mercruiser 5.0 tbi/efi pops above 3/4 throttle

[norcal racer]

i am working on a 1998 mercruiser 5.0 efi ( not dfi ) it had a fuel issue at first was not getting fuel. i replaced the high pressure cool fuel pump first helped but would only run a couple minutes and run out of fuel. i added a boost pump to supply fuel from tank to high pressure pump and that problem is solved. now the boat runs perfect up to 3/4 throttle i think its about 3500 rpm and then starts popping up through air cleaner, any thing below it will run clean and smooth all day. you can hammer the throttle to get on plane but after a short time it starts popping until you back off the throttle. i disconnected the tack wire just to see but did nothing to help. also i changed the two tbi injectors,cap,rotor,plugs did a fuel pressure test, hooked to merc scan tool and no codes checked the voltage on the tps and its fine. i am out of ideas

 

[norcal racer]

Re: mercruiser 5.0 tbi/efi pops above 3/4 throttle

just check plugs all look okay any ideas here thanks

 

[TilliamWe]

Re: mercruiser 5.0 tbi/efi pops above 3/4 throttle

Is the bottom of the boat dirty?
Have you done a compression check?
How's the ignition timing?

 

[norcal racer]

Re: mercruiser 5.0 tbi/efi pops above 3/4 throttle

i forgot to post the problem once resolved.we changed just about everything fuel related lots of cash later, ends up that the shift delay switch at higher rpms was fibrating enough to cause the intermitted popping. wow after all this part replacement i hope this helps the next guy before he spends a couple grand in parts/labor