# 1996 chevy s10 4.3L wont start



## johnnydakine

I have a 1996 chevy s10 pickup 4x4 4.3L v6 automatic. My truck ran fine until I went on vacation for 3 weeks. I just got back and now it wont start. It has spark, gas, air and suction from the carb. New parts include: fuel filter, starter, rotor, cap, battery. The spark plugs arent new but are in good shape. When I try to start it wont turn over. I can try strating 5x and nothing but when I try to start it and turn the key all the way off it sputters a little bit. Almost like a backfire but not really. I've also jumped the starter so I know its not the ignition switch. I had a friend who only works on chevys come take a look and hes pretty stumped. He thinks it might be the spider injectors or the CPI whatever its called. But the new spider injectors are over $300 and I dont want to buy unless I know for sure thats what I need. Once again it has spark even from the coil, has gas and has suction from the carb so I know its not a timing issue. I've poured gas directly into the carb to and no start still. Something weird is going on for sure. Any help would be appriciated!!! Aloha Nui Loa!


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## octaneman

Hi johnnydakine


Locate and replace the fuel pressure regulator, on the 4.3's they leak when cranking the engine.


post back your findings.


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## johnnydakine

I can try that but if that was the problem wouldnt it start if i put gas in the carb? I have spark,air,compression and fuel. everytime I drain the gas line when I try to start it again there is new gas in the line and even if it didnt it should still start with fuel poured directly in carb right? I'm not a mechanic by any means. I change oil and starters on my vehicles and save anything else for when theres people who know what there doing around to help and teach. Someone whos at my house right now said maybe its a crank sensor? Thanks for the post any ideas are always good.


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## octaneman

When the fuel regulator cuts out, the engine wont start and the computer will not register a code. A crank sensor will register a code and the service engine soon light will be on constantly. But knowing the 4.3's the regulator spews out fuel because of an engineering defect. That would be the first step and extracting computer codes will be the next step in troubleshooting.


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## johnnydakine

Thanks I will try the regulator tomorrow.


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## johnnydakine

So one more question. My mechanic says its my spider injectors for sure. Spider injectors cost almost $300. The fuel regulator cost like $50-$80. Is there something that tells you its the regulator and not the injectors? I just took a vacation that cost me a bunch of money and im just trying to get the part thats going to work first try if possible. Thanks for your help Aloha!


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## johnnydakine

just talked to my mechanic again he was looking at his book and said my truck doesnt have a fuel pressure regulator. he said its for sure the spider injectors or CPI(central port injectors). I would still like to get your input before I order this part. Thanks for the help I appriciate it!


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## octaneman

I don't know where your mechanic is getting his/her information. The fuel pressure regulator on the CPI system on 4.3's is under the intake plenum. The spider injectors are fed from the tubes ( which also have a tendency to leak) on the regulator. The regulator and tubes can come as kit which you can pick-up from your local auto-parts for about $140.00. When the regulator is replaced the gasket for the plenum is also replaced.


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## mack1

johnnydakine said:


> I have a 1996 chevy s10 pickup 4x4 4.3L v6 automatic. My truck ran fine until I went on vacation for 3 weeks. I just got back and now it wont start. It has spark, gas, air and suction from the carb. New parts include: fuel filter, starter, rotor, cap, battery. The spark plugs arent new but are in good shape. When I try to start it wont turn over. I can try strating 5x and nothing but when I try to start it and turn the key all the way off it sputters a little bit. Almost like a backfire but not really. I've also jumped the starter so I know its not the ignition switch. I had a friend who only works on chevys come take a look and hes pretty stumped. He thinks it might be the spider injectors or the CPI whatever its called. But the new spider injectors are over $300 and I dont want to buy unless I know for sure thats what I need. Once again it has spark even from the coil, has gas and has suction from the carb so I know its not a timing issue. I've poured gas directly into the carb to and no start still. Something weird is going on for sure. Any help would be appriciated!!! Aloha Nui Loa!



Hi Johnny,

I have the same engine in a 96 S10 Blazer and have had the same problems, so I might be able to offer some help. 

