Engine losing power

[MOBILEMERCMAN]

Check your pick up tubes before you install the rebuilt engine. Don't assume anything.. Nothing is worse then fixing the same thing twice.

[Xtreme Air]

nothing in pick up tubes. replaced #6 exhaust valve and put in two new billet fuel pumps and guages. fuel pressure is good at7lbs at idle and 6lbs at running. Once again engine got up to 2000 rpm before port motors rpms fell off. Getting frustrated now and I know the engine builder is also.Next move is taking engine out and putting it on dyno. Don't know what else to do.

[MOBILEMERCMAN]

So fuel pressure is stable during power loss? Are all other gauges normal? Did you try disconnecting the tach? Have you tried a jumper lead to the ignition on the engine? Can you check to see if the timing is stable during power loss? I hate phantom problems...Good luck.

[fixxxer22]

good fuel pressure... low volume?

[Xtreme Air]

So fuel pressure is stable during power loss? Are all other gauges normal? Did you try disconnecting the tach? Have you tried a jumper lead to the ignition on the engine? Can you check to see if the timing is stable during power loss? I hate phantom problems...Good luck.

Yes, fuel pressure stays the same. I did try diconnecting the tach. I have not tried a jumper lead to the ignition yet. Timming has been checked and seems to be fine. This one is driving me nuts. I will now be going on week #3 and in NJ our summers are too short to have this kind of problem. Thanks for your advice. I will try jumping ignition

[Griswald]

will it rev out of gear?

[Xtreme Air]

will it rev out of gear?

Yes, but seems a little sluggish..

[stevesxm]

good fuel pressure... low volume?

can't be... if the pump or the float bowl runs out of fuel, the press goes to zero. i think i would shoot a timing lite at it ... if it was retarded like crazy it would do this...

[fixxxer22]

can't be... if the pump or the float bowl runs out of fuel, the press goes to zero. i think i would shoot a timing lite at it ... if it was retarded like crazy it would do this...

good point didnt think of that

[Xtreme Air]

Found the problem... Switched Tachs and the engine giving me trouble, came to life. The other engine developed the same problems the previous engine did. Seems the tach was bad and causing some sort of short. Brand new Livorsi guages..... Well looks like I'll be back boating this weekend. Once again thanks to everyone for all your input... Have a GREAT boating season and be safe..

[MOBILEMERCMAN]

Great,, Thanks for following up with the answer to your problem

[MacGyver]

Found the problem... Switched Tachs and the engine giving me trouble, came to life. The other engine developed the same problems the previous engine did. Seems the tach was bad and causing some sort of short. Brand new Livorsi guages..... Well looks like I'll be back boating this weekend. Once again thanks to everyone for all your input... Have a GREAT boating season and be safe..

WOW, I'd never expect a bad tach to cause this kind of trouble. Thanks for keeping informed.

[Bear442]

hate to sound stupid, do you have exhaust sensors, My bud Big Block has a bad senor..that did it///

[Xtreme Air]

hate to sound stupid, do you have exhaust sensors, My bud Big Block has a bad senor..that did it///

No exhaust sensors. Just went through every thing else. Engines always sounded fine. Swithced the tachs and bingo! that was it. Ran boat yesterday and all was well. Put in the old gaffrig guages and every thing seems to be working fine.