KansasTwister
1/2 ton status
buddys 88 ford bronco doesnt seem to have any power to the fuel pump relay. ran three months ago. Any ideas? is it wired at all off of the solenoid or where does the main lead pick up?
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
any ford mechanics in here?
- Thread starter KansasTwister
- Start date
I know my 89 mustang had a fuel pump inertia switch in the trunk in case of an accident or w/e. Bronco should have one in the RH kick panel. it is a black square with a button on top
KansasTwister
1/2 ton status
checked interia switch already.
It should be a negative ground right?
When i put the test lead directly to negative, i get nothing on test light, but with key on and test light to positive i get the bulb to light up.
He said they did some retrofitting to the fuel pump wiring (owners before him) and i think im gonna have to start prodding around there. Relay wiring looked like it had alot of corrosion, but i got a good portion of the wire and still didnt get test light to work.
Funny part? ran fine 3 months ago, and has just sat since. So idk what happened, was pouring rain today, they are gonna keep playing with it. Im gonna go over there agian when its dry and try to help. he gave away one of his jeeps, other jeep just blew a head gasket, and the bronc hasnt been running, hes not having good luck
It should be a negative ground right?
When i put the test lead directly to negative, i get nothing on test light, but with key on and test light to positive i get the bulb to light up.
He said they did some retrofitting to the fuel pump wiring (owners before him) and i think im gonna have to start prodding around there. Relay wiring looked like it had alot of corrosion, but i got a good portion of the wire and still didnt get test light to work.
Funny part? ran fine 3 months ago, and has just sat since. So idk what happened, was pouring rain today, they are gonna keep playing with it. Im gonna go over there agian when its dry and try to help. he gave away one of his jeeps, other jeep just blew a head gasket, and the bronc hasnt been running, hes not having good luck
My old bronco had a freakin touchy inertia switch i hit a good bump on the highway and it would trip, hardwire it to get rid of the pos, since it rained go through yoiur connections, if they're wet spray em with wd40 and wrap em watertight, where it was runnin fine before and now it aint as long as your fuel system aint plugged around pump or filter its gotta be something little like that
KansasTwister
1/2 ton status
said hes only 3v at the main power for the relay, should be 12v id assume.
Well, in the words of Mythbusters, theres your trouble right there!
Ok, my truck is an 89, but I don't think there were any changes. Its multiport fuel injection, right?
When you turn the key on, the fuel pump should come on and run for about 5 seconds and then stop. Off and back on, another 5 seconds.
The computer has to see trigger pulses from the dist. to keep it running.
Do the off-on test and see if it runs for 5. I have my shop manuals around here somewhere, and I will see if I can find the trouble shooting tree for the pump and let you know what to look for.
J.
KansasTwister
1/2 ton status
Well there are two relays, second out was badly internally rusted!
KansasTwister
1/2 ton status
Only getting 6v after jumping the relays at the pump. He wants to run straight power to pump. I'm saying use a switch and relay. Any advice on how to wire it up and what gauge of main lead to use? Low pressure works but high pressure isn't.
KansasTwister
1/2 ton status
We ran 12v straight to the pump via a relay, still nothing. Well it seems someone had added a helper pump on it before him and it was making noise, removed it, still just around and round. We have spark, compression, so maybe the interiors arent firing? time for a diode tester.
Last edited:
wasted wages
1 ton status
Radiator cap issue.....
rgorsuch87
1/2 ton status
Check all of your grounds
OK, here are some things you should know. The pump in the tank is a lift pump for the high pressure pump on the frame.
When the engine is running, the tank pump is running, and the booster pump is running. The fuel goes up to the fuel rail which all the injectors are mounted on, then to the fuel pressure regulator at the back of the engine, and then the excess above the set pressure, goes back to the tank.
The fuel pump relay is hooked directly to the positive side of the battery. The EEC-IV computer grounds the relay when its supposed to run.
When you turn the key on, the computer turns the pump on for 5 seconds, and then if it does not see the engine running, it turns the pump back off.
