Hi,

A 1990 Honda Civic Si, 1.6 liter here.

The engine starts fairly easily. It begins to falter as it warms.
After driving for 10-15 minutes it's barely running. If the engine is
shut off or stalls, it won't restart until cooled to ambient.

With an old mechanical distributor I would remove the cap with high
voltage wires all connected. Rotate the crank shaft until points are
closed. With the inside of the cap facing up, place a coin between
the center contact and a spark plug contact, not touching both.
Switch on the ignition. (Not the starter of course.) Then lift the
points open with finger nail or screw driver tip. The spark should be
visible jumping via the coin. The spark at each plug is easily
checked by shifting the coin.

In the Honda distributor, no points are visible and high voltage is
created in a module inside the cap. No external coil as in the old
style ignition.

Can the coin test be done with this type of disributor?

Thanks, ... Peter E., Pender Island, BC

Whether there is a visible coil or not, there is a coil, AKA "Ignition Control Module". A thermal fault in these devices is not uncommon, and the typical failure-mode (after 30 years). About a US$55 part, or so. That being written, do you have a spark when the system is hot? You can verify that rather easily by pulling any given sparkplug wire (at the plug), installing a spare plug, grounding said plug and checking for a spark by running the starter for a few seconds. Or, if you have an old-fashioned induction timing strobe, seeing if it will fire (with the wires connected).

No spark, suspect the ignition module.
Good Spark, suspect the fuel filter, fuel pump or fuel system. Old fuel filters will often flow fine until the dirt particles pull back into the elements under suction. So one attributes the failure to ignition... A filter is about a US$35 ordeal.

Be systematic as repair-by-substitution is expensive.

https://shop.advanceautoparts.com/p/...ntrol%20module

https://shop.advanceautoparts.com/p/...=fuel%20filter

Peter Wieck
Melrose Park, PA

On Thursday, January 28, 2021 at 9:25:52 PM UTC-5, Peter Easthope wrote:
Hi,

A 1990 Honda Civic Si, 1.6 liter here.

The engine starts fairly easily. It begins to falter as it warms.
After driving for 10-15 minutes it's barely running. If the engine is
shut off or stalls, it won't restart until cooled to ambient.

With an old mechanical distributor I would remove the cap with high
voltage wires all connected. Rotate the crank shaft until points are
closed. With the inside of the cap facing up, place a coin between
the center contact and a spark plug contact, not touching both.
Switch on the ignition. (Not the starter of course.) Then lift the
points open with finger nail or screw driver tip. The spark should be
visible jumping via the coin. The spark at each plug is easily
checked by shifting the coin.

In the Honda distributor, no points are visible and high voltage is
created in a module inside the cap. No external coil as in the old
style ignition.

Can the coin test be done with this type of disributor?


Coin? No, but you can still check spark much easier than that. But...

I had friend's Honda do the same thing yours is doing, and it was a bad fuel pump that stiffened up as it ran. Put a gauge on the Schrader valve (fuel rail) and see if the pressure holds.

If the fuel pressure is good and you want to check ignition, pull a spark plug when the engine is cold (leaving it connected to the ignition wire) and ground the threaded part. Have someone crank it over and watch the spark. Repeat again once the car is hot and see if the spark stays a nice fat blue spark or if it's now a weak yellow spark or no spark. If the spark is strong when the car is hot, it's not ignition.

If it's ignition, you can buy a rebuilt distributor that includes the coil, pickups, and electronics, any of which can cause ignition problems. A distributor assy will cover all bases.

A 30 year old car that won't run hot sounds like fuel to me rather than spark.

You can check spark easily so I guess you might as well, but not at the distributor. check it at the plug, or even at the spark plug wire boot.

Remember anything you take apart in a car that old may break either uninstalling or reinstalling. (speaking from experience)

You did check the fuel line for a hot spot that might vapor lock, right?

In article ,
says...

Hi,

A 1990 Honda Civic Si, 1.6 liter here.

The engine starts fairly easily. It begins to falter as it warms.
After driving for 10-15 minutes it's barely running. If the engine is
shut off or stalls, it won't restart until cooled to ambient.

With an old mechanical distributor I would remove the cap with high
voltage wires all connected. Rotate the crank shaft until points are
closed. With the inside of the cap facing up, place a coin between
the center contact and a spark plug contact, not touching both.
Switch on the ignition. (Not the starter of course.) Then lift the
points open with finger nail or screw driver tip. The spark should be
visible jumping via the coin. The spark at each plug is easily
checked by shifting the coin.

