I have a 1987 5.7 TPI motor in my 85 chevy truck and it is always hard to start i did a little research on it and when i unplugged it and tested the wire to the cs injector i got power so my next step is to check the cold start valve but i dont know where it is and how big it is and is there any way of testing if its broken or the cold start in jector is. it take 10 sec of constant cranking some morings to get it started but if i turn the key for a few sec then turn it off and do it again after a couple trys it starts up and if the engine is off for a few minutes then it will start right up sometimes and if it sits a couple hours then its really had to start, any info would help i would also like to know how i can test these parts out so see which one is broken.

 

the cold start valve and cold start injector are the same thing.. you can also check the thermo time switch located in the front of the intake manifold , next to the coolant temp sensor, it has the same harness as the injectors, this controls the cs injector.

[This message has been edited by ron rizzotti (edited May 28, 2001).]

 

check the fuel pressure first the cold start injector is only used to enrichen the motor whenit's cold to get it to operating temp it sounds like you are losing fuel pressure when the car sits you mentioned that after you run it and turn it off a few minutes it starts right up which leads me to believe its either leaky injectors not hold the fp or the regulator letting all the pressure to bleed back out of the fuel rails

 

I too had a hard start problem. It only occured if the engine sat for a while. If you ran in for a cup o java and came out, it would start fine, well better at least.

My situation turned out to be a leaky cold start injector.

To find it, I pulled the upper plenum and runner off. Then I lifted the injector rail and all the injectors out ... high enough that I could place paper towel under them. Then I would turn the ignition key on (not starting the engine, just enough to prime the pump. Do this a few times and come back and check for leaks. There should be spots on the paper towel ... don't take too long to check as the fuel will evaporate.

I have read that some people leaked ALOT. mine was no more than a stain, but I assume if you let it sit long enough, it would pool.

I recall changing my intake gaskets and tipping the intake over only to find a whole pipe of fuel come out.

You may also find the leak is from one of your main injectors.

Cold start injectors are very tough to find. I found one at a local parts store ... bosch unit too!

If you find out that yours is leaking and you can't find one to replace it, email me and I can check locally for one. I am in Canada.

Mark.

 

The cold start operates much like the fuel injectors and is subject to the same crash and burn that they are too.

If you suspect your injectors are dirty or leaking down you can send them as well as the cold start to <A HREF="http://www.cruzinperformance.com">Rich at Cruzin Performance</A> Rich at Cruzin Performance for a rebuild and flow match. Cost me about 100.00 for all including new gaskets and it made a world of difference.

If it's just the cold start I think he charged me 6 or 10 bucks for that item.

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Red 86 T/A 5.0 TPI (LB9/WS6)
~HyperTech Cap/Coil/Rotor/AFPR
~Derale Adjustable Fan Switch ~ 170° Stat
~Flow Matched Injectors ~ K & N Air Filter
~Ported Polished Plenum ~ Runners ~ TB
~Polished Wheels ~ Alternator ~ Fuel Rail
~SLP TB Airfoil ~ Pirelli 245/50/16
~All Else Stock

 

The cold start injector isn't used to bring the car to operating temps. It's only powered under cranking since it's power is taken from the starter solnoid and has a 8 second max time limit at -20 degrees celsius(-4 degrees F).

 

Additional info: The cold start injector is activated by the Cold Start Injector Switch. This is not computer controlled, but a thermally activated switch with a built in timer. It is located on the front of your intake manifold next to your ECM coolant temp sensor. You can get them at Checker/Autozone..but they are not cheap, and are a special order item. Dealers still have them also.

Alternate fix: (easier than trying to replace the injector or switch) Get a custom prom. Program an eprom with 89 TPI code, which would not have the cold start injector. (You have to disable VATS) Unplug the harness from your cold start injector and voila! no more cold start problem.

If you want to be neat about it, you can then remove the injector and line, plug the hole in your fuel rail and runners. This eliminates one more item of "plumbing" under your hood.

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