Electrical / starting problem

[Bukowski]

Ok I finally have a clear idea about this :

Usually after sitting for at least a few hours, I have to hold the key all the way down for as much as 20 seconds straight, then the car “rummm!” starts right up.

Battery is between 12 and 13 V, jumps down to 11 during the hold. Lights are great, but go out during the hold down. Can happen hot or cold. I thought my 140W cigarette lighter inverter was causing this before but took it out for a long time. This is happening more often as time goes on.

[944 Ecology]

Bad starter solenoid.

[mytrplseven]

Bad fuel pump check valve? Fuel draining all the way back to the tank. check the fuel pressure at the rail.

[Bukowski]

Wow - interesting responses, thanks!

Fuel pump is old.

Starter practically all brand new.

Can I rule out the relay?

[944 Ecology]

Originally Posted by Bukowski

Can I rule out the relay?

No, not until you test it and are sure. Many folks have been fooled by assuming that a new part was working, only to find out that it was bad out of the box.

[thomasryan]

if you can get a helper, see if the key switched wire at the starter is supplying B+ and the current draw if you have a clamp on amp meter that will do DC. the electrical part of the ignition switch can get 'pitty' if used with a dragging starter for a while.

[Bukowski]

How do check valves go bad?

Can the check valve be replaced without removing the whole pump?

when a bad check valve let’s fuel back to the tank, does the fuel push the vapor in the tank out through the charcoal canister, after the expansion tank - that is, is that system always open to atmosphere?

Google searches suggest most likely check valve...

[Bukowski]

More observations:

Colder weather now.

Hold key down for 60 seconds now - seems longer than before - but not working now.

Battery fully (12.6V taken as 100%) charged and no start. Gauge also reports above 12 V.

Jumpered DME (to run the fuel pump) does not fix this.

FLAPS gives good starter, good cranking, good battery.

Alternator iffy - belt probably just a bit too loose. Sometimes HF tool says it’s good, sometimes no (like right after starting).

To be continued....

[Bukowski]

One “Click” heard when the key goes to the ignition position, with nothing else - no cranking, “errrrr”, or anything but “click”.

There are known accessories running like the temperature sensor, blower, making a background “mmmmm” but those are active before the key gets to the ignition position.

[djnolan]

If it is not cranking at all, try checking for voltage on the small starter terminal as you turn the key using an alligator clip lead to a volt meter if you have one, with the other volt meter lead to ground.

I think someone on pelican had an ignition switch problem recently, you may have the same. If there is voltage to the starter terminal, maybe it is the solenoid. There is also something know as the X-relay, not sure what it does but could also be involved in starting.

Have you looked at Clark's for ideas, too?

[Bukowski]

@djnolan : dumb question: can the starter be completely connected for the measurement?

[djnolan]

Yes check those things with everything connected and in place.

[Bukowski]

hooray, I got a chance to look into this. long/tedious because I need details:

conditions:
car : sat a week or so (gas stabilizer already ran in entire fuel system).
temperature : about 60 deg F.
battery : fully charged

minutiae because I can never keep electrical stuff straight:
attach red alligator clip to "small starter terminal"*
attach red alligator clip to red pin-style multimeter lead
attach black alligator clip to black pin-style multimeter lead
attach black alligator clip to one of the screws for the driver side (L) fender liner

wrap all exposed terminal/clip/metal on the lead with duct tape.

*looking at starter, there is a large lug/wire attached to the starter by a nut on a threaded post. I think there are in fact two wires and two lugs attached to this post.
there is another wire, but small in diameter/lug size, attached to the starter by a separate nut/post. It is this small post that the red alligator clip was attached to.

multimeter:
Harbor Freight freebie
switch set to DCV, number "20" - so that would be measuring from 20 volts down to zero.

red clip/wire/lead from above: plug into the "V (Ohm) mA" port of multimeter
black clip/wire/lead from above: plug into the "COM" port of multimeter
(tested some 1.5V, 9V batteries with this setup, output seems sensible)

turn multimeter on: read "0.00" in display. might fluctuate a bit to -0.00, 0.01, ...

try a few times:

1. audible cranking/starting sounds didn't let it catch. read over "10.00" on multimeter display.

detached everything, try to start. nope. back to the "click/thunk" then nothing while battery drains down to about 11 volts, then interestingly, stops going down*using yet another electrical testing gizmo not described here.

reattach all leads as before.

2. try again: "click/thunk", battery voltage decreases, multimeter display reads zero, no start.

try a different body screw for a ground with black alligator clip, work it on good.

3. try again: "click/thunk", battery voltage decreases, multimeter display reads over "10.00", no start.

4. try again : same result as (3) above.

that's all for now.

[Bukowski]

Starter bench test : good.

[djnolan]

Troubleshooting - Engine

So my conclusion is the Engine Will Rotate But Not Will Not Start (Fire). So per Clarkes:

When the engine will rotate but, will not start, it can typically be attributed to one of two causes:

Lack of fuel
Lack of spark

This is where a fuel pressure gauge, a spark tester, and a digital multimeter are essential. For the most part, these two problems can be diagnosed independently of each other. However, there are several failures which will prevent the fuel pump from running and cause a no spark condition

[Bukowski]

For supplemental info, see my “car died while driving puzzler” post - though, this problem pre-dates that event.

Fuel pressure 2.5 bar with DME jumpered. Couldn’t test how long pressure stays there.

Also noted that jumpered DME runs pump but still no start.

Ignition switch sounds interesting right now.

[Bukowski]

... today on "A Very Special No-Start condition":

rotated engine using 24mm deep well socket, 1/2" drive ratcheting wrench.

rotated wrench towards passenger (right) side of car (my instinct says this can be done either way - asked about it here but can't be bothered to look it up)

looked at ring gear. no obvious damage. teeth seem ok.

rotation of engine generally conforms to expectation - an easy part (down stroke), followed by a harder part (compression), and repeat. no obvious weird sounds. not sure if went all the way around - lost track. did it for a few minutes.

relevant relays (for the record):

G2 = "ignition relay 15"
G14 = "ignition relay X"

... I think the "click/thunk" sound is some combination of relays clicking plus the starter motor popping out to engage the ring gear, but somehow, starter does not turn the ring gear. having found no obvious reason on the ring gear or the starter motor for this to happen....

for the record : a look through the timing belt inspection hole shows an apparently in-tact, dry, timing belt.

[Tom944]

Could be too much resistance in the starter cable - look for corrosion. If this is the case the starter won’t be able to draw enough current to spin.

[djnolan]

If it were a Chevy I would say the starter needs to be shimmed to adjust the clearance between the starter nose gear and the flywheel. On a Chevy loosening the starter mounting bolts a bit sometimes would clear it up by reducing the wham factor.

But on a 944 I have never heard of this issue. It makes me think the solenoid or starter engagement mechanism is hanging up as 944 Ecology alluded to. You could remove/take the starter apart and look for hangups, lube, etc. First I would loosen the starter bolts slightly and hope for the best...

Incidentally my 85.5 944 is occasionally doing the same thing with a recent rebuilt autozone starter...

[djnolan]

Just to make sure I understand the symptom, the starter is rotating, but not the engine, as in click-whirrr?