I can't get my fuel pump to run unless I jumper the plug for the DME relay. The car starts and runs with the connection jumped but the fuel pump then runs all the time. Just want to know where to look and what to do.
I'm very electrically challenged so you might need to really dumb it down for me. Thanks

You did try another dme relay? Otherwise the Bentley 911 Carrera manual is what I used to wire and trouble shoot my conversion.

I had a similar problem on my 930. Engine would run, then lose power. Sometimes it wouldn't start. The pump wasn't running. I traced it to the relay (not sure if 930 calls it DME) not making contact. I took it apart to find a smaller relay inside with some circuitry. Pulled the smaller relay off and found the contacts were barely making contact and sometimes wouldn't. Bent the relay contacts and haven't had any issues for 2 years.

Tried 4 new relays. One was solid state.
Flummoxed.

The solder joints can also fail on them too,pop the cover off and have a look,could just be the contacts as Spoke mentioned,normally they are pretty reliable.
If you have to buy a new one don't buy it on price...URO part one is about half what a decent one is worth .
Nice to have it running eh

They are all new and none are uro.

Doesn't sound like it's the relay. Are the schematics online somewhere? I'd like to help but would need the schematics to follow the electrons.

Which pins are you jumpering? I see this DME relay schematic online:

Is this the correct schematic?


Click to view attachment

Some tests with your voltmeter:

put a small wire in the socket at 85b then install the relay.

Turn the car on or crank and measure 85b to ground. I think it should be 0V.

Put a small wire in the socket at 87 then install the relay.

Turn the car on or crank and measure 87 to ground. Should be 12V.

This manual is awesome!!
Click to view attachment

Click to view attachment

Click to view attachment

I hate wiring...do you have the red wire (fuel pump) coming out of the dme harness going straight to the fuel pump? It should and just put an inline fuse to protect it (25A).

Here is the link for my 3.2 wiring:

http://www.914world.com/bbs2/index.php?sho...7&hl=wiring

Yes. Did all that. Thanks
Got tied up today but will work on this tomorrow.

Looks like a pretty simple circuit:

1) Ignition key provides power to 86; 85 is ground thus top relay should turn on.
2) With top relay on, battery voltage from 30 connects to 87; 87 should be 12V.
3) 87 is also top of bottom relay coil; 85b from DME must be grounded to power bottom relay; bottom relay provides path from battery (pin 30) to 87b.

Tests:
Jam a small wire in plug for 87, install relay, turn ignition on, test 87 to ground; measure 12V

Once 87 verified at 12V:
Jam a small wire in plug for 85b, install relay, turn ignition on and/or crank the engine, test 85b to ground; measure 0V. DME should provide ground at 85b. If not, the issue is with the DME.

I know the dme is good. Runs fine in other cars.

Do what Spoke suggested and put an ohm Meter on pin 20 of the dme. It should be grounded while cranking the starter. If it's not then something else connected to the DME is causing the problem. Have to troubleshoot each sensor / inputs on the DME to figure it out. I have had lots of interesting problems with my injection that I used the Bentley manual to trouble shoot.
Motor won't start after installing for the first time
- turns out it was a pinched fuel line under tank which doubled the fuel pressure
Car sat for 3 years and wouldn't start (rustoration)
-Pelican guy's on there 911 forum recommended unplugging the injectors one at a time. After unplugging the last one it started and ran on 5 cylinders. Shut motor off and plugged it back in and now it runs fine on all six cylinders for over two years now.
The flywheel sensors are also known causing no start issues. Some people replace them and get rebuilt injectors when they overhaul the engine.
Otherwise mine runs great and I have not had any problems besides the above.
Not bad for 33 year old original motor with a bazillion miles on it!!

Remember, i did say my car starts, I need to figure out why the fuel pump wont run unless I remove the dme relay and jump it with a wire. But I will follow all the advise you guys have given me and report back. As always, I appreciate the help.

Do not over look the DME Relay socket itself; shorted, bad spade connectors, etc. particularly the pins you are jumping and the fuel pump runs.

If you've tried the DME in other cars and they run....
And you've tried multiple DME Relays and none work....

That only leaves the wiring itself and the AFM.

Disconnect the DME wiring.
Pull the DME Relay.
Multimeter on Ohms, test between DME pin 20 and Relay pin 85b.


If that works tests good (0 ohms)...
The fuel pump only runs when the AFM flapper is open. So get access to the air filter side of the AFM, turn the key on (everything reconnected), and push the door open. That SHOULD turn on the pump. If it doesn't, the wiring between the AFM and the DME may be suspect, or the AFM contacts inside may be suspect.

The AFM point is a good one. Before I put my 3.2l I had a 1.8l ljet. It sat long enough that the flapper "hinges?" got kind of corroded and stuck. The cranking of the engine and the compression wasn't enough to open it. After doing the test above and then hearing the fuel pump turn on...some lub and I was good to go.

Mark and Ray stopped by my house today to do some debug on the fuel pump relay issue.

We made several steps forward and a couple of steps backwards.

First when trying to see what works on the car, I put the turnsignal stalk to left turnsignals and it wouldn't go back to neutral. So every time we powered the car the left turnsignal was blinking.

We traced a couple of wires on the 911 harness and realized the switched power to pin 86 of the fuel pump relay wasn't connected to switched power. Once connected, the fuel pump would run with ignition power. Success 1!

Next the wire to the starter from the DME needed to be connected to the 914's yellow starter wire. After these 2 connections, the car started and ran as expected. When the engine was turned off, the fuel pump would also turn off. Success 2!

The step backwards was realization that the ignition switch did not switch power off. Power on fuse #8 was always on. Once started, the engine could not be turned off until it stalled on its own, or the fuel pump relay was pulled or the battery cable removed.

Things to do to finish the install:
1) Figure out why the ignition switch doesn't switch off power.
2) Connect yellow wire on the 911 harness (runs fuel pump when cranking) to the 914 yellow wire to the starter bendix.
3) Fix the turnsignal stalk so it doesn't stick on the left turnsignal.

Question about the starter wire from ignition switch for those who know 911 engine transplants: Where is the best place to tap into the starter wire from the ignition switch? This is the smaller yellow wire that goes from the ignition switch to the original 914 relay board on pin 1 of the 14 pin connector, to the bendix on the starter.

Huge step to have the engine start with the turn of a key!
Driving the 10 hours to Octeenerfest is getting real.
Jerry is the man! I owe him a lot and will push him to collect.
I bought some more Spoke LED's while I was there.
If you see the lights in person you really see the difference from stock. Even in daytime.
Ben's heat exchangers and M&K - R exhaust sound amazing.
I will use his stock style muffler for my other conversion so my wife will ride with me.

Thanks for the help everyone!

Glad to hear you resolved that issue and will be driving the car.

congrats!

You are correct, the start wire enters pin 1 of the 14 pin connector. Assuming the relay board is still being used in his setup, The start wire is again present at pin 6 of the 12 pin connector. You could also use either terminals II or IV on this relay board. This would be my first choice if you need this start signal from inside the engine bay.

If you need to tie into the starter wire while inside the cabin, you can find a bundle of wires under the passenger seat. It is the same color wire from the ignition switch, it's pretty easy to differentiate from the other wires. Also, depending on the year of Mark's 914, you may want to bypass the seat interlock circuit under the seat as well.