'89 CRX starts then stalls

I'm going to attach an LED (with resistor in series) to the fuel pump
connector and bring the led out where it can be seen during the starting
sequence.

The LED will tell me when the fuel pump is given power. Normally I would
expect to see 1. LED lights up for 2 seconds when ignition is turned then
goes off 2. LED lights up as I crank the engine 3. LED stays on when I
release key (once engine has started). Perhaps there could be a small
pause between 2 and 3?
The clicks method would do the same thing but I find it hard to feel the
click when the engine is been cranked. Also the relay could be clicking
but not delivering power to the pump (if the relay contacts are bad).

It will be interesting to see what the LED will show but I have to wait
until the problem happens again.

I will post the results of the investigation.

 

Sounds cool, but all you really need to do is backprobe terminal 7 of the
Main Relay with an analog multimeter set to VDC. In fact, this would give
you an even more accurate result, revealing any low voltage condition or
hitches in power.

 

it's a cool tool, but is there much point? fuel pump is on all the time
the motor's running. it's only off if the ignition [switch] is off or
the motor is registered as off for 2 secs [ecu].

 

-------------------------------

When you resolder a Main Relay, it's best to remove all the old solder,
add some resin, and put on some new solder, otherwise you may not get
good adhesion and a nice meniscus. The factory solder was very thin, BTW.

I wouldn't even bother if I only had a soldering iron but no solder
(unless I was stranded in another city).

'Curly'

 

I did remove most of the old solder and I did put new solder. Resin I did
not have but I assumed the resin contained in the new solder itself was
enough.
In any case, I attached the LED to the fuel pump power now so I will wait
for the malfunction to happen and get some more diagnostic information.
Unfortunately the problem is intermittent and did not happen yesterday.

 

You are right an analog multimeter would have been easier, I did not think
of that. But in any case I only have a digital multimeter which would have
been harder to read. If I had an analog one I would still attach it to the
fuel pump connector though because acessing the main relay is difficult.
Anyway, I attached the LED and it is working as expected but unfortunately
the car started fine all day yesterday. I'll wait for the malfunction to
happen again...sooner or later, then I'll have some more diagnostic
information.

 

I thought that if it is indeed the main relay that's causing the problem
then the fuel pump will not run (except for the initial 2 second priming).
Not?

 

Finally. I cought the engine not starting.
This afternoon the engine failed to start on 4 attempts. In all 4 attempts
the LED shows power to the fuel pump been cut off after I return the key
from the cranking position to the driving position.
So,
1. I turn the ignition and the LED comes on for 2” (I also hear the pump).
Here I feel the 1st relay click (relay goes on). Then after 2” LED and
pump go off and I feel the 2nd realy click (relay goes off).
2. I crank the engine and the LED comes on (cannot hear pump over engine
noise), engine starts. Here I feel the 3rd relay click (relay on).
3. I return the key from the cranking position to the driving position and
the LED goes off!! and I feel a 4th relay click. Engine then stalls about
1” later. This 4th realy click must be the relay going off again.

So this points to the main relay being at fault. I guess it could still be
the ECU’s fault for failing to maintain the relay closed but from what I
know blaming the ECU for problems is usually a loosing proposition.

So I will probably replace the main relay. If that fixes the problem I
will then take the older relay apart to see if I can determine where it
was failing, just out of curiosity.

 

--------------------

If turning the key to another position kills the relay, does it really
implicate the relay, or the ignition switch?

'Curly'

 

Good point. The ignition switch is not out of the hook.
In fact the relay is demostrating that it is capable of getting
instructions from the ECU and closing sucessfully to give power to the
fuel pump. I say this because the fuel pump always comes on for 2 seconds
when I turn the ignition. So why would the relay not close sucessfully if
it is getting a signal from the ECU to close once the engine has started.
Perhaps the ECU signal for the 2" priming and the ECU signal for
continuous fuel pump operation follow a different path? I'm not sure I
understand the electrical schematic to anwser that. The honda shop manual
has a diagram on page 11-111 which shows the connections to each pin of
the main relay. But from that schematic alone I cannot figure out the
electrical logic. I will try to look at the full electrical schematic this
evening see if I can figure out more.

 

You'd think so, yes.

 

It sounds like that.

I'd supect the ignition switch, but...

What you can do to help narrow this down is to hook up your LED to Main
Relay Terminal 2. If when the car stalls the terminal 2 LED goes OFF, then
the ignition switch is failing to provide power through IG1.

 

Thomas, it is a REALLY, REALLY bad idea to scatter your posts over many
threads. By doing this, you have just destroyed the original thread for
anyone Googling for an answer to this issue.

You should post ALL updates to the original thread, so future searchers
will find the whole thing in one place.

 

yes, but you can already hear the pump. unless you are hearing
challenged, i'd have thought the led redundant. but it's your call i guess.

 

ignition switch. if the relay's not setting code 16, that's the next
place i'd look.

 

I do not understand why terminal 2. My Honda manual shows terminal 2 being
ground.

 

Yes, but terminal 2 is supplied by the ignition switch and is not switched
on and off by the Main Relay.

If power disappears from terminal 2, the ignition switch may be failing to
send power. Double-check that by backprobing terminal 5, the feed side of
terminal 2.

 

Looks like it’s probably the ignition switch!
The car is now reliably not starting so it is easier to diagnose. AND the
ignition switch behavior seems to have changed. Before, I could hear the
2” fuel pump priming when I turned the key to position II. Now I often
hear the priming only while the key is IN TRANSITION from position I to
position II and/or when from position II a little bit of clockwise torque
is applied on the key towards position III.
Also when the engine stalls after being cranked I notice that the ECU
diagnostic light makes one short blink. Is that normal or does it mean
that the power to the ECU is being cut off. If the power to the ECU is cut
off when the key is returned from position III to position II then this
would also point to the ignition switch.

 

--------------------------------

Both terminals are on the ground.

Terminal 2 is closed since they opened Terminal 3. I'll be passing
through there on the way to NFLD.

PLEASE stop posting a new (unconnected) thread for every new thought ! !

'Curly'

 

Sorry to bother you about this but...
I’m not sure I understand how topics and threads are intended to be used.
I cannot find a description. Can somebody perhaps send me a link to some
guidelines?

I thought that every topic has a number of posts and that the posts are
organized in a tree like structure, much like files are organized on PCs.
So if the discussion goes of in some tangent talking about some small
detail of a particular topic then that entire discussion remains under
that subtree. The root of the subtree is then the initial post that
started the tangent. Then I see that the Talk About website software shows
the tree structure using indentation levels.
Are you saying that you would like to see all the posts in a topic
organized strictly hierarchicallly with each new message being the child
of the previous message? In other words would you prefer to see in the
topic presentation every new message being indented one level more than
the previous one? I.e.

Original post
2nd post
3rd post
4th post
etc. ?

or
Original post
2nd post
3rd post
4th post

or
Original post
2nd post
3rd post
4th post
5th post
that is stay at the same level or indent to the right but never indent to
the left? Ie. don't do:

Original post
2nd post
3rd post
4th post
5th post
6th post (don’t do this?)

Or are you talking just about NOT changing the title of the post. That way
every post title is “Re: Initial topic title”