First, check the ignition. Pull a sparkplug or get a used one and lay it on the metal block with the plug wire connected to it. Get someone to hit the starter and make sure you have a strong BLUE spark across the plug gap. If you have a weak red spark, that could be a problem. Get a volt-ohm meter (a cheap one for about 10 bucks) and measure the resistance of the spark plug wires. Normally a short plug wire will measure about 8k (8000) ohms. I remember that the book says that much larger is OK. (12K or more). If you suspect bad plug wires, tell us what resistance you are getting and we will get better data on resistance. ( I looked in my book and find that I will have to do some reading to get the exact resistances) If you are between 8K and 15K, they are OK, so move to the next items. The main thing is a good spark. If you get a red weak spark, report back on that issue and we will persue it further.

If spark is OK, then move on to fuel. For about 18 bucks, you can get a fuel pressure gauge. (the voltmeter and pressure gauge are somewhat inexpensive compaired to the injectors and other parts that might not be the problem.) Remember, the idea is to find the problem and fix it, not to throw parts at the problem. A fuel gauge connected to the capped plug on the fuel line coming up on the drivers side of the engine, near the firewall will let you check the fuel pressure. To check the pressure, get a friend to turn the key from off to on (NOT START). The pump will run for about 2 seconds and then stop. Turning the key off then back On will get you another 2 second pump. At the end of the second Pump sequence, you should read about 60 PSI on the gauge and it should hold that pressure for quite a while. If it holds the high pressure for a while, you probably don't need to replace the pressure regulator. Octaneman gave you good info on the regulator. It is under the top intake manifold and has a fabric diaphram which can fail. Intereting note is that you can usually smell raw fuel under the hood when the regulator leaks. I replaced one on mine and you could smell fuel under the hood. 
Try using a can of starter fluid instead of raw gas. Take all the plastic plentems off to get to the intake. If you have good spark and starter fluid, the engine should try to start and run. If you can keep it running using starter fluid, then the problem is fuel. If it won't even start, the problem is likely to be ignition. 

Also, I'm not sure what you meant by "strating 5x". Does the engine spin over when you hit the starter? 

Let us know what you find and we will try to help you further.

Very best regards,
Mack1


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## johnnydakine

Oh man I just ordered a spider injector kit which includes the regulator for about $180 after I turn my core in. I live in Hawaii so I have to order online or get charged ridiculous amounts from local stores. I did try using starter fluid and it did nothing. I'm really not a mechanic at all so I just have to take what I can get from any advice. Two mechanics gave me basically the same part to order so I ordered the whole kit and figured it would get it fixed. I should be able to return the spider injector kit if I dont use it. Now it's the weekend and no one will be at my house all weekend but me. So its going to be hard to do any of the things you just listed to test. So just jumping the starter isnt a way to test your ignition? And if it is the ignition are you just talking about the electrical ignition switch? If so, my chevy guy can rip one out of a chevy hes got and I can try that. About the part of my post you didnt understand. I can try starting it five times without turning the key to the off position and it will spin but not cough or try to start. If I try to start it then immidiatley turn the key to all the way off position it will give a little cough or backfire. It's really weird. Thank you both for your help. I'm going to get it figured out one way or another.


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## mack1

Hi Johnny,

I'll try to explain things a little clearer. 

If you can turn the ingition switch from off to on and then to start and the engine spins, the ignition SWITCH is OK.

If you have a good spark across the sparkplug gap, the ignition SYSTEM is OK. See the post above about puting the plug on the block for testing. 

About the fuel pump. It is in the gas tank. When you switch the ignition switch from Off to On (not all the way to start), the pump will come on for about 2 seconds. If you are near the tank, you can hear it run. If you move the switch back to off then back on, it will run again. Your 5x test sounded like simple fuel starvation. The fact that a normal start tries to caugh or backfire says it got some fuel and ignition. 

Do your truck a favor. When starting it, don't go straight from off to start in one motion. Stop at ON for a couple of seconds to let the pump run. Then switch over to start with you foot off the accelerator. 

