I cant figure out my fuel problem. fuel pump wont kick in on its own. Unless i jump it from diagnostic box.
It occurred for me, by starting the car and drive for less then a mile. Also I don't know if that was due to this problem or not, my apex seal went, when engine died.
It was automatic.
So now i put new engine in. Did auto to manual swap, with new manual engine wiring going to the ecu. (manual ecu installed) still same problem. I replaces F.P relay. as well as F.P. speed relay.
Any idea where the problem could be? anyone had similar problem? what would usually couse that problem

 

Im still trying to diagnose this problem.
Just an update. On the B1-01 connector, the blue/black wire (1T) that goes into PCM, if i ground that wire with key on, F.P. turns on. But for what ever reason something tells PSM not to ground that wire when its plugged in. and its second PSM that im having same problem.

 

its a wiring problem, recheck them.

 

Hmmm... I wonder if the fuel pump rewiring mod would work in your situation. Do a search for it, and see what kind of results you get.

Here:
https://www.rx7club.com/showthread.p...el+pump+rewire

And Here:
https://www.rx7club.com/showthread.p...el+pump+rewire

You've done engine work, and a trans swap, I would think this would be a piece of cake. Try it out, I think it may solve your problems.

 

the 1t is the switched ground to engage the circuit opening relay. if manually grounding that wire engages the fuel pump well there you go. if you are grounding it at the ecu pin itself then the ecu is most likely the cause, if you are grounding the wire somewhere else down the circuit it may have an open from the ecu to the point that you are grounding.

Get a high impedence test light
connect it to battery +
go to the ecu and with the connector plugged in probe the 1T pin
turn the key on
the light should turn on for a second

no light = bad ecu
light = open in the wiring

 

where would you think the wiring problem could be? if its all good all the way down to PCM connector!

 

question for you then. You must have done this FP rewire mod. I was reading both of these links. If i understand this correctly. Looks like the rewire Mod actually bypasses the wire going to PCM. is that right? if so, then the really i don't need to freak out about why 2 of my PCM's does not what to turn FP on!

 

Right, It skips all that stuff, and just uses the red/white wire to trigger the relay. You bypass all the stock relays and stuff, giving the pump full power at all times, instead of the stepped version that is stock.

Try what mad 7tist said with the light. To see if you can Identify the cause. If you could find someone close with a stock ECU, you could swap it, and rule out the ECU as well. I would think the wiring would be the cause first, but strange things have been known to happen in this car.

Either way, this mod needs to be done, for reasons mentioned in the other threads, but try to solve one problem before you modify anything. It will lead to less headaches later. I think it would fix your problem, but I would check everything else first, then do the mod.

 

tnx for the help guys! tomorrow il see if i can diagnose this any further. But i mean im sure wiring is all good all the way down to ecu. but who knows. and its not like i used 1 PCM. ether both of them are burned. or problem is else where. but yeah i definitely want to fix this problem so i don't go through another engine.

 

you need to look at the re-wire diagrams again as they do not bypass relay control. i did not check the links but most simply cut the power wire to the FP and use it as the trigger to an added on relay that will bypass all of the voltage drops. so if the circuit opening relay does not engage (recieve a ground from the ecu, assuming it has a good power source) then the FP rewire will not work either, the ecu still controls the FP via the circuit opening relay. if this does not make sense then someone else a bit more familiar with electric circuits needs to take a look at it for you

 

mad 7tist, you have any idea what tells ecu to ground that 1T wire? I'm thinking something like factory alarm or something Like TP Sensor or some other faulty sensor that has something to do with FP circuit inside the ECU. I mean something has to tell computer to turn the fuel pump on!

 

Now that you say that Mad, I agree with you.

zheka, if you installed new relays, and still have the same problem, you either don't have a signal, or you have no ground. Garb the light and unplug the connector going to the fuel pump (in the hatch) and see if you get a light on back there. You could test both wires that way. Check the signal wire and ground at that plug, work your way forward. Don't forget the fuel pump resistor. It's the last thing in line to the pump, and if something is wrong with that connection, it could be the problem.

You said you lost a motor to this? Have you been over your harnesses in the engine bay, and made sure they are all plugged up the way they should be? Take a look under your fenderliners, and make sure you haven't had any major rubbing issues, there is a big harness above each tire.

Other wise, for a better view of the fuel system, grab section F of the manuals, it may be of some use to you.

 

I think i lost the motor due to no fuel pressure as i was driving. fact is apex seal went!

also now that you mentioned about wiring underneath fenders. About year ago i was fixing right side one of the connectors, also 2 weeks before i got into this problem some one hit me in left side fender. When i was fixing it, i didn't pay attention to the wires there if they where damaged. is that where fuel wires run? on the left side or right?

 

so wait, does the car start and drive right now if you jumper the F/P connector?

 

yes it will.
it will also start and drive if i will take b1-01 connector and ground the 1t wire.

 

but you have not verified the wiring from the b1-01 connector to the ecu? i am assuming that the b1-01 is not the actual ecu connector number.

 

b1-01 is the ecu connector!

 

The fuel-pump relay is not controlled by the ECU for unknown reason. Install a
new relay, which you did, and replace the old fuel-pump wiring with a new solid one. In this case, you can remove the fuel pump resistor.

 

where is the 1t wire coming from, on a b1-01 connector? from what i understand looking at wiring schematics its looks like its going to diagnostic box, and FP relay. And like i said before, that same wire (1T) if i ground it out right at ecu, witch would make complete circuit for FP relay. it will kick FP on.

 

i will consider doing that later. But first i want to find the problem on factory wiring, just to be safe.

 

Do you get a signal on the signal wire in the back by the fuel pump? I looked at the diagram, and seen the 1T wire, and am curious where the signal stops. Check the red/white wire, and the ground wire to see if you lose light on either of them. My guess is the ground.

 

so you have
a bad ecu
or a bad connection at that terminal

when you supply the ground at the ecu connector (doing the ecu's job) the car runs showing that all the wiring to the pump is intact
this means the ecu sees the crank signal etc

i dont think the ground path the ecu uses to establish a circuit for the relay is a seperate one, just the seperate driver. so i dont belive a loose/missing ecu ground could cause this problem without showing some other issues.

 

i find that hard to believe to. But i also find it hard to believe that both of my PCM's would have same problem.

Im clueless now, dont know what else to look for.
..........Thanks guys for trying to help out!