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I’m at ViR today, did warmups and started feeling a weird vibration when higher speeds (95+) that when it came on the car was losing power, almost like a lost cylinder. Then the vibration disappeared and the engine came back to full power, it did it on the straights mainly. Then during the first session (still not pushing hard) it kept doing it again pretty frequently, then the engine cut completely. Any ideas where to start looking? Is that an indication of a fuel pump problem or maybe wiring? I have no idea. When I took the lid off the spark plug cover was loose (the 2 bolts had shaken off I guess). Don’t if that’s coincidence…

 

Any suggestions appreciated!

 

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Have you tried going upstream of the spark plug coils to where they connect to the harness?  A loose connection there would account for losing one or more cylinders due to vibration.

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Wiring looks good, no fraying, everything connected solid. There’s no gas smell coming out of exhaust when turning over. I think the fuel pump may be toast :( it did all of 1,300 miles, I guess it wasn’t designed for track days! 

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I'd take a look at the pins in that connector.  I say this from experience - from the factory I had a pin that wasn't properly seated so even though the connection was solid the electrical contact was not.

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Weird vibrations over 95 usually are tire out of balance.  However, you have matched them with engine revs/power output.  Dropping a cylinder is usually fairly mild vibration. Check if the coils on plugs are firmly seated - they can pop out.  Fuel pump usually has a priming whine before you click to ignition and turn the engine over - its noticeable even after start up - can you hear it?  May need a friend to stick his head in the boot to listen while you operate key.  If your boot floor can be removed easily then check a connection has not come off the fuel pump - easiest to come in from top of boot once floor is removed.

 

Fuel pump is a crappy in-tank one from Rover - quality was never good.  

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Thanks guys for the pointers. A mechanic took a look under the tank to listen for noise when I turned the car on. No noise at all. Took off the fuel hose - no fuel. 

The end of the last last track day I did run out of gas, which was a bit embarrassing, but maybe that caused some damage to the pump? Not sure if that can cause damage.

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Only mentioning it because it's so basic it's easy to overlook: have you checked the fuse and/or relay for the fuel pump?

 

-John

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Good idea, we checked fuses they are good. I'm currently on my 2nd beer so I think I'm done for the day :). Thanks for all the quick replies, you guys are awesome!

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Wish I could have joined you at VIR - love the track but have never driven it in the dry!

 

The in-tank pumps rely on gasoline around them to cool them.  They can overheat in a dry tank but they are supposed to self cut out if not pumping to prevent damage.

 

I suspect you did nothing wrong and the pump decided to expire on its own.  

 

Enjoy the beer!  :cheers2:

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It was the inertia switch that caused the cut off, I guess the ribbed curb on the exit of oak tree caused it to trip. That doesn't explain the vibration/loss of power still but at least the cutout is explained!

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I am laughing because the Caterham lot at NJMP have all had this happen at least once to them.  Me included.  You get towed in.  You look baffled.  Then a buddy walks up, clicks the roll over button and by magic everything is restored.  

 

Glad that was a nice quick resolution of that part of the problem.  Good luck with the vibration/loss of power...

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Yep.  Been there done that.  Sat in the infield at NJMP for a whole 25 minute session as it happened on the first lap of the session.  Croc was the guy with the shiteating grin, who came over an sorted it out.  I had the switch moved from under the bonnet to under dash on the drivers side so I could get to it on track if it ever happened again.  

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