Help!

[Tolly40]

try changing the spark plugs,they might be crabbing out under a load????

That would be a cheap fix if that is the problem. I will change them this weekend. Thank you!

 

[Tolly40]

Check for strength of spark coming out of coil tower while cranking. Or with engine idling, pull coil wire out of coil tower and see how far it can jump before engine stalls. Spark should jump at least 3/8" and engine still idle fine.

Focusing on spark right now as cylinder pressure goes up (add throttle) it requires more volts to jump the gap at the plugs. Weak spark will easily cause it to die under load.

Could still be fuel, but checking spark is cheap and easy. Just don't get bit!!!

It is beginning to sound like it may be an electrical issue. #1 Change Plugs #2 Replace coil #3 replace sparkplug wires? Sound reasonable?

 

[Tolly40]

Get rid of points and install electronic ignition....you'll love it.

Conall

Are you referring to an MSD distributor?

 

[Tolly40]

A fuel constriction sounds like the most reasonable explanation -- as distributor problems won't necessarily be restricted to whether the engine is under load. When the engine is under load, it uses more fuel, thus being more subject to failing if there was a fuel flow restriction.

The screen strainer at the fuel pick-up might be your culprit. You need to identify and eliminate sources of constriction systematically to trace the problem. As for the strainer in the tank, one thing you can do is run a line from a small tank (make sure it is approved for marine use) and connect it to the fuel intake port. Start your engine, place it in gear, and slowly increase throttle. You can most likely do this in your slip as long as your boat is well secured with dock lines and that your dock and cleats are in good shape.

If that doesn't eliminate the problem, look for any in-line strainers that might exist between your fuel tank and the fuel intake port. While it is not a normal practice for Crusader to supply or install these, they could have been placed there by the previous owner.

Also, check your fuel/water separator (if you have one). If there is water in there, it could cause a flow restriction.

Hope this helps.

Thank you for your advice. I like the idea of drawing from an auxiliary tank to eliminate the fuel pick up screen in the tank.

 

[ben2go]

It is beginning to sound like it may be an electrical issue. #1 Change Plugs #2 Replace coil #3 replace sparkplug wires? Sound reasonable?

Are you referring to an MSD distributor?

Plugs,plug wires,points/condenser,distributor cap,ignition rotor under distributor cap,and then coil if that doesn't make a difference.You can free rev to 4000rpm isn't a sign of a dead or dying coil.

Pertronix makes a kit that replaces points.Depending on the kit,you may have to remove the distributor.Either way,the ignition timing will need to be tuned to get the most of upgrade.I have done Pertronix kits on some sterndrive boats,cars,and trucks.They are extremely good and maintenance free once installed.I noticed a slight increase in fuel economy and all of my ignition parts lasted a little longer too.

Ignitor

 

[ben2go]

Another thing,has the valve lash been checked and adjusted?I had an old Honda motorcycle that acted in a similar way and it turned out to be a couple of the valves were out of adjustment.Maybe the lifters have bleed down if it has hydraulic lifters.I know this is grasping at straws but it's all I can do without having my hands on the engine.

 

[Capn Craig]

Somewhere near the tank there should be an anti siphon device. it is a check valve with a spring behind the check ball. It prevents the tank from siphoning itself into the bilge in the event of a leak. they do go bad sometimes. they shut off the fuel supply unless there is adequate suction crated by the fuel pump. it could be restricting fuel flow to a trickle.

 

[MyBad]

I remember reading this on the Tollycraft Classified site Tolly Classified - Special Information

Poor Engine Performance - If your Tollycraft is having poor engine performance it might be a good idea to check out the following: From as early as 1970 and as late as 1986, the fuel pick up tube had a small screen at the end . (See photo #1) It is possible for this screen to become plugged with contaminates in the fuel and cause poor engine performance or even shut down the engine.

Photo #1​

We have heard of some cases where a motor is running well and suddenly looses power and in some cases stops only to be restarted an hour or so later and run fine. This could be caused by the contaminates being washed away from the screen by the motion of the fuel in the tank. It is possible a competent mechanic could misread the engine symptoms as a bad carburetor, bad spark plugs or even bad fuel. To alleviate the problem simply remove the screen. (See photo #2) Most Tollys do not have a provision for removing the fuel pick up tube. If you suspect this could be a problem with your vessel, we suggest you take it to a competent repair yard or marine mechanic.

Photo #2

​

MB

 

[Capt.Bill11]

If it was me, before I started to tear into the ignition system, I too would hook up an external gas tank, say like a 6 gal outboard tank, and see how the engine behaves running on that.

 

[Pierce]

I believe there may also be a screen at the fuel line connection point on the carburetor. Something to check.

 

[Forkliftt]

If it was me, before I started to tear into the ignition system, I too would hook up an external gas tank, say like a 6 gal outboard tank, and see how the engine behaves running on that.

Good plan, and before I disassembled or "disturbed" any more of the systems I would try to isolate the problem. The last thing you want is for it to just go away after shaking some wiring. You won't know when it might come back.
We keep these spark testers on our service vans. You may want to get one of these, set the gap at 1/4" since you still have points (1/2" for electronic), put the alligator clip on the top of an easy to reach spark plug and slip the plug wire on the other end.
Start the engine and reference the color and size of the ignition spark, then increase the RPMs in neutral to confirm the color and size of the spark stay the same. Repeat the test in gear, and this should tell you if the ignition system is holding up, or that you have found a problem in the ignition system. Good luck! Keep is informed. Napa or OReilly should carry these.


1983 Present 42 Sundeck
Twin Lehman 135's

 

[LWW]

Any news on the engine problem.Larry