running on 7 cyl untill warm

[26aftcab454]

1996 7.4/bravoIII- carb
the boat takes several pumps & starts untill it fires( 3 min). It runs on 7 cyl for 15-20 min then the 8th cyl fires and does great after that rest of the day.

any ideas or suggestions appreciated.
thx-Joe

 

[Bt Doctur]

Re: running on 7 cyl untill warm

compression test to rule out a stuck valve,then look toward the ign, spark plug wire, sparkplug.

 

[GLENN M]

Re: running on 7 cyl untill warm

have you pulled plug and checked to see if oil fouled, could also be carboned up.try swapping sparkplug wire with a differant one,when was last tuneup.as stated eliminate systems one at a time compession test all these things you can do for free. goodluck!

 

[wire2]

Re: running on 7 cyl untill warm

To find which cylinder is slow coming on line; While it's running on 7, pull 1 pug wire at a time, then replace it, engine will stumble worse on 6, until you get to the dead cylinder, and no difference.

 

[Don S]

Re: running on 7 cyl untill warm

Faulty plug wire, spark plug, distributor cap can prevent a single cylinder from firing.
If you aren't sure it's just a single cylinder and your engine is just running rough when cold, then it could be a choke or even a carb adjustment problem.

 

[Bondo]

Re: running on 7 cyl untill warm

any ideas or suggestions

Ayuh,... Atleast a Tune Up,....

Do a Compression Test while yer at it...

 

[26aftcab454]

Re: running on 7 cyl untill warm

Thx Guys-- 75 degrees here today-& 0 -10mph winds---I plan to go down to the slip and see what I can see. I am over due a tune up and maint. Cash is tight right now and will have to wait on $$ items but I can check several things without spending anything.

 

[dan t.]

Re: running on 7 cyl untill warm

If you pull plug wires to isolate the miss make sure you pull them off the cap not the plug,unless you like a good jolt, easer yet is use a test light, ground the lead then slide the probe under the wire boot to short it out. Do NOT puncture the boot. The light will not flash, it just acts as a ground.

 

[26aftcab454]

Re: running on 7 cyl untill warm

Welp- I pulled the distributor cap off-looked good -but the rotor contact was a little dirty- scuffed it up with a brillo pad- secured the distributor cap back down tight- boat fired right up and ran on all 8cyl. warmed her up briefly while I put tool bucket away , cast off the dock lines and idled out of the no wake zone.I ran her up tp 4400rpms slicker than snot!. there is alot of slimy growth on the hull that needs to be removed probaly preventing the last 200 rpm.
I still need to really service her properly before it warms up. ( only 63 degrees today lol)

 

[GLENN M]

Re: running on 7 cyl until warm

Re: running on 7 cyl until warm

you gotta like those easy fixes,at least you know everything is working you can now give it the attention it needs.you cant let maintenance slide for very long before it bites you in the *** sorry pocket book

 

[telstar1]

Re: running on 7 cyl until warm

Re: running on 7 cyl until warm

Somehow I think you jostled something when you removed cap and thats why you got cyl 8 back. I guess anything is poss., but a little soot on the rotor would be a new one for me. Main thing is it works I guess.