engine won't go past 2800 rpm

Here we go-
I have 78 twin Crusader w/re built engines in 2006-prestolite elect distributors etc. maybe 300 hrs total on them.new fuel tank-new filters-re built carb-new fuel pump-new spark plugs scuba cleand bottom two weeks ago..I replaced the elect module in the dist 18 months ago because of the same problem and it ran fine for a year -now the same symptom,before I buy another module and coil and just throw money at it.I post here.any suggestions as to why the newer module would go bad (if in fact that is the problem)???
Ps the other engine has the original module from 2006 -which was replaced with in a few weeks of the re-build because it went bad back then but it still runs good.have at it guys.

some products are of higher quality than others...

Sometimes the part selected isn't the best for the application....sometimes the directions aren't followed.

I'd suggest reviewing the instructions and making sure no corners were cut...

Jac, if all else is up to snuff........ fuel system, fuel delivery system, cylinder pressures, ignition spark quality, etc, etc,.... consider checking your ignition's progressive advance.

Mark off your harmonic balancer up to approx 35* to the advance side of TDC.

This process will the same for either a Std LH or Rev RH rotation engine, with the Rev RH being marked off in the opposite direction.

With your timing light connected, start the engine and set your BASE advance.
Bring your RPM up, and strobe the timing marks in increments of lets say 250 rpm.

Write this info down in graph form... similar to this curve graph below.

NOTE: this is an example image ONLY... not to be used for your engines.



Compare this to your OEM Crusader ignition specs.

NOTE: Most all Marine curve graphs will be minus BASE or Initial advance in the vertical scale to the left.
However, as you strobe your timing marks dynamically, BASE or Initial cannot help but to be included.

So when comparing your actual dynamic numbers to the OEM curve graph, BASE must be added to the OEM graph curve values.


If your ignition system is not delivering the correct progressive and TA, your engine's performance will suffer.



.

also I noticed that the tach in upper station for that engine -which I replaced a few yrs ago seems to go hay wire during all this could it be the cause as in a short or just showing the symptom???The lower station tach for the engine remains stable during all this.

jac said:

also I noticed that the tach in upper station for that engine -which I replaced a few yrs ago seems to go hay wire during all this could it be the cause as in a short or just showing the symptom???The lower station tach for the engine remains stable during all this.

Click to expand...

Jac, somewhere within your Hull Harness and/or your Engine Harness/Hull Harness interface, will be a connection(s) or connector(s).
All of your helm and engine data circuits will be in this harness, including the tachometer circuit.
Try pulling the connector(s) apart, and looking at the terminal connecting pins.


.

rick
the wire harness seem to be hard wired all the way to the up and lower stations except for a terminal block in the engine compartment.the only connector I have is in the back of the tach -a 3 pronged deal which slides off 3 scewed posts attached to the tach (faria) easy to remove-if I remove these and dis able the upper station tach and run the boat **if the symptom disappears is it in the tach or wiring maybe??

OK..... then look to see where your upper helm and lower helm harnesses join in parallel.
These are typically always in parallel with each other, so somewhere there is a junction.

We go from the engine to a terminal strip installed when they did the new engines in 2006.then out from there to the original wiring group and over to the lower station (keys plus starter button and toggle switch for lower or upper starting.then it seems out from the lower to the upper station.where there are a set of gauges for each engine including a toggle switch to be able to start from either upper or lower(no key switch up top just a starter button etc.(for some reason the engine wont turn over from the upper station starboard the troublesome one ) will turn over the port engine just fine.push button for upper is new.I do not see a place where the harness can be pulled apart .but why would the tach go bonkers like that at that rpm??and not at the lower tach for that engine??

could be the upper tach....most tach's have a "CYL" selector on them....try rotating that switch a few time to "clean" off any debris on its contacts...

You can always disconnect the suspect tach...another option is to switch them from side to side and see if the issue follows the tach; if it does, a replacement may be in order.