2 Honda Accord Starting Issues
 

My friend has two 1998 Honda Accord 4-cylinder cars. Within a few weeks of each other, both have suffered different starting issues.

The first issue seems straight forward. Turning the key to the start position results in a click from the starting solenoid, but the starter doesn't engage. I hit it with a hammer, and now the clicking doesn't even happen. The battery charge and grounds are good. Bad solenoid?

The second car will spin the starter and engine, but will not start unless the throttle is opened a little and the starter is run for a few seconds (perhaps 5) longer than normal. Sometimes the car will die when letting off the throttle to coast to a stop. No CEL, and otherwise the car appears to operate normally.

I swapped the IAC valve between the cars thinking this was the culprit, but the problem remained. Once the car is warm, stopping the engine and restarting it functions normally.

Diagnosing parts should be easy since there are 2 identical cars. I'd just like an educated guess as to what is wrong before spending all my time swapping every part between cars.

On the first problem, replace the starter. Costs probably less than 100$ and less than an hour to do.

Second problem, replace the coolant temp switch, or any other tempurate-reading sensors. The car doesn't know it's doing a cold start-up, hence why it dies when cold/rolling up to a stop. Could be a transmission issue as well, but I doubt it as it runs ok when it's warm.

^ +1 on that.

Plug in an OBDII device (SG/UG) on car #2 and see which sensor readings are missing or off.
Check with #1 to verify.

I hadn't thought of that. Thanks!

I did have my ELM237 connected and thought it was odd that I was seeing 170 F from the engine coolant temperature sensor so soon. Didn't pay attention right away though because I first ran a scan for stored codes.

It is common for Chrysler sensors to fail mid range. It is common for GM sensors fail extreme cold. It is good to know about this Honda sensor.

Oh, check the connection. I would not be surprised if it mimicks normal operating temperature reading if not connected; that way the car would still run in most conditions even if the wire snaps.
If you unplug it and it reads the same then the problem is likely just a bad connection.

It turns out that for the second car that would turn over, but not start, that the fuel pump was bad. Swapping out fuel pumps between cars remedied the problem. Strange considering I could get the car to start by opening the throttle slightly for a while, and once running, would operate normally with no CEL. You would think starting would be relatively easy for a fuel pump, and acceleration difficult.