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Fuel pump secondary circuit?


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11-19-03, 07:15 AM   #1  
clover
Fuel pump secondary circuit?

Hello! New here and seeking advice. My hubby and I have been having problems with our '93 Mercury Tracer SW (LOL, but at least it's paid for). The fuel pump wouldn't come on when trying to start it. He replaced the fuel pump, no luck. She has spark. We did the test to find out trouble codes using our Haynes repair manual. The code came up as "Fuel Pump secondary circuit failure". The guy at the auto parts store confirmed what I came up with as it being the "fuel pump relay". We purchased a new one and it did not help, so we returned it.
Hubby checked the fuel pump inertia switch/gas shut-off switch, played around with fuse box in dash, stuck key in ignition and waa-laa, she started. I asked him what he did and he was clueless as to what it was. She ran for a few days, when I filled her with gas the car smelled of gas vapors inside. He had to go back and double check his seal where the pump is, last night. She started up no problem, last night and this morning, gas vapor smell was gone. I shut her off at the bus stop and she wouldn't start up and is still sitting there. I don't hear the fuel pump engaging when I try to start it. I am angry that this Haynes manual doesn't simply say what the secondary circuit of the fuel pump is. Does anyone have an idea? I am wondering if it has to do with Mass Air Flow? Or maybe the EEC? Thank you so much for any advice. Hubby wants to install some dynamite. Ironically I need the car so I can start a new job to help make ends meet and possibly buy a new car.

 
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11-19-03, 07:37 AM   #2  
clover...

...sounds like hubby is fairly mechanically inclined so with all the help here you can probably get this one done! the trouble codes don't tell what's wrong with the car, rather, they give you a starting place for diagnosis...obviously the fuel pump control circuit has a problem in it. this circuit contains the pump, the relay, wiring, the inertia switch and the PCM. My guess is that when he was "messing around with" the inertia switch and all, he disturbed a bad connection or reset the switch because it was tripped. the inertia switch trips if there is an impact with the vehicle, such as an accident, and kills fuel supply for safety. does your hanes manual show a wire diagram for the fuel pump circuit? i'd start at the inertia switch with a test light and check for light when the key is turned on...it will only be on momentarily, about 2-3 seconds...so check on one wire at a time and turn the key off in between checks...the light should also come on during cranking...if the light is on in both places have him go to the connecter at or near the fuel tank and check the wire to the fuel pump in the same manner. if you have light there, the problem is in the tank (probably a bad connection)...now...if you have light on one side of the inertia switch, try pushing the little button/plunger on the top or side of the switch, if it resets...it should start. if it won't reset, the switch itself is bad. now...onething you said that concerned me is that smell of fuel vapors...make ABSOLUTELY sure that there is NO issue with the seal on top of the tank where the fuel assembly goes in...fill it up again...gasoline vapors are extremely volitile, not to mention hazardous to your health...if you have garage, park it outside until you are completely convinced there is no leakage. not sure? take it to someone who can raise it up on a lift and check it out. good luck...

 
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11-19-03, 08:32 AM   #3  
clover
Fuel pump secondary circuit?

carguyinva,
Thank you for your time and advice, we will try the test light as you recommended.
Yes, the manual has a wiring diagram. My frustration with Haynes not being more to the point as to where/what the fuel pump secondary circuit is, is because they have a trouble code listed below the one we came up with. Ours was 542, but 556 is "fuel pump relay primary circuit failure". I realize the codes won't tell me the exact problem, just would be nice if they would state what and where the secondary circuit is so we know where to start.
The electronic engine control wiring diagram is broken up into 5 sections in the book, but no notation as to which one is the secondary circuit of the fuel pump.

Lol, he wasn't really messing around with the inertia switch. The guy at the auto part store suggested jumping out the inertia switch. Hubby did and then tried to start the car and it didn't start. Then he went to the fuse box in the dash board, checked fuses and she started up. I had the feeling he discovered it was only a fuse and was too embarrassed to tell me. He insisted he didn't do anything that might have started it. He is really handy, I read the directions and guide him.
So, we will do the test light, thank you again!

 
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11-19-03, 09:09 AM   #4  
this is what i get...

...for not consulting the wire diagram first! The inertia switch is on the GROUND side of the fuel pump...my first description i was, gosh i hate this...ASSUMING...that it was on the hot side. On the switch connecter you should have a dark blue and a black wire...if you DISCONNECT it and probe the DB wire with a test light, you should get a light when the key is turned on. I believe that the PCM wants to see voltage when the relay is turned on and that is the secondary circuit...in other words, it monitors the pump circuit operation at the relay. If you have no light (which i suspect you won't if it's still not starting) go to the relay and check for power on the white/dark green wire AND the white/red wire (the diagram is confusing here so it may actually have two wh/dg wires...you should have light in both places with the key on. next...if not check the fuel injector fuse (30 amp) in the underhood fuse box...perhaps a bad connection that he disturbed and that is why it ran for awhile. Sorry for the bad info earlier...good luck

 
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11-20-03, 07:03 AM   #5  
clover
Carguyinva...

