Printable View
How can I check if the fuel pump is working?
I changed the IAC because of my car stalling. After the change I cant get my car to start again. I have a AEM EMS connected to where the ECU was.
Can it be a fuse thats the problem here? or one relay im not thinking about.
I can hear a relay clicking on the passanger side(MFI relay?). and there are some relays in the enginge compartment clicking when i turn the ignition key.
The easiest way to check the fuel pump is to locate the 3 test connectors located on the passenger side firewall tucked down beneath the wiper motor.
Attachment 4460
The wire with the black connector goes to the fuel pump (the tan is for setting timing and idle, the blue is the tach signal).
Take the cover off the Black connector (if it's still there) and connect a voltmeter to it.
On a stock system (I'm not sure about how the AEM works) there should be power on that connector WHEN YOU CRANK (turning the key on is not enough on a stock system). If there's no power you need to look at the fuses and/or MFI relay. If there is power than the fuel pump is getting turned on as expected.
The other thing you can do with that wire is test the pump itself by connecting it to the battery (+) with a jumper wire, which is handily located right near it. With battery power connected to the test connector you should be able to hear the pump humming in the fuel tank, and at least on the turbo models, you can hear fuel circulating through the fuel pressure regulator.
Good luck!
With the default EMS settings the pump primes before initial cranking. Unless you messed with the settings, it will turn on with the key in the acc position.
OK so i checked the fuel pump. I hooked up the black test connector to the (+) terminal on the battery and I could here the fuel surging.
But i cant hear the pump when I have the ignition in just ON, if i try to crank and release i can hear the pump(not sure if its actually running for 3 sec just by having the ignition in ON)
I get about 40psi/45psi when i try to crank.(pic only showing 20psi due to drop).
http://i1092.photobucket.com/albums/...816_214248.jpg
I can hear the MFI relay click.
Im not sure if i can hear the fuel relay click..but Im guessing its working when the fuel pressure is increasing.
http://i1092.photobucket.com/albums/...816_214253.jpg
Tomorrow im getting help to check for spark..maybe thats the problem?
What fuse should i look at? I found one fuel fuse in the main box in the engine compartment and it is ok.
thoughts?
Bypass the relay in the engine bay, if you haven't already done so.
isnt the relay working when i the fuel pressure is increasing and i can hear the pump when i try to crank?
so what you are saying is that it has to run before you crank, for 3 sec like normal? :)
Usually I let the pump prime before I crank. I have my settings set to 4 seconds. This fills the system with fuel and allows you to have a somewhat constant cranking condition.
I want to check the fuel relay, before doing the bypass.
how do i hook it up with a 12V power supply? is it (+) to pin 5 and (-) to pin 1? how to check the continuity?
i heard that the fuel pump doesnt prime on our cars before cranking? i cant remember if it does or not when you have ignition in acc
Stock it does not. With an EMS it does.
Well, like I said I don't know much about the EMS but I think your problem is there.
Here's what I'm thinking..
With a stock system the fuel pump turns on with the starter relay. Once the engine starts the ECU takes over and keeps the pump running. There is no priming.
From what MB3000 is saying the EMS takes over right away, as soon as you turn the key on, and primes the pump.
From what you're saying it acts kind of like a stock system, with the pump turning on and off with the starter but without either an ECU or an EMS taking over to prime the pump and keep it running.
In other words there's something wrong with the EMS. It's probably not doing other things either, like turning on the injectors or spark.
I suppose this is kind of a Duh! post, since I admit I don't know anything about the EMS but I don't think your problem is a relay or the pump. I think it's the EMS itself. Check to make sure it's getting all the power it needs, and that you haven't knocked loose any input signal it uses (if this is a '91 or '92 the cam sensor is right near where you were working on the IAC..)
i thing you guys are right..i just tested the fuel relay and its working. I need to check the fuel relay harness next, then work my way to the EMS.
i am kind of a noob when it comes to cars, so usually i dont know what im doing :)
i found this for testing relay
http://i1092.photobucket.com/albums/.../FuelRelay.jpg
stupid question, but where to I check if the EMS is getting the power it needs? there are 3 connectors there and im not sure which pins to check..
i was hoping to get some help today so the jobs gets easier.
i hope theres nothing wrong with the EMS, my wife would kill me if i get another expensive post on that car :S
I checked for spark, and of course there was none. I even found one of the spark plugs not being inserted properly, one 0-ring was still attached to it so the connection was minimal. But no spark on either.
