RPM relay issue

[kbendor]

Last week, the fuel pump was pumping without any problems. I hadn't updated my relays yet and since I had a kit laying around from Harvey, I decided to replace them. After I replaced them, the fuel pump won't pump anymore. I jumped 30+87 and it works. I tried putting the the old RPM relay in and still nothing. Any suggestions?

[DeLorean03]

You did replace the lambda relay - which is DIFFERENT than the regular "typical looking" relays - with another lambda relay right ?

Here's your "typical" relay:

19207

Here's the lambda relay:

19208


If I recall correctly, the original relays looked nearly identical to the lambda relay, hence why I'm making sure a "regular" one wasn't put in place of where the lambda goes.

[kbendor]

Yea, his kit came with a lambda relay. It's brown though, not a silver one but the rest are the purple ones.

[DeLorean03]

So when you turn the key to position 2 (lights on dash come on), you don't hear the fuel pump prime at all?

Check your inertia switch. It is in the driver's footwell on the left wall behind the loose carpeting. . Make sure it looks like this:

19210

If the little stalk on the top is up or shows any color (I believe it's red), the inertia switch has been tripped, and your fuel pump will be disengaged.

It's just something to check - we're going through all the lil' things. Speaking of lil' things, fuse #7 good?

[kbendor]

I checked fuse #7 and the inertia switch and they are both good. Is the lambda light supposed to turn on in the 'on' position?

That's correct, in the 'on' position, the fuel pump does not prime.

[DMCMW Dave]

I checked fuse #7 and the inertia switch and they are both good. Is the lambda light supposed to turn on in the 'on' position?

That's correct, in the 'on' position, the fuel pump does not prime.

Does it run if you "bump" the starter? The so-called "priming" is not something you see 100% of the time.

[David T]

If the pump will run by jumpering the relay it means the fuse #7 is OK and the inertia switch is good too. The problem is with the relay he is trying to use. Either it is the wrong one or it is defective. In the meantime stick the old one back in and it should work. If it doesn't one of the connectors in the base of the socket may have "backed out" and is not making contact. Pull the relay and try jumpering the relay again and look at each connector.
David Teitelbaum

[chris williams]

As an FYI I also replaced my RPM relay with one of Johns and it was a dud, the only thing I have ever bought from him that was mind! Refunded so no issues.
Chris

[kings1527]

If I can make a suggestion if you're considering a new RPM relay, I'd contact bitsyncmaster and grab one of his solid state RPM relays. Chances are, you'll never have to worry about the issue again!

[DeLorean03]

I jumped 30+87 and it works. I tried putting the the old RPM relay in and still nothing. Any suggestions?

Do what David said and make sure none of the female connections that the RPM gets plugged into back off. I do that by holding all the wires really tightly where they insert into the plastic molex connector, and then I gently but firmly push the RPM relay into place.

If you do that and still nothing, access the pump via removing the moon-shaped fuel pump cover in the trunk underneath the spare tire. Youll see a pigtail connector with two wires - one will be purple/white and the other will be black. Disconnect the connectors. Get a voltmeter and put it on DC voltage. Then put the key in the position just before you try to start the car (dash lights come on). At that point, put your voltmeter's leads on each wire (red on P/W wire, black on black wire), and see if you're getting 12 volts (do it on the wires that come from the harnes - NOT the ones that lead to the fuel pump). If you are, clean the connectors with a dab of alcohol or electronics contact spray (can get at any auto parts store), and then put a dab of di-electric grease on both the P/W wire lead and the black wire lead. Re-hook it back up, and try to start the car. See if you get anything from that,

Does the engine try to start but the engine never turns over and idles under its own power, or when you turn the key - does the engine not even try to start?

[1batt4u]

Which is the relay next to the engine cover switch? Its silver. I was taking everything off there so I can clean and paint engine compartment soon. Relay cover just fell off.

[kbendor]

David's suggestion worked! Seems as though I was too rough on the connectors and one of them came loose.

[DeLorean03]

David's suggestion worked! Seems as though I was too rough on the connectors and one of them came loose.

Awesome! Glad to hear your car is all good!

[DMCflux]

I too had a "Dud" RPM relay from Hervey

[DeLoreanDMC81]

I too am having the same exact problem.

