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Old 10-29-2012, 08:39 PM   #1
towbar
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2001 4.3 S10 wont start

hey guys, bought a 2001 4x4 S10 4.3 with 125k on it for my step son the other day, ol guy I bought it from said it had been running good and all of a sudden wouldn't start. got it home and was almost positive it was a the cap and rotor, changed that stuff out and still no start. weird thing is that if you let the truck set over night, it will crank and run rough for about 2 or 3 seconds, then quit and wont start the rest of the day, till the next morning. checked the fuel pressure and had 62 psi, but didn't check the leak down rate. has spark at the plug, slight smell of gas under the hood when cranking, cranking normally and no burpin or farting so I dont think its a jump time issue. need to to hit it with some ether with the mass air unplugged to see it it fires, but its been in the 30's and snowing all day so that'll wait for warmer days. thought I hit you guys up and get some opinions??

thank a bunch!!
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Old 10-30-2012, 08:30 AM   #2
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Re: 2001 4.3 S10 wont start

Did you test each wire for spark? Remove and test the ignition module. You can test the coil with an ohm meter. Pressure is good. Pour a little fuel down the TB. Does it run for a few seconds? If so, you have fuel delivery problem. Check timing order and marks. Connect an ODBII scanner. Does it have any codes? Remove and clean the EGR valve.
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Old 10-30-2012, 11:24 AM   #3
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Re: 2001 4.3 S10 wont start

gchemist: no, just checked for spark on a couple cylinders, spark was not really blue/white, was more orangeish, of course battery was somewhat discharged too. got to charge the battery up so it'll be 100%. Pulled the coil wire and was getting strong multiple sparks as engine turned, but have not did the ohm meter test yet either...just got it friday night and weathers been crappy since. did sprayed some ether and pored some fuel down the TB but forgot to unplug the mass air sensor so didnt get anything when we cranked it. from what I read if the hat is off the TB and the mass air is still pluged up the ecm wont fire the coil or ignition module since it thinks there is no air available to the engine? will need to recheck as soon as the weather breaks! hooked up the OBDII scanner and no codes stored. have not checked the EGR....are they known to give a no start condition? have had them plug up before with a chunk of carbon and it would load up, run rough and set off a code imeaditly.

thanks for your help!!
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Old 10-31-2012, 07:36 PM   #4
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Re: 2001 4.3 S10 wont start

Check all fuses first!
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Old 10-31-2012, 09:24 PM   #5
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Re: 2001 4.3 S10 wont start

clinbarer: I pulled all the major fuses that might create an issue, both underhood and dash, checked continuity on them with a DVM and all were good to go. thanks for your help!
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Old 11-02-2012, 10:08 AM   #6
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Re: 2001 4.3 S10 wont start

update: went home yesterday, charged the battery to 100%, pulled the throttle body cap, unplugged the mass air sensor, had my step son crank the engine over while I sprayed starting fluid into the throttle body, still no start. So it led me to believe that its ignition related. So I got one of the KD tool calibrated ignition testers for the HEI style ingnitions. it has a huge gap to arc across so if ther was an ignition problem, the tester wouldnt arc. pulled the # 4 cylinder plug wire and connected the tester....plenty of spark!! I pulled the plugs on the pass side, all look really nice, cleaned them and reinstalled...still no start.

OK, now what, back to the fuel system, I checked fuel pressure again, with key on I have 62 while the pump runs, will drop back to about 58when the fuel pump quits priming. after about 5 minutes, pressure will drop off to about 52-53 so I dont feel the regulator is the problem.

any ideas??
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Old 11-03-2012, 09:13 PM   #7
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Re: 2001 4.3 S10 wont start

update: pulled the plugs and did a compression test today, had 140-150 psi on 1, 2, 3, and 6. had only 90 on #4 & 5. So some loss on 2 cylinders but I don't think that will keep it from starting??

rolled it up to TDC #1 and pulled the distributor cap, was pointing directly @ #1 firing position.

put new plugs in and new plug wires to go with them. pulled the ignition control module and coil and installed them on my sons xtreme s10 and it started fine. also verified that it has spark on each plug wire with my calibrated ignition tester. l also pulled the harness for the fuel injection and used my noid light to verify the ECM was firing the injector and it was.

I'm down to thinking that the injection spider is crapped out and not spraying fuel into the cylinders....only issue with that theory is that the truck doesn't fire off when I spray ether down the throttle body which contradicts that.

anyone want to chime in....I'm sure there are better mechanics on here than me.
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Old 11-04-2012, 07:44 AM   #8
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Re: 2001 4.3 S10 wont start

PLEASE stop using ether!!

