Fuel pump stopped working a couple of days ago, could it be the relay board Options

[JimN73]

I have no power at the pump.

I have 12.4 volts at pin #13 on the relay board.

No power at pin #5 or 7, old eyes can't see the stripe colors very well.

Fuses are good.

Am I missing something?

Thanks in advance.

[JimN73]

and:

3.5 psi pump for carbs, and

the relays are good

[Elliot Cannon]

Mine stopped working about a month ago. I tapped it with a screw driver handle (technical trouble shooting) and it started up. If you haven't driven it in awhile, the pump could be buggered up. Give it a try. Takes 2 minutes. (IMG:style_emoticons/default/smile.gif) It worked fine after that but I replaced it anyway for the 1000 mile trip to the RRC. (IMG:style_emoticons/default/driving.gif)

[JimN73]

Mine stopped working about a month ago. I tapped it with a screw driver handle (technical trouble shooting) and it started up. If you haven't driven it in awhile, the pump could be buggered up. Give it a try. Takes 2 minutes. (IMG:style_emoticons/default/smile.gif) It worked fine after that but I replaced it anyway for the 1000 mile trip to the RRC. (IMG:style_emoticons/default/driving.gif)

Thanks, Elliot. Sadly, didn't work.

[Dave_Darling]

and:

3.5 psi pump for carbs, and

the relays are good

How is it wired? Many different ways to power the pump; whomever did the conversion picked one of those ways. Some don't use the stock relays at all. You have to figure out what they did.

--DD

[JimN73]

and:

3.5 psi pump for carbs, and

the relays are good

How is it wired? Many different ways to power the pump; whomever did the conversion picked one of those ways. Some don't use the stock relays at all. You have to figure out what they did.

--DD

David, apparently used the "Sir Andy classic method", connecting one wire from the 4-prong FI connector to ground. The original plastic 'wrap' is on the wires from the pump. but there have been other splices and I can't see whether the original wiring is being used. I can answer that by making a jumper cable for the ohm meter and checking resistance between the relay board and the pump.

Additional display of ignorance: Does the power from pin 14 go to pin 13 on the relay board? What's the connection between pin 13 and pin 7?

Jim

[JimN73]

After cleaning some corrosion around pin13 and 14, I think I have come to the final problem.

I have power to pin #14, through the relay and the fuse.

There is 0 resistance between pin 13 plug and and the fuel pump. There is 0 voltage to the pump when the plug is installed over pin 13.

Looks Like I'm not getting power from the board to the pin 13 plug??

Is there a solution, am I missing something?

thanks,

[Spoke]

Power to the fuel pump relay is provided by the power supply relay.

With your voltmeter, measure voltage from the FI plug pin 1 to chassis ground. With the ignition switch on, this should be 12V.

Also check the voltage on both sides of the 25A fuse. Touch the spades holding the fuse, not the fuse itself. This will check the connection of the fuse to the spades.

[euro911]

When you turn the key to the 'on' position, check for 12 volts at pin 8. This voltage energizes the coil (contact point 85) in the power relay, which upon closure (contact point 87), passes 12 volts to energize the coil (contact point 85) in the fuel pump relay. This is where pin 13 derives power to run the pump. (Make sure to check for voltage at pin 12 too. Voltage from pin 12 passes through the power relay to the pump relay's coil).

Also, make sure that contact point 86 from each relay socket on the relay board have continuity to ground.


You can test the individual relays by using test leads with alligator clips and a multimeter (VOM)

Remove the relay(s) from the board. Apply 12 volts to contacts 85 & 86 to energize the relay ... you should read continuity (closure) between contact points 30 & 87. If not, repair or replace the relay(s).

Yes, you can pop the covers on the relays and lightly burnish the contacts. I typically use a small strip of standard 20# bond [printer] paper, as it will clean the contacts without removing the protective coating.

[Olympic 914]

try this troubleshooting sequence. it worked for me.

http://www.google.com/url?sa=t&rct=j&a...S8A4uDTjQ-CvZDQ

[cary]

Here's what I finally did on Matt's car. Hopefully this will rid us of the fuel pump gremlins for a while. Once I'm satisfied we've cured the problem all the female sockets will get a dab of dielectric grease.

http://www.914world.com/bbs2/index.php?s=&...t&p=2532812

This I got from Doug. Much easier to read. Just remember the power supply relay has to work to power the fuel pump relay. Took me a while to get that to sink in.

[JimN73]

Thanks, all. More troubleshooting and maybe some new knowledge

[JimN73]

Well, here is the final answer - I think.

