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4.3l needs help getting started!!


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jeremy2269
Novice

Jul 22, 2010, 3:27 PM

Post #1 of 15 (5314 views)
4.3l needs help getting started!! Sign In

i have a 1995 gmc sonoma with a 4.3L vortec it got hot and fried my heads so i replaced the heads and a few sensors cap rotor plugs and wires put it all back together and went to time it and its a edi distributor so i put it up on compression stoke went to the next notch on the dampener and pointed the rotor to the number 6 castd in the dist. tried t start it up it cranks but no fire and back fires sometimes im not 180 out i checked over and over again i have 150 compession on all of the cylinders exept the num 1 which is only 115 anyone have any ideas?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 22, 2010, 4:04 PM

Post #2 of 15 (5304 views)
Re: 4.3l needs help getting started!! Sign In

The timing is not adjustable in that engine. When the distributor is turned all it does is throw the rotor and injectors out of phase. In order to set it properly you need a professional scan tool and there is a PID in there called offset that has to be set to "0". Your probably setting a code P1345.

Double check your firing order because the contacts don't run in sequence inside the cap.





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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jeremy2269
Novice

Jul 22, 2010, 4:06 PM

Post #3 of 15 (5300 views)
Re: 4.3l needs help getting started!! Sign In

so there is no way i can set the timing unless i have a pro scan tool?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 22, 2010, 4:13 PM

Post #4 of 15 (5294 views)
Re: 4.3l needs help getting started!! Sign In

There are some marks on the distributor that will get it close enough to run but you need the scan tool to get it right.

These are aligned at TDC





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jeremy2269
Novice

Jul 22, 2010, 4:17 PM

Post #5 of 15 (5290 views)
Re: 4.3l needs help getting started!! Sign In

ok ill give that a try thanks for your help ill post what i find


Hammer Time
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Hammer Time profile image

Jul 22, 2010, 4:18 PM

Post #6 of 15 (5290 views)
Re: 4.3l needs help getting started!! Sign In

Here are the complete instructions assuming you have OBD2







~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jeremy2269
Novice

Jul 22, 2010, 4:39 PM

Post #7 of 15 (5282 views)
Re: 4.3l needs help getting started!! Sign In

:/ i just did all that perfectly like you decribed it turns over and backfires. dont start


Hammer Time
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Hammer Time profile image

Jul 22, 2010, 4:45 PM

Post #8 of 15 (5278 views)
Re: 4.3l needs help getting started!! Sign In

You might have it 180 out. It's definitely a distributor or firing order problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jeremy2269
Novice

Jul 22, 2010, 6:18 PM

Post #9 of 15 (5273 views)
Re: 4.3l needs help getting started!! Sign In

i noticed that my marks on my dampener are not tdc to number one i found the tdc and timed my dist to it but still no fire


Sidom
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Jul 22, 2010, 7:58 PM

Post #10 of 15 (5264 views)
Re: 4.3l needs help getting started!! Sign In

HT has posted the procedure that should get it going for you.

The 2 questions are....is it in on TDC & is the firing order correct. Try an old school trick to see if you're close. Take the dist cap off & pull #1 one plug, tap it over & bring it up on compression (note the direction the rotor is turning while cranking), put a screwdriver or whatever in the cyl & careful rotate by hand it until the screwdriver is at it's highest point (use extreme caution doing this or you could punch a hole in your piston). Find the #1 electrode in the cap (It's not where the wire goes in) and verify the rotor is pointing to the electrode inside the cap. If it is verify the firing order AND rotation is right.


jeremy2269
Novice

Jul 22, 2010, 8:06 PM

Post #11 of 15 (5261 views)
Re: 4.3l needs help getting started!! Sign In

yup i did that i watched my valves and i put a screw driver in the num 1 hole and found tdc, i aimed the rotor at num 1 which is also very close to the 6 stamped on the dist case i have moved it one tooth up down and dead on and it still wont do anything but turn over


Sidom
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Jul 22, 2010, 9:00 PM

Post #12 of 15 (5253 views)
Re: 4.3l needs help getting started!! Sign In

Well something is missing....... You did double check the firing order & rotation....yes??

Maybe it's time to take a quick fuel pressure reading and make sure the pressure is good. Then grab a spark tester (not a screwdriver or old spark plug) and check coil output, check it off the coil wire 40kv min & down at the plug 15kv min. You mentioned a new cap, maybe toss the old one back on, I've had crossfire problems with new caps before, never a no start but I guess it's not out of the question. Get a can of starter fluid, pull the fuel pump relay and see if it will run on starting fluid. Pull codes see if there is anything there.

Also you kinda hazed over what exactly you replaced and did, maybe a indepth list of all the sensors and parts that have been replaced might right a bell for someone reading this.....


Hammer Time
Ultimate Carjunky / Moderator
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Jul 23, 2010, 2:48 AM

Post #13 of 15 (5246 views)
Re: 4.3l needs help getting started!! Sign In

I think I would hold off on that starting fluid right now. You are getting backfiring so there isn't much question that you have a timing issue and starting fluid could end up causing a real explosion and some engine damage under these circumstances. You didn't have a fuel problem before putting the new heads on so you shouldn't have one now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jeremy2269
Novice

Jul 23, 2010, 12:09 PM

Post #14 of 15 (5238 views)
Re: 4.3l needs help getting started!! Sign In

i checked fuel pressure its good no internal leaking ether, i replaced the temp sending unit and the air temp sending unit a water pump i had both heads re done new cap rotor plugs wires (old cap is busted up cant use) i think thats about it, i did try starter fluid to try to get it to start so it would throw a code but it just backfired like a shotgun out the exaust i changed timing around to where its on true TDC and not the dampener marks and it doesnt backfire it just cranks over, i tested spark also i am getting spark... i dont get it air spark fuel combustion should go right


Loren Champlain Sr
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Jul 26, 2010, 5:37 PM

Post #15 of 15 (5222 views)
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PMJI;
Jeremy; When bringing it up on TDC, the crankshaft will rotate twice. Once on the compression stroke, and again on the exhaust stroke. To get it on TDC, on the compression stroke, have a helper 'bump' over the engine until you feel the push of compression in the #1 spark plug hole. This will be the compression stroke. Then, align the timing mark on TDC, then recheck where the rotor is pointing. Do this with the ignition coil unplugged so it doesn't fire during the procedure. Just trying to make it as crystal clear as possible.
Loren
SW Washington






 
 
 






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