new motor problems. Help me!

[Huntdakota]

Hi all. ok i froze the old stock motor, enough said and done. Ordered a new motor online after a lot of research! Boat is a 2004 so I decided to get a complete motor. That is everything is on the motor, new 4 barrel carb, exhaust manifold and risers, as my old is 10 years old and just thought would be better to get new. Only parts we had to swap are the starter, power stering and altinator. they said the motor was in their words SIM tested....iguess that means they spin it and check for leaks and commpression before it leaves their shop. So got the new motor and installed it.... the only adjustments needed are on the timing and the carb. Set timing between 8-10 and now is at 9 adjusted carb as they sent directions, new 4 barrel turn each side screw until motor runs faster then turn back 1/4 turn did on both sides and seems to be correct. The motor by the way is a 4.3 vortec V6 We have checked the fuel pressure and is good. ok my problem is....The motor runs great and idles great!! purrs like a kitten! Now start to give it gas and it sputters back, I baby the gas as I give more throttle and backfire! Only thing we havent tried to replace and have on order is a new ignition module? Is this my problem? Someone help This is a brand new motor and spend to much money not to be working!!

 

[lonewolf41]

Timing sounds a little high. Mine, a 1998 4.3L V6, says 6 degrees with 89 octane and 1 degree with 87 octane. That coupled with a misadjusted carb would cause what you are seeing. Also, not sure about your model, but with mine, there is a timing shunt that you have to hook into the distributor to time it correctly. Make sure it is or is not required for yours.

 

[MikDee]

It sounds like a lean sneeze, check out your fuel supply, & filters for gunk, completely from Tank, to Carb!

 

[bruceb58]

Tagging onto Lonewolf's question, what distributor do you have on this?

 

[John2037]

Wires on right? Wrong order could cause this. Also the timing is prob wrong since the specs are for base timing, which usually requires an adapter to be plugged in - I guess you could do it by ear for now. Then it could also be too lean. I'd start with double checking the firing order, then timing (since it idles good) then readjust the carb settings more rich. 1-6-5-4-3-2

 

[Huntdakota]

wires are on right, came already wired and pluged in from the motor place. That being said I did double check to make sure they where right and in correct firring order! The company that built the motor said 8-10 degrees and its timed in at about 8 1/2 -9 That was done with the plug in the back of the dristibutor and then removed after timing was set. Carb is set correctly. Do you think I could have a bad ignition module? It seems like the timing doesnt change when rpm's get higher?

 

[Bondo]

Hi all. ok i froze the old stock motor, enough said and done. Ordered a new motor online after a lot of research! Boat is a 2004 so I decided to get a complete motor. That is everything is on the motor, new 4 barrel carb, exhaust manifold and risers, as my old is 10 years old and just thought would be better to get new. Only parts we had to swap are the starter, power stering and altinator. they said the motor was in their words SIM tested....iguess that means they spin it and check for leaks and commpression before it leaves their shop. So got the new motor and installed it.... the only adjustments needed are on the timing and the carb. Set timing between 8-10 and now is at 9 adjusted carb as they sent directions, new 4 barrel turn each side screw until motor runs faster then turn back 1/4 turn did on both sides and seems to be correct. The motor by the way is a 4.3 vortec V6 We have checked the fuel pressure and is good. ok my problem is....The motor runs great and idles great!! purrs like a kitten! Now start to give it gas and it sputters back, I baby the gas as I give more throttle and backfire! Only thing we havent tried to replace and have on order is a new ignition module? Is this my problem? Someone help This is a brand new motor and spend to much money not to be working!!

Ayuh,... Welcome Aboard,...... Check the accelerator pump on the carb, sounds like it's Lean,...

 

[bruceb58]

It seems like the timing doesnt change when rpm's get higher?

So you have observed this with a timing light?

 

[achris]

Are both idle mixture screws out about the same? If one is in most of the way and the other is out a long way to give the 'correct' mixture, it will lean out on the barrel that has the screw in too far as the throttle is opened (progression holes).... That can cause a 'lean pop'....

Chris.......

 

[Huntdakota]

ok all.....figured it out!! Called the comopany I bought the new motor from, said I cant get to run good and explained whats going on. Lady says it might be a faulty ignition module. Says we have had a bunch of bad ones lately!! Sends me one out for free, installed and viola!! no more pops and I have great power!