Thanks for all the diagnostic tips, tried them all. The answer came from the 22 step diagnostic that Olympic 914 sent.

http://www.google.com/url?sa=t&rct=j&a...S8A4uDTjQ-CvZDQ

I started at the beginning and got positive results until I got to number 21 (skipped the ones referencing the ECU): Fuel pump harness to relay board. No power. I removed the terminal at the end of the fuel pump wire, still no power.

The board tests OK - no resistance between relay and pin 13), so plug half of the 14 pin connector is toast?

I'm not sure what to do next, for now, I'm running the pump off a switch power fuse.

Thanks for all your help.

[euro911]

You can probe the wire outbound of the connector to verify if the wire is disconnected to pin #13 on the connector.

Note that you won't have constant power on the wire from pin #13. There's a timing circuit (I believe it's in the ECU) that shuts the pump off after several seconds unless the motor is running.

You can remove the cover on those 12 and 14-pin plugs if you need to check for a bad connection inside, and if you might need to re-solder any wires.

[JimN73]

You can probe the wire outbound of the connector to verify if the wire is disconnected to pin #13 on the connector.

Note that you won't have constant power on the wire from pin #13. There's a timing circuit (I believe it's in the ECU) that shuts the pump off after several seconds unless the motor is running.

You can remove the cover on those 12 and 14-pin plugs if you need to check for a bad connection inside, and if you might need to re-solder any wires.

Thanks, Mark. I have tried to 'slide' the cover on the connectors - doesn't want to go. And I'm afraid I'll trash the cover if I try to pry it off.

What would you suggest?

Power is not a problem, carbs with no ECU so there is constant power.

[injunmort]

here is a simple test, fast, effective and isolates the issue: run your hot wire directly from the fuel pump to the positive post of the coil. assuming you have power at the coil in the ignition position. i am suspect of your diagnostics. fuel pumps fail, relay boards are old. if you power up the ignition, your pump will run continuously. if it does, your problem is in the wiring. if the pump does not run, your pump failed. pretty simple really. if the car wont start but the pump runs, it aint the fuel delivery or a wiring issue to power the pump problem. not injected, no need for volt meters and adding questions as to where next.

[Spoke]

I'm a bit confused on what you have found so far.

Have you determined that the Power Supply Relay is on?

The power supply relay on will provide 12V at pin I of the FI connector. Do you have 12V at pin I of the FI connector?

Have you determined that the Fuel Pump Relay is on?

Checking the FP relay is a bit more tricky. You can pull the relay and place a small wire in the FP socket on pin 87. Install the relay, turn power on, and measure 12V on the test wire.

If this is ok, pull the 14 pin connector and FP relay and measure resistance from the FP relay pin 87 to pin 13 of the 14 pin connector. Should have zero ohms.

As an aside, I've found when working in the engine area for more than 1 hour, if you remove the engine hood you will have much better access to the items you're working on. The hood is held on with 2 10mm bolts and is easily removed and replaced.

[euro911]

... As an aside, I've found when working in the engine area for more than 1 hour, if you remove the engine hood you will have much better access to the items you're working on. The hood is held on with 2 10mm bolts and is easily removed and replaced.

Especially when the 'slot mod' to the hinges is performed (IMG:style_emoticons/default/shades.gif)

[euro911]

You can probe the wire outbound of the connector to verify if the wire is disconnected to pin #13 on the connector.

Note that you won't have constant power on the wire from pin #13. There's a timing circuit (I believe it's in the ECU) that shuts the pump off after several seconds unless the motor is running.

You can remove the cover on those 12 and 14-pin plugs if you need to check for a bad connection inside, and if you might need to re-solder any wires.

Thanks, Mark. I have tried to 'slide' the cover on the connectors - doesn't want to go. And I'm afraid I'll trash the cover if I try to pry it off.

What would you suggest?

Power is not a problem, carbs with no ECU so there is constant power.

I'd go along with 'Mort's' method first ... seems easy enough.

Since most wiring fatigue issues happen at connector plugs, I would remove the plug, place one probe on pin #13 and stick the other probe through the insulation of the wire going to the pump (a few inches away from the plug) and see if you have continuity there (you can seal up the hole with a dab of liquid tape).

[JimN73]

Here's what I have done. I think I covered everything and have found the problem.

I tried to print it here, but the font size that would print here is too small to read. It's Excel. If you want more detail, I followed the procedure in this Google doc.

 fuel_pump.xls ( 8k ) Number of downloads: 33


http://www.google.com/url?sa=t&rct=j&a...S8A4uDTjQ-CvZDQ


Everything checked out until I got to item #21, power to fuel pump.

Final question: What's the easiest way to remove the capon the 14 pin connector?

Thanks for your help