1978 928 Was Running Perfect - Now no Spark or Fuel Pumping

[ckcarr]

I had tuned up my old 1978 928 last weekend. On last Tuesday it started right up and was running perfect. Took for a nice drive.

I decided to change out the anti freeze so I jacked up the car and put on Rhino lifts under each wheel. When I jack it with a floor jack it gets angled a little as I put the Rhino Lifts under each wheel. However, I ended up not changing the anti freeze (got busy on other things).

So I lowered the vehicle back down. Now it cranks, but there's no spark and no fuel pumping, and no start. If I try a little shot of starting fluid there's no firing even with that. I thought I read that the tach should move when cranking, but it just sits there.

Any ideas? Could I have pulled some wire or ground somewhere when jacking? I heard that the starter needs to send a signal?

Any advice appreciated.

[harborman]

Check all your grounds. There is one from block to frame. Many others. Check fuses. Check everything associated with the ignition and fuel system. If it turns over, the starter is working.

[Linderpat]

how old is the battery? Sounds like a battery issue. Did you leave the door open or something with a light, like the hatch, while it was sitting up?

[harborman]

Originally Posted by Linderpat

how old is the battery? Sounds like a battery issue. Did you leave the door open or something with a light, like the hatch, while it was sitting up?

Battery voltage should sit around 12.6 volts with engine off.

Another thing, check the ground strap from battery to frame. They tend to become corroded at the body connection. (Inside the cable itself).

[ckcarr]

Well, an update is that I now have the problem figured out. Like many things, there actually was no correlation between jacking up the vehicle and it's failure to start. Just coincidence.

What it turned out to be is the fuel pump relay. Now the trick is finding one, or a more modern equivalent. Or, even repairing this one (as I saw on YouTube). 30 & 87 never close to complete the circuit.

[harborman]

Originally Posted by ckcarr

Well, an update is that I now have the problem figured out. Like many things, there actually was no correlation between jacking up the vehicle and it's failure to start. Just coincidence.

What it turned out to be is the fuel pump relay. Now the trick is finding one, or a more modern equivalent. Or, even repairing this one (as I saw on YouTube). 30 & 87 never close to complete the circuit.

I think that is a fairly common relay. I replaced all of mine and kept a few extras in the car. Type 53 comes to mind. You can maybe find them here on this site or on others. Maybe even your local parts store.

[Opelotus]

Are you sure it's the fuel pump relay? Because that would not prevent spark. If only the fuel pump relay was dead, your test of spraying starting fluid down the intake should have resulted in the engine firing.

The fuel pump relay will not kick on unless it receives an RPM signal from the ignition box below the 14-pin connector under the hood, passenger side. The ignition box will not send an RPM signal if the main green wire from the distributor is broken or damaged. Inspect the green wire and both of its connectors carefully.

Also make sure that power and ground to the ignition box are present with the key on. If the boot on the connector for the ignition box is torn, I'd unplug the connector and verify none of the terminals are corroded. Hopefully that should get you going in the right direction.

In summary, I wouldn't conclude that your fuel pump relay is the culprit without further testing of the related circuits (based on your info thus far). That being said, replacement of the fuel pump relay is good preventative maintenance.