OT: Truck Won't Start in the Morning, "Cold" Start Issues Options

[Nogoodwithusernames]

Way off topic I know, but this forum is also WAY better than others that would maybe be more appropriate for this.

I've got an Isuzu Hombre '98 4 cylinder pickup. It does have a bit over 200k on the odometer, but it runs good. This last winter it started acting up not wanting to start in the morning. I'm in CA so morning temps can range from 30°f upwards just depending on weather.
It has gotten steadily worse where to now it won't even start when it's 50° outside.

I have tentatively narrowed it down to lack of spark, it will crank and crank and crank but not fire. A timing light on a spark plug wire while cranking will not flash.

I started with new coils figuring those might be going bad and not wanting to fire when it's cold out. No dice.

I am also getting codes for cam and crank sensors (as well as codes EGR valve and low efficiency on CAT, though I believe those are unrelated to the no start, and I believe the one caused the other so I cleaned out the EGR and made sure it was moving freely and seated okay, and have some BG 44k in the tank to help clean things out)
Anyways replaced the cam and crank sensors with NTK brand and it started two mornings in a row, and now won't start in the morning again.... Temps were all about the same all four mornings.

It will start just fine later in the day though.

Of course with all of this registration renewal is coming up and it's a SMOG year (IMG:style_emoticons/default/headbang.gif)

Any troubleshooting tips would be appreciated since it feels like I'm (IMG:style_emoticons/default/dead horse.gif)

[76-914]

Have you tested the sensors? If you can't and want to throw parts at it I'd replace the crank sensor 1st. If that's kaput the ECU won't know the engine is cranking. Search eBay for a factory repair manual and it will walk you thru the process. SB< $40 for that model.

[Superhawk996]

The simple act of replacing sensors moves wiring around may affect any intermittent short / open circuit behaviors that were previously related to temperature.

(IMG:style_emoticons/default/agree.gif) with suggestion above to get a manual. The factory manual which usually has the wiring diagrams and connector pinouts which are mandatory to troubleshoot with IMHO.

With a vehicle that age it’s becoming common to have issues all the way back in the ECU with cracked solder joints and leaking electrolytic capacitors. Investigate issues common to the vehicle on google. I have a 93’ Mazda B2600 that needed capacitors replaced. Not saying this is your issue but that age, heat cycles, and vibration take a toll on PCB’s and the electronic ECU.

You’re probably going to need to troubleshoot this methodically with a DMM since throwing parts at it isn’t working well.

Good luck with the troubleshooting. (IMG:style_emoticons/default/beerchug.gif)

[technicalninja]

NTK is a brand I trust (I don't trust much now-a-days).

A common diagnostic process is to clear codes, run, pull codes.

If you're still getting crank/cam sensor codes look to wiring first.

You're working on a 26 year old car...

I've stopped taking anything over 20 as the only parts available are Chinese and I cannot warranty those.

You're also working on a niche vehicle. Isuzu anything is hard to get good parts for.
26-year-old Isuzu will be even worse.

You're also in Calif which has the strictest emissions laws so you may have to get a CARB certified cat. On Rock Auto CARB cats are 600+ and the one I'd pick say's "last one". You're going to see that or NLA often.

I'd bet money that if you found a factory service manual it too would be stupid expensive.


If I was constantly getting crank/cam sensor codes I would try to fix it first.
At the point I needed an ECU I'd slit it's throat...

Just checked RA. They have a Cardone ecu for 100!
It says it needs programming...
Find someone who can do that BEFORE ordering.
I'd be worried that the necessary program will be NLA.
You're going to need Calif specific coding.

I'd advise my customer that the truck will only get harder to find parts for.
You're going to start losing "black boxes" for the reasons that SuperHawk described.
Any vehicle can be repaired but you should look at the 3-5 year cost and that if it was a human it would be the equivalent to a 98 year old person...

How much work would you do to a 98 year old human?

[technicalninja]

Just did a bit of research.

Isuzu is common to re-brand other vehicles.

That is simply a Chevrolet S10...

S10 stuff should be VASTLY more available.

Not sure if Calif will accept S10 emission parts...

Look to S10 videos for diagnostic help.

[Nogoodwithusernames]

Thanks for the responses folks, good to get some feedback and help keeping me from pulling out all my hair. I'm only out $150ish so far in the "throw parts" department, but don't want to continue if I don't have to.

Sorry I did forget to mention it is identical to the Chevy S10 and GMC Sonoma, just a different emblem. In fact the wheel covers have the Chevy logo on them even.

I'll look for a shop manual and in the meantime this thing may just end up on non-op until I can figure it out.

I do have a decent DMM and some needle pin leads so I can go through all the harness with time.

It is just throwing me for a loop that something temperature related would cause complete lack of spark. ECU might well be the culprit. Maybe I should convert it to D-Jet.

[r_towle]

At 200k with no spark I would ask a simple question.
What system tells the coil pack to fire?
A combination of crank sensor, some distributor, and wiring.

No spark at plug while turning over…
Back up…is there power to the distributor?
Is there power to the coil?
Does the distributor tell the coil to send voltage? How and check that is working.

The last thing I would even consider is the ECU on a car with 200k on it.
Old wires, corrosion, worn out parts etc.

At the end of the day, you are sending voltage to a spark plug at the proper moment…..figure out what part of the electrical system is no longer doing its job

Djet is a fuel deliver system….nothing todo with spark at the plug