Hey, no problem. Thank you so much for all your help =). We were not able to test it last night thanks to the storm, way too much rain. We will check it like you suggested. I have a funny feeling it is a fuse too. I wanted to note in my last e-mail but forgot: the fuel smell went away but when and if she gets running again I will fill her up again to be sure the smell is gone for good, thanks for that tip. I was driving with the windows open when there was a smell. We don't have a garage, and have been very careful because of the danger of gas and vapors. When Hubby checked to see where the gas smell was coming from he had discovered the seal/gasket had twisted when he originally closed up the fuel pump. He fixed that.
On another website I found, thank you to Sharp Advice whose posting: "Read this before posting" linked to http://www.batauto.com on this page: http://www.troublecodes.net/Ford/ I discovered a more detailed discription, compared to Haynes', of our trouble code 542- it was written "Fuel pump open, bad ground or always on...Power/Fuel pump circuits"
So maybe it is the inertia switch since, as you noted the the inertia switch is on the ground side of the pump? Maybe I confused you, because I am confused myself due to lack of sleep and too much stress. Guess we'll know for sure what is wrong with it by tonight.
We will test the wiring as you suggested. Thank you again for all your help, it is much appreciated. =)

 
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11-20-03, 07:22 AM   #6  
of all the cars...

...that i've had the pleasure of working on, i find ford diagnostics some of the most difficult to interpret and follow. i have to have an understanding of circuit operation and then be able to interpret what the diagnostic routine is having you do and why...most of the time if I can find a circuit operation description and a wire diagram, i can write my own diagnostic routine...good luck...i feel sure that you two can locate the problem...i think it'll be something pretty simple once you find it

 
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11-20-03, 02:52 PM   #7  
clover
We tested with the light...

Carguyinva,

..and there is light at the ground wire of the inertia switch there is also no reset button but a green wire with a stripe, along with the other wires. Just for fun, LOL we went to the fuel pump relay and checked for power at the white/dg wire, and there was a white/orange wire. there is a light at the DG wire with key off AND key on. orange one there is a light only with key on. The next thing inline would be the fuel pump? Shouldn't be a problem at fuel pump if there is light at ground of inertia switch? Another thing is that we hear the fuel pump relay come on but the fuel pump itself doesn't kick on. So what is between the relay and the pump? Ugh too much.
Thank you for your help =)

 
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11-20-03, 04:14 PM   #8  
clover
Forgot to add...

that we disconnected the DB wire at the inertia switch and tested it and there was no light with key on or off. Hubby mentioned that we didn't get a light because we disconnected it? No that just doesn't make sense, it has to be because power is coming beyond the relay?
We agree with you about Fords! What a pain they are.
Thank you for wishing us luck and for your help.

 
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11-21-03, 06:44 AM   #9  
clover
Power isn't getting past fuel relay...

... Last night I mistakenly wrote that it is. We went back and tried jumping out the inertia switch with a wire, connecting to the DB wire at inertia switch. She still didn't start, the fuel pump didn't make a sound so we know it wasn't "enabled". However, the DG/R striped wire at inertia switch connects to "Passive restraint system", which is the seat belts? To properly jump/bypass the switch how would you connect the jump wire? Thinking maybe we did it wrong. The reset button is the red button on top of inertia switch? That was not popped up/in shut off mode.
From book: "Ignition switch supplies power to EEC power relay which then supplies power to the computer (PCM?) which in turn activates the fuel pump relay. Fuel pump relay supplies initial line pressure to the fuel system." We cannot figure out where the wiring is from relay to pump. And does the wiring go from relay to pump or to inertia switch first?

Thank you for any advice.

 
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11-22-03, 03:57 AM   #10  
The EEC relay powers up the EEC computer. From that the fuel pump relay is also powered. The EEC Computer controls the fuel pump relay by grounding it. The system feeds like this EEC relay - EEC Computer - Fuel Pump Relay - Fuel Pump - Inertia Switch - to Ground. What is the Voltage Drop on the circuit to the Fuel Pump when it is turned on? Low Voltage could be the problem? It might light a test light but may not have enough to move the pump?

