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89 merkur xr4ti - no PWR @ fuel pump relay
#1

Hello, new to me merkur xr4ti has no power at pin 30 side of fuel pump relay.

I can jump the pump and hear it buzz. But once I install the relay and fuse and try to start it, fuel pump does not buzz to prime or anything. Inertia switch does test okay. according to step 3 of the merkur shop manual in print I have. I have some sources for my tests and results, so ask, and I may have info . I DO have to re-learn how to post pics here.

Has a PF3 ECU. I have fixed 2 grounds so far, I am currently interested in the wire in my wiring diagrams labeled as 54-15. A black and red wire. It appears to run from relay (by window wipers) to inertia switch (by spare tire) then back up by ECU (pass. Side kick panel) to a connector, then back to ECU as 361 BK/R to pin 17? Of Ecu. I really want to find and test this connector (near Ecu in diagram)

DOES have continuity between pin 30 side of fuel pump relay and IAC (throttle air bypass solenoid) red wire.

Thanks in advance for any help or direction.
Nick M.

88 mustang coupe, t5,8.8, air research 63./.60, E6, gutted upper, ported lower, Engle cam, MS2
70 elco
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#2

(09-13-2021, 03:01 AM)Stillslow70 Wrote:  Hello, new to me merkur xr4ti has no power at pin 30 side of fuel pump relay. 
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WELCOME back, Nick! <thumbup>

Look at the little "stick-figure" circuit drawing on the side of the relay and tell us/me whether pin 30 is one of the coil winding ends OR one of the switched terminals (fixed or "armature"). Only one of each should ever be powered by 12V when the relay isn't activated. IIRC, Ford's typical f/pump circuit is such that switched power (from ign sw) powers one end of the coil winding, while the other end gets grounded by the EEC to activate the relay.

Of the three "switch terminals", only two are used to operate the f/pump circuit (the 3rd "normally-closed" terminal is unused). One of 'em is continually powered from the battery and the other goes to the inertia switch in the trunk (then on to the f/pump) whenever the relay is activated.
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#3

Thx, Turbo Ray! For the help today and years past!

So, the relay does not have a drawing on the plastic cap. But I believe pin 30 to be post energized relay.
Pin 87 however, does have power (even with key off, this pin is what I used to jump the pump to see if it would run. Pin 87 is a large spade, 30 is a large spade too (12v?) Where as the ground and unused leg are smaller/shorter.
Maybe I'm testing it backwards, but my merkur diag tree that I'm following claims that pin 30 is powered and should illuminate a test light when the relay is removed and the light is grounded. 🤔 Opposite of what I've found.
Relay does energize and click when installed.
If you need pics of it, plz let me know
88 mustang coupe, t5,8.8, air research 63./.60, E6, gutted upper, ported lower, Engle cam, MS2
70 elco
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#4

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Hmmm......it's odd that there's no schematic on the relay case! Sometimes it's not in ink, but rather cast into the plastic surface. Oh well, I'll have to do a little more research then. What I CAN say is that there shouldn't be any "click" from the relay when it's simply plugged in......key on OR key off.

The typical Ford f/pump relay from "that" era is only energized by the ECU (1) When the key is first turned on for only about 1-second, OR (2) When a PIP signal is generated by a rotating motor (cranking or running). At all other times, the relay coil should not be grounded by the ECU (hence.......no click).

• ADDENDUM: Below is a generic automotive relay "schematic" that I gleaned from the web. Note that the relay's coil terminates at pins 85 & 86, soooo.......if it's the same as your relay, one of those pins should be powered by 12V from the ignition switch, with the other being the "trigger pin" that gets grounded by the EEC to close/connect the contacts. 

OTOH, pin 30 appears to be the "armature contact" which would be powered by continuous 12V from the battery.......and pin 87 appears to be the contact that would lead off to the inertia switch/fuel pump (with 87a being unused). AGAIN.....this is merely a generic automotive relay and may NOT be the same as yours. <shrug>  GOOD LUCK!

[Image: 120-volt-relay-wiring-diagram-120-volt-r...ss-15g.jpg]
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#5

Spot on except I think the power (+12v) at 30 probably comes from the ignition switch instead of being continuous hot, but I definitely could be wrong.
83 & 84 GT turbo, 84, 85.5 & 86 SVOs
87 & 88 TurboCoupe
93 5.0 notch, 95 GT coupe & vert, 96 GT vert  (Yes, I have a probem, garage's too small!)
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#6

I got a few hours on it the other night and made some progress.

I was looking at the wrong relay after all.. duh.. but, it has some issues there im getting sorted out. 

The REAL fuel pump relay does have power at Pin 30. It is not clicking when you turn the key though. If I close it with my hand the pump will run.

So next, I'll check continuity from the relay terminal in fuse box to pin 22 on ecu and go from there and report back!
88 mustang coupe, t5,8.8, air research 63./.60, E6, gutted upper, ported lower, Engle cam, MS2
70 elco
Reply
#7

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If your relay has the same internal schematic as the generic version I posted.......pin 30 is the "source power" for the fuel pump and shouldn't have anything to do with whether or not the relay "clicks" or activates, Nick ~ regardless of the key position. What makes the relay click/work is the internal electromagnet, whose coil terminates at pins 85 & 86. 

Therefore, check for key-on power at either of those pins. IOW, if the switched battery power is applied at, say, pin 86 ~ the relay would then be triggered by the EEC when it selectively grounded pin 85. Soooo........if your  relay and wiring are the same,  you should have battery power at 30 and key-on power at 86. <shrug> GOOD LUCK!
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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