Fuel pump died? (long)

Yesterday's drive to work had me all jazzed. I don't think my car has run better since I had it ( found one of the distributor cap clips not clipped over the weekend and re-fastened it - might have had something to do with the misfiring and rough running. )
Anyway, went out to leave for home and she wouldn't start. Fired a few times but wouldn't run. I can hear the fuel pump, but as I wasn't expecting problems I didn't pay attention when I first turned her on, so I'm not certain if fuel pressure built in the system. Mine is one of those that's wired so the pump comes on with the key. I usually listen for the change in pitch before kicking in the starter.
I began trying the simple diagnostics.
Pulled a plug and checked for spark (yes), plug was bone dry.
Lifted air sensor plate, but didn't hear anything particular (how loudly do injectors spray, anyway?)
Lifted air sensor plate with a line removed from one injector and got a steady stream, but it wasn't really high pressure, though I have to admit I'm not sure how powerful the stream ought to be.
I'm leaning toward fuel pump, blocked line, or empty tank. I really doubt the last one: the gause reads about what I expect and hasn't been wrong yet. Fuel pump sounds a little louder than I remember, but that could be that it's finally warm enough to be driving with the windows open .
I half-remember how much fuel pressure there was when I replaced the fuel filter in October, so I'm tempted to begin diagnosis there. No fuel pressure gauge, so it's seat-of-the-pants for the moment. At least I can tell the difference between some pressure and no pressure.
Standard fuel pressure at the filter in a CIS car is ~75psi? I read that in one of the old posts, I think. Does that sound about right? That ought to be noticeable if I remove a fuel line and actuate the pump.

Any other things I can diagnose easily ( in a remote parking lot with a minimum of equipment)? Next step is the flatbed, I guess.

Thanks for listening.

[chuckr]

I would agree, it is your fuel pump, mine took a dump last year. I was out on a Sunday drive, pulled up to a red light,car just died, she would turn over but not start.I am pretty sure that your pump is between your front wheels under the stearing rack, it has a metal cover plate with four bolts, get to it and see if it is warm(has voltage)mine was almost hot to the touch but no gas, it is easy to replace.Hope this helps and good luck

weather yesterday was beautiful, sunny and warm (near 80, I'd say) when I went out to go home.
Cool and damp this morning, it rained overnight and temps are in the 50's.

Got to work (and to the car) this morning. Turned key on and listened to the pump: normal high-low tone of pressure build-up.

Ticked the starter and she fired up instantly. Shut her off and ticked the starter again, fired up the same way.

Ran her down the road and filled the tank, just to be sure. Had a half-tank already, so that's not the problem.

The question of the hour is: What was it and (when) will it recur? What do I do next?

I've been going out every hour or two and restarting, first couple of times she fired right up.
Now I'm back to where I was last night - cranks over, coughed a couple of times but won't start.

Ambient temp now about 69 degrees.

What the h is going on?

[nhromyak]

Fuel pump relay? Fuel-pump fuse (corroded)?

Bad CD unit?

Bad coil?

Good luck.

Ran the car in to the shop this afternooon. First look by the owner didn't yield a definitive answer. Will keep y'all posted.

The fuel pump is a centrifugal device, right? Spinning the pump motor throws out rollers that are loosely caged to contact the pump walls, making moving chambers that push the fuel from intake to outlet?
If the rollers were to become stuck (occasionally, due to dirt, waxy build-up, whatever.) and not "fly out" when the pump spun, the pump would operate at less than full efficiency, if at all, probably not sound normal.
This seems like a problem that could "cure" itself depending on just how sticky the roller cages are or whatever it ws that kept the rollers from extending in the first place.
Can't verify this without replacing the pump and tearing it apart, but it has the feel of a possible explanation for the problem I'm experiencing.
If the pump does get replaced I'll tear the old one apart as much as I can.
Any one had one of these apart? Am I on a reasonable track?

[gregk1]

I had a permatune in my 930 that did the same thing I would wiggel the wires and it would start I put a bosch back in and still would do it. Reworked the wire conections and I ran fine so you mightlook at that also

[alan911]

This is going to sound far away from your problem but believe it or not I had the same problems 2 years ago and had them constantly intermittant until I changed out the 14 pin connector in the rear of the car. My 77s drove fine, then for no reason it dies. Won't start. Hour later it starts and runs fine. Then it happens again.