Have a nice day,
Mack1


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## johnnydakine

ok I did the spark test when my friend was here and I have good spark. I got spark in the cap, out of the coil and to the block. The fuel pump sounds like its going strong when I turn the key half way on. It DOES NOT cough when I try to start it. Thats whats weird. The only time it coughs is when I try and start it then turn the key to the off position. If I try to start it then just turn the key back to accesories it does not cough. Like I said I ordered the spider injector kit but I dont think it will even get shipped until monday. Thank you very much for your help. I'm going to try and have someone start it while im underneath to see if I can smell raw gas.


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## mack1

Hi Johnny,

When my pressure regulator leaked, you could smell it under the hood. I didn't go under the vehicle to smell it. 

That fuel pressure gauge I mentioned earlier would tell you if you need a regulator. Normally it takes quite a while for the pressure to bleed down after you turn off the ignition switch. A pressure gauge would show if it was bleeding down fast. 

Make sure your battery is fully charged. 

Installing that injector kit will be quite a bit of work. Make sure it is not something else before starting that job. Also, take some pictures as you disassemble the engine. Helps when you start putting it all back.

Wishing you luck,
Mack1


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## kjms1

might want to check the timing chain


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## Raylo

I don't see anywhere that you actually checked fuel pressure. Even tho the fuel pump is running it may be putting out inadequate pressure. CPI motors will not start if the fuel pump output pressure is even 10 psi lower than spec. I'd check this before doing anything else and replace the fuel pump if necessary. If fuel pressure is good then you might want to follow up on KJ's thought about the timing chain.


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## johnnydakine

ok i probably have a week before the regulator and injectors get here. I will go get the fuel pressure gauge and try to check the psi out. I'm stuck at my house today though. should be able to go get it monday. Thanks!


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## johnnydakine

Fuel pressure gauge cost about $60. Is that about right?


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## buba1975

having the same pro with my 96 i posted a thread under my name....help pls running out of ideas


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## mack1

johnnydakine said:


> Fuel pressure gauge cost about $60. Is that about right?


Too high. I bought one for about $18 at Auto Zone. Hard to believe they went up to $60 since I bought mine. Check around for a better price. 

Best regards,
Mack1


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## johnnydakine

Decided to listen to my chevy guy who has never steered me wrong and put the new injecters and regulator in. It did absoulutly nothing. Totally pissed, totally annoyed. I havent driven my truck in 8 weeks. I never checked the fuel pressure because the guage cost 60 bucks. So injectors and regulator are out of the question now since I have a new $250 set in. whats next?


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## Raylo

Check the fuel pressure! Your pump may be not be putting out enough. Spec is 60-65 IIRC but if it is putting out much less than ~55 the thing will not start. It won't even sputter or cough, either. It takes a certain threshold pressure to even fire the injector at all and if you don't have that pressure, then no gas gets to the motor.

Doesn't matter how the pump sounds, you really need to check the fuel pressure to be sure it is working up to par. I've "been there, done that" with this one.

FP gages aren't $60. I got mine for half that. You can even borrow one for free from Advance Auto.

If fuel pressure is OK, then we'll have another data point to go on.


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## johnnydakine

ok im so fed up i think I will just go buy a fuel pump because a fuel gauge is $60 in hawaii. I checked 3 stores and thats cheapest I found. I can get a fuel pump online for $100 so I mine as well spend an extra $40 to eliminate another problem. Thanks for everyones help! I cant wait to get this truck running so I can drive off a f**king cliff!


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## Amd_Man

How much gas was in the tank when it first started sitting for three weeks. I know it's a long shot but perhaps with the high heats/cooler nights in Hawaii the gas has gotten contaminated. Try some fuel stabilizer.


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## johnnydakine

It basically was empty when it sat for 3 weeks. I dunno whats going on. When I bleed the gas out it has plenty of pressure though so that meens the pump is fine right? I dunno my mechanic is coming up right now to tow it to his house so he can mess with it until he figures it out. I dont know what else to do. I have been with out a car for four weeks since i got back from my vacation and Im about to just go buy another car. Im so pissed at this truck. Ive replaced everything its ever needed and still every couple weeks it breaks down. I have a feeling after I get it started and sold I wont ever own a chevy again. Sorry about going off but Im just pissed right now!


