Sonett community forum

Intermittent engine problem V-4

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Hi Everyone,

Having an intermittent problem with 1968 Sonett V4 with Weber ICH. Only in 4th gear, during deceleration, the engine loses all power and will not take gas. This lasts a few seconds, then engine takes gas and runs fine. This happens 3-4 deceleration cycles in a row, then no problems for next 4-6 deceleration cycles. It feels like it is out of gas? Any ideas?

Thanks, Mark

 

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Are you using electric or mechanical fuel pump?

 

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Hello Fossman,

Thanks for you interest. I have a mechanical fuel pump. I installed it 12 year ago (only a few thousand miles in 12 years) with a clear fuel filter just before it. Filter was clean, but replaced anyway.

A little more info on the symptoms, car must be warmed up, approx 3 miles, before engine dies, it mostly dies during deceleration in 4th gear, but once in 3rd and a few times not decelerating.  When it dies, it is immediate, like someone turned the ignition off, then a few seconds later it just starts back up, just as immediate, no hesitations ever. When it dies, the tach seems to stay at whatever rpm's it was when it died, it does not drop to zero. The heater fan and gas gauge continue to work properly during this dead engine time. What I typically do to test, drive 3 miles to a freeway frontage road, drive a few more miles typically at 50 mph, the engine dies intermittently, then does not die the 3 miles home!

So far I have: swapped the coil and coil wire, added a 2nd ground to the distributor, replaced the Weber 34 ICH fuel shut off solenoid and wire to the coil, replaced the ignition switch, replaced the Petronix electronic ignition, replaced the engine to body ground strap, disconnected the tach/coil wire, checked (and still checking) wire connections everywhere in the car.

I am lost! Have no idea where to look next.

Mark

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Is the gasoline overheating? It is possible you need to raise the carburetor body up and provide more separation between the carb body and the engine. I have seem discussions on this before and people uses additional carb/engine gaskets or a phenolic plate between the carb and the engine to raise it about 1/4 - 3/8 inch. I have not tried this. But I am ready to add a 34ICH to my 1974 Sonett III so I would like to know about this.  An article comparing various carburetors for the V4 by Mike Szoskiewicz notes re the 34ICH: "Drivability is good with one exception. In warm conditions and stop and go traffic, heat soak builds up and boils the fuel in the float bowl resulting in stumbling and snorting for a few seconds." He also says once it cools down, it returns to normal. Hence the other discussion that calls for addition but minor separation between carb and engine. Good luck let know what you do.

 

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Hello Juan,

I added a 1/8" thick teflon spacer between carb and engine.

This small amount, 1/8", caused the air cleaner to rub on the bonnet (1968 year)

I had to remove the bonnet, elongate the "hinge" holes and adjust, a few times!

My engine dying problem seems to be solved, not positive what the problem actually was.

I installed an electric fuel pump, insulated the fuel lines, added the above teflon spacer,

(after much electrical troubleshooting and electrical parts replacement)

Thanks, Mark