8 replies to this topic

[danielmo]

I recently purchased a 1991 Spec Miata 1.6 that had been in a wall banging incident. The car has been repaired now. The engine idles and revs just fine in a no load situation (stationary), but if you attempt to drive it for more than a few feet or even attempt to back up or move forward and quickly put on the brakes, the revs start to drop and eventually the engine dies. Sometimes you can feather the gas to keep it running, but not always. I had an extra AFM that I swapped in, but it made no difference. I'm new to the Miata and not so familiar with electronics and fuel injection. Sure would like to get it running reliably so I can get it on the track for the first time. Any suggestions for what else to check? Thanks in advance for any help. -Dan

[Jason J Ball]

Sounds like the fuel pump switch in the AFM turning the fuel pump off. If you have a spare AFM, swap it out and see if it fixes the problem.

[Jason J Ball]

Guess I should've read the whole post! Ignore that

[Keith Novak]

A couple people earlier this year tracked down the same symptoms to something coming loose in the fuel tank and preventing fuel pickup. I had the same symptoms myself but it magically went away. (Which reminds me...I need to look in my fuel tank.)

[Bench Racer]

Check the fuel pressure from the pump input to the fuel rail. Not down stream from the regulator. I had a fuel issue where if I touched the gas pedal the motor would kill. Got the pressure up to FSM spec & issue was gone.

[Jim Boemler]

I had a similar problem once, which turned out to be an intermittent connection (the MAF sensor wire) at the ECU connector. After I twisted all the pins for greater contact pressure, it was fine. The behavior does sound like bad MAF connection, but it doesn't have to be at, or inside, the MAF itself.

[danielmo]

The bulk of the impact was at the RR corner, so something loose in the tank could be an issue. Do you mean like a fuel pick up? I'll check electrical connections and fuel pressure as well. Thanks.

[Keith Novak]

It was actually one of the baffles in the tank that came loose. Here's the thread:
http://mazdaracers.c...p?showtopic=959

Looking at it again, there are a number of ways people have had similar problems.

[Bruce Wilson]

100% agree with Jim (clown) A connection between AFM and ECU has been disrupted.

-bw