Need help from the SVO masters of knowledge.

[TTop Dave]

While driving the 84 Silver State SVO last week it just quit running. Pulled over and tried to restart, and the fuel pump wouldn't come on. I have replaced both of the Relay's and still nothing. I bypassed the relay under the seat and the fuel pump primed, and the engine turned over and showed 40 pounds of pressure on the fuel rail but it still wouldn't start. It still has both fuel pumps. Inertia switch is not tripped. Pulled the #1 spark plug and car is firing.

What am I missing?

[Mike S]

Try wiggling the ignition switch while KOEO position to see if you hear the pump prime.

[TTop Dave]

Wiggled ignition switch in KOEO and no luck, what else could it be. I really need to get this figured out quick so I can get it on the Autox track. Any other ideas?

[SVOC]

Wiggled ignition switch in KOEO and no luck, what else could it be. I really need to get this figured out quick so I can get it on the Autox track. Any other ideas?


Not to sound rude, but wiggling the switch is not where the key goes, too often I see this when asked.

Take the two halves of the steering column off and it will reveal the switch, which is of poor design:

https://sphotos-b.xx.fbcdn.net/hphotos-snc7/424599_489449151074143_1973596095_n.jpg

[Kendal Coker]

That looks like most of mine. They fall apart in you hand before you can get them out.

[Mike S]

Wiggled ignition switch in KOEO and no luck, what else could it be. I really need to get this figured out quick so I can get it on the Autox track. Any other ideas?

As SVOC pointed out the ignition switch is most likely fubar. The point of wiggling the key is to see if you get intermittent connection of the ignition switch which would indicate the failure in the picture above. Pull the column cover see if you can pull the switch apart. Pull the ground off the battery so as to not cause a short.

[MikeFleming]

Plan B: If you do not know the history of the ignition switch that's currently in the car, replace it with a new one.

If you DO know the history, and it's older than a decade, replace it with a new one.

Total time: 30 minutes. Cost $15/US

[TTop Dave]

Replaced the switch and still no fuel pump. What should I try next?

[svopony]

computer?

[TheSVOTrust]

Boy sounds like what I went through with my 1984 ! (Remember Kendal)

CHASED all you talked about. Mine turned out to be a bad rail pump! (actually wasn't even a correct SVO pump) Car had a E2000 style Delco put on it - but got gummed up and "worked when it wanted to".

At one point I removed and used 12V to run and run backwards - BUT ended up replacing with Bosch after 3 weeks of dicking with it.

Mark

[Kendal Coker]

If you put 12 volts to the pump and it works I agree with svopony it is the computer.

[caroth]

You have verified that the distributor rotor is turning when you crank the car?

[Larry_S]

You have verified that the distributor rotor is turning when you crank the car?
Good call. I have seen this one 2-3 times on my cars over the years.......

[Meotchh]

Call Stacey & demand a refund. He obviously sold you a light blue lemon:p

[MikeFleming]

When the ignition key is first switched to Run, the EEC sends a timed (~2 seconds) ground signal to the inertia switch then to the coil side of the fuel pump relay (via a red/black hash wire). Then when RPM is greater than 300 OR when cranking mode is engaged, the EEC maintains that ground signal output to the fuel pump relay. If the RPM signal goes away, after a short delay (nominally 2 seconds) the signal to the fuel pump relay ceases.

So troubleshoot it in sections. First get a test light onto the coil signal wire of the fuel pump relay (one of the thin wires). Watch it during key on. Should get a short (2 seconds) flash (where it goes OFF). Then crank and look for it to be flickering also. If it's NOT flickering, look for the EEC to have a problem - or the wiring to/from the EEC.

If all is working so far, make sure the yellow wire at the fuel pump relay has constant power. This is fed via a fuse link that feeds the EEC, the EEC relay and the fuel pump relay. It's a very poor design that joins those four wires together (a solderless crimp with tape around it - unfortunately a common theme in this era of Ford that has led to lots of trouble over the decades) and it's hidden in the harness up behind the dash above the EEC. MAJOR trouble to locate and repair. And this type of crimp connection will fail anytime too much current is asked from it.

So if you have the test light going off when cranking (to energize the relay coils) AND the yellow wire has full-time +12VDC power, this portion of the system is working. Time to check power to the fuel pump(s) themselves - again using the test light.

If the yellow wire DOES not have power, see the next post.

[MikeFleming]

If you have no power to the large yellow wire at the fuel pump relay (HOT at all times), first verify the fuse link is still good. It's connected, via a brown lugged wire, to the battery side of the starter solenoid. About 6 inches sown is the 18GA fuse link bulge, then the wire turns yellow as it disappears into the harness wrap.

1603 1606

The crimp I refer to above is near the other end of the harness, best to access with the dash out. Note the locaiton of the white tree mounting pin.
1598

The following pics show where the crimp is located and what it looks like (with the EEC harness removed). This pic shows the EEC relay socket at the bottom left and the above referenced mounting pin.
1599

Some tape removed and red circle showing location of yellow wire crimp.

1601
1604
Note ruler is measured from end of EEC connector.

Close-up of the "crimp". I prefer to separate all attached wires, clean them then solder. In come cases - where more current is needed than these wires can provide - I just run a separate fused larger wire from the starter solenoid.
1608

Wiring diagram for those that read these things.
1607

[TTop Dave]

I am going to try what you have recommended. If its the computer, I know the LA3 is the best replacement. Since I am running the Superchip, would it matter what computer I use?

[Patrick]

If you had a Superchip in it all along, that may change the diagnosis. Several people using a Superchip have had the above happen as a result of bad contact and corrosion between the Superchip and the terminals where it mounts to the EEC-IV. Test by removing the Superchip and see if it will fire up. If so, you may just have to clean up the contacts with some electrical contact cleaner and an eraser.

[Larry_S]

If you had a Superchip in it all along, that may change the diagnosis. Several people using a Superchip have had the above happen as a result of bad contact and corrosion between the Superchip and the terminals where it mounts to the EEC-IV. Test by removing the Superchip and see if it will fire up. If so, you may just have to clean up the contacts with some electrical contact cleaner and an eraser.

My brother had an SVO for a year that was not running well that he finally diagnosed by pulling superchip off and it ran night and day different (better).

[TTop Dave]

Pulled the Superchip, still nothing. Checked the wiring that Mike suggested and all looked good. Now I am on the search for a computeris there any other ones I should be looking for?. I know the La3 is the best for these cars, but with me going to put the chip back in

[MikeFleming]

With ignition in Run, ground the "tan/light green dashed" wire that goes between the fuel pump relay and EEC pin #22 (see wiring diagram above). If the fuel pump(s) DO NOT come on, it's probably NOT an EEC problem.

If they do come on, replace the EEC (or replace the TO-220 driver transistor inside the EEC case - some disassembly required).

[TTop Dave]

Replaced the computer and it started right up. Thanks for all the information and suggestions. Glad there is still a group of guys around that have a passion for these cars. Once again thanks.

[svopony]

and another home run