run up to speed and see what psi pressure its holding

Never heard of a mechanical fuel pump working intermittently. It almost sounds like the pickup tubes might be sucking air instead of fuel.

How much fuel is in the boat 1/4, 1/2, 3/4?? or more

That or the tank is not venting air in and its creating a vacuum.

Thats a good idea, all diff levels mainly at 1/4-1/2 lol
I can remove the fuel cap for a quick blast down the intercoastal

I was thinking the same thing about the vent...but he said he checked it. ???

My tank has 4 pick ups. I'm going to take the air compressor and blow air down them this morning and see what happens. I just blew down the fuel line with my lungs last night If the issue pops up again I'll try the other set of pick ups. Someday this things going to run right but I'm sure the issue is a fuel issue!

Aren't the tanks always vented
Where the fuel shoots out of sidebar boat, I just installed new distributer I have the 34 degreed timing now :)

Yes, they have vents, but that does not mean the vent tube did not get plugged somehow.

Why 4 pick ups????

Pull the pick up tube out, and make sure it does not have a crack in it. If the tubes cracked, it will pull air, and loose its prime once the level of the fuel gets down low enough.


Darrell.