97 Jimmy, no start in cold

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Dr_No

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Hi there, so we have a 1997 GMC Jimmy with the 4.3 vortec. It has a newer MAF sensor, fuel filter, plugs, wires, distributor cap and rotor, and a strong battery.

So this winter apparently at the beginning it actually started fine around -30c. Then another day in -18c the Jimmy would not start. This happened several times in that temp range. After being plugged in for 45 minutes it will start fine. Without plugging it in, you can crank and crank and crank until the end of time the most you get is a sputter and nothing more.

I would like to find the problem and solve it so there are no more reliability issues.

The only hunch I have at the moment would be the intake air temp sensor?
Thanks for any advice in advance.
 
How are your fuel injectors?

I also have a 4.3. A 1994 engine. I know there are some differences in years, but I have very similar issue. Sometimes will crank crank crank until the battery dies or the starter breaks, (I have a strong starter that has taken more than its fair share of abuse..) but only starts sometimes.

The first time it cut out on me while driving, mechanic replaced my distributor after diagnosis. (Said "No Spark.") Now.. I am being told it is injectors.

I would check fuel system. Pump, FPR, injectors.

*basically every car I have had that wanted to start stubbornly all the time, with a perfect start-up once in awhile sprinkled in, has had some kind of fuel issue. Pump

*I also have a new fuel filter, and dist. Cap and rotor - that is ON TIGHT. The distributor itself was rusty when pulled out. And new fuel filter.. is a nice touch.
 
The fuel system is fine. It will run for days and at any rpm and speed. The only issue is starting in sub zero temps when air is more dense
 
Sounds like a fuel issue. Maybe you need a fuel system cleaner like Techron to clean the injectors out.
 
I don't think these have individual injectors. I think it's called a spider injector or something and feeds into all cylinders with one unit. They're problematic too.
 
The intake manifold gaskets were changed and the fuel pressure regulator aswell. The spider assembly was inspected and all appeared to be fine. The fuel system is clean, redline and gumout in the past 6 months. Like I said, the issue is only when the engine is cold. Plugging it in for 45 minutes solves the problem. I don't see how the spider assembly has any relation to the issue.
 
Originally Posted By: Nick1994
I don't think these have individual injectors. I think it's called a spider injector or something and feeds into all cylinders with one unit. They're problematic too.


You are correct about the spider assembly, and them being problematic.
I apologize if I seem short, quitting smoking and this is day 2 for me.

Due to the fact the engine never skips a beat otherwise leads me away from the fuel system. There were starting problems due to the common issue of the fuel pressure regulator leaking into the manifold causing a rich condition. This was fixed and I am clueless as to what will cause the starting issue in extreme cold.
 
The IAT sensor I will replace.. it hasn't thrown any codes though. Is it possible the engine has two coolant temp sensors? The gauge on the cluster works properly.
 
Originally Posted By: Dr_No
The IAT sensor I will replace.. it hasn't thrown any codes though. Is it possible the engine has two coolant temp sensors? The gauge on the cluster works properly.


Yes, there is usually a 2nd one for the ECM.
 
Total wild guess. You have bad fuel. Change gas stations, mebbe add some cleaner such as a can of B 12. Not impressed with your mechanic either. First spark then fuel. He is throwing parts at the problem
 
Originally Posted By: andyd
Total wild guess. You have bad fuel. Change gas stations, mebbe add some cleaner such as a can of B 12. Not impressed with your mechanic either. First spark then fuel. He is throwing parts at the problem


He is, but, having the same truck, this does not seem uncommon...

These S10 Blazers pretty much are "amazing" but then you have to add "when they work"..
 
Originally Posted By: andyd
Total wild guess. You have bad fuel. Change gas stations, mebbe add some cleaner such as a can of B 12. Not impressed with your mechanic either. First spark then fuel. He is throwing parts at the problem


My first thought for temperature related failure to start is ice in the fuel system. 10% ethanol only works to clean out water, up to the point that the fuel is saturated. Plus, it tends to form layers, when the water percentage gets above a certain level. If the tank is low, fill it first chance, when you get it running. If it isn't low.......Additives might help, not HEET, something like Techron or even SeaFoam may break up the layers. Good luck.
 
Last edited:
Originally Posted By: Dr_No
Doing a part lookup I found 2, Ac Delco numbers 213-4396 and 213-928


Coolant temp sensor could be your issue- that would explain why plugging it in makes it start. Hook a scan tool up and read the value the sensor is reporting (without starting it). The coolant temp and ambient temp should be very close after sitting over night. Also the coolant temp and ambient temp sensors won't always set a code.

Another thing you can try is cracking the throttle open when cranking to see if that helps.



Originally Posted By: andyd
Not impressed with your mechanic either. First spark then fuel. He is throwing parts at the problem


What mechanic? What parts is he throwing at it? I saw mention of one part the O/P wanted to try.
 
I did try opening the throttle 100% before, no result. Scan tool isn't available to me, I may just try replacing the sensor.. It's cheap enough. And you're correct there is no mechanic, these are parts that have been changed over time. I replaced the fuel pressure regulator because it was leaking, and the manifold gaskets went a day after I was in there. So everything came out again and replaced the gaskets. The ignition parts were simply tune up items in the past. The weather here has been warm and I don't think I'll see temperatures that cold for awhile still.
 
IAT nor CTS sensors go bad on GM vehicles very often.

CPI Injection is very sensitive to fuel pressure, Below 58 psi & the Poppet Valves will not open on a cold start.

Next time it "no starts" Try priming it with carb cleaner through the PCV hose. If it now starts....Fuel System issue.
 
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