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I have an 89 Ford F-150 with the 4.9l 300 l6 and my truck sat for about a week while I was on vacation. When I returned the truck will turn over but not start. I’m pretty sure the problem is electrical due to no voltage at the pumps or injectors with the key on. I thought it might lie with the relays so I have been trying to check them. Replacements are 5 prong but connector only has 4 wires so I ordered two 4 prong relays one for the EEC and one for the FP tried this twice but no luck. I’ve checked everything I can think of that could cause a power issue but no luck their either. Both relays have a hot wire from battery. EEC also has a 12 volt with key wire but only puts out 2.7 or so on the high side of the relay running to the fuel pump relay. Any ideas?
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see if this link helps.
http://www.justanswer.com/ford/1erci-1989-ford-f150-6-4-9-manuel-trans-won-t-start-cranks.html
Hello 🙂
Here you have wiring diagram, in case you havent..
So you have battery volt at yellow wire inn to EEC relay, and only 2,7 V out on the red wire?These EEC-IV systems are pretty easy to troubleshoot.
Do you hear the fuel pump hum for a few seconds when you first turn the key on?Have you cranked it over and verified spark or lack of?
Have you checked the fusible links which source the power to the relays?
This era of Ford is notorious for ignition module problems and lack of SPOUT and PIP signals from the module can cause various issues.
That is correct the red wire only reads low voltage (2.7 V) when checked with a multimeter and isn’t enough power to make a test light come on when tested that way. The Haynes manual says that the red wire should have 4 to 6 V but I have read online that it should have 10 to 12 V.
The fuel pump is not humming when turned the key is turned on and there is no power to its electrical connector. It has good spark and good power going to the relays just no power to the fuel system.
I checked the inertia switch and it’s not tripped and has continuity. The voltage is so low coming from the relay that the voltage at the inertia switch is very low.
Ok, I was confused because you said this:
[quote=”Cemmons97″]Both relays have a hot wire from battery. EEC also has a 12 volt with key wire but only puts out 2.7 or so on the high side of the relay running to the fuel pump relay[/quote]
and then said this:
[quote=”Cemmons97″]good power going to the relays just no power to the fuel system.[/quote]
and then said this:That seems contradictory, because low volts is not good power. If you look at the diagram allhan posted, you will see the red wire carries 12v fused power (battery voltage) to all of the relays, solenoids, fuel injectors, and engine computer. If there is not 12v on this wire, something is shorted and consuming the power. First pull the fuselink (fuselink N) and double check that the 12v is present on the line side of the fuse. Then, if there is 12v there, you will have to reconnect the fuselink, and check at each relay and connector on the load side of the fuselink to see where the voltage is getting lost. If the 12v is not at the line side of the fuselink, you’ll have to instead check between the fuselink and the battery to find where the voltage is being lost.
[quote=”Cemmons97″] The voltage is so low coming from the relay that the voltage at the inertia switch is very low.[/quote]
Another contradiction is here. The inertia switch isn’t powered by the relays. It gets power from fuselink W (brown wire), while the relays get power from fuselink N (red wire). If the volts on the inertia switch is low, AND the volts on the relays is low, then there is a bigger problem. If the volts are low on the inertia switch and the volts on the relay = battery voltage (12v), then that doesn’t follow your earlier post where you said the red wire has low volts (2.7). Since the inertia switch has low volts ALSO, then there is a common problem between the circuits of fuselink N and fuselink W. That common problem is either the battery or alternator, or a wiring fault at the battery or alternator. BTW, have you checked your primary grounds? Are the battery terminals clean and free of corrosion, and tightly clamped to the battery posts?So you have 12v in to relay on yellow wire even when relay is activate? same time red wire out of relay is 2,7V?
if thats the case, someting wrong with that relay..
