Vehicle repair rant

[Mobuck]

It seems I'm in a persistent failure loop these days.
First off, it appears the 1990 truck I bought in December may have a transplanted school bus chassis engine. I spent 3 weeks coming to that conclusion and still can't find the correct coolant temp sensor. One would think that with all the GM school buses in the Midwest, someone would carry that part. The one part I did find turned out to be DOA and didn't work right out of the box(and no refund either).
Second, the recurring problem with my "old" 1998 K3500 farm pickup failing to start at random intervals(usually after sitting for several days and/or during damp weather). Yesterday, the pickup absolutely refused to start(cranks over but doesn't start). Today after sitting overnight, it started fine-not a hiccup. I may have stumbled onto the culprit after 2 years of this intermittent no-start situation--we'll see if it recurs after I install the new sensor tomorrow.
If anyone has a late 90's Chevy that presents this "cranks over but won't start" symptom, check in after I have a chance to see if this is the answer.

 

[snowman2]

Could be a weak fuelpump not supplying enough pressure. or it be a clogged fuel filter whens the last time you changed it. just guesses lots of luck.

 

[golferboy426]

mine had moisture issues.. If it happens again hit the distributor with a hair dryer.. See if it starts... Have you verified spark out of the coil?

 

[Goldstar225]

My 98 Chevy had a pass lock security device as part of the ignition switch that would intermittently fail.

 

[Acorn]

Had a Ford that wouldn't start in the AM. Later in the day it would fire right up. My garage replaced the coolant temp. sensor. No more problems.

 

[Mobuck]

Not a fuel problem, not a security device problem, not a spark problem and totally non-repeatable. The only pattern has been that if it doesn't start in the first rollover or two of the engine, it's not going to start unless it's pulled and then it may take 100 yards of dragging. When this happens, I've noticed it seems to be firing out of time and this led me to the crank position sensor. I've also noticed that at times it seemed extremely "doggy" under load but not consistently. If it was that way all the time or at least consistently, that might indicate low fuel delivery issues. This series had issues with fuel pump failure which I've experienced twice on this pickup so I'm familiar with those symptoms.

 

[ndcowboy]

The Crankshaft Position Sensor died on my 1998 Jeep Cherokee this winter, but it died slowly. I'd be driving and it would shut the engine off for a second or two then come back on. One late night it shut off three times driving home from town. Then the next day it quit in my yard for about an hour. Funny thing was it never threw a code. Took a guess it was the CPS, replaced it with a new $15 part of ebay, and the old Jeep hasn't missed a beat since.
It was a pain to change. Took four long extensions to reach it with a socket.

 

[Bull Barrel]

If its a crank position sensor it most certainly is a spark problem. No signal from the sensor, no spark.
But that is exactly the part I thought of. Common problem.

 

[Dave P.]

I take it that truck has a 5 speed manual and you were trying to pull start it ?
Dave

 

[graygun]

Does it have an igniter (does what points use to do) somewhere? I had one fail in a 1993 Civic but it was a go/no-go manifestation.

Electronics components can fail in various ways. I worked as an electronics technician for many years and found that sometimes you can't induce the failure,as with a heat gun;they had to fail in their own ways.

 

[Rusty W]

I had a 90 model Z71 & the distributor was wore out. The bushing/bearing had just enough wear it would only spark intermittently.

 

[graygun]

I'm glad my 81 C-10's coolant sender only operates the gauge.

 

[Mus408]

After all the years of heat cycles the wiring harness and all those plastic connectors can loosen up,crack and corrode inside. The old carbed non computer vehicles are just plain simple to fix and keep running as the years pile up!

 

[graygun]

What you said about sometimes doggy under load does seem like it could be timing-related.

 

[Mobuck]

Yes, it's a 350 & 5 speed manual. All of the symptoms are intermittent and non-repeatable like the CPS was getting tired. It's replaced at a cost of $80. If that solves the problem, good enough. If not, I'll bring Tom's code reader home and hook it up next time it fails to start. Even if that isn't the fix, it's one ? off the list. If I take it to one of the local wrench monkeys, it'll cost $100 to drive it in and have him open the hood and for the most part, all those guys do is replace parts until the problem goes away or the vehicle owner says stop. I have a mechanics & farmers discount at a couple of parts stores so if it's just a matter of swapping parts, I'll do that myself at a 20-25% discount and save the $60-100/hour labor charge.

 

[Rick Courtright]

I'm glad my 81 C-10's coolant sender only operates the gauge.

Hi,

LOL... that's all they're SUPPOSED to do!

But somewhere along the line people started making hi-tech electronic stuff try to do lo-tech mechanical things and we end up with the coolant sensor talking to the right headlight which then sends a message to the left brake light to get in touch with the second idler pulley on the serpentine belt which then checks the torque on the ball of the trailer hitch which sends a note to DMV to up the price of your registration next year and if you're a day late on your payment the fuel pump will shut down...

