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Crusader bogging down high rpm

1

1987Luhrs29

New member
Hello I have a 1987 Luhrs Tournament with twin 270 crusaders. Port motor is running fine but when cruising at around 3500 rpms after about 30 mins or so the starboard motor starts to lose rpms and fluctuate from around 3000 rpms back up to 3500 rpm. Then after a few minutes of this the rpms start to drop and will die if I don't lower the throttle. I tested pickup tubes spark plugs alternator and fuel filters. I put on a new coil and after putting on a new one I realized that when testing the voltage I am only getting around 3-6 volts. I have a new electronic ignition in it and no ballast resistor. Any help is appreciated
 
At this point in the troubleshooting process it is time totemporarily T in a pressure gauge between the fuel pump and carb/injectors tosee if there is a correlation between rpm loss and fuel pressure. I had asimilar issue with a 454. After a fewminutes of high rpm run time the line pressure slowly dropped from 9 psi to 4psi and the surging started. I then checkedthe voltage going to the fuel pump while running and noticed the voltage to thepump slowly dropped from 13 vdc to something like 6 vdc and again followed bythe surging. Turned out the relativelynew oil pressure switch that powers the fuel pump was defective. If your line pressure is in spec but theengine surges the fuel system is probably not the problem. Might monitor coil voltage while running toensure 13+ volts are there. If not, abad connection or faulty ignition switch may be a player. Please let us know what the problem was whenyou get it sorted out. Good Luck.
FL Panhandle

 
I'd be inclined to eliminate the voltage drop assuming the "3-6 volts" measured was VDC and between a good ground at the + terminal of the coil.

Also curiuos how the pickup tubes and fuel filters were tested...??
 
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