backfiring

WANIAC

Cadet
Joined
Aug 2, 2007
Messages
13
I have a 1996 chaparral 1930ss with a 5.0 mercruiser with thunderbolt ign. My problem is that it is bogging past 1200 R.P.M. I rebuilt carb ,replaced water seperator,rpl coil,Cap,wires,plugs,rotor,sensor in dist. And still bogging out. I found that the dist was loose but snug I could turn it by hand. I set it at 8 deg BTDC and now it just back fires . It is carburated with a mercruiser 2-barrel. Any ideas of what to do next?
 

DayCruiser

Ensign
Joined
Sep 24, 2004
Messages
953
Re: backfiring

Have you checked the water seperator for water? May have water in it and you need to empty it and reinstall. Keep on doing that until there is no more water. May not be your problem. Just one idea. Could be old gas too
 

PondTunes

Petty Officer 1st Class
Joined
Jun 7, 2007
Messages
387
Re: backfiring

If the dist was loose your timing is probably off, sounds like perhaps its too far retarded to crank now, try advancing the timing until you get proper operation.
 

WANIAC

Cadet
Joined
Aug 2, 2007
Messages
13
Re: backfiring

New gas and new seperator. Ran 6 tanks thru this summer before i started having problem. it started off slow and then got to where i can not go over 1200RPM. But I will pull seperator to see. Thanks
 

bomar76

Lieutenant Commander
Joined
Jun 27, 2002
Messages
1,963
Re: backfiring

A few ideas:
Crossed plug wires
FUBARED rotor and or cap
Misadvenure on carb rebuild
Engine was wildly of of time due to loose distributor and detoation caused piston/valve damage
Loads of water STILL in fuel

I'm guessing the last one.....you got a sh!tload of water in somehow.
 

Limited-Time

Vice Admiral
Joined
Mar 30, 2005
Messages
5,820
Re: backfiring

I have a 1996 chaparral 1930ss with a 5.0 mercruiser with thunderbolt ign. My problem is that it is bogging past 1200 R.P.M. I rebuilt carb ,replaced water seperator,rpl coil,Cap,wires,plugs,rotor,sensor in dist. And still bogging out. I found that the dist was loose but snug I could turn it by hand. I set it at 8 deg BTDC and now it just back fires . It is carburated with a mercruiser 2-barrel. Any ideas of what to do next?

TBIV or TBV ing. If it's the TBV (should be in 96)you must put the ing system in base timing mode to correctly set it. That may explain the backfiring.
 

WANIAC

Cadet
Joined
Aug 2, 2007
Messages
13
Re: backfiring

I finally got around to reseting the timming And it runs without backfiring . Ran into another problem. While working on timming muffs came off lower unit and it got hot . I replaced impeller in lower unit {alpa 1 Gen 1 } but it is still getting hot. Am I supose to put water in the motor to prime the system or do I have something else going on ? Any help will be greatly apreciated .
 

95yj

Petty Officer 1st Class
Joined
Feb 21, 2007
Messages
279
Re: backfiring

No priming. How bad was the old impeller? If it burned up and came apart, you might have pieces of it restricting the flow of water. How's the stream of water coming out of the transom while on the muffs?
 

WANIAC

Cadet
Joined
Aug 2, 2007
Messages
13
Re: backfiring

Old impeller did not burn up that bad . But I will pull boat out of garage and check the flow. Will keep posted .
 

rock&reel

Cadet
Joined
May 31, 2010
Messages
23
backfiring at 3000 rpm on just rebuild volvo aq125a 1988

backfiring at 3000 rpm on just rebuild volvo aq125a 1988

aq125
 
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