Rough acceleration/vibration from 600-900 rpm 2700 SCR

[Luvdamaxums]

Hey All I am experiencing a rough acceleration/vibration and RPMs between six and 900 start up and plane. When I bought the boat it was repaired when broken but not maintained. So I went through and changed the plugs the wires, cap, rotor, electronic ignition sensor, fuel filter and did an oil change. When I inspected the parts they appeared to be original and the boat is a 1996. After replacing the ignition I noticed a rough acceleration between six and 900 and some hesitation, once It gets to 1000 RPMs it runs like a clock. Looking for insight? Does the new ignition change require timing to be adjusted? I did have to raise the idol afterwards as it was lower once everything was changed. Thanks Sean

[mmwjr]

The ignition sensor is not a normal maintenance item and typically only gets replaced upon failure. Ignition timing should always be checked/set after replacing any ignition component however improper timing should not cause a roughness. I would re-install the old ignition sensor to see if that clears things up. It would also be helpful to know the year and engine we are talking about.

[Luvdamaxums]

1996 7.4l

[Luvdamaxums]

The reason I replace sensor was it was very gasy at start up. I was told by a mechanic the new sensor corrects that which it did.

[shrew]

Moved from "Forum Support | Suggestion Box | News" to "Engines"

[mmwjr]

Originally Posted by Luvdamaxums

1996 7.4l

Yeah figured that out as I latter saw you said 1996 and its a 2700 which to my knowledge only came with the 7.4

[mmwjr]

Originally Posted by Luvdamaxums

The reason I replace sensor was it was very gasy at start up. I was told by a mechanic the new sensor corrects that which it did.

None the less I would put the old one in to see if it fixes the issue as even new parts can be bad. I believe the new ones have three wires where the old one only had two connections, is this how yours is?

[Luvdamaxums]

Originally Posted by mmwjr

None the less I would put the old one in to see if it fixes the issue as even new parts can be bad. I believe the new ones have three wires where the old one only had two connections, is this how yours is?

Yes it has 3 wires. Extra is a ground.

[gmc60]

I found my vibration came from some barnacles on forward prop 1600 rpm anything before or after was smooth .It must have thrown is out of balance. Bravo 3. It felt like motor was going bad on me.

[Luvdamaxums]

Good suggestion with prop but just changed mine to SS. So it is clean. Fresh water boat. I'm going to put old ignition sensor back in and check the choke operation. It's prob original1996 as well.