So, the first check is to see if the pump runs when the key is turned on.
I have the complete schematic and troubleshooting instructions from the shop manual for my 89 back home.
If you want, I can look up the pinouts and test procedure when I get home tonight.
J.
When the engine is running, the tank pump is running, and the booster pump is running. The fuel goes up to the fuel rail which all the injectors are mounted on, then to the fuel pressure regulator at the back of the engine, and then the excess above the set pressure, goes back to the tank.
The fuel pump relay is hooked directly to the positive side of the battery. The EEC-IV computer grounds the relay when its supposed to run.
When you turn the key on, the computer turns the pump on for 5 seconds, and then if it does not see the engine running, it turns the pump back off.
So, the first check is to see if the pump runs when the key is turned on.
I have the complete schematic and troubleshooting instructions from the shop manual for my 89 back home.
If you want, I can look up the pinouts and test procedure when I get home tonight.
J.
KansasTwister
1/2 ton status
I knew that the piece in the distributor told the fuel pump to keep running, but for whatever reason we were only getting 6v at the frame pump. If you post out the procedure that would be awesome. His jeep has a blown head gasket or cracked/warped head and we are trying to diagnose that as well
Its never easy with him. (jeeps coolant smelled like exhaust, back two cylinders had water around the compression rings, im thinking because the diverter valve split and he kept driving it because he was somewhere where you dont want to shut her down that he got an air pocket on the rear of the motor (common for the 89 Cherokees that had a closed system) that he warped either the block or the head.
KansasTwister
1/2 ton status
Oh ya, hes a ford/jeep guy mainly, and because of all this he told me "Ryan, after all this bs im really considering buying a chevy"
So i looked at him and said "Joe, that may have been the smartest thing you have ever said."
I did link him to a decent 81 2wd chevy wtih a 305 for 800. Would be a simple small block that would be hard to maintain and not ballsy enough for him to treat like the jeep and take mudding lol.
So i looked at him and said "Joe, that may have been the smartest thing you have ever said."
I did link him to a decent 81 2wd chevy wtih a 305 for 800. Would be a simple small block that would be hard to maintain and not ballsy enough for him to treat like the jeep and take mudding lol.
Ok, got the book in front of me, but its real complicated, and the step relate to a breakout box that you don't have.
I can figure out what they are saying and translate it to indivdual wires and connectors, but at this point it would be a waste of time.
You need to make sure that the fuel pump relay is getting a full 12 volts from the battery.
If not, you need to find out why. Its fairly straightforward, just a wire from the relay to the battery.
You did not say which engine. It makes a difference as to wire color, and in some cases fuse location in the circuit.
First of all, if you are serious about fixing this thing, save yourself some possible extra work, and hook a long medium heavy wire to the battery negative post.
Not the frame, not a good ground. Go straight to the battery. Use it when you need a ground. Don't trust any other grounds until you have found the problem.
If my pinout for the relay socket is correct, look at it in such a way that you see three pinholes down the left side, with another pinhole on the right side bottom. There should be a hole on the right side upper, that has nothing in it.
If this is correct, the single right side bottom should be hooked to the battery. Measure the power there with a meter with the other wire hooked to your ground wire.
If you do not have full battery voltage there, you need to find out why. Its a fairly straight shot to the battery.
That wire supplies power for the fuel pump, but not the relay its self. It gets its power through the middle connector on the left which comes from the EEC power relay. That is the other one there.
Power to the fuel pump comes from the lower left pinhole. All the relay does is hook the bottom left and right holes together to power the pump.
If you have run power to the pump and only get 6 volts, you either have a battery that is dying under load, a bad connection somewhere, or a bad ground.
Check to see what the voltage is in reference to your ground wire.
Plus, its not unheard of for the tank or pump ground to be bad.
Study on what I have given you so far, and let me know.
J.
I can figure out what they are saying and translate it to indivdual wires and connectors, but at this point it would be a waste of time.
You need to make sure that the fuel pump relay is getting a full 12 volts from the battery.
