fuel pump relay not getting power

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fuel pump relay not getting power

Postby boost_creep » Tue Jun 03, 2014 12:50 am

hey guys, im terribly sorry for asking this, but ive been searching the whole evening to find some sort of fuel wiring diagram or any previous thread that people might have posted... also, im far from being a mechanic and i lack in self-confidence when working on the st185.

okay so i was suspecting my fuel pump not working because i wouldnt here it prime when i would turn the key on. so after checking everything i found out that there wasnt any power going to my fuel pump relay. so what i did is i bypassed the fuel pump relay (taking power from the alternator) and i heard the fuel pump turn on and prime, so i turned the key and it started just like that. so now im left wondering where to look next to fix this problem, i checked the EFI fuse and its good. what else should i check? does anyone know any websites with every wiring diagram i will need so i can follow that and maybe find the problem? any help will be greatly appreciated
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Re: fuel pump relay not getting power

Postby alltracman78 » Tue Jun 03, 2014 2:01 am

Was your engine running OK before you started messing with it?

To start; your fuel pump will not work unless the engine is starting or running. Just turning the key on won't do anything.

Power runs from the COR [Circuit Opening Relay]; it's screwed to the side of the ECU on the drivers [L] side. It gets power from the starter when the engine is starting and from the ECU when the engine is running.
Power then runs to the FPR [Fuel Pump Relay] which either runs the pump at slow speed or full speed.
Then it runs to the pump.

You can bypass all this by jumping FP and B+ in the DIAG box. This will run the pump any time the key is in the on position.
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Re: fuel pump relay not getting power

Postby boost_creep » Tue Jun 03, 2014 11:39 am

Okay, so when you put the key to the on position, you should hear a ringing noise comming from the back? Cause my car only starts if i heard that quiet little ringing, which i was told it was the fuel pump priming up for ignition... What i did yesterday is that i checked if there was any power getting to the FPR and there was non so i bypassed everything by taking power from the alternator to the FPR anf thats when i heard the said little ringing noise from the back, right there i knew i was going to get ignition, and i did, the car started right up... So i guess your telling me theres probably still somethi g wrong with my ecu, even if i just put a new one in
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Re: fuel pump relay not getting power

Postby boost_creep » Tue Jun 03, 2014 11:58 am

Forgot to mention, the car wasnt running no, last year it stop working and , because i was broke and in college, i just parked it for the winter like that, so right now im trying get back up and running again... I was told that it was my ecu by my mecanic who checked it briefly, so i got a new ecu in it and still had issues, so this is where im at now.
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Re: fuel pump relay not getting power

Postby underscore » Tue Jun 03, 2014 3:59 pm

You can't conclude anything yet, for starters jump the pins in the diagnostics box and go from there, don't just throw parts at it. Also it sounds like you need a new mechanic.
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Re: fuel pump relay not getting power

Postby boost_creep » Tue Jun 03, 2014 4:29 pm

Yea lol i figured... Ive finally found a wiring diagram that i needed. I will have to test my efi relay and circuit opening relay, then that should narrow down the search.

I might sound like a noob but i dont get what you mean by jump the pins in the diagnostics box? Im french so it might take me a while lol
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Re: fuel pump relay not getting power

Postby underscore » Tue Jun 03, 2014 6:03 pm

You take something like a paperclip or piece of wire, stick one end into the FB port and the other into the B+. If you flip open the cover labeled DIAG there should be a diagram showing which is which.
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Re: fuel pump relay not getting power

Postby boost_creep » Tue Jun 03, 2014 11:50 pm

ughh i was almost done my post as a reply, and i had explained myself pretty well and deleted it accidentaly -_-

Anyhow, here is where im at. I had my car running fine when i bypassed the FPR by taking power from my alternator like this: <a href="http://fr.tinypic.com?ref=285tn4" target="_blank"><img src="http://i60.tinypic.com/285tn4.jpg" border="0" alt="Image and video hosting by TinyPic"></a>
as soon as i connected this, i could here a buzzing sound, which i assume it was the fuel pump or anything else fuel related. and when i turned the key it started right up. as soon as i would disconnect it, it stalled out.