 
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11-22-03, 04:45 AM   #11  
clover
Last evening we checked to see if there is power at the pump, there is. We applied battery power from another hot source (car's overhead light) to see if the pump would start, it wouldn't. He took the old pump out of a box and applied the battery power directly to it and it ran. So it seems that the original pump and possibly the new pump are good because the problem started before we replaced the pump. I read somewhere that if the fuel relay is bad it would stay in the on position and the pump would continue to run? If there were a short in the circuit the fuel fuse woud go bad. The only fuse related that we can find is the "engine fuse" in fuse box under dashboard and it is good. We will run a check to see how much voltage is in the circuit...thank you for the advice hogfan. And for explaining the route of the circuit for me.

 
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11-22-03, 07:21 AM   #12  
Engine Compartment Fuse Box - The fuse is ST SIGN 10 amp. That's the 12volt power to the fuel pump relay coil. The white/red wire that feeds the fuel pump relay for the fuel pump comes from the EEC relay. Which is In the Engine Compartment Fuse Box - Fuel Injector 30amp. I hope this helps.

 
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11-24-03, 06:20 AM   #13  
clover
Please help

I'm confused. Are you saying the EEC relay is in the engine compartment? We located the EEC relay next to the fuel pump relay, under the dashboard, passenger side. Is there another name for this 10 amp fuse you mentioned? We found only a 15 amp fuse i fuse box mounted to dashboard on driver side.
Hubby and a mechanic referred to us got the car started, he jiggled a wire above gas tank and jiggled the key while in ignition. Not positive what exactly got her started, but he is feeling certain but not positive that it is the "ignition switch" as one of the contacts is slightly damaged. Is it possible that if that part doesn't work, we would still have power at the fuel relay, and at the pump, But applying voltage directly to the pump she still won't start? He jiggles the key and she starts, other times she won't. If that part is the problem, is there anything in line that can cause the damage or do they just go bad? He is scratching his head as much as we are. I need my car to get my kids to the bus and preschool, its a half hour walk one way, and to go get my turkey. I don't like bothering my neighbors for rides.=) Thank you for the help...

 
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11-24-03, 08:34 AM   #14  
Something is wrong here it dosen't make sense

If you power the pump the pump has to run. Maybe there is a problem with the pump installation or the pump is bad.

 
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11-24-03, 10:13 AM   #15  
clover
Have to agree it doesn't make sense. Mechanic feels it could be both the ignition switch and fuel pump sending unit. Fuel pump is good, hubby had double checked his installation too. Found out at alldata.com that there was a recall on this yr, make & model for "fuel pump/sending wiring modification". At fords website they claim there was no recall for my vehicle, using my vin#, so maybe the previous owner took it in for the recall repair. Question that remains is what exactly was the "modification". And I discovered many fords have caught fire from their garbage ignition switch. So being our switch is slightly melted I think that is a problem. Thank you for your help and so sorry for starting a new thread, but had figured maybe someone who knows about ignition switches might answer that, if they are not opening and reading this thread.

 
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11-26-03, 04:04 PM   #16  
Sorry about your trouble. I, on the other hand, believe Ford wiring diagrams and trouble shooting diagnostics are far superior than anything else out there. Anyhow.....

What engine is in the Mercury - 1.8L or 1.9L? If it's a 1.8L, it's a Mazda engine, with Mazda engine controls (MECs), which I believe uses a VAF (vane air flow meter). The fuel pump relay ground circuit is wired through the VAF. Once the VAF door starts to move (during engine cranking), the fuel pump relay is energized. Make sure the air tube between the VAF and throttle body is PERFECT. Any airleaks and the VAF door may not move. If ok, try this (assuming this is a 1.8L), manually move the VAF door while cranking and see if the fuel pump operation is restored.

If this is a 1.9L, sorry I wasted your time. Get down and dirty with the wire harness and hard shell connectors. Any signs of green corrosion is bad news. If you find a bad connector, the good news is that your local Ford or Mercury dealer can sell you most engine compartment hardshell connectors with a pigtail of wire off the end.

 
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11-27-03, 05:03 AM   #17  
clover
Problem solved...

It's a 1.9L.
The mechanic went to a car graveyard and found alot of Tracer SW like ours with no fuel pumps--curious, then finally came across one that had one with the recall "modification" done to it. It's wiring had fuses in it, mine didn't. Once he put it in she started right up, when he turned the key off and then back on without jiggling it she started right up. He got an ignition switch too-gotta love plastic, and a bunch of relays in case we ever need them.
Thank you everyone for your help!!!! We probably wouldn't have gotten anywhere with the darn car without the help I got here. =) Have a Happy Thanksgiving!

 
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