If not, you need to find out why. Its fairly straightforward, just a wire from the relay to the battery.
You did not say which engine. It makes a difference as to wire color, and in some cases fuse location in the circuit.
First of all, if you are serious about fixing this thing, save yourself some possible extra work, and hook a long medium heavy wire to the battery negative post.
Not the frame, not a good ground. Go straight to the battery. Use it when you need a ground. Don't trust any other grounds until you have found the problem.
If my pinout for the relay socket is correct, look at it in such a way that you see three pinholes down the left side, with another pinhole on the right side bottom. There should be a hole on the right side upper, that has nothing in it.
If this is correct, the single right side bottom should be hooked to the battery. Measure the power there with a meter with the other wire hooked to your ground wire.
If you do not have full battery voltage there, you need to find out why. Its a fairly straight shot to the battery.
That wire supplies power for the fuel pump, but not the relay its self. It gets its power through the middle connector on the left which comes from the EEC power relay. That is the other one there.
Power to the fuel pump comes from the lower left pinhole. All the relay does is hook the bottom left and right holes together to power the pump.
If you have run power to the pump and only get 6 volts, you either have a battery that is dying under load, a bad connection somewhere, or a bad ground.
Check to see what the voltage is in reference to your ground wire.
Plus, its not unheard of for the tank or pump ground to be bad.
Study on what I have given you so far, and let me know.
J.
KansasTwister
1/2 ton status
well we have already bypassed the factory wiring, and after finding out my buddy put the pump in backwords, its now getting fuel, but still wont run, only turn over. The scary part is we have verified spark, as well as smelling fuel in the exhaust, and it never tries to run on its on. So im at a loss. Im wondering if the factory wiring has something within it to tell the computer to allow spark or something like that.
Yes, there is. There is a fuel pump monitor wire that comes off the output to the fuel pump to tell the computer that the fuel pump is getting power.
It goes to pin 8 on the EEC-IV module. I don't know what color wire it is, since it is a different color depending on which engine you have.
This is a mulitport fuel injected engine, right?
Remember, that computer module does most of the engine controlling. If it is not in the loop any more, there is no telling what it will do.
For instance, that engine will not start if the computer has not opened the air bypass valve unless you are holding the throttle open a little.
If the computer is satisfied that the engine should crank, then I would suggest that you hold the pedal to the floor.
This tells the computer it is flooded, and it modifies its strategy accordingly.
But if the computer thinks that the fuel pump is not working, then it probably will not do it.
Let me know what engine you have, and I will try to come up with a workaround that will get the computer back in charge.
Right now, it sounds like its flooded.
Try pulling the vacuum line off the top of the fuel pressure regulator to see if there is any fuel in it. If you see any fuel in the vacuum line, then the diaphragm is busted and the engine is almost certainly flooded.
J .
It goes to pin 8 on the EEC-IV module. I don't know what color wire it is, since it is a different color depending on which engine you have.
This is a mulitport fuel injected engine, right?
Remember, that computer module does most of the engine controlling. If it is not in the loop any more, there is no telling what it will do.
For instance, that engine will not start if the computer has not opened the air bypass valve unless you are holding the throttle open a little.
If the computer is satisfied that the engine should crank, then I would suggest that you hold the pedal to the floor.
This tells the computer it is flooded, and it modifies its strategy accordingly.
But if the computer thinks that the fuel pump is not working, then it probably will not do it.
Let me know what engine you have, and I will try to come up with a workaround that will get the computer back in charge.
Right now, it sounds like its flooded.
Try pulling the vacuum line off the top of the fuel pressure regulator to see if there is any fuel in it. If you see any fuel in the vacuum line, then the diaphragm is busted and the engine is almost certainly flooded.
J .
KansasTwister
1/2 ton status
Ill check the vacuum line tommorow, thanks for the help.
Duh!
Never posted engine. Its a 302 multipoint EFI with an auto.
Duh!
Never posted engine. Its a 302 multipoint EFI with an auto.
