5.7 gl high idle shake engine at switvh off

[SeaLord]

my 5.7 gl-a has only 130 hours. I have recently changed starter and work some new wires for bilge pumps and gps.
I have now 1100 RPM at idle and I try to screw in and out what it looks the carburetor mixture adjuster without any result.

Also when I switch off the engine (in neutral position) the ngine keeps going and shakes for a few seconds before turning off.

Any idea ?

 

[captmello]

Re: 5.7 gl high idle shake engine at switvh off

my 5.7 gl-a has only 130 hours. I have recently changed starter and work some new wires for bilge pumps and gps.
I have now 1100 RPM at idle and I try to screw in and out what it looks the carburetor mixture adjuster without any result.

Also when I switch off the engine (in neutral position) the ngine keeps going and shakes for a few seconds before turning off.

Any idea ?

Why are you adjusting the mixture screw and not the idle adjustment screw? If the Idle is too high it will cause the engine to run on. Sounds like the problems are related. Make sure the throttle is returning to the closed position and that the butterfly is closing at the same time.

It was idling normal previously? If so, retrace your steps...

 

[Fun Times]

Re: 5.7 gl high idle shake engine at switvh off

Maybe you somehow leaned on the throttle cable, connector, bracket, carburetor area bending something just enough to hold open the throttle while working on the engine.

You'll want to remove the cable from the carburetor to see if the idle will come back down on it's own and be sure the throttle bracket/stud on the carburetor is returning back to the idle position described by captmello above.

Also readjust the carburetor to specs with the cable disconnected. Then connect the cable to ensure everything still works normal.

Let us know what you come up with, good luck.

 

[SeaLord]

Re: 5.7 gl high idle shake engine at switvh off

Thank you all
Yes i had also screwed in and out the idle screw with no success and yes I checked the remote cable and it seemed to work normally.
By the way what are the specs Fun times talks about ? I even have the workshop manual that includes 5.7 gl-A model but there is not such an info.

Due to your insistance on the control cable I anyway decided to disassemble it from the carburetor. The butterfly seemed not to have moved and in fact..... engine started to obey to the idle regulator. Long story short I greases the cable ending and the butterfly spring and I have resumed normal 800 idle rpm. Fact is that a low rpm increase only takes less than 1/132" opening so you cannot really spot it visually. As suggested one needs to remove completely the cable from the equation. Lesson learned.

As mentioned I had changed the alternator. New belt. Then why does the belt slip when I accelerate ?
Also the GPS installation througthe fuse block was a failure since anytime I started the engine energi dran by the starter caused the GPS to power off (5 minute nd 5 clicks to reboot. I the decided to connect the GOS power to the battery direct leaving the ground attached to the fuse box. GPS now stays on even at ignition. I am only wondering whether a neater design may be applicable. What do you think ?

 

[Maclin]

Re: 5.7 gl high idle shake engine at switvh off

On the alternator belt, be sure you have the right size on the width. Too wide and it will not sit all the way into the pulley and also cannot make that sharp turn as easy on that small diameter pulley. Too narrow and it will bottom out and not get a full bite on the sides.

What does the wear on the belt show? Are threads showing on any of the layers?

Are you getting a lot of belt dust? If so then one or more pulleys may be rusty and need to be sanded and painted.

 

[Bondo]

Re: 5.7 gl high idle shake engine at switvh off

Thank you all


Due to your insistance on the control cable I anyway decided to disassemble it from the carburetor. The butterfly seemed not to have moved and in fact..... engine started to obey to the idle regulator. Long story short I greases the cable ending and the butterfly spring and I have resumed normal 800 idle rpm. Fact is that a low rpm increase only takes less than 1/132" opening so you cannot really spot it visually. As suggested one needs to remove completely the cable from the equation. Lesson learned.

Ayuh,.... Yer throttle cable should be adjusted so that it applies tiny bit of pressure, pushin' the throttle against the idle screw,...

 

[Fun Times]

Re: 5.7 gl high idle shake engine at switvh off

By the way what are the specs Fun times talks about ? I even have the workshop manual that includes 5.7 gl-A model but there is not such an info.

You'll also need the Volvo Penta 5.7 gl-a electrical, ignition, fuel, service manual for specific technical specifications.

 

[Walt T]

Re: 5.7 gl high idle shake engine at switvh off

Choke fast idle step probably got bumped on. Or distributor was moved

 

[SeaLord]

Re: 5.7 gl high idle shake engine at switvh off

Thank you Maclin.
About the size of the belt: belt is original spare from volvo and it has maybe 15 hours on. Problems came as soon as I replaced the alternator (that short circuited and repaired here in Tanzania waiting for a new one to come). The new alternator is aftermarket and guaranteed to replace the original volvo part but it is difficult to tell whether the belt sitting is the same. The belt has slipped a couple of times during acceleration (not all the times) so if there is no clear diagnosis of such a case I will try to tighten again and see occurrences.