Injector problem or something else?

[flux3d]

Injector testing - Help needed.

I'm stumped on this one. I've had a hard starting problem for a while. The D takes quite a few cranks before she bursts into life. She does always finally get going, but its annoying as hell. What;s more there is a strange "whistle" sound when the pump primes from the engine bay. I suspected a leaking injector for some time, but checking them today there doesn't seem to be an obvious candidate. My results are as follows:

All injectors hold pressure and don't dribble with the pump jumpered.
They all seem to deliver the same amount of fuel.
2 and 5 have good spray patterns.
1,3 and 6 have slightly one sided spray patterns.
4 seems to have the worst, one sided pattern.
On cranking the cold start injector works fine.
On cranking 2,3,4,5 don't give out any fuel, with 6 and 1 slightly letting out fuel (1 more than 6)

New injectors all round, or just a clean, or a mix?

Any ideas guys?

[Rich]

Interesting questions. What about "None of the above" as an answer?

You seem to have jumped to the injectors as the cause, which may or may not be accurate.

Is this problem only when the engine is cold? Or warm/hot or every time?

Does it run normally and idle smoothly after you get it started?

Does it run OK at higher loads/speeds?

Did it ever start normally in the past?

[David T]

Test the cold start valve. Remove it and stick it into a jar. Watch it as you crank the car when it is cold. If it isn't spraying you have to figure out why.

[DMCMW Dave]

Test the cold start valve. Remove it and stick it into a jar. Watch it as you crank the car when it is cold. If it isn't spraying you have to figure out why.

I think line 6 "On cranking the cold start injector works fine" covers that.
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All six should be balanced at all flows.

Set the CO slightly richer. You should get a very tiny flow when cranking. Have you done a CO check once running?

Answers to Rich's questions would help.

[flux3d]

Thanks everyone so far. In answer to those questions:

Is this problem only when the engine is cold? Or warm/hot or every time? The hard cranking is only with a cold engine, after it has sat a while. Happens every time there is a lapse of a couple of hours between. Every time there is a "whistle" from the engine before this problem when the fuel pump primes, like air escaping somewhere. Hence my thinking that an injector is leaking.

Does it run normally and idle smoothly after you get it started. Just lately it has been less smooth, especially on first start up

Does it run OK at higher loads/speeds? Seems to be OK at both.

Did it ever start normally in the past? yep, right on the key. However, this has been happening for quite a few months, I've just got used to it.

I've checked the pump pickup, pressure, and cold start valve. All OK. It's had new fuel lines, and all secured correctly. The accumulator was changed a couple of years ago, and there is no problem warm starting. The fuel filter has also been changed this year. There was a problem with the small o ring in the fuel measuring head, which was replaced. This was causing the car to have zero power, and it would also stall. The dwell has also been adjusted correctly.

So, everything else has been ruled out really, unless people have any other ideas?

[Michael]

You seem to be on this whistle sound like it's new and related to the fuel pump priming. Are you sure? Jump the rpm relay when the engine is cold and see if you hear it. Without the engine cranking or running it should be easy.

If it's only present when the engine is cold and running it may be a small intake leak somewhere messing up your mixture. Once the engine heats up and things expand the leak is no longer present.

If the sound is present during the rpm jump then it should be easy for you to track down and eliminate that as a probable related issue.


Does the whistle sound go away after the engine starts? How soon?
If you do start the engine cold and immediately shut it off and restart it is it still hard to start?
Have you recently did ANYTHING to the car prior to this?

[Bitsyncmaster]

You may just hear the primary pressure regulator noise when your fuel pump primes.

[David T]

You say the cold start valve works. Does it work immediately when turning the key or does it take a moment for fuel to come out? Try turning the key on and off a couple of times before starting the car. When you next try starting it right after does it start any quicker?

[David T]

You say the cold start valve works. Does it work immediately when turning the key or does it take a moment for fuel to come out? Try turning the key on and off a couple of times before starting the car. When you next try starting it right after does it start any quicker?

When you first start a cold car, there is no fuel pressure. It takes a moment for the fuel pump to pump up the accumulator and the pressure to get high enough to crack open the primary fuel injectors and start spraying. Till then the motor starts and runs on the fuel sprayed by the cold start valve. My guess is either the cold start valve is not working or you aren't getting enough fuel pressure up enough to get the cold start valve to spray. Eventually, with enough cranking and time for the fuel pump to work up enough pressure, the motor starts on the primary injectors. The question of balance on the primary injectors is important but not for starting when cold. Another way to test this is to jump out the RPM relay and run the pump directly for a moment. The car should start right up confirming either the cold start valve is not working correctly or for some reason you are not building fuel pressure fast enough. Maybe a partially blocked filter, a kinked hose, or some other problem. The OP said the cold start valve works. From the symptom it would seem it does not. I rule out an ignition problem because it DOES start and run.

