Port engine misses at 3000 rpm after warms up

[WILLOWBROOK]

My 1989 tournament 400 engine always start to miss at 3000 rpm's and slowly dies, but restarts and keeps on dying. If I let it cool for a few minutes is starts and runs great until it warms up again and dies. refitted new fuel lines, carb,filters 30 microns, water sep,carb filter,drained fuel tank and siphoned out fuel and flushed it, don't matter if tank is full or low, new cap rotor, wires, plugs,ignition module, new coil, timing set at spec. only the port engine does this, the starboard engine goes all day long not missing a beat.:banghead: help

[Douglas Fairchild]

Did you put a timing light on the engine. If not, do so, see if spark advances as engine revs increase. Also check to make sure spark is still there through out RPM range. How old are plugs? These problems are usually electrical. When circuit board heats up with engine temps the heat causes metal to expand causing loose connections. Also check your wiring, make sure no green gremlins (corrosion) is present in your connectors.

[Artcruise]

I had a similar problem with a 34 Searay I used to own with twin 454 Mercruisers. It turned out to be a pin hole leak in the oil cooler that sprayed on the underside of the distributer. Once the water got to the distributer the engine started to miss and then died. After about a half hour, it would start up again and run for another half hour or so and the same thing would repeat. The problem was you could not see the leak however if you put a paper towel between the distributer and the oil cooler it would get wet rather quickly.

Port engine went first, then the same thing occurred about six months later on the starboard engine. Replaced oil cooler and all was fine.

Hope it helps .

Art

[WILLOWBROOK]

I will check the timing again to see if it advances with the rpms. thanks, all is brand new, just bought two sets of everything for both engines. I did not replace the advance weights springs which were rusty at the time I replaced or repaired both engines. No one had replacement springs for my distributers when I rebuilt them.

[WILLOWBROOK]

I will check to see if there is any fluids reaching my distributer with the paper towel. Thank.

[WILLOWBROOK]

Timing has been set as indicated on the plate in the back of the block, new plugs,cap,rotor,wires,carb,coil,ignition module,new fuel filters. still quits when hot.

[WILLOWBROOK]

no oil on distributer

[Esquire]

What kind of engine do you have? Make, model, size?

[WILLOWBROOK]

Twin 1989 454 cuin 350 hp

[witeagle]

Are you getting fuel to the engine after it warms up? Maybe the carborator is choking itself out? I had this happen on my old camaro years ago....

[fishn luhrs]

have you checked the vents on your tanks. I had mud dobbers clog mine one time on a trailered boat.

[WILLOWBROOK]

Ifinally got the twin 454's to go to 4000 rpm without fail today. My original distributers were only going to 24 degree advance timing at 3000 rpm's.they were supposed to go to 36 degree advance timing at 3000 rpm's. I will have the bottom and props cleaned to see if the motors will go to 4400 rpm's. I bought the degree timing tape and installed them on both harmonic balancers and thats how I found the problem with the rpm's and speed. The boat is now going 23 miles per hour at 4000 RPM. What a difference and my idle is sweet and responsive at all rpm's. The timing degree tape is a great way to see if your distributers are working properly after you timed the engines. Also my problem with the port engine dying after it ran for a while was my anti siphon valves coming from the tank ball valves to the filters. They were the wrong size and they were not opening well enough to allow full fuel flow to the carbs. Hope this helps some one down the line who may have the same symtoms as I have.

[Esquire]

Where did you get your timing tape?

[WILLOWBROOK]

I went to my local Carquest and ordered the timing tape for a 8" harmonic balancer for a 454 ENGINE. That was a life saver for my motors and a great fuel saver for my pocket.