Before you spring for a new pump I would suggest you fiddle with that connector first just to make sure that it's not the culprit. Pay particular attention to pins 1 and 10 and 14. Don't forget to check the fuse and relay.

Easy relay check is - turn key to run, barely remove the fuel pump relay then rock it back in and out. If you hear or feel a click it's probaby o.k. If not pull it out and put the "horn" relay in it place and do the same thing. any relay will work to drive the fuel pump.

There have been more mis-diagnosed "no starts" due to the 14 pin connector. It gets old and corrodes and becomes extremely temp. sensitive. Also bad connections would cause fuel pump to just click and very little or no fuel being distributed.

These test are free.

So far, my thinking is leading me away from electrical solutions. The pump hasn't once stopped turning (with the key on), so I think it's power supply sysem is intact.
Could be something with the CDI unit leading to less-than-ideal spark, could be a strange vacuum leak that sorts itself out.
I still like my hypothesis about something mechanical inside the pump.
Intermittent problems can be the hardest to solve. And to prove that you've solved.

[nhromyak]

Do you have an update?

No news yet, but the shop told me it wouldn't get looked at right away.

[Gunter]

My friend's '77 had the same frustrating intermittent problem of start/no-start and it turned out to be the CDS unit.

[Bobboloo]

Intermittent problems usually suggest electrical problems. Most common cause of electrical intermittent problems is connectors. Next most common cause of electrical "intermittent" problems is thermal.

Your car is over 20 years old. The connectors get corrosion on their surfaces. I would venture to say many times people replace components when the problem was actually the connector. Unpluging and replugging cleans the connector to a certain extent making it seem like component replacement fixed the problem.

There are several different types of connectors in your car. 14-pin (as mentioned), relays, fuses and switches. I would suggest cleaning your connectors.

You can buy some tuner cleaner at Radio Shack and spray it on the connector surfaces and plug and unplug a few times. as for the relays, you can't clean them because they are sealed but you can check them with two wires going to the battery to power the relay terminals and a voltmeter to check continuity across the switch terminals. Also clean the terminals where they plug into their socket on relays.

Other causes of intermittent problems are fuel pressure and fuel contamination. I think you can rule out contamination because you can tell that from driving the car. i.e. runs fine loses power,runs fine loses power etc.
I don't think it's your accumulator either (pressure) because you left the car and came back and it started suggesting the accumulator is doing its' job.

How about your fuel filter?
You said the car wouldn't start. You left and came back and it started. Fuel filters can sometimes cause this by obstructing the line.

Well those are some ideas to bounce around. Now maybe someone might suggest a methodical approach.(Not one of my strong points)

Bobby

We're now in wait-and-see mode. The service manager ran some tests but couldn't get my car to fail to start.
He offered some diagnostic suggestions to help isolate the problem if/when it comes back and sent me on my way.
I'll re-post if I get any further news.

Does anyone have an old, dead fuel pump they'd be willing to part with in the name of science? For the cost of shipping one I'd be willing to undertake disassembly just to see what's inside and figure out if my hypothesis has any merit. Someone got an extra?

[Wayne 962]

It could be the pump. There is also a check valve in there that works in conjunction with the fuel accumulator in order to help hold pressure in the system.

There should be an audible *meow* from the injectors when you lift the sensor plate up. If you don't hear this, you don't have enough pressure. When I put my 914-6 conversion on the road for the first time, I couldn't get it to start. Turns out one of the hoses to the front fuel tank were crimped. Fuel was circulating, but not at high enough pressure. The injectors didn't meow...

-Wayne

It took some time and warmer weather, but the fuel pump did finally quit. Based on the symptoms, I'd guess it's been doing only an adequate job of delivering fuel at pressure most of the time, and occasionally giving up altogether.
It's replaced now, and once I got the mixture recalibrated it's running very sweetly. The miss at idle and light throttle I now think was low fuel pressure not quite making the threshhold to force #2 injector to flow fuel until the piston put on a little vacuum.
Getting it all sorted out.