sh!tsWEAK!

iTrader: (1)

I've been trying to figure this out for the past couple days, I've searched for and read almost every topic on H-T I could find about this. Basically, I am getting no power to the fuel pump. The pump itself is good, I tested it by hard wiring it directly to the battery and it turned on, however, it does not prime when the key is turned. I thought maybe it was the main relay, but I took mine out and swapped it with a good one from a friends car. His car is now running with my old main relay which was fine, and I have his old one in my car, which is fine as well. When I test the power line at the plug running from the main relay, the test light does not light up, meaning it is not sending power. All of the engine grounds are good, the ignition switch is good, the ground by the seat is good (are there others on the interior harness that I might be missing?), the motor turns over fine...just needs fuel.

Jimmy

iTrader: (5)

Try lightly tapping on the relay while turning the key off and on.. untill you hear it prime

timaa66

have u messed with your grounds under the hood? check those i wasnt getting prime and found a ground on the back side of motor that wasnt connected well after i fixed that started right up

Jimmy

iTrader: (5)

Oh and also check all of your ACG fuses under the dash.. I believe theres a 7.5 amp one

sh!tsWEAK!

iTrader: (1)

Just tried tapping the main relay, still nothing. The under dash fuses are fine, starter signal (7.5) doesn't light up, but I'm pretty sure it only does once you crank the car. My car was stolen, and I've been rebuilding it from a shell basically so I'm hoping there isn't anything serious missing. I took a picture of the under dash fusebox, do I look to be missing anything? The 3-prong plug next to the green one lights up when the test light is applied, however I don't see any loose plugs around there that would plug into it.

MasterKwan

You know the power's to the pump's only on 2 seconds at a time every time you turn the key on right?

This is simple trouble-shooting. The relay has power going to it and a signal to activate the relay. First you make sure the relay has power when the key is on. Then you make sure the line that activates the relay's powered a couple seconds each time you turn the key on (comes from the ECU I believe). Then check that the output from the relay has power the same time the input has power.

If all that's true, the main relay's fine. If you don't have the activation signal, you need to fix that. If you have power and activation signal but, no output. It's a bad relay or the relay ground is bad.

Jimmy

iTrader: (5)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sh!tsWEAK! &raquo;</TD></TR><TR><TD CLASS="quote">Just tried tapping the main relay, still nothing. The under dash fuses are fine, starter signal (7.5) doesn't light up, but I'm pretty sure it only does once you crank the car. My car was stolen, and I've been rebuilding it from a shell basically so I'm hoping there isn't anything serious missing. I took a picture of the under dash fusebox, do I look to be missing anything? The 3-prong plug next to the green one lights up when the test light is applied, however I don't see any loose plugs around there that would plug into it.

</TD></TR></TABLE>

Check the blue fuse to the far right.. I believe its a 15 amp

le0ftw

Dude I had this same exact problem and the damn pump will not start. I dont know what it is

sh!tsWEAK!

iTrader: (1)

I checked the blue 15 amp ACG fuse, it's fine.

MasterKwan, I'm pretty much positive that the main relay is fine since I pulled it out of my friends daily driven civic (same bodystyle and trim as mine), and it worked perfectly fine for him. I put my old one in his car, and his still started right up and he is driving with it as we speak. It is bolted down in the same way it was from the factory, so that ground should be good as well.

sh!tsWEAK!

iTrader: (1)

I've also read mixed things, some people say the main relay should "click" when key is turned to the ON position, some say it doesn't click. Mine does not click.

Whig-it

I had the same problem with m fuel pump not turning on. I even swaped under dash harness and stuff. turned out the Ground on the Tstat hoursinf in the engine bay, was loose. don't ask me why they included that ground in the fuel system, but check it.

sh!tsWEAK!

iTrader: (1)

Thermostat ground is good.

sh!tsWEAK!

iTrader: (1)

bump!

MasterKwan

You haven't trouble-shoot the problem so, bumping's pointless. Get the wiring diagram and do what I suggested. Clearly either the main relay's not getting power, the relay's not getting activated or the relay's not grounded. The ground's not going to come from where it's bolted, it comes from the harness.

Here's what I think. The ECU isn't getting power so, it's not activating the relay. If you followed my steps and saw no activation on the relay then that's pointing you in that direction. ****, if it was me and I knew nothing about electronics, I might apply 12 volts to the activation pin and see if I get power to the pump.

The car will crank just fine without an ECU even being hooked up so, whether it cranks or not doesn't matter much.

sh!tsWEAK!