Anyway, what could possibly go wrong in a scenario like that? ;)

Best of luck, Mobuck! Hope you guessed right before getting too many dollars tied up in the project.

Rick C

 

[Rusty W]

If it's like mine an OBII won't fit,the plug is too old on a 90 model. Mine had letters on the plug & I took a paper clip, bent it into a L shape so one end wound fit C slot & the other fit D slot. Not sure if those are the correct letters because it has been many years ago since I've used this technique. When you turn the key on with the jumper in place the check engine light will flash, count the flashes, e.g. 2 blinks pause 3 blinks is 23. You can search the net for the code or get a Haynes manual to look it up, I'd list the codes if I had my manual but it went with the truck when I sold it.

 

[gramps]

I'm glad my 81 C-10's coolant sender only operates the gauge.

Hi,

LOL... that's all they're SUPPOSED to do!

But somewhere along the line people started making hi-tech electronic stuff try to do lo-tech mechanical things and we end up with the coolant sensor talking to the right headlight which then sends a message to the left brake light to get in touch with the second idler pulley on the serpentine belt which then checks the torque on the ball of the trailer hitch which sends a note to DMV to up the price of your registration next year and if you're a day late on your payment the fuel pump will shut down...

Anyway, what could possibly go wrong in a scenario like that? ;)

Best of luck, Mobuck! Hope you guessed right before getting too many dollars tied up in the project.

Rick C

I am impressed Rick! Here I thought you were an accountant? :P
gramps

 

[Mobuck]

Update, the new crank position sensor didn't solve the problem although it did seem to make it run better(maybe just skewed perception). After 3-4 days of sitting, it's back to the same non-start deal. BUT, I hooked the Super Chip box up to see if there was a code and may have the real answer. After connecting the box, I followed the on-screen instruction to "turn key to run and press >" after a few seconds, the screen displayed "ignition not on, turn key to run and press>". After 4 replications, results were the same. That indicates something in the key switch isn't making all the connections as the dash gauges are active, fuel pump is running, and all that stuff. Guess that will be my next target.

 

[Dan in MI]

Not so fast. That means the PROCESSOR isn't seeing the key power. Not necessarily the ign switch is bad. Could even be the ODB port isn't getting the correct power.

If you have a wiring diagram and can get at the processor check to see if power is making it to that pin. (39 years of blue oval diagnosis, 0 on the general)

 

[Seventy7rs]

I had a similar issue on a similar vintage Ford. It was the neutral safety (clutch) switch. The switch was intermittantly failing, and when I depressed the clutch pedal, the switch would sometimes work sometimes not and sometime partially work. It was easy to jumper past on my truck, so that was my test.

 

[Mobuck]

"when I depressed the clutch pedal, the switch would sometimes work sometimes not and sometime partially work. It was easy to jumper past on my truck, so that was my test."

I had a problem with that "safety switch" in the past but all it did was fail to trigger the starter. In this case, the starter works fine but the actual circuit that fires the plugs doesn't always activate.

The other thing is:once it has started, it's good for as long as it's used frequently. I mean it will work fine all day through maybe 20-30 starts w/o a hitch and the next day, also. Leave it sit for several days and it's 50/50.

 

[graygun]

Is this the 1998 truck?

 

[Dan in MI]

Bear with me I'm not a GM guy. Are you sure it is not firing the coil(s)? or is it not firing the injectors, or both? That could mean intermittent PCM power. That would allow cranking all day long but no fire.

Also why the code reader doesn't read. I f you can take codes on a day it is running you should be able to get codes. Is the MIL (check engine) light on?

 

[Dave P.]

Sorry for the delay in follow up....life.
Ours was a year newer with automatic trans.
It would sometimes fire like it was out of time but
not start,other times just crank. Random issue on a service truck that might sit for
a few days to maybe a week between use.
Ended up being a ground wire for the PCM ignition trigger. It
was corroded in the crimp at a terminal bolted to ground.
Dave

 

[Mobuck]

"Is this the 1998 truck?"

Yes, it is. I tried a low tech approach this morning--I put considerable upward force on the key and the "ears" on either side of the key as I turned it to the start position. It started.

 

[graygun]

"Is this the 1998 truck?"

Yes, it is. I tried a low tech approach this morning--I put considerable upward force on the key and the "ears" on either side of the key as I turned it to the start position. It started.

good news

 

[K1500]

I had a 89 with the 350 with TBI and HEI. No/hard start and rough running in the morning. Drive a bit. Shut it down. Restart fine the rest of the day. It was a worn distributor cap/rotor/moisture issue. It would run bad until the engine heat drove the moisture off.

 

[Rusty W]

Is it equipped. With an anti theft on the ignition? If so the connector on the 2wire plug loses connection, I'd check that connector.

 

[Mobuck]

Well, I shoved the new key turnie thingie into place, hooked up the battery cable, and it started right up w/o the stumbling and sputtering even @ 7*. I won't even try putting the flimsy plastic trim back together until I'm confident this is the answer. Turned out to not be nearly as difficult to remove as I'd expected.