Hey guys.....took a drive qand loving the 914 and stopped for a while and could not restart the car. I finally noticed there was no ful pump sound..(three port pump mounted by the steering rack. Checked the fuses, swapped out relays with new 914 rubber relays, and still nothing. If anyone wants to share an idea I am all ears. Fuel pump relaticely new...not the original one but identical. Thank you very much !!!
gg

how about use direct 12 volts to fuel pump if it will run the pump. And maybe just go with the 2 port (late type) fuel pump for less return fuel hose.

What do you mean by relatively new? New used?

as windforfun says - what do you mean by relatively recent?
a reconditioned one or a second hand one?

if second hand the motor has probably given out.
powering it up direct from a battery will tell you.

i rebuilt two of these myself earlier last year.
both of them were only worth doing because the brushes and commutators were barely worn. i rebuilt them with new seals all the way through to stop them leaking.
but did not do anything else to them.

most of them are going to be so worn out they will jam at the armature either when the brushes fail or a chunk of armature comes off. the failure will be immediate and catastrophic.

ps, if you have a L jet the pump won't run anyway until you crank.
unlike the d jet cars.
even with fuel pump relocated that wiring circuit is probably still intact that means it only runs on cranking.

I would get out the trusty test light (or multimeter) and check for power at the pump. If you have power, then you know the pump is the problem,

If no power, first check the fuel pump fuse on the relay board. Then try grounding pin III on the relay board, with the key on (and the FI system plug pulled). If the pump runs then the problem is in the engine management and wiring. If not, then the problem is in the wiring between the relay board and the pump.

You guys are awesome....thank you very much! I can't recall the name right now but I sent my old three port pump and they sent me back a "remanufactured" one.....the most popular place here in California....just can't think of the name....very reputable.....I would say 6-7 years ago and I drive about 5,000 miles a year....on a 50 year old car I would call that relatively new... Anyway, is it possible for a relay to fit in the socket but not be in the correct position? Can I rely on the 914 rubber relays? First time I have used them....I appreciate all of your help...!!!!
gg

Can someone please answer the relay question of can they go in the socket incorrectly? Or is there only one way that they will fit and that is the correct way? Thank you very much.
gg

IIRC all the connectors & relays are keyed so there's only one way they can be inserted. The above diagram also indicates this. Also, what was changed between the two states of pump operation (running vs. not)?

Nothing changed.....I drove up a fairly flat driveway and parked and when I went to go home no start no fuel pump sound....thank you for your help...
gg

Relays can only go in one way.

Do your headlights work? If so, snag one of the relays and swap it with the fuel pump one. And/or take the relays on your board and see if they work in the headlight socket.

common go to place as relay is easy to remove,something I learned after a non running problem with new pump was that it ran fine when direct powered,I had replaced the pump relay but found the power supply relay was the culprit in the end.
Had a bunch of spares (12) so spent the time and tested all of them,only found one dead one and marked the rest as useable spares....saves confusion and time later.

I FIXED IT!!!! Only one catch.... I did nothing!! I made my repair kit with wires and jumpers and meters and a bunch of other stuff. Before I did anything I turned the key to see if anything had changed and sure enough I hear the fuel pump...one crank later the car is running and being back too its old self....which is awesome!! So my main 914 guru threw out an explanation but I would enjoy to hear what other guru theories are? Lets here your two cents and this should be fun! Fire away....the big clue is that it sat overnight.....thank you for you replies!!!!!
gg

Intermittent problems are the worst. I wouldn’t drive too far from home if I were you. Just my opinion of course. Start wiggling your connections to see if you can find the culprit.

I couldn't agree more......intermittent sucks!! My dear 914 guru of 35 plus years of 914 experience thought that somehow there was a heat issue with the ECU which will not activate the fuel pump if too warm....interesting....would love to know what really happened....???
gg

ps. maybe he is right?
gg

I had a similar intermittent problem with my fuel pump. Relays verified good, yet it would occasionally cut out while driving or not prime when the key was turned. Ended up being a bad relay board. I figured it out when I noticed that gripping the bottom of the board temporarily fixed the issue. I got a refurbished one from Bruce and never had the problem again.

Rumor has it that the connections to the ECU are suspect due to gravity and age....anyone else have any comment on this hypothesis?
gg

My car started today as I was returning it home and it died on the way home....extremely hot here is Los Angeles todday (go Rams)....boy the car sure stops running fast when the pump stops working....anyway I walked home and letting it cool off and we shall see if it starts.....please tell me as many details as you can so I can solve this problem for good....or until the next time as everything is 50 years old.....thank you very much!!
gg

Gravity & acceleration only slow down time.

Have you done this yet when the pump stops working?

Being methodical is the key. It's a series of "if/then" statements:

If there's power at the pump, but the pump isn't running, then it's likely the pump is bad.

If there's no power at the pump, then it's likely in the relays / board / wiring

If the pump is running, but the car isn't, then it's not the pump

The hows and whys are more "analog", but solving the problem is a "digital" process.

As @bkrantz and @rjames suggest...it all starts with testing the power at the pump

Had a similar problem, there was power to the pump but it still would not run. it was a newer pump, (But they can go bad also) Turned out the problem was in the ground wire I had run to the pump mounted in the front. Bad connection there.

Increased the wire size from 16 ga to 12 ga and ran a different ground wire to the point under the dash.

No problems sine then. YEMV