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## Amd_Man

I left my 4.3l Safari van for a month in the summer with less than a quater tank of gas while on vacation. When I came back it would not start so I towed it to my mechanic. He told me that what gas I had in there was basicly water because it was low and had lots of room in the tank for condensation. The heat of the day and cool of the night creates lots of condinsation when the tank is low. Next year I put fuel stabilizer in before vacation and it fired right up. I also had the tank almost full too. I'm just throwing you some ideas.


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## johnnydakine

Right on man. thanks. I will get stabilizer. It had like no gas when i left but there could still be a bunch of water in the tank. Ive put new gas in to try and start it but maybe there is alot of water in the tank making the new gas bad instantly. Thanks. I will give it a shot.


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## Amd_Man

I hope it works for you! It was my problem because at the time it was very humid here when I was gone, but cool at night so it heat cycled alot creating condensation and hence water!!


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## Raylo

Stabilizer is cheap... definitely worth a shot. Also, I'd be surprised if your mechanic doesn't have a FP gage.


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## buba1975

i had the same issue with my 96 it turned out to be the pickup/strator in the distributor


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## johnnydakine

my mechanic towed my truck to his place so he could tinker with it. this morning he put jumper cables on it and said it started first try. he said its idling ****** now and it didnt before. but hey im just glad its running. we will see what the story is tomorrow. Thanks for everyone time and input.


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## AirwizRick

I know this is a really old thread. But my truck is doing something very similar and I'm at my wits end with it. Did you figure out what the problem was?


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## johnnydakine

I sold that truck because it pissed me off so much. What ended up fixing it was replacing the spider injectors. My friend replaced them and it started right up. They were like over $200 I think. I wish I could remember the website because you could send your old injectors back and get like 50 bucks back. That's all I got man. good luck. my advice is... sell it and get a toyota!


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## AirwizRick

lol Yeah I am going to sell it once I get it running. Thanks for the response! Hope I dont have to do that but at least its a direction! Cheers


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## riverrat46

I have a 96 s10 that won't start. I poured a little gas in throttle body and it started. I can't hear fuel pump running so I am going to see if pump is getting voltage. I was looking at a wiring diagram on autozone web site and it shows an oil pressure switch in the loop with the fuel pump. Could that be your problem. I pulled the fuel pump relay and went from hot side to fuel pump side and pump didn't run.


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## mack1

Hi riverrat46
This sure is an old thread. I looked in my book and didn't see an oil pressure switch in that loop.
By now, you will have measured voltage at the pump. If it is there, you will have to pull the pump. I hate that job.
Lots of luck,
Mack1


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## riverrat46

mack1 said:


> Hi riverrat46
> This sure is an old thread. I looked in my book and didn't see an oil pressure switch in that loop.
> By now, you will have measured voltage at the pump. If it is there, you will have to pull the pump. I hate that job.
> Lots of luck,
> Mack1


Where is the fitting to check fuel pump pressure located? I have a fp gauge. Getting the truck tonight and starting on it in the morning.


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## riverrat46

If it is fuel pump I will pull bed off. That is easier to me than dropping tank.


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## mack1

Hi riverrat46,
Taking the bed off is the easy way. Good thinking on your part. 
I have an s10 blazer, so I had to drop the tank. The fuel fitting to measure the pressure is on the fuel line at the engine compartment where the lines start over the block. There is a valve there for your pressure gauge.
Hope this helps,
Mack1


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## riverrat46

Thanks for all the info. It was the fuel pump and is now running okay.


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## mack1

That's great.
Have a nice day
Mack1


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## Wrenchhead423

I know this is an old thread but, these trucks mainly have an Issue with the pressure regulator, mine has almost 200k on it and I've only replaced the regulator. The regulator nipple points towards cylinder 6 and as that's the second cylinder in the firing order it usually causes extended starts first. If you pull number 6 plug it will be black. 

I work in a small shop in Florida and I just had one nightmare of a blazer finally replaced the crank sensor and it fired right up, even though I had strong spark and good fuel pressure it wouldn't start without the crank sensor.


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