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RPM gauge flutter ?

B

Blackfin27

Contributing Member
RPM Port gauge bouncing up and down. Engine seems to be smooth and not missing.

What would be the source of this, gauge is pretty new this winter.
 
Check the main feed wire behind the tach. My port tach was acting the same way and found the nut holding the wire to the tach was loose.
 
Today I had a backfire on the engine with the gauge flutter. Mainly seems to be bouncing while accelerating and then settles in for the most part. Im not hearing any missing though.
In view of the back fire, could there be another related cause to the gauge flutter? We checked the contact on the VDO gauges and they seem tight.
 
Blackfin27 said:
Today I had a backfire on the engine with the gauge flutter. Mainly seems to be bouncing while accelerating and then settles in for the most part. Im not hearing any missing though.
In view of the back fire, could there be another related cause to the gauge flutter? We checked the contact on the VDO gauges and they seem tight.[/QUOTE
The plot thickens! Depending on the type of ignition system you have, the backfire along with the gauge flutter/bouncing may be an indicator of a bad or faulty spark plug or coil wire. I'm no expert, but you may wanna set aside some time to visually look everything over.
Click to expand...
 
Couldn't it also be caused by fuel starvation or bad fuel? Fuel filters been replaced recently? Check the anti-siphon valve...could have some debris in it causing a partial clog.
 
Bob H. said:
Blackfin27 said:
Today I had a backfire on the engine with the gauge flutter. Mainly seems to be bouncing while accelerating and then settles in for the most part. Im not hearing any missing though.
In view of the back fire, could there be another related cause to the gauge flutter? We checked the contact on the VDO gauges and they seem tight.[/QUOTE
The plot thickens! Depending on the type of ignition system you have, the backfire along with the gauge flutter/bouncing may be an indicator of a bad or faulty spark plug or coil wire. I'm no expert, but you may wanna set aside some time to visually look everything over.
Click to expand...

So I wanted to report back as I have found this site very helpful. We changed out the distributor with a fresh new GM kit and issue resolved. So both engines with different 'gremlins' are now smooth. The pick up coil seemed to be the culprit in both cases but with original 1997 hang-ons the new Distributor kits took care of it. I should have done it sooner!
Click to expand...
 
Blackfin27 said:
Bob H. said:
So I wanted to report back as I have found this site very helpful. We changed out the distributor with a fresh new GM kit and issue resolved. So both engines with different 'gremlins' are now smooth. The pick up coil seemed to be the culprit in both cases but with original 1997 hang-ons the new Distributor kits took care of it. I should have done it sooner!
Click to expand...

Glad to read this! Simple fixes are the best.
Click to expand...
 
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