[flux3d]

Thanks Guys, the whistle seems to have come along and become more pronounced with the hard starting issue. It only makes the noise when the pump primes the lines, and it's more pronounced the longer the car has been standing. The cold start valve seems to spray fairly quickly once the key is turned, o all seems good there

[David T]

A whistle usually indicates a vacuum leak. That leans the mixture out and may negate much of the effect of the cold start valve. If we assume the cold start valve is OK and decide the whistle is the problem, you must find and fix it. Often when you hear a whistle it means the leak is where something can vibrate like a reed. That brings to mind joints with gaskets like where the W pipe meets the intake manifold.

[flux3d]

Well i agree with everything people have said. I'm pretty sure it's not a vacuum leak because the sound comes when the pump primes, before the car starts. Therfore no vacuum to leak at that point. I'm going to try and get home before dark tomorrow and try to film the noise and post that. Checking the spray patterns four out of the five injectors are not spraying as they should. They are over thirty years old so to beer expected I suppose.

[Elvis]

is it the noise of the fuel injectors that you normally only hear when you press down the air measuring plate ? (while fuel pump is jumpered and engine off)

[David T]

Noises you can hear before the motor starts are the primary pressure regulator, the idle speed motor and the frequency valve. More like buzzing than whistles. You're right, if the motor isn't running it can't be a vacuum leak!

[JohnZ]

I have to chime in because lately I've been having the exact same problem.

Since last winter, whenever I prime the pump a loud whistle (that lasts just 1/4 of a second) is heard. It is the first thing I hear when I prime the pump, and then I hear the pump priming. It's so fast that it's like someone blowed through one of those funny whistles for just a 1/4 of a second... very brief but very loud (must be the garage I'm in, that amplifies sounds). And since this noise came up, I've always had relatively hard starts... the car fires up eventually, after like 5 seconds of cranking. The whistle is more intense when cold (at first I thought that it was related to cold temperatures that made some spring, like in the fuel accumulator, squeal... but this thing went on through spring and summer) and the car has this hard start 2 to 5 hours after it has been off.

Also: I often smell fresh fuel, and sometimes (VERY rarely) a bang or a misfire when I fire the car up. I suspected some leak from the injectors, but now that I read this thread I'm starting to link the whistle noise to this problem! The fuel accumulator has something like 8 years, and not many miles on it, although I use the car very much (3 to 4 times a week). It's basically brand new.

Reading the experience of mr. Flux3d made me say: "Just like me!"... so was this whistle thing taken care of, in the end?

:)

[JohnZ]

I was able to record the sound I was talking about... there you go (it's exactly when the silly image appears from black)

https://www.youtube.com/watch?v=qPAMlmL0ls0&feature=youtu.be

I should say that, aside from a surging idle, especially when hot, the car runs good, with no hesitations at "high" speeds and it's a great sounding engine, with no noticeable flaws in terms of performances!

:)

[dn010]

Does the noise come from the fuel distributor?

[JohnZ]

Does the noise come from the fuel distributor?

It's hard to tell! I should try to have someone to set the key in RUN and try to track down the source of the noise. But it's very brief, so it might be very challenging. Also: it just happens on cold starts, when the car has been running even for 1 minute the squeak is barely noticeable, shorter and "thinner". I never gave this noise much importance.

One note about the injectors (and perhaps even about the FD): some months ago I replaced the fuel lines, and I did the spraying test. Everything was fine, but at the time I did not suspected an injector leak, so I didn't really check for leaks!

As for the extremely rare backfire: my guess is that more often than not, when I cold start the car at least one cylinder has some fresh fuel in it. That would explain the injector leaking theory, but how does this whistle noise come into play then?

[dn010]

It sounds like fuel is rushing into the fuel distributor to me. Leaky fuel injector = empty fuel distributor.
I've heard that sound come from mine when running the fuel pump and pressing the air meter plate.

[JohnZ]

That's interesting!

I made another recording, basically it's the same, but maybe you can hear it a little better. Also this time I catched the 5 second cranking...

https://www.youtube.com/watch?v=unfssWU6-Ik&feature=youtu.be

I remember too a whistling noise when I did the spray test, it was like a high pitched whining while the injector squirted... this one is a flash though, like someone slipped on a banana peel in the cartoons :D

[JohnZ]

I forgot to say something important: since the beginning of these fuel related "troubles" (more like annoyances) I unplugged the CSV, because with the additional fuel it was beginning to be really hard to cold start the car. Also fuel smell all around... Unplugged the CSV and everything went fine ever since!

So my theory has been slowly developing: there must be already fresh fuel in there when I go and start the car after a while, hence the assumption that one or more injector is leaking! Plus the whistling noise and occasional fuel smell... does it make sense? :hmm: