Last night while driving the car started having a bad fueling issue under boost it wasnt richening up. At that point I attempted to cruise somewhere to park. Once parked after letting it sit and then trying to start the car was running extremely lean at iidle. 14.7 or so. Towed it to my shop and found the walboro had gotten weak. Replaced it with a known good pump and d3ad heading the pump gives me 70psi. Try and start it goes to fast idle and as it comes down it stumbles and dies. Fuel pump is running. Tested vaf per all data and seems okay. Have tried a second map sensor with the same result. Im at abit of a loss as it seems a feuling issue but dont know where to go next. Any advice is appreciated

 

Digging deeper. If I didnt mention it before. The VAF is fine. Bypassed the fuel pump relay/resistor box to see if that would help the situation. Nope. Started testing tps. Pins a to b at idle full warm 1k ohms. WOT 12k ohms. Thats out of spec. Same with a to c being out of spec. Wouldnt think the tps would have that much effect on idle or wot. But I have been known to be wrong about this car before...

 

Revisting again. Replaced tps. Issue is still present. Will be double checking the vaf tomorrow. Its the only thing that makes sense. Wish these cars would run without it.

 

Okay, so looking at the FSM. E2 to Vs should be 200-600 ohms. The FSM shows 2 E2's. So should both E2's read that? I have one that reads Open the other reads correctly. So have I found my always lean/hardly respond to throttle issue?

Go back over what I have done... Verified fuel pressure. Find it weak. Replaced with a brand new fuel pump, tested new pumps pressures. New pump pressure is correct (As far as I can tell. Dead heading the pump gives well over 70PSI. at idle pressure is 36psi if I remember correctly. Flow of new pump is good.) Bypassed fuel pump relay/resistor pack. Replaced faulty reading TPS, adjusted to spec.

Whats my next step? I have an 89 probe gt that the part number is coming back as the same on the flow meter so I am going to swap it over on moday and see how it runs then.

 

Without looking in the FSM isn't one for fully closed and the other fully open?

And did you check for error codes by chance?

 

Honestly? Skipped codes as it seemed fuel related and at the time the fuel pump was weak so I put one in it after the tests. I will check that as well on monday.

I've attached the diagram with the test I've been referencing so far for my checks with the diagram of the vaf. I'm abit off my game as its stumped me when what I first found wrong didnt fix it.

 

Compared the vaf to one off another car. Readings are the same. Swapping them has no effect. No codes with KOEO test. Removed upper intake and checked resistance of primary injectors. Both injectors are 2.4ohms. Spec is 1.5 to 3 ohms. They test fine. Will pull them up later this evening to check spary pattern.

 

Didnt get them up to check spray pattern. I am begining to believe that Ive killed the primary injectors. Full throttle and above 3k rpms its responsive. Just not enough to drive.

 

Gonna use the same logic we use when flying... keeping it simple, when was the last time you replaced your fuel filter? Any fuel leaks enroute to the engine? Not too much that would cause that drop in pressure if it was running fine before.

 

Replaced fuel filter 2 weeks ago. Thanks for the thought though. Noted in todays testing/checking. At WOT and above 3krpms when the secondary injectors are firing the car will rev as it should Still looks lean but will rev. All this started happening a week after I installed a FMIC. I went back through and recleaned the grounds that I had touched.

With it reving when the secondaries are firing I am going to swap them to the primaries and come up with a rig to see pulse width via a LED. Hopefully one of these two things will reveal my issue.

 

Injectors pulse. Injectors spary.... Map has correct powers an grounds. Signals out need to check fsm on signals out. Lookin like I might have lost the ecu

 

Burnt spots on the ecu. New ecu car starts and runs but looses injectors now and again so still a running issue. Vaf. Map boost sensor and tps control injectors in the ecu. What else does it?

 

You could have a poor connection within the primary injector plugs. There are two wires and both need to be making proper contact with the injector. The light Green injector wires at the ECU should have 12 volts w/key to on and this basically confirms the connection is good. Also, if the car just dies it might be because the wire which powers the injector w/key to on/start power is faulty and this comes from the main relay's Black/Yellow wire. If the car dies and key is left to the on position then this B/Y wire must still read 12 volts. If it does not then this is likely your issue.

 

Went to check the main relay and all checks okay. Car is starting and running minus cold start and BAC. Havent gone through those systems yet. It has a stumble at 2k rpms. Not going to dig too deep into that till I replace the upper intake manifold gasket.

Had to put a fresh set of plugs as they ended up fuel fouled. Found the screw in my orignal vaf that holds the screw to the potentiometer had come out. Car now starts and runs every time. Will update on monday when I do some testing of the cold start and bac.

 

Leaky injectors? Also Verify that the map sensor is in the right position (Flat not angled up or down) and make sure that the black side of the map is facing up so that the door opens sideways.

 

Just about every sensor, 02 sensor and intake air temp sensor are two sensors that haven't been mentioned

 

I know there is 1 issue with the air flow meter. The 2 pins farthest to the left read .2 ohms when it should be higher/open. opened the cover and made an arm for the air flow meter to correct that. didnt make a difference. put a new in the box reman airflow meter on it today and the car would not run at all. put the old air flow meter on it and the car runs and drives.

The airflow meter angle is not the best, but its been the way it is since the day I bought it. The IAT at the throttle valve is good. The O2 feedback sensor doesn't seem to make a difference either in how the car runs.

If the injectors were leaking the car would be running rich all the time. This is not the case saddly.

I need to get a 9 ohm resistor to check the response of the ecu for the coolant temp sensor on the back of the water pump housing.

 

I've now opened both what was good ecu and my old ecu. Both have burned resistor 961 to an open circuit. Following the trace it comes out of the ecu on 3D. Following the wiring diagram it goes to connector FEM-02.

Now anyone know where that connector is and what all it connects to?

 

So, somehow the fuel pump relay/resistor combo fried that leg of the ecu. Replaced the resistor at 961 with a 5 ohm 1/2 watt resistor and put the original ecu back in the car. starts runs, power has returned, still have a hicup at cold start. Not sure what the cause of it is other then the fact that the car is not richening up on cold start.

 

most likely high resistance in the circuit, the relays that power the fuel pump are known to have issues at this age.

 

The draw in coil side of the relay had 80ohms of resistance. Coils typically have resistance to them, but wasn't able to find a like relay to compare measurements let alone one to replace it with. The auto parts stores and Mazda looked at me funny. It is what it is, the whole thing has been wired out. I know the resistor box definetly didn't have any resistance through it, so it was shorted internally as well.