no current reaches the fuel pump plug when i turn the key! i changed the relay and still no go. any other possibilities? i checked the cables and they are all in good shape. i dont understand. it is a full resto project... and the starter is now a button. key is still needed to provide the rest of the car with energy. i need help

 

Whats the engine in the car? Original engine or swap? Year? Have you checked the ECM, ignition, and fuel pump fuses? Are you working with a DMM or a test light? Does anything in the car(radio, gauges) come on when you turn the key to "Run"?

 

its a 1986 v6 2.8 FI. its an original engine and it does not have the dashboard installed so i dont know if anything turns on. but when i do kno it passes current to what is supposed to have it when i turn the key. but no run and the pump is a no go. and i'm using a test light the ignision does not work properly with the key. i was wondering if it could be the plug on the key thing but some things DO work. and i'm running out of ideas to try. it would be great if you could help

 

You mean the plug on the wiring connector at the base of the column?

I would check for power at the relay. Disconnect the plug and probe each socket with the key on and with the key off. With the key on, you should get a light on 2 of the connections. The green/white wire should only have power when the key is on, and only for about 2 seconds after you turn the key. Is the oil pressure sender connected?

 

no not the one that belongs to the signals the one that is on top of the column. i dont know which is the oil pressure sender connector? where is it located?

 

no not the one that belongs to the signals the one that is on top of the column. i dont know which is the oil pressure sender connector? where is it located? is there a way we could have a phone conversation? (me close to the car of course)

 

I'm at work now, so phone call is probably not the best idea.

The oil pressure sender is located on the back of the engine, right beside the distributor. If its not there, it may be on the side of the engine, right above the oil filter.

If some things are coming on with the key in "Run", then the connector on the column should be fine.

On the fuel pump relay's connector, you'll want to check for power on the orange wire at all times, the green/white wire and the red wire when the key is in "Run".

The tan/white wire is the one that goes to the fuel pump. You can try either connecting the test light to the pump connector in a way that you can see it from the front of the car, or connect it to the pump itself. Then take a piece of wire or your test light and connect the + terminal on the battery to that tan/white wire in the relay's connector. If its just a piece of wire, make sure you have a fuse in it to protect the fuel pump.

Here's a link to the wiring diagrams for fbodys:

http://www.austinthirdgen.org/index.php?pid=19

 

Look to see if there is a fuse in a weather pack beside the battery in the fenderwell - if there is, check that fuse.

 

theres no orange wire i found the green white and i tried it while the relay was still connected. is it supposed to be disconnected when i try that? and the current cable for it is brown. and it goes to the comp. there are two cables on the passengers side that i dont know what they belong to.. that thing was torn and i fixed most of them but those two because they were exactly the same and did know which was for which. could that make a difference? i tried it anyway both ways since there are only four different combinations..

 

hey sorry but there are three relays i found that one is the main power relay, one is the fan relay and the other is the fuel pump relay. there is one that has two thick orange wires and one of them has constant current and the green with white wire. it does not turn on at all though not sure what that means and the oil pressure connector is connected and fine.. thank you

 

The green/white wire needs +12V to turn the fuel pump on with the relay connected. You might have a bad relay. Disconnect the relay and on the connector, hook up a test light to the green/white wire connection and to ground. It should light for about 2 seconds when you turn the key to "Run" or "Start."

If no light, then you need to look at the ignition/ECM wiring. If it lights up, then turn the key off and connect a jumper wire from the green/white connection to the tan/white wire. Try the key again and see if you hear the pump. If you do, then the relay is definitely shot. If nothing, then you need to look at the fuel pump itself, or check for broken/shorted wiring going back to the pump.

The orange wire should have constant +12V.

Are you sure you're looking at the right relay? The coolant fan relay also uses a green/white wire which runs to the ECM. That wire is grounded to activate the relay and turn the fan on. The coolant relay also has a brown wire which has +12V when the key is in "Run." The fan relay should only have 4 wires, while the fuel pump relay should have 5. The other relay there is for your A/C. Looking at the wrong relay can cause all kinds of problems. I removed what I thought was the A/C relay last winter when I took the V6 out of my Camaro only to find out it was really the fan relay. Having to find the wires buried in the looms and resolder them sucked.

 

do you happen to know the numbers of the relays? it is very confusing. should i just follow the wires from the oil pressure to the relay? the connectors from the oil pressure are fine. and well i was thinking. you know when you turn the key all the way like to turn it on the springed part of the switch. could that be what is wrong with mine? because the ignition motor does not start either. i have it connected to a button that makes the starter go. how would i check that out? i greatly appreciate your help thank you

 

It could be the problem, depending on what was disconnected to hook up the button. Make sure all the connectors at the base of the steering column are still connected and that any spliced connections are good.

As for the relays, I'm not sure which one is which in the stock locations. I'm not sure what you mean by the numbers for the relays?

