fuel problems on a 93 5.0lx

[crownline19]

93 crownline 5.olx merc. with a rocheter 4bbl. problems started with a carb. rebuild because it had been sitting a while and was running rough. hard starting ect. after carb.rebuild by an authorized and exp. mercruiser mechanic ran better but had a wot rpm that varied from 4,000 to 4,500 up and down up and down and then sometimes it would run fine. mechanic suggested fuel pump replacement. filters are new and tank is clean by the way. replaced fuel pump with brand new mercruiser pump. old pump looked terrible and appeared to be original one. started boat and carburator flooded over like crazy and ran gas all the way up and out of the vent tube. figured carb was shot replaced carb with reman one. 3 reman carbs later and the same problem i put the old fuel pump back on. started good and idled fine but falls on its *** when you open the throttle and then when it winds up still had the same wot rpm goin up and down. mechanic suggested it was that old fuel pump and the new one was defective that was flooding the carbs over and a fuel psi guage proved it b/c it was pumping 20 psi. mech. gave me a new pump but it was time to winterize so i waited until this month to replace. also had original carb rebuild again to mercruiser specs with new from merc jets metering rods float power piston needle and seat ect. installed carb and new fuel pump went to start boat and wouldnt hit a lick. no fire. figured out that there is some kind of switch on the shift linkage on the motor that if i wiggle it it will fire. got the engine to fire and it started right up. within 20 seconds carb went to flooding like hell. fuel psi guage proved once again the second new fuel pump pumping 20 psi............. need help guys im ready to burn this boat!!!!!!!

 

[crownline19]

Re: fuel problems on a 93 5.0lx

any suggestions

 

[zbnutcase]

Re: fuel problems on a 93 5.0lx

Of the inline electric fuel pumps there are 2 different ones that look identical;1 is high pressure for FI engines, the other low pressure for carb engines. Sounds like you have the wrong pump, have see this before. 'nutcase

 

[viper10000]

Re: fuel problems on a 93 5.0lx

Hey, I have a Mercruiser V-8 305 5.0LX with the Rochester 4bbl also. I realize this post was from last April but I am also having the same problem. I recently learned that the Rochester Quadrajet requires 4-6lbs of fuel pressure, 7 absolute max. Anything more and the float will not be able to keep the needle closed! I had replaced the fuel pump due to fuel finding its way into the oil, and now I cant keep the carb from loading up. I'm in the process of finding a fuel pressure gauge to test the pressure on this pump. Did you ever find the right fuel pump?