Jumping the 2 areas on the RPM relay with a wire will get the fuel pump working. My car turns over just fine, it just doesn't have any fuel to get it to run.

I too installed Hervey's relay kit, and it just won't start. It's starting to drive me crazy.


If the pump will run by jumpering the relay it means the fuse #7 is OK and the inertia switch is good too. The problem is with the relay he is trying to use. Either it is the wrong one or it is defective. In the meantime stick the old one back in and it should work. If it doesn't one of the connectors in the base of the socket may have "backed out" and is not making contact. Pull the relay and try jumpering the relay again and look at each connector.
David Teitelbaum

Here's my question for Dave, which relay are you talking about jumping? The RPM relay?

I stuck my old one back in and it still doesn't work. Also I've checked the connectors, and none have popped out.

Cheers,

James
6408

[David T]

I too am having the same exact problem.

Jumping the 2 areas on the RPM relay with a wire will get the fuel pump working. My car turns over just fine, it just doesn't have any fuel to get it to run.

I too installed Hervey's relay kit, and it just won't start. It's starting to drive me crazy.



Here's my question for Dave, which relay are you talking about jumping? The RPM relay?

I stuck my old one back in and it still doesn't work. Also I've checked the connectors, and none have popped out.

Cheers,

James
6408


The RPM relay controls the fuel pump and it is underneath the door lock module (or at least that's where it should be).

[louielouie2000]

I too had a "Dud" RPM relay from Hervey

This is making me seriously question if my Hervey RPM relay was the source of my car's intermittent dying episodes. My original RPM relay went out during the Pigeon Forge show, and I was fortunate enough to have John Hervey stop and diagnose my car on the side of the road, and provide me with a new RPM relay. After that, the car would intermittently die while I was at stoplights, or wouldn't start after it had been recently driven. I always assumed this was a fuel accumulator issue, but now I wonder. I never connected the issue to the relay, since it was brand new. However, I've read recently where some of the soldering on the RPM relays is quite suspect. I guess I should have considered this, since I also had a Hervey Fan Fix fail on my first DeLorean.

[David T]

This is making me seriously question if my Hervey RPM relay was the source of my car's intermittent dying episodes. My original RPM relay went out during the Pigeon Forge show, and I was fortunate enough to have John Hervey stop and diagnose my car on the side of the road, and provide me with a new RPM relay. After that, the car would intermittently die while I was at stoplights, or wouldn't start after it had been recently driven. I always assumed this was a fuel accumulator issue, but now I wonder. I never connected the issue to the relay, since it was brand new. However, I've read recently where some of the soldering on the RPM relays is quite suspect. I guess I should have considered this, since I also had a Hervey Fan Fix fail on my first DeLorean.

If you suspect the RPM relay then jumper it out and see if the car still dies. If it seems better then the RPM relay is probably bad. There are several things in that fuel pump circuit that can cause the pump to stop. Some of the more common things include:
Bad connections at the plug in the wiring harness up by the windscreen washer bottle
Bad connections by the fuel pump
Modifications to the fuel pump wiring
Bad inertia switch or pre-recall and being on the Lambda counter
Bad RPM relay
Burnt #7 fuse

Shutting down intermittently can be caused by a bad impulse coil in the distributor or bad connections on the ballast resistor. You need to isolate the problem to a specific system, fuel or spark. One way is to squirt some Ether into the intake after it dies and see if that starts it back up. If it does then it would imply a fuel problem.

Bad solder joints are known to occur on the OEM relays, not any aftermarket ones as far as I know.

[Bitsyncmaster]

I don't get many Hervey relays for cores (maybe 25 in 6 years). Most of those have not had the flux removed so i probably would not notate bad solder joints.

There are many different OEM and NOS circuit boards in the black case, blue connector. The early ones had two connects on the relay and even some NOS units were bad not making contact on both circuits. I guess they found that problem as later units have only one contact to drive both outputs. Probably 20 % of those core returns have broken solder joints. But many people send me working cores to update with my solid state design.

[DeLoreanDMC81]

I just received Dave's solid state RPM relay And that fixed my problems, with my car not starting up.

I couldn't be happier with Dave's relay and can't say enough good things about it. My recommendation, if you don't have one get one from him.

James
6408

[sdg3205]

Every Delorean should be running daves rpm relay.

[DMC-81]

Every Delorean should be running daves rpm relay.

+1