Im a so please be easy on me...Ok well i have a 93 mb fd and it wont run , big suprise right....anyways .Its getting spark and fuel to the fuel rail but it wont start unless i spray starting fluid..the car runs perfect when spraying (i dont spay alot or run it for a long time) please help.

JUST SOME QUESTIONS?

1.Where is my main fuel relay?
2.Is their anyway i can test the fuel system without pulling the injectors.
3.Where is the fuel pressure regulator?
4.Where is the injector relay?

Thanks alot.

 

there is a manual in the first sticky, first thread that will help answer these questions. F section.
I wouldn't spray starting fluid to start these rotaries for fear of detonation, breaking an apex seal.
1. prime your fuel system by jumping a small wire between the F/P to GND in the diagnostic box located on the driverside fender with key on. you should hear the fuel pump
2. test fuel system, how completely? don't have to pull injectors, but nearly everything else to get to them.
3. end of fuel rail
4. i don't know where the injector relay is but sounds like a plan to check the voltage and operation there first.

 

Thanks ill try that tomorrow....

 

The injectors all ground through the main relay.

Dave

 

If it will run with the starting fluid then your not getting fuel from the injectors. Danny's deffinately on the right path with fuel system troubleshooting. Good luck, Jack

 

Where is the main relay at?

 

How long with your car?

Did you see some check engine light before the problem?

Try to pull an error code from the ECU.


good luck.

 

this is a car that he has never driven, this car was almost a total loss. We bought the car and have been rebuilding it from the bottom up. Well most of the engine compartment was all there. Now after about a month of putting the car back together it wont start. I have searched and if any one has any other idea let me know.

here are some befor pisc.

 

The main relay is in the box just aft of the battery - er, wait! you need a battery to start the car!!!

Actually it's labeled EGI Main relay.

As for the fuel questions: I agree - first make sure it's getting fuel. These injectors like to clog and stick, so try using a few volts (like a 9v battery) across the injector wiring to see that they click.

Dave

 

I thought it might be the fuel pump so i installed a new one and nothing changed so tomorrow im gonna pull the uim and replace all the injectors for the heck of it. and maybe the fuel rails... Its not going to cost me anything to replace them and i have the time...I have the parts extra... We have looked all over for a disconected clip or loose wire but havent found anything.

HELP!!!!!!!!

 

well if its not the pump and you dont have a pool of fuel on the floor it must be electrical.

check your relays.

 

If I press the gas padel all the way down and try to start the car up, it will do the same thing. In the owner's manual say with the gas padel floored. it will cut fuel to the engine. this is to deflood your engine in case you have a slightly flooded engine.
So I hope you are not mashing or pumping the gas padel to try to get it started. If you are then you are cutting your own fuel supply..

chino

 

Yeah we know more than that I've been working on these cars for about 4 years. Its just that there are only 2 reasons a car wont start. No fuel or no fire. The car has fire as it started on starter fluid. It also has fuel pressure to the fuel rail. I lossened one of the banjo bolts and when we turned the car over it sprayed fuel every where. Which I then had to clean up. So the problem is some where in the electrical going to the fuel injectors. Or the fuel injectors.

 

I like the idea of replacing the injectors. I do not like the idea of using injectors that were laying around. Send them out to RC or somewhere that can clean, test, and validate right before you install them in the car. It's a horrible thing to do all that work and have the injectors not work right, especially since the injectors on this car are so fidgety.

Dave

 

We have a car that is a parts car but it runs you can start it up. And it was a nice runner with a good boost pattern and all untill it was hit by a stupid truck a few weeks ago. So hes just going to swap them out for now and we can send the ones from his car to be rebulit by RC or witchhunter. We will just keep swaping over parts till it runs i guess.

 

I would still never take the time to install any injectors without them being cleaned. If they're out of the car, they get cleaned and/or tested before going back in. Learned that the hard way.

Dave

 

I like to be confident in the injectors too.

If you are interested in checking the injectors quickly: to give yourself some working room, remove the rail, add some longer lengths of fuel injector hose and reconnect them to the rail and line. aim an injector to a container and hit it w/12v, compare the spray.

But, you'll need your fuel pump working as you have to jump f/p to gnd.

 

yeah we call that doing a 21 gun salute here in nor cal and we are most likly going to due that for the moment.

 

thought previous post didn't take but i'll add:

Before the above, disable the plugs so it wont start, put a voltmeter across the primary injector lead and see if you get power there when turning the motor over.

if not try to test connectivity from injector back. check breaks in wire. consider swapping ecu. good luck.

 

Well at first i was going to just pull my injectors and rail and replace them with some ones out of our parts car (That runs just fine i might add) but insted i sent the donor injectors to witch hunter performance for a rebuild just for the heck of it. Are their any grounds in the engine compartment i should be looking for specificaly, or any under the dash? Thanks

 

you mean they power through the main relay right? the ecu controls the ground side to open the injector
with a high impedence test light you can check for power on the b/y wires in the primary injector clips. then with the test light lead hooked to the batt + carnk the car and check for a flickering light at the lg/b and the lg/r wires. or go buy a Noid light that fits or injector clips

 

Ok. you say the ecu controls the ground side to open the injector? Can i check this ground with out opening the ecu or is it in the ecu? If its in the ecu how can i check this ground..

THANKS,
Chris

 

If you have a spare parts car that runs ..... why not swap the ECU's and see if the other car will start.

 

We all ready did.

 

the ecu has a driver that allows and disallows ground to the injectors thus completing the circuit. the longer the duration of the pulses the higher the Duty Cycle.

if a new ecu did not help i would disconnect the ecu and ohm the wiring harness from the injector clip to the ecu. use the FSM for the wires. this is if you are sure the prob is fuel or injector related (i did not read the whole thread