 

There won't be any wires running from the oil pressure sending unit to/from the relay - they are seperate units, with seperate wiring.

I don't know if any of this will help you, as it sounds like the PO hacked up your wiring pretty well, but I'll throw it out there - locations are based on Camaro's - Birds may be different as I know some of them had batteries on driver sides, etc.

The electric fuel pump system uses two seperate and independant - what most call 'redundant' (although it's not) electrical systems.

The first is the ECM system - when the key is turned on, the ECM will send power to the relay that in turn runs the pump for 'priming' (2 seconds) - this pressurizes the fuel lines with fuel, so fuel will be there for the injectors to fire at startup (injector system doesn't have fuel reserves like a carb with it's fuel bowls). That's all that happens here - nothing else - this system does not run the fuel pump continuously while the car is running.

(BTW - This point will be heavily argued by many - but anyone with a completely stock car can remove the relay after the car is running and the car will run all day as long as it has oil pressure - there is no complicated system that "switches over" to the oil pressure electrical system if the relay or ECM goes bad, and the systems do not run continuously at the same time, as this would lead to electrical feedback from the oil pressure sending unit system through the relay system that would fry the ECM. But, they will argue it, and so be it.)

The second is the oil pressure sending unit (OPSU) system. After the car is started, and the oil pressure comes up, this sytem runs the fuel pump. It does so with an electrical connection directly from the battery to the OPSU to the fuel pump - the ONLY interruption to this system is the presence (or not) of oil pressure, as well as the fuse that is tucked in the fenderwell beside the battery. With oil pressure (or with the sending unit falsely reading oil pressure), the pump will run, regardless of key position (the key could be in the house, and it will run). This is fact, not theory from looking at diagrams, and is easily tested.

One more thing - the fuses under the dash that read fp or inj1 inj2 are for the ECM system, not the OPSU system. As mentioned above, the fuse for the OPSU system is under the hood.

OK - so here's the process:

1) Key turns on, ECM sends power to fuel pump relay for 2 seconds, thus relay sends power to fuel pump for 2 seconds, thus 'priming' the system so that fuel is available for the injectors when start is enabled.
2) Key to start - injectors have fuel available from the 'prime', car gets ignition, fuel sprays, car starts, now have oil pressure.
3) Oil pressure enables the direct connection of power from battery to fuel pump through the OPSU, running the pump continuously until oil pressure is lost (ie car is turned off). If the fuse at the battery is removed, or the OPSU unplugged, the car will die - the relay system will not 'take over'.

So -
1) Did you check that fuse by the battery that I mentioned?

2) Does the pump prime? get a helper - crawl under the car with a long screwdriver - place the metal end of screwdriver on the gas tank, place the plastic handle end GENTLY against your ear - have helper turn key to on (not starting) - do you hear the pump whine?

3) OPSU - you can take a paperclip to the connector on the OPSU and jump the two wires for the fuel pump and see if the pump gets juice from this system. KEEP reading before you run out and jump anything....

Oil Pressure Sending Unit - there were two different systems, depending on the year.

The older cars has a divorced system - there were two seperate oil sensors - one was usually on the china wall on the driver side of the distributor. The other was on the block above the oil filter. One only had one wire, that sent oil reading to guages, the other had 2 wires - this one ran the fuel pump.

The newer cars got a married unit that served both functions in one unit, usually located above the oil filter, and it has the same 3 wires in one connector - the two larger wires being the fuel pump wires, and the smaller one sending reading info to the guage.

One more thing about the OPSU - we all know that it can go bad in a manner where it won't sense the oil pressure, and thus the pump won't run - this is kind of intuitive. BUT - rarely does anyone ever think about the possibility of it going bad in a manner that it would 'sense' oil pressure even when the car is off, thus making the fuel pump run 24/7 until the battery is dead, regardless of where the key is. But it can happen - it did for me.

The Relays - usually there are two, driver side firewall between brake booster and fender located on a bracket held to wall with 2 10mm screws. One relay will have a very large black wire with a red stripe - this relay is the fan relay is you have an electric fan, so the fuel pump relay is the other one. These relays are identical - they can be swapped for test purposes, but remember which relay is which (mark them) so you don't end up with a bad relay on the fan and overheat.

Fall asleep yet?

Now - having this info, maybe you can figure a way of making it all work, or at least figure a way to rig it to work.

I personally switched to carb, thus my ECM is gone, and my relay didn't do anything, and didn't need to, as a carb has enough fuel in the bowls for starting. But, I didn't like the idea of the OPSU controlling the pump, especially after my little episode with the OPSU running my pump 24/7! So I switched to the older 'divorced' sending unit to feed my guage, removed the pump wires from my 'married' OPSU connector, and ran them to the relay with a hot-in-run wire, so that NOW, my fuel pump runs as long as the key is in the run position - thus no worries about a bad OPSU either stopping me or making my pump run 24/7. The only downside is that if I were ever in a really bad wreck, my fuel pump would run as long as the key is on, and my battery is functioning.

