1985 s15 2.8 liter idle problem - S-10 Forum
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1985 s15 2.8 liter idle problem

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Old 10-16-2011, 12:57 AM   #1
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1985 s15 2.8 liter idle problem

Just Got this little truck but it will not stay running had it tow home mess with
it today found the timing was 180 deg: out got that straight out and replace the EGR valve it wasnt holding vaccum. but still will not idle put it in to gear
and it dies.

Any takers on this whats next
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Old 10-16-2011, 04:26 AM   #2
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Re: 1985 s15 2.8 liter idle problem

fun times!

i've spent the last 2-3 months working over an 85 s15 with the 2.8l

you are going to need to make sure that you have the timing set correctly. if you can, verify that you have the #1 cylinder at tdc. with the distributor cap off, you want the rotor pointing about the 4 o'clock position as you are standing in front of the truck facing the engine. the firing order is 1,2,3,4,5,6 and the next position is #2 and so on. with it 180 out, you might be seeing some backfiring through the carb.

next, make sure ALL the vacuum lines are good and make sure nothing is disconnected.

is this tbi or carberuretor?
Old 10-16-2011, 10:13 AM   #3
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Re: 1985 s15 2.8 liter idle problem

has the carb ever been rebuilt? what kinda shape is it in? mileage? general condition of the vehicle? filters?
Old 10-16