6 replies to this topic

[jswitzer360]

Hey guys so I finally decided on a 1990 Miata... It test drove fine it drove fine on the way home but I did notice some kind of hesitation at lower rpms... I parked it for two days without driving it and when I walked out and started to fiddle with it I found a small puddle of gas on the ground I looked under the car and its coming from the rear you can see wet fuel clearly under the car.. Kinda wonder what's leaking?.. Im wondering if this is the source of the hesitation? I don't think its the small crank nose issue I looked at the crank pulley and there's no wobble what so ever... I'm just kinda confused and don't wanna start throwing every part in the book at it

[Bench Racer]

Chase the leak to  it's origin. The fuel tank has a hex shaped plug with a sealing washer for draining the fuel tank. If the leak is at the plug don't go nuts tightening the plug. It would be wiser to gently loosen the plug. Drain pan required. The fuel filter is inside the right rear tire ahead of the axle behind a plastic cover.

[Ron Alan]

What Bench said. FYI...If its an original 90 motor...it is a short nose crank. Long nose started coming out mid 91 I believe.

[davew]

This is in my book, but...

 

Short nose cranks have 4 slots in the crank pulley, long nosers have 8 slots.

 

Dave

[jswitzer360]

yes im aware of how to identify a short nose crank and I do have the short nose all I was saying is that there is no wobble on the crank pulley so I figured the keyway is still good? or should I pull it off and really look?  and the leak is coming from the rear drivers side ill have to lift her up in the air to get a really good look.. as far as the fuel filter I was already planning on changing it and giving everything a good tune up... and I was planning on swapping the motor out with a long nose with less miles.. anyone know of any good places to pick up a strong motor that's not exactly a race motor but still strong?

[Alberto]

yes im aware of how to identify a short nose crank and I do have the short nose all I was saying is that there is no wobble on the crank pulley so I figured the keyway is still good? or should I pull it off and really look?  and the leak is coming from the rear drivers side ill have to lift her up in the air to get a really good look.. as far as the fuel filter I was already planning on changing it and giving everything a good tune up... and I was planning on swapping the motor out with a long nose with less miles.. anyone know of any good places to pick up a strong motor that's not exactly a race motor but still strong?

 

 

Can't hurt to have a look.  Gives you the opportunity to inventory how the crank looks, ensure the belts are good, replace any leaking oil seals and make sure everything is tight and correct.  

 

Through pure dumb luck, I decided to switch out the 180k SNC motor and tired transmission from my 90 with a low mileage, big nose motor and transmission from a 91.  I basically did it b/c the price on the newer motor was great and I knew the guy selling it.  The dumb luck parts comes 3 years later when I go to dis-assemble the SNC motor and realize that the pulley bolt was hand tight and the keyway was starting to show wear b/c the bolt had loosened up.  If I had left the original SNC motor in the car w/o checking the pulley and keyway, that pulley would have started wobbling and hurt the motor during a race and I would have been out and entry fee.

 

 

Regarding the fuel leak, take a look at the fuel filter, hoses and clamps and replace as needed.  I believe you can test the fuel system for leaks by pressurizing it.  Run a wire between Ground and Ten (iirc)? at the diagnostic box to activate the fuel pump and then looking for a leak. 

[jswitzer360]

Can't hurt to have a look.  Gives you the opportunity to inventory how the crank looks, ensure the belts are good, replace any leaking oil seals and make sure everything is tight and correct.  
 
Through pure dumb luck, I decided to switch out the 180k SNC motor and tired transmission from my 90 with a low mileage, big nose motor and transmission from a 91.  I basically did it b/c the price on the newer motor was great and I knew the guy selling it.  The dumb luck parts comes 3 years later when I go to dis-assemble the SNC motor and realize that the pulley bolt was hand tight and the keyway was starting to show wear b/c the bolt had loosened up.  If I had left the original SNC motor in the car w/o checking the pulley and keyway, that pulley would have started wobbling and hurt the motor during a race and I would have been out and entry fee.
 
 
Regarding the fuel leak, take a look at the fuel filter, hoses and clamps and replace as needed.  I believe you can test the fuel system for leaks by pressurizing it.  Run a wire between Ground and Ten (iirc)? at the diagnostic box to activate the fuel pump and then looking for a leak.

Will do tomorrow I figured I should look just to be sure anyways I've heard all the bad stories bout them... Thnx guys