dont know hat that haynes meen with 4-6V.. But it should be battery voltage..Sorry for the confusion let me clarify. Both relays have 12 volts on the yellow wires, the fusible links on the diagram. With the key on the EEC relay receives 12 volts to open the relay but the red wire where voltage travels once the relay is open only puts out 2.7 volts or so. I’m my opinion that is nowhere enough to open the FP relay to which the red wire runs. The voltage on the brown wire is even lower than that of the red wire. The brown wire is the hot side of the inertia switch and from there it feeds the fuel pumps. Keep in mind the voltage can be checked on the brown wire of the inertia switch and it has low voltage similar to checking the brown wire directly at relay. I’m assuming due to the low voltage feeding the wires and resistance in the wires some voltage is lost by the time the wire reaches the fuel pump as it only reads 0.01 volts which is basically 0. I’m beginning to wonder if the relays are correct. The original relays are four prong so I had to special order the aftermarket relays. The relays they stock for the truck are five prong and that has been bothering me since the original is four prong.
Correct, the yellow wires are hot all the time as the Haynes manual shows. The manual has a list of what the voltage ranges should be on each wire of the relay and I believe it showed 4 to 6 for the red wire. I agree though it should be a full 12 volts to properly open the relay and supply sufficient power. It appears that it is constantly leaving the FP relay open with the key on because it is trying to prime the fuel rail but can’t due to lack of power to the fuel pump.
So, unplug the relays. There should be 12v on the yellow wire coming from fuselink N and 12v coming from the yellow wire on fuselink W. With the relays removed, if you still don’t have 12v on those wires, there is still an issue. If you DO have 12v on both places, then the relays are a problem. Make sure the relays aren’t installed backwards. The coil side of the EEC relay (standard pins 85 and 86, the ones I labeled 1 and 2) should be where the white/light blue and black wires go, and for the fuel pump relay, the coil side (pins 85 and 86) should be where the red and tan/light green wires go. The contact side (standard pins 30 and 87, the ones I labeled 3 and 4) of the EEC relay should be where the yellow and red wires go, and for the fuel pump relay, the contact side (pins 30 and 87) should be where the yellow and brown wires go. You can tell which side is coil side and contact side with the relay unplugged and using an ohmmeter. There should be infinite resistance between normally open contact terminals (3 and 4), zero resistance between normally closed terminals (3 and 5), and a low resistance (usually less than 100 ohms) between the coil terminals (1 and 2).
Note, the wiring diagram posted shows a 5-pin relay. The normally-closed contacts (the ones I labeled #5, standard pins 87a) are not connected to a wire, but are depicted on the drawing.
Both yellow wires are in fact getting 12V. On the relays it is true the #5 position would be the closed position until power is applied to the coil of the relay and then the switch would make contact with the #4 position. The original like I said only had 4 pins but operated to the same logic for both the EEC and FP relay. It shouldn’t make a difference then between a four or five prong relay as it can only be connected one way anyway.
If the power into relay is good, and power out of relay is bad, then you have a bad (or incorrect) relay.
On the fuel pump relay, pin 30 connects to a yellow wire which you just confirmed has 12 volts. After it passes through the relay it goes straight to the inertia switch, which you confirmed has low voltage (you said close to zero). First, verify that the 12v passes through the contacts of the relay (12v on both contacts, pins 30 and 87, when relay is closed). Disconnect the brown wire from the inertia switch. If you have 12v on the brown wire now at one end but not the other, then I would check that wire for damage between the relay and inertia switch. If it has 12v at the relay, at both ends of the wire when disconnected from the inertia switch, but not at the inertia switch when connected, the inertia switch is bad. If 12v doesn’t pass out of the relay (no 12v on pin 87), the relay is bad.
As to your statement about the relay operation, in a perfect world, that would make sense. However, this is not a perfect world. While the contact logic may be the same, the electrical characteristics of the coil and electromagnet may not be. If the relay you are using is not the manufacturer specified part number, or equivalent, it is quite possible the coil in the relay requires higher power (ohm’s law: volts times amps) to close the contacts. If the circuit cannot supply that amount of power (computer controlled circuits are current-limited by their transistors) then the contacts will not close fully (flutter) or remain open. This will prevent the load side of the relay from operating properly.
However, I think the issue here is you are using the incorrect relays. Look at the photo below. The EEC and FP relays are in fact 5 terminal relays. Take a closer look at yours, and please post a picture of yours (sockets and original relays) if it is different.
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