Hi I am having an annoying fault with my 1990 MX-5 Eunos. I use the car for track days and auto tests and it been great but has now developed a problem. In runs fine revs into the red then I come to a corner or after some heavy breaking I then put my foot on the throttle and it dies on me I take my foot off back on again and its is going again. I have changed the fuel filter that didn’t work so I removed the pump out of the tank and cleaned the fuel pick up filter it was ok for a while but now the problem has come back and it’s getting worse. When I drive it on the road normal driving conditions its fine but as soon as I put my foot down it sometimes starts dying on me and it’s doing it more often I drove over 100 miles on the motorway this morning and it was fine as soon as I got off the motorway and started going through the gears it started dyeing on me it’s just like fuel starvation just not sure if I am barking up the wrong tree ???

 

This car is 23 years old. It could be a lot of things. Is the check engine light on?

Check the ignition parts (plugs, wires, coil pack)
check the vacuum lines
Look for vacuum leaks
check throttle position sensor
check, clean the maf sensor
clean egr system.
Check fuel pressure
check fuel injectors
use a fuel system cleaner

Start with the inexpensive stuff.

 

Thanks for your reply i have changed the plugs when i serviced it a few months ago there are no warning lights on would the coil pack and leads affect the starting as one thing about this fault its never failed to start. you have give me somthing to go on. Cheers

 

How old is the fuel pump?
Have you checked the fuel pressure at the fuel rail & fuel flow rate?
How accurate is your fuel gauge?
How full is your fuel tank when it plays up?

 

This could be caused by a short ram intake. This is a cone filter under the hood which is not isolated from the engine heat. You are experiencing heat soak. Being a racer, i'm sure you have done something to the intake, but haven't told us.
However, i think you have more issues than heat soak which have already been stated as well as old O2 sensors!.
I do not have heat soak, as my intake is shielded from hot engine bay. I had a stumble in rpm's at around on the low rpm scale before i put my heat shield on, now no more stumble. My baffle is sealed to the hood.

 

Thanks for both your replies just to answer a few of your questions. I dont know how old the fuel pump is i am guessing its is the original which would make it 23 years old. the fuel gauge seems accurate enough and the problem seems worse as the fuel level goes down. i have not checked the fuel presure as i dont know what it should be or how to do it but i shall find out. with regards to the air filter you are right i have changed it for K/N filter (cone type) but have bolted it near the inner wing away from the exhaust manifold but i will put a shield like you surrgested to try and deflect the heat away. I am using it daily now and dont get any problems normal driving its only when i drive it hard which is why i think its fuel nor electrical.

 

My $ is on the fuel pump.

 

Mine was in same place when i got heat soak!
I didn't move it, I just put a heat shield on it.
When the rad fan kicks on, hot air is forced over to the air filter!
Heat shield makes a big difference. Make sure air can be accessed to where your filter is.

Just read that your fuel pump is 23 years old!LOL.

 

Just ordered a new fuel pump of ebay let you know how i get on when it arrives. Thanks Everyone !!!