So today I spent all day at work trying to figure out what my prob could be and searching for a wiring diagram for my fuel system and found this:
<a href="http://fr.tinypic.com?ref=9gg2hf" target="_blank"><img src="http://i60.tinypic.com/9gg2hf.jpg" border="0" alt="Image and video hosting by TinyPic"></a>
here`s a zoomed picture at what I was looking at:
<a href="http://fr.tinypic.com?ref=2wqd4lw" target="_blank"><img src="http://i61.tinypic.com/2wqd4lw.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

Now I just used this diagram to know what to check first to track aproximately up to where the power gets to. I`ve checked the EFI fuse, good, I`ve then checked the Main EFI relay, good, then the circuit opening relay, which was also good so my hypothesis from here is that the power gets cut off between the circuit opening relay and the FPR, but where? I dont know where there could be any connections that could be at fault, or any other fuses that I could check? Has anyone else run into this kind of problem before, or anyone who knows what I should look for next? Btw I would like to say thanks alot to anyone trying to help and giving suggestions... it often helps alot! You guys are great!
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Re: fuel pump relay not getting power

Postby boost_creep » Wed Jun 04, 2014 12:00 am

are the pictures working for you guysÉ
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Re: fuel pump relay not getting power

Postby underscore » Wed Jun 04, 2014 3:50 am

The pictures weren't working so I cleaned up the links, here you go.

boost_creep wrote:ughh i was almost done my post as a reply, and i had explained myself pretty well and deleted it accidentaly -_-

Anyhow, here is where im at. I had my car running fine when i bypassed the FPR by taking power from my alternator like this:
Image
as soon as i connected this, i could here a buzzing sound, which i assume it was the fuel pump or anything else fuel related. and when i turned the key it started right up. as soon as i would disconnect it, it stalled out.

So today I spent all day at work trying to figure out what my prob could be and searching for a wiring diagram for my fuel system and found this:
Image
here`s a zoomed picture at what I was looking at:
Image

Now I just used this diagram to know what to check first to track aproximately up to where the power gets to. I`ve checked the EFI fuse, good, I`ve then checked the Main EFI relay, good, then the circuit opening relay, which was also good so my hypothesis from here is that the power gets cut off between the circuit opening relay and the FPR, but where? I dont know where there could be any connections that could be at fault, or any other fuses that I could check? Has anyone else run into this kind of problem before, or anyone who knows what I should look for next? Btw I would like to say thanks alot to anyone trying to help and giving suggestions... it often helps alot! You guys are great!
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Re: fuel pump relay not getting power

Postby boost_creep » Wed Jun 04, 2014 10:18 am

Thanks lol, why wouldnt they work?
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Re: fuel pump relay not getting power

Postby underscore » Wed Jun 04, 2014 2:24 pm

The coding around the image was wrong, if you hit "quote" you can see what I did to the links to make them work.

For the relays, how did you test them?
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Re: fuel pump relay not getting power

Postby boost_creep » Wed Jun 04, 2014 8:05 pm

With my olms setting on my multimeter(pretty sure i didnt do this right), after seeing there was a resistance between certain legs of the relay, i figured they were good, but now that i think of it, it doesnt really prove anything. after i got back home i seen a video on youtube of how to do it, the guyhad a special tool to send power throught it and he was testing to see if there was resistance between the other two poles (video by ericthecarguy), now im wondering if i could do the same with a 9v batery and a few electrical wires... Also, if i want to test if the powers goes throught from the circuit opening relay to the FPR could i just send the power throught the blue amd orange wired hole on the COR( which i seen somewheres that was the one who sent power to the FPR) amd put my volt meter on the other end to see if the power goes throught? The if it does, then it would tell me for sure that the COR is not good(since the power is getting to the COR... Am i on the right track? Lol :crazy:
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Re: fuel pump relay not getting power

Postby boost_creep » Wed Jun 04, 2014 8:18 pm

Image
Heres what im going with, i had the power coming throught the hole num 4 (green)
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Re: fuel pump relay not getting power

Postby underscore » Wed Jun 04, 2014 9:29 pm

The easy way is to find a circuit that uses the same type of relay and swap them, you need a circuit that you know to be working (something obvious like lights or a fan).
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