'74 2L Starts Then Dies, Never a convenient time... Options

[76-914]

Fuel pressure. Well I'll be. As far as the intermittent ignition problem; double check that the molex plug on the dizzy is clipped in place, both ears. (IMG:style_emoticons/default/beerchug.gif)

[GregAmy]

I don't believe it's an ignition problem. Recall that I wrote I could keep it running with starter fluid or brake cleaner but it wold die when I stopped spraying. Further note that I demonstrated the fuel pump is running and flowing fuel, and that with the fuel pump jumped on constantly it still would not start.

It's a fuel delivery/engine management problem, either component failure and/or wiring problem.

[GregAmy]

Aaaaand it's back. After starting and running perfectly fine yesterday for a couple hours.

Nice-sounding carburetors are looking miiiiiiighty tempting right now.

[GregAmy]

Ok, yeah, this thing is really pissing me off now.

- Car won't start. Turn on key, hear pump. Cranks, brief fire, then dead cranking. I smell fuel.
- OK, maybe fuel pump isn't staying on during crank, so I jump the relay, pin 87 directly to battery. Pump on, hear fuel sloshing through the return.
- Cranks, brief fire, then dead cranking.
- I remove each electrical connections I can get to easily, one-by-one: TPS, temp sensor, both large connectors to the relay plate, each relay individually. Try cranking after each: Cranks, brief fire, then dead cranking.
- After doing each one-by-one, ensure terminals are clean, wipe with dieletric, ensure proper secure connection, try cranking after each: Cranks, brief fire, then dead cranking.
- I ask my wife to briefly join me in the garage, sit her in the driver's seat, ask her to try and start it. Cranks, brief fire, then dead cranking.
- I ask her to try again, but this time I remove the air cleaner and snag some brake cleaner to spray into the throttle body as she tries to start:

Cranks, fires, then runs.

I keep it running by hand (as well as one can do without an AAR) and the engine continues to run after I stop spraying brake cleaner in the TB. I keep it running until it warms up, and ask her to turn it off, and retry.

It starts and runs.

I just took it for a ride around the neighborhood, starts and idles fine (it's warmed up now). I get home, shut it off, it restarts and runs.

I have no idea what is wrong with this thing.

[Porschef]

Sure seems like fuel. Sounds like your pump is running.

Filter's clean?
Pressure's good?
How bout them injectors, are you getting a proper flow? Those drove me nuts on an engine that sat for a while...

HTH

[GregAmy]

I'm not convinced it's fuel pump or pressure. Filter's clean (both it and the pump are new) and I removed the line last year in the engine compartment to check the flow into a dump can, and it was "quite brisk" and I couldn't stop it with a thumb (made a mess trying). But I'll break down and buy a pressure gauge and leave it in there for the next time the car decides it won't start (because I guaran-damn-tee you it'll be fine for the next half-dozen times I try.)

Dunno about the injectors, but the car runs fine - when it runs.

It's something binary. And dirty injectors and a bum fuel pump or clogged filter are rarely binary.

Sure wish Cardone still reman'd those distributors. I'd love to replace points and condensor (both a couple years old), and trigger points and have it all nice and clean inside.

[ThePaintedMan]

I had a similar problem, but in a more modern car. Turned out to be bad plug wires, though aesthetically they were great.

I also have seen a similar scenario on an L-jet 914 and it was a bad CHT.

[76-914]

Greg, just for "shits n grins" check your dizzy cap coil contact pin. You know, the spring loaded one in the top center of the cap. Be sure it hasn't worn down past the limits. (IMG:style_emoticons/default/beerchug.gif)

[GregAmy]

Thanks for the tips; keep 'em comin'!

I re-checked what Tangerine did when I left the car with him after I bought it, he only noted "Engine Tune-Up, Adjust Valves, Set Timing" but no points/condensor on the parts list. I think the car is well due for that and possibly some wires and plugs, and I'll toss in a Bosch distributor cap and rotor while I'm at it.

Advance Auto seems to think they can get the Cardone distributor. I'll give 'em a shot at it and remove any possibility of the trigger points being an issue.

I tested the CHT sensor last summer per the book, and values were within range both hot and cold.

And I'll buy a fuel pressure tester.

This is one of those problems that is seemingly random, leading me to lean toward something electrical. I hate to get into just replacing parts, but that's about where I think I am right now...

[Dave_Darling]

How's the fuel pressure? You've been kicking with this a long time; it is worth knowing what happens to the fuel pressure when the engine dies.

Could it be a kinked supply line somewhere? That would give you very low fuel pressure. How about a clogged inlet in the fuel tank? Low pressure after a little while.

What does the pressure do?

--DD

[GregAmy]

And OF COURSE it starts fine yesterday and today. Of course!

Sure seems like fuel. Sounds like your pump is running. Filter's clean? Pressure's good?

27 psi on initial key start, with it running, and with the fuel pump jumped as before, on my new Harbor Freight Master Fuel Injection Pressure Test Kit (which is a nice comprehensive setup for only $80 out the door with the 20% off coupon).

Recall when it would not start earlier this week I jumped the fuel pump and heard it running and cycling fuel through the system, same as it does today.

I'll adjust fuel pressure to the desired 30psi, but I'm even less convinced this is an issue with either the fuel pump or the mechanical pressure regulator.

Fortunately (unfortunately?) it's 18* outside and we're expecting up to two feet of snow Monday, so there's no pressing motivation to drive it...

More ideas appreciated.

- GA

[GregAmy]

OK, here's some more data.

I was playing around with it just now, and of course without an AAR it idles like hell cold (future project). Started it a few times, fuel pressure is now at 30 steady, and then one time it died. And then it wouldn't start, same symptoms! Crank, brief fire, died.

