It is an 88 10th anniversary, stock with air bypass solenoid deleted(plastic tube broken and wires aged, hence I am plugging the vacuum connections). The last few weeks I was able to start and have the engine rev up to 6k rpm with light foot on the gas paddle, engine stalls once I am heavy on gas. And these couple days it doesn’t even want to start, it spins for few seconds then rpm drops to 0. I have visually checked all vacuum hoses and made sure intercooler has no leak, I have fuel pressure gauge near the oil filter and it shows 28 psi, too low? maybe the fuel pump doesn’t receive 12v? I was gonna jump the “yellow connector” near the pressure sensor like the manual said and see if I receive higher fuel pressure, but I wouldn’t locate the “yellow connector” instead I found these two connectors(red circle from attached pic, and they were connected), so I jumped both, turned on ignition, no response from fuel pump. Then I removed both jumpers and tried to start again, still cranks and engine ran for few seconds then rpm drops to 0. I turned off the car and waited about an hr, fuel pressure gauge showed 22 psi, which eliminates leaky fuel injectors.
Sorry about the poor writing skill, any advices would be welcome!

 

I can be lots of reseasons. Are you sure there is no vacuum leak? Did you check the compression? Also, check the throttle body

 

As if fuel pressure, the stock idle pressure should be around 27~29, WOT pressure should be 35+. 22psi is definitely too low

 

22 psi is after car shut off for about an hr. Ur right, would be many reasons. Let me go thru the vacuum lines and make sure plugs r getting proper spark first.

 

It has spark, both rotors has compression of 110psi under regular compression kit. The engine ran for few seconds then dies down regardless I hit the gas peddle, definitely has fuel spark and compression. Fuel pressure went up to 37-40 psi while engine was running during that few seconds. I am thinking there may be a large vacuum leak? Or faulty MAF?

 

The connectors in the picture are not for jumping. They are for your two emissions solenoids, which have likely been removed since they aren't connected. Those two connectors fit together, but don't plug them into each other. It can burn up part of your ECU (I have pictures of one). Best to block those connectors off. The connector that you need for the fuel pump is over by the MAP sensor. If you can't find it, look for a broken-off wire. It should be a single hole, female connector. Use a spade connector end on a wire, and ground it to the strut tower. Then key on the ignition and it should start pumping fuel.

 

Thank u pyroman, I will look for hat connector at the same time I am replacing all the vacuum hoses and injector grommet and o-rings. Hope it is vacuum leak issue.

 

SO I replaced all the vacuum lines and fuel injectors o-rings and grommets , and found out the oil injection vacuum line wasn’t plug in. After I reconnected everything, car starts and idles around 1100rpm, it will smoothly go up to 7k rpm if I gently press on the gas pedal, but it hesitates and back fires when I gas a bit faster. I had it idle for around 30 mins, idle stays steady and all. Then I shut it off for about an hour, restart again, I can hear the engine about to start then dies down, kept trying for few times l, same thing. I am clueless, any ideas?

 

Turned out it was flooded, I pulled all the plugs and purge the gas out, it starts again but still the the hesitate during fast gas paddle. I turned off the engine after 20 mins of idling, start right up again. Then I shut it off again, it won’t start, even I pull the plugs off and did the gas purge. I ran the compression test using regular compression gauge, shows 92psi from T2 hole and 95psi T1 hole. During the 20 mins idle I notice the air fuel ratio gauge shows lean(see pic below). Does anyone know what causes the starting and hesitate/back fire problem?

 

I am sending the fuel injectors our for cleaning.

 

Flooding is commonly caused by three things: weak compression, weak cranking ignition, and weak cranking speed.

The FC ignition system is pretty robust, but it never hurts to throw in new ignition leads and spark plugs.

Your compression seems fine.

i’d examine your cranking speed- replace the starter power feed and the main ground, upgrade
to a faster starter.

Mazda’s solution for the RX-8 flooding was to upgrade the starter. Its amazing the difference it makes.

 

Sent the plugs out for cleaning they told me it wasn’t that bad. Received the plugs and throw them back in, car wanted to start but dies down, tried around 10-20 times still the same, the turbo felt warm-hot I assume there was compression going on during the cranking. Maybe I should upgrade the starter and see, any suggestions? Other than the starter upgrade, I am running out of ideas.

 

I probably should get new plugs and wires before the starter upgrade, and try the MSD I had from the previous FC.

 

Sent fuel injectors our for cleaning I meant.

 

Turned out one of the vacuum line wasn’t plugged, it starts up now. Went out for a test drive, if I hard on gas, it cuts off, once I let go it accelerates a bit, same applies on first and second gear. Would that be ecu and pressure sensor?

 

Tested the tps, 1.5v to start with, went up to 4.95v when the tps Rod was fully extended, I believe the throttle plate is not fully opened when the tps Rod is fully extended, since the gas paddle is only about 40% down when I reach the 4.95v(tps rod fully extended). Should I adjust the tps to 1v to begin with?

 

I’m starting to think that the engine may have low compression, need a proper compression test kit to run the test.

 

Rear rotor

Front rotor
Cold test at 60F, gonna look at the CPS next.

 

The compression drops after the engine heats up. Looks like its time for a rebuild.

 

What is the minimum cold cranking pressure in order to start a rotary engine? Isn’t cold test gives lower reasons since all seals shrank

 

The whole engine expands and contracts. You will read lower compression when the engine is warm. That is why you don't hear of the dreaded cold start.

 

Found out one of the spark plug is bad, one fuel injector defective and the ignition 12v to all 4 injectors r disconnected somewhere. Hope these r the only problems. Will try to get her running again once the injectors arrive next week.

 

It runs now, but I Am having fuel cut problem whenever I am hard on gas pedal, both with load and without(on the road/idle). Any suggestion where I should look at?

 

“T” the secondary signal wire from ecu and connected to a test light, I was testing on the road, once the rpm past 3800, the test light didn’t blink, there’s no signal sending out from the ecu. Is it a bad ecu? Does the secondary kicks in only past 3800rpm or anytime during hard acceleration?
I will start another thread, but I will still check here periodically.