Fuel Pump Woes... no power??

[bfloyd]

Heading out to a concert yesterday afternoon and made it about 25 miles before the car died on the interstate. Merging from one interstate to another the engine starting sputtering going up the crossover ramp, loosing power as I went. Engine completely shut off by the time I hit the entrance ramp and we coasted to a stop along the shoulder.

Tried cranking and cranking, and it seemed like it wasn't getting fuel. The tank was full. I have in my car the new DMCH combo fuel pump / fuel sender unit that was installed in the summer of 2015. Noticed on the dash that all of the gauges worked EXCEPT the fuel gauge. It read zero. I'm assuming that since the gauge didn't read anything that would indicate no power going to the pump / fuel sender. I checked the fuse and it was fine. I checked the inertia switch and it was fine. The only thing I haven't done is physically check the electrical connections at the pump. Kinda hard to do on the side of the road with trucks whizzing by at 80 mph. Will take the trunk apart this weekend to verify the connection and put an electrical tester on the connectors to see if I've got power.

This "new pump" has roughly 11k miles on it since installed in 2015. Any other suggestions as to what I can look for?

[iflights]

I'm not an expert, but these are what I would do.
Check the connections and voltage at the pump.
Inertia switch plug is troublesome as well, you could jump center pin to end pin (black wire) to take switch out of the electrical loop.
Jump the RPM relay in an attempt to isolate it to the relay or pump if not seeing voltage at pump.

[David T]

Verify power and ground to the pump. You will have to jump (bypass) the RPM relay. If you have power & ground to the pump and it isn't running you found the problem. Can also be the RPM relay so you have to check it too. Check that your inertia switch has a white splotch of paint on it and it is NOT attached to a bracket hanging off the Lambda counter but is on the side of the footwell. Other possibility is a bad connection in the wiring harness plug up by the windscreen reservoir.

[mr_maxime]

Also, are you sure the inertia switch is functional? Mine didn't work and was bypassed. Then that bypass got burnt up.

[bfloyd]

My inertia switch IS located on a bracket on the side of the lambda counter, but it does not have a white splotch of paint on it as far as I know. The inertia switch IS functional as I had to test it while doing the DMCH Fuel Pump recall wiring modifications. I'll start digging into it on Saturday morning.

[David T]

Look up Safety Campaign No. RA-0003. Service Bulletin SC-06-7/82. You need to get it done, the original inertia switch has a high failure rate and must be removed, relocated and replaced. Since you don't have this recall done you now must make sure ALL applicable recalls have been completed. BTW, the white splotch of paint tells you that you have the replacement inertia switch. If you don't have a switch with that splotch of paint you have an original.

[bfloyd]

Have determined that its probably not the pump but the electrical power to the pump.

Jumped the RPM relay, key in the "run" position, and measured 0.001 volts at the two pin power connector at the pump.

Read another thread about jumping the inertia switch to take it out of the loop, but my inertia switch seems to be an early model. There is no connector at the bottom of the switch. The wires just come off the harness and go directly into the bottom of the switch.

[Bitsyncmaster]

Have determined that its probably not the pump but the electrical power to the pump.

Jumped the RPM relay, key in the "run" position, and measured 0.001 volts at the two pin power connector at the pump.

Read another thread about jumping the inertia switch to take it out of the loop, but my inertia switch seems to be an early model. There is no connector at the bottom of the switch. The wires just come off the harness and go directly into the bottom of the switch.

You don't need the key on when jumping the RPM relay. You can use the black wire on the fuel sender as a ground for your meter and test if the white/purple wire gets power. If so than your problem is in the ground side (inertia switch).

[DMCMW Dave]

Have determined that its probably not the pump but the electrical power to the pump.

Jumped the RPM relay, key in the "run" position, and measured 0.001 volts at the two pin power connector at the pump.

Read another thread about jumping the inertia switch to take it out of the loop, but my inertia switch seems to be an early model. There is no connector at the bottom of the switch. The wires just come off the harness and go directly into the bottom of the switch.

That is actually a plug. Unplug it and put in a jumper wire.

64134

[bfloyd]

So, went out to the garage tonight to poke around with a tester.

On the fuel pump wiring diagram fuse #7 should be HOT all the time. Found a good ground and pulled #7. The fuse itself is good. Took the test probe and found that one side of the fuse terminals is hot with 12.79 volts. That's good. Put the fuse back in and moved on to the RPM relay connector.

According to the pump circuit wiring diagram the power from Fuse #7 goes directly to pin #30 on the RPM relay connector. Verifying my ground was still good, I took the probe to pin #30 and got nothing. I dont get it?

Does a wire just randomly break driving down the road at 80mph?

Got more digging to do.

[DMCMW Dave]

So, went out to the garage tonight to poke around with a tester.

On the fuel pump wiring diagram fuse #7 should be HOT all the time. Found a good ground and pulled #7. The fuse itself is good. Took the test probe and found that one side of the fuse terminals is hot with 12.79 volts. That's good. Put the fuse back in and moved on to the RPM relay connector.

According to the pump circuit wiring diagram the power from Fuse #7 goes directly to pin #30 on the RPM relay connector. Verifying my ground was still good, I took the probe to pin #30 and got nothing. I dont get it?