Did some testing on the connectors to the coils. Didnt get time to do all the tests, but it seems there is coming about 11.5-12V there. At one point I could only read 3V, not sure about that though.
http://i1092.photobucket.com/albums/...itioncoil1.jpg
getting someone to inspect the AEM EMS, and im going to find a laptop to see if i can find any errors on it.
there is a relay fuse i believe #12 or 15? under teh dash. its a 15amp. Bet its blown :)
I'll take that bet.. :)
If fuse 12 were blown the pump wouldn't turn on when he cranks it ;)
Could be another fuse though. I still don't think the EMS is turning on.
Mine was doing the same thing. was pumping fuel but couldnt get spark. bet its the fuse
Ill go over those fuses. It would be nice if it was something like that :)
but you should have seen the wireing behind the mid console, wiring for the AEM true boost and fuel/air ratio was in a total mess, and the wires for the fuel/air was disconnected. And im getting a week humm because of the wiring to the AEM true boost. I have to re-do all of those. The previous owner havent done that properly thats for sure..but first things first..when my kid gets his morning rest :)
Its the fuse box underneath the dash on the driverside, right? I checked the engine fuse was a 15A fuse, it tested good.
When i reset the battery cable it sounds like the ems primes the pump on first try, but after that not.
Did i check the right fuse? Its bad that the cars suddenluy fail starting after just changing the iac
Tested the car today again, there is no fuel pressure when i try to crank the car. The fuel pump still doesnt prime when i turn the ignition and there is still no spark.
Going to see if i cant get my EMS to the shop that programmed it to see if there is something there, or buy myself a cable so i can try and check the aem ems myself.
There is allot of work that needs to be done to the car, troubleshooting a car unravels more stuff. Found a selfmade connector were someone had used cable heads to connect wires to a connector. Not sure were it goes, but just a little moisture can cause problems..bah
just wondering if it is possible to test the car with the original ECU? got bigger turbos, injectors and all that, not sure if ill brake anything?
you test the mfi relay?
i havent tested it no, can hear it click dou, ill do a proper test of it tomorrow
i disconnected the MFI relay
http://i1092.photobucket.com/albums/...823_134151.jpg
notice the 9pins
the schematic looks like this for testing
http://i1092.photobucket.com/albums/...ty/testmfi.jpg
im not sure on how to actually pin out the relay. i counted so i got pin 5 over pin 1, But testing doesnt give the results i need. when applying power to pin 6 and 8 i hear the click.
#2 on test doesnt show 90ohms between pin 5-7,
#4 i dont get battery power on pin 1 and 5 either
i decided to start over on the test sheet i found.
#1 test power to ignition swith on the ECU harness side. I had disconnected all plugs going into the EMS, and had a little suppries when i turned the ignition to ON. Car cranking, and pin 62 showing maybe battery power.(got spooked and only saw 9-10V at that time).
#2 meassued power to the mfi relay on mfi relay harness. (test says pin 8, put i meassured the battery power on pin9??)
didnt get to next step as i had to get my kid out of kindergarden..
any ideas? how do i actually count those pins on the mfi relay when manual is showing 8 pins, when its actually 9?
im so stupid..found this pic..i should have had a closer look at the electric diagram..shows 10pins, but pin 1 is not there..figures..
http://i1092.photobucket.com/albums/...y/mfirelay.jpg
going to start testing soon, hope i find something.
have seen several posts of people with the same issue, and broken wires have been the cause. Just need to figure out what that pic with the broken wires go to..its not the CAS is it?
used this diagram to test the MFI relay..the relay works
http://i1092.photobucket.com/albums/...menty/MPI1.gif
Tested the fuel pump and got it working, A bad cable, replaced the wire. But the connection in the trunk looks like crap, so have to redo that.
Tested camshaft and crankshaft sensor, tested good. However looks like the harness have gotten some damage, so its a little bit intermittent. So that needs to be troubleshoot more, redo wires.
Car starts and the fuel pump primes as it should..its a nice feeling :)