I hope any of this info helps, and I wish you the best of luck - I know it's aggravating - the wiring stuff makes me crazy some days!

 

While I agree that there are no wires directly connecting the OPSU and the Fuel Pump Relay, they do both run the pump concurrently. As listed in my 92's shop manual, the OPSU powers the fuel pump as long as there is more than 3PSI of oil pressure. The ECM will energize the fuel pump relay for 2 seconds after the key is turned to "Run" AND for as long as it is receiving ignition pulses. So in a completely stock car, BOTH systems would be energized at the same time. You could remove either the fuel pump relay OR the OPSU and the car would still run fine.

When I mentioned the OPSU being connected in an earlier post, I was not trying to imply that it needed to be connected for the fuel pump to prime, or that it was connected directly to the fuel pump relay.

 

Since it appears that the fuel pump isn't priming when the key is turned to "Run", the fuel pump relay & power to it is what needs to be checked. I think we can all agree we can forget about the OPSU for now. Swapping the relays is a good thing to try. I suggested starting with the wiring since the ignition wiring has obviously had some changes made to it.

Forgot to attach the wiring diagram from my shop manual.

 

um i think i got what you did.. can i keep the FI and just make the fuel pump run as long as the car is running.. like when the key is on on...? would that affect it? no overheating issues or anything?

 

yes i tried swapping the relays and still no go.. it is getting frustrating.. is it likely to have a broken cable somewhere? because the current cable from the pump goes to the computer... and then from there i dont know.. there is something i dont know how to fix either.. there are two cables on the bundle that it has on the passenger side that are not connected. they are both green/white and i dont know which goes with which... could that make a difference?

 

Yes, those are your signal wires from the ECM to the fuel pump and radiator fan relays. Figuring out which one goes to which relay is the easy part, just pull on one of the green/white wires at the relays and see which of those 2 wires moves. Figuring out which is for the fuel pump relay and which is for the radiator fan relay is only slightly harder. Connect your test light to one of them and then to ground. Turn the key to "Run" and see if it lights. If it does, that one is your fuel pump relay. If not, it is the radiator fan relay. You can switch which green/white wire the test light is connected to and repeat to double check it.

 

I actually have my Camaro set up like this since I swapped to carb. You'll need to find a wire that has +12V only when the key is in "Run." I ran a wire through the firewall and under the dash to the fuse box. I have a couple of unused spaces on mine that have power only when the key is in "Run" and soldered a spade connector on the end of the wire and plugged it in to one of the fuse connections. I can remove it anytime I need to for troubleshooting or anytime I need to have the key in "Run" so that the pump isn't constantly running while I'm working. I will eventually connect it to the back of the fuse block properly so I can put a fuse in, but for now it works just fine.

 

even if it is a Fuel injection car? it would work fine?

 

Yeah. It doesn't make any difference whether its carbed or FI. You still need the pump to be running while the engine is.

You're gonna want to fix the other green/white wire though, or your radiator fan isn't going to work.

 

hmm true. i hope its those green wires the ones that are causing the problem.. how do you manage to keep it on? should i make a switch if i want to only use the radio or something?

 

If I'm reading that right, the fuel pump stays on as long as the key is in "Run." If I want just listen to the radio, I turn the key backwards to "Acc." The only time it gives me any problems is times when I need the key on "Run" but the engine off to test something. Like right now, I'm tracking down a problem with my coolant temp gauge and I need to have the key on to test it. All I do then is just pull the wire out of the fuse block to turn the pump off.

 

hmm true. sorry. did you have problems to get though inspection and all that jazz?

 

Not with my wiring of the fuel pump, no. The guy I have been using the last few years wouldn't pass the car based on a leaky rear wheel seal(which should fail it, I just missed it), my using flexible exhaust pipe to connect my y-pipe to my cat(which is BS, the only requirement for type of pipe/connections is that it doesn't leak and must exit the car behind the passenger compartment), and the fact that I removed all my emissions equipment except for the cat. Even though PA has an exemption in the inspection laws stating that if you drive the car less than 5k/year it does not have to pass emissions. So I took it to a guy recommended by a friend who knows about the exemption and he didn't give me any problems. Neither guy said anything about the fuel pump wiring.

 

hello, today as i was connecting the fuel pump directly to a cable i decided to check if there was a different cable that would be better to use instead of the button i had for the ignition motor. and i discovered that there is a thick yellow cable that gave current when i passed to the part of the switch that has spring resistance. and i followed it to a female connector that was disconnected.. but i have no idea where it goes. it has 6 cables. could you tell me what that is?

 

Your description needs help...can you take a picture?

 

Pics would be a big help. Is this under the dash or in the engine bay? The only yellow bundle of wires I can think of atm is for the airbag, which your car shouldn't have.