Does a wire just randomly break driving down the road at 80mph?

Got more digging to do.

Luckily its a pretty short run from the fuse to the RPM relay. Probe both sides of the fuse while plugged in. You may not realize it but you can probe the top of the actual fuse. There is a tiny hole in the plastic above above the fuse terminal. I've seen fuses that look good but aren't.

On the RPM relay socket jump the Brown wire to the White/Purple. This should make the fuel pump come on, if not, jump the White/Purple to the door lock breaker (as a source of power). If that works, go back and trace from the fuse block to the RPM relay socket brown wire. Failure is most likely at a terminal, not in the middle of the wire somewhere.

[bfloyd]

Finally got this figured out. Turns out I was jumping the wrong pins on the RPM relay connector. Once I got the jumper in the right spot I now have 12volts at the pump connector. No ground. Pulled the wires from the inertia switch and touched them together , pump fired right up.
Looks like I need a new inertia switch. I'll call DMC Midwest in the morning.

Thanks everyone for your help.

[WHO1DMC]

Finally got this figured out. Turns out I was jumping the wrong pins on the RPM relay connector. Once I got the jumper in the right spot I now have 12volts at the pump connector. No ground. Pulled the wires from the inertia switch and touched them together , pump fired right up.
Looks like I need a new inertia switch. I'll call DMC Midwest in the morning.

Thanks everyone for your help.

PM sent

Dave B.

[mr_maxime]

Finally got this figured out. Turns out I was jumping the wrong pins on the RPM relay connector. Once I got the jumper in the right spot I now have 12volts at the pump connector. No ground. Pulled the wires from the inertia switch and touched them together , pump fired right up.
Looks like I need a new inertia switch. I'll call DMC Midwest in the morning.

Thanks everyone for your help.

I'm drinking to that. First time I was ever right about a bad part. I've come a long way since thinking the ignition coil was the fuel pump lol

[Bitsyncmaster]

That is why I always state to jump the colored wires Brown and white/purple. You don't even need to remember the colors, just jump the larger two wires.

[jerrysony]

Hello every one. I had to tow 2607 because the starter just broke. I replaced the starter and now I´m having a very hard time starting the car. I no longer hear a faint hum or buzz from the front of the car when the key is switched to the run position but not started. When I try to start, the pump is heard, so it´s getting power, I have gas on the carburetor (yes, it´s converted),but still won´t start, or start after a hundred tries. (have a battery charger on hand). If I finally got her started, I have gas on the pedal, rmp, etc. If I turn her off, it´s start all over. The only difference I see, as mentioned, is the fuel pump buzzing when the key is switched to the run position. What could be wrong? Is it possible to be the ignition switch at the steering?

[David T]

Start with the basics, check for fuel and spark.

[jerrysony]

Already done. There's fuel on the tank, removed and cleaned the 6 sparks. Checked hoses.

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[Ron]

Unlike K-Jet, a carb system doesn't need to have the pump run to start the engine, if it has ran in the last few days -- There should be plenty of fuel in the carb's bowl to start it (and run a bit). Look down in the carb and see if fuel squirts when you work the throttle. If it does, it's not a lack of fuel problem.
A timing light should flash while cranking (with any plug wire).

Did you replace the starter with the exact same type of unit?

[jerrysony]

Thank you Ron. I replaced the starter with the eagle premiere version that's sold on AutoZone. I "feel and ear" that the car is not starting, but when I release the hand of the key, it actually starts (sometimes). I have gas on the carb as I press the pedal.

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[Ron]

Thank you Ron. I replaced the starter with the eagle premiere version that's sold on AutoZone. I "feel and ear" that the car is not starting, but when I release the hand of the key, it actually starts (sometimes). I have gas on the carb as I press the pedal.

YW!

Check out the pic HERE (http://dmctalk.org/showthread.php?9208-Is-this-the-correct-Eagle-Premier-starter-for-our-cars&p=135240&viewfull=1#post135240) note the pigtail for the Blue with Yellow stripe resistor bypass wire.

Sounds like someone may have mixed up the wires connecting the coil/starter/resistors (bypass).
Before getting into that, try connecting a jumper from the jump post (or any 12V source) to the coil's (+) terminal and see if it starts.

66633

[jerrysony]

YW!

Check out the pic HERE (http://dmctalk.org/showthread.php?9208-Is-this-the-correct-Eagle-Premier-starter-for-our-cars&p=135240&viewfull=1#post135240) note the pigtail for the Blue with Yellow stripe resistor bypass wire.

Sounds like someone may have mixed up the wires connecting the coil/starter/resistors (bypass).
Before getting into that, try connecting a jumper from the jump post (or any 12V source) to the coil's (+) terminal and see if it starts.

66633Thank you Ron! I guess you're on the right track. I'll check that hopefully this very weekend. The starter was the only thing that changed on the car, so that must be it; a messed connection.

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[jerrysony]

Thank you Ron! I guess you're on the right track. I'll check that hopefully this very weekend. The starter was the only thing that changed on the car, so that must be it; a messed connection.

Enviado desde mi SM-G996U1 mediante TapatalkI just saw this picture from yours on another thread. I guess this is the correct setup.66634

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[Ron]

Yes, same pic as in my link above, with labels. :)