In the Honda distributor, no points are visible and high voltage is
created in a module inside the cap. No external coil as in the old
style ignition.

Can the coin test be done with this type of disributor?

Check the main relay. It is a well-known failure point in Civics/CRXs of
that vintage. I used to have a 90 CRX Si (same engine as the Civic Si),
and went round and round with a local shop replacing all manner of
electrical components until finally discovering that the main relay was
the culprit.

https://honda-tech.com/forums/honda-...-3/car-starts-
dies-when-warm-2119566/

https://honda-tech.com/forums/honda-...91-3/checking-
main-relay-pics-2535047/

--
Dave

Jan 29, 2021, 3:23:38 PM (2 days ago)
Put a gauge on the Schrader valve (fuel rail) and see if the pressure holds.

Haven't found a Schrader valve.
https://en.wikipedia.org/wiki/Schrader_valve
Is it hidden inside something?

Dave Garrett 3:39 PM (1 hour ago)
Check the main relay. It is a well-known failure point
in Civics/CRXs of that vintage.

The Haynes manual has almost nothing about the relay.
It's under the dash? In the engine compartment?

Thanks, ... P.

So we have established that it is not ignition, but fuel related? Have you _ever_ changed the fuel filter in 30 years?

Fuel-pump relay failures are seldom (not never) thermal. Once they latch, they tend to be fine.

Peter Wieck
Melrose Park, PA

On 01/02/2021 12:32, Peter W. wrote:
So we have established that it is not ignition, but fuel related? Have you _ever_ changed the fuel filter in 30 years?

Fuel-pump relay failures are seldom (not never) thermal. Once they latch, they tend to be fine.

Peter Wieck
Melrose Park, PA




OK

This is just an observation, from a man who has never owned a Honda car

In the normal course of events, if a car starts from OK from cold, and
then doesnt want to start when its hot then it might be caused by the
mixture being too rich - like as if the choke is stuck on (for those of
us old enough to remember what a choke is)

I have experienced this problem a few times on various petrol engines,
and its usually something to do with a thermostat somewhere - so maybe
something in the system thinks that the engine is still cold ?

My instinct tells me that if its got enough fuel to start and run when
its cold (and needs more fuel) then its not likely to be a problem with
the fuel filter.

Probably of no relevance whatever in this case, but just may be worth
thinking about ...

AT

My instinct tells me that if its got enough fuel to start and run when
its cold (and needs more fuel) then its not likely to be a problem with
the fuel filter.

Patient: 1999 VW Eurovan Camper - VR6 engine. 72,000 miles.
Symptom: Started fine. Ran fine for about 20 minutes or the first hill. After which it would get progressively weaker, then stall.
Spark at start: Good.
Fuel Pressure at start: Good.
Spark hot: Good
Fuel Pressure hot: Poor.
Cause: Clogged fuel filter - OEM to the vehicle, I replaced it in 2012. Specs call for every 50,000 miles.
Action: Replaced the fuel filter. Problem solved.

Apparently, the within fuel filter when cold (not under pressure) contaminants will separate from the element and settle at the bottom of the can. Apparently, this allows enough fuel flow to get the engine started, even running for a while until the element reclogs and restricts flow.

Hence the suggestion.

Peter WIeck
Melrose Park, PA

On 02/02/2021 20:47, Peter W. wrote:
My instinct tells me that if its got enough fuel to start and run when
its cold (and needs more fuel) then its not likely to be a problem with
the fuel filter.

Patient: 1999 VW Eurovan Camper - VR6 engine. 72,000 miles.
Symptom: Started fine. Ran fine for about 20 minutes or the first hill. After which it would get progressively weaker, then stall.
Spark at start: Good.
Fuel Pressure at start: Good.
Spark hot: Good
Fuel Pressure hot: Poor.
Cause: Clogged fuel filter - OEM to the vehicle, I replaced it in 2012. Specs call for every 50,000 miles.
Action: Replaced the fuel filter. Problem solved.

Apparently, the within fuel filter when cold (not under pressure) contaminants will separate from the element and settle at the bottom of the can. Apparently, this allows enough fuel flow to get the engine started, even running for a while until the element reclogs and restricts flow.

Hence the suggestion.

Peter WIeck
Melrose Park, PA


as I said

Probably of no relevance whatever in this case, but just may be worth
thinking about ...

AT