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MasterKwan &raquo;</TD></TR><TR><TD CLASS="quote">You haven't trouble-shoot the problem so, bumping's pointless. Get the wiring diagram and do what I suggested. Clearly either the main relay's not getting power, the relay's not getting activated or the relay's not grounded. The ground's not going to come from where it's bolted, it comes from the harness.

Here's what I think. The ECU isn't getting power so, it's not activating the relay. If you followed my steps and saw no activation on the relay then that's pointing you in that direction. ****, if it was me and I knew nothing about electronics, I might apply 12 volts to the activation pin and see if I get power to the pump.

The car will crank just fine without an ECU even being hooked up so, whether it cranks or not doesn't matter much. </TD></TR></TABLE>


I don't know a whole lot about electronics, and this is my first time trying to trace a problem like this. I appreciate your input. How exactly do I go about testing if the relay is getting power, if it is activating, or if it's not grounded properly? The ECU is a virgin p28 that I bought off a friend when mine was stolen, but I will try plugging up a p28 that my friend has in his car and seeing if that does anything.

MasterKwan

I posted the color codes in another topic here. What year is it? Wish I could find the link, it would save time.

sh!tsWEAK!

iTrader: (1)

95 CX.

turbo sol

relays are funny. look up the reistance called for in the helms and check it out.

your friends maybe flaky too. not to say it cant be the relay, but I would check that as thoroughly as possible, not just swaping it out.

Jimmy

iTrader: (5)

Ok anyways, i can't find the post on the write up.. So basically if you know how to use a soldering gun you can fix the problem.
You'll need to carefully pull the relay apart.. and you'll see the joint on the relay some may be corroded have hairline cracks,etc thus being the reason it's acting up. Pick up some 40/40 soldier.

I always very easily scuffed the only joints up with a wire brush and then went around and added a tiny bit of soldier to the dry joints..

Put the relay back together and your fixed.

Refrence: http://autorepair.about.com/cs...1.htm

pm me if you have any further ?'s.

sh!tsWEAK!

iTrader: (1)

Thanks for the responses guys. I'll try checking the relay tomorrow, although I have a hard time believing that's the cause of my problem due to the fact that it was working fine in my friends care, and then when I swapped the old one out of my car (the one that I thought was problematic), his car started up fine.

perseverance

check ur fuses doing a continuity test not with a test light. test light will deploy an airbag and only test's when current is being flowed. continuity tests fuses at any time.

deguzmanEG

i had the exact same problem with my car a month or so ago, turned out to be the ecu. Switched it with a new one and it started up, been running smooth since.

MasterKwan

I don't think it's the relay either. The swap test pretty much guarentee's it. Last time I saw one of these, on an S2000 theft recovery no less, one of the couple ECU fuses was plain missing so, the ECU wasn't powered up.

Yel/Grn goes to the pump.

Grn/Yel is from the ECU and activates the main relay.

Yel/Wht is supposed to be 12 volts all the time. (ECU Fuse, even with the ignition off)

1) Put your light on ground and Yel/Wht Should be lite all the time. Key or no key

2) Put your light on Grn/Yellow. Should be lit. Turn on the key, light should go out for 2 seconds. That means the ECU is turning on the pump. You might find that using the light on that pin turns on the fuel pump. Be ready for it. The ECU grounds that pin to turn on the pump.

If that doesn't happen, you need to trouble-shoot why the ECU isn't activating the pump. First thing to look at is power to the ECU.

3) If 1 and 2 are ok, put your light on Yel/Grn and turn the key on. You should see the light on for 2 seconds. If that works, you have a bad wire to the pump or the pump's not grounded/not working.


When I say "put your light" I mean ground one pin on the light and use the probe to look for voltage. A meter is better but, you have to use what you've got.

I was looking at the pinout again. Both Yel/Wht AND BLK/Yel should have power all the time. Both go to fuses. One feeds the ECU, the other the fuel pump.


Modified by MasterKwan at 9:07 PM 1/2/2007


Modified by MasterKwan at 9:09 PM 1/2/2007

93FlatBlackHatch

I have the same problem right now and have been stumped for a week. Sometimes the fuel pump primes but most of the time it doesnt. I have checked all of the fuses, grounds that I know of, replaced the main relay and nothing happened. I have power at the fuel pump but the main relay isnt sending it. The relay clicks once when I turn the ignition, and it supposed to click a second time to get the fuel pump to prime. And I think the relay gets power and clicks once, then sends power to the ecu back to the relay to click again causing the fuel pump to prime. Maybe our problem is the connection that goes the ecu from the relay? I hope it isnt the ecu itself.

MasterKwan

Sounds like it could be the ignition switch.