So I break out the brake cleaner, open the TB and give it a squirt, then get in the car, starts up fine and I can keep it running with my foot, though it is running rough. Eventually it warms up enough to idle on its own. Starts and runs fine now.

Then I remembered something. A couple summers ago I had a hell of a hot start problem, where the car would not start when really hot, and I could smell fuel. If I kept my foot on the floor it would eventually fire and I could be on my merry way. And the car was getting shitty fuel economy, to the tune of 19-20 mpg.

Before you ask...fuel pump is in the front.

In reviewing the system - recall this car was a basket case when I got it - I found that there was no thermoswitch installed, the one that grounds the cold start valve. So, obviously, the CSV never worked and on the possibility that it was leaking I removed the hose and disconnected the plug.

I'm now thinking that this may be a/the problem, especially since it starts ok on brake fluid.

I searched through my Box O Parts and I can't find a thermoswitch. And it took about a half hour to find the wire for it as someone had just cut it off (it's another white wire buried inside the same pigtail as the harness for the distributor trigger points.) I still don't know if my CSV was the hot start problem, though I never had that problem again after removing it, could have been coincidence.

So I guess my next step is to obtain a thermoswitch and install it, and repair the wiring harness to it, and remove and test the CSV for wiring harness grounding and leaking.

Anyone have a thermoswitch and/or CSV laying around?

What is the correct control function of the CSV? I've read in one place that the valve only gets power from the ECU under cranking conditions, but I read in another place that if the thermoswitch fails closed the CSV is running all the time.

1:32 PM EDIT: We having fun yet? CSV does not leak under constant 30 PSI. CSV does not fire with key in the "on" position when wire for thermoswitch is grounded. CSV does fire when key is moved to the "start" position, then stops when released.

I need a thermoswitch.

[Dave_Darling]

The CSV is powered by the yellow starter wire. It only gets power when the starter is cranking. The TTS grounds the other side of the CSV, and it provides the ground only when the engine is very cold.

Spraying starting fluid is something of a replacement for fuel. If the car runs on the starting fluid but not otherwise, you do not have enough fuel going in.

It's not your CSV.

--DD

[McLovin]

Aren't the injectors electrical? Maybe you're not always getting electricity to them. Perhaps you've got a bad ground somewhere....like where the injectors are grounded. Do they screw in with electrically conductive (dialectric?) grease? I only dabbled with injectors once on another type of car so I don't know. But...As your engine warms up, you could gain even more resistance from the heat...perhaps enough to go over the tipping point to where the injectors don't work.

Can you re-ground the injectors?

Mclovin

[Dave_Darling]

The only injectors I know of that are not electrical are MFI and CIS ones.

I don't believe there are any injectors that ground through the injector body. They all have a ground wire. Most injectors, in fact, have rubber holders that isolate them from the metal parts of the engine, so the body of the injector would be a lousy ground path anyway.

Most injectors are supplied a steady 12V (or less), and the ECU grounds the other pin of the injector to open it, and disconnects the ground to close the injector valve. D-jet is the main exception, as the injectors are always grounded and the ECU sends power to the other pin of the injector to open it and disconnects the power to close it.

The ground for the injectors is the same as the ground for the FI. It is a ring with three tabs on the case seam on top of the engine near the flywheel end. The ring goes under one of the case through-bolts. Always worth checking these grounds.


I will want to know what the fuel pressure is when the car does not start. Doesn't matter if it's 29 PSI when the engine is running, because the problem isn't occurring then.

--DD

[GregAmy]

30 psi.

See post #32, specifically paragraph 2.

[McLovin]

The only injectors I know of that are not electrical are MFI and CIS ones.

I don't believe there are any injectors that ground through the injector body. They all have a ground wire. Most injectors, in fact, have rubber holders that isolate them from the metal parts of the engine, so the body of the injector would be a lousy ground path anyway.

Most injectors are supplied a steady 12V (or less), and the ECU grounds the other pin of the injector to open it, and disconnects the ground to close the injector valve. D-jet is the main exception, as the injectors are always grounded and the ECU sends power to the other pin of the injector to open it and disconnects the power to close it.

The ground for the injectors is the same as the ground for the FI. It is a ring with three tabs on the case seam on top of the engine near the flywheel end. The ring goes under one of the case through-bolts. Always worth checking these grounds.


I will want to know what the fuel pressure is when the car does not start. Doesn't matter if it's 29 PSI when the engine is running, because the problem isn't occurring then.

--DD

Interesting stuff. So he needs to check the ground and maybe the wires themselves for cracks or partial breaks.

[TheCabinetmaker]

Sounds like Mctrolling to me.

[Dave_Darling]

30 psi.

See post #32, specifically paragraph 2.

All you said was "fuel pressure is 30 psi", with no indication of when it was checked. I did not realize that you had checked it when the car was not starting.

If you did, that tends to rule out fuel pressure.



So, what we know right now:
- Starter cranks
- Starting fluid makes the engine start
- Fuel pressure is 30 PSI while the starter is cranking
- CSV is not hooked up


Since the starter cranks, we can rule it out.

Starting fluid takes the place of fuel, not of air or spark. So you have air and spark.

What you appear to be missing is fuel. But you have fuel pressure even when the car is not starting. BTW, if the pump is wired as per stock it is turned on and off by the FI's ECU, so if the pump runs then you do have power and at least some function of the ECU.

Next question: When the car does not start, do you have injector activity? A "noid" light from you FLAPS will tell you if the electrical signals are getting through. If you want to see the activity directly, you can stick one injector in an empty pickle jar while the starter is cranking and the car is in its no-start mode.

--DD

[JeffBowlsby]

There is always Chris Foley around the corner from you before you give up.

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