2001 was the last year of the poppet FI spider. Yes, the poppets could be clogged. Did you pour just straight gas down the TB and try to start it? If ignition is good, it should run for a few seconds. Low pressure is a big concern.
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Old 11-04-2012, 10:09 AM   #9
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Re: 2001 4.3 S10 wont start

gchemist: well the ether isnt working so I might as well stop using it.

Yep, I have put fuel down the TB and it wont start on that either.

The low compression does concern me in the long term somewhat however its not the reason it wont start, if those 2 cylinders were totally dead it should still fire on the other 4 each time the engine rolls over but it doesnt.

The truck will start up for a second or 2 when its left alone for 24hrs or so, but subsequent attempts to start immeaditaly after fails. That fact makes me think that the poppets are clogged or the injector coil is fried and just over time fuel will dribble into the cylinders allowing it to momentarly fire up for a second or so if left alone long enough.

gonna pull the upper intake today to check the poppets for fuel flow. pressurize the system, hook up the injector harness, disconnect the coil harness and have someone crank the engine over.....if I have fuel spray then I have another issue, if there is no fuel spray that should verify if there is a spider issue.
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Old 11-04-2012, 10:48 AM   #10
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Re: 2001 4.3 S10 wont start

Since you are tearing it apart, update the FI spider. I updated my 96 shortly after buying it. Performance and milage both improved. Be carefull removing the injector fuel lines!! Take note of the o-ring order and location! Use crowfoot wrenchs to remove the fuel line at test port. Unbolt and move the compressor forward. Bolt it back down using the back side. Do you plan on take off the lower intake? If so, replacing the intake gaskets will save you time later. Dexcool and poor quality gaskets will fail in time. If you need better info on taking it off or pictures let me know. I have a write up on another site.
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Old 11-04-2012, 09:37 PM   #11
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Re: 2001 4.3 S10 wont start

gcemist: pre-paired to pull the upper intake, I unhooked the injector harness from the spider, had my step son crank it over for grins and giggles with the ignition hooked up....and it fired up and ran a couple seconds like it normally does first thing in the morning, then it fired up 3 or 4 more times and ran for 4 or 5 seconds during one of these attempts. keep in mind the injector harness was unplugged and laying about 4 inches from the spider!!!! wtf?? it finally stopped firing up tho.

so i went ahead and pulled the upper intake only, re-installed the fuel lines, unhooked the coil leads, pulled each poppet valve and had my step son crank the engine while I held the poppet in a bottle. each poppet valve sprayed fuel fine??? this thing is puzzling me big time!! So, now get to put it back together, going to clean the spider up....but might replace it, I dont know?? what the crap is this things deal.

so now with the thing starting up with the injector harness unplugged I'm thinking it may be flooding out when the injector harness is plugged up. with the harness unplugged it allows the cylinders to clean out till the a/f ratio is right then it fires off....I don't know, down to grasping at straws now.

one other thing, the truck sat for about 3 years with a 1/4 tank of fuel, i'm thinking maybe big time condensation?? gonna pull about a quart of fuel and check it out. also gonna unhook the exhaust in front of the converter to see if that may be plugged up??
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Old 11-05-2012, 07:41 AM   #12
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Re: 2001 4.3 S10 wont start

Three years is a long time!! Remove as much fuel as you can and add fresh high octane fuel. After it starts, run a full tank with Seafoam. Seafoam will help clean out the fuel line and clean injectors. Replace the fuel filter after a Seafom tank.
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Old 11-05-2012, 08:36 AM   #13
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Re: 2001 4.3 S10 wont start

aside from pulling the bed or dropping the tank, is there another way to remove the gas?
not sure if thes FI truck can be siphoned or not....maybe straight wire the pump and remove the filter and drain there? any other ideas?
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Old 11-05-2012, 09:04 AM   #14
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Re: 2001 4.3 S10 wont start

Removing the bed is ideal. You can clean and make repairs to anything needed. If the tank level is really low enough, just add fuel/octane booster. You can hook up a connection at the test port too. Either way be safe.
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Old 11-05-2012, 11:32 AM   #15
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Re: 2001 4.3 S10 wont start

think I'll use the test port and pump out a quart in a glass jar, so i can see if its loaded down with water....that would give me a good feel for whats in the tank.....if I see bunches of water then pulling the bed will likely be in order, if it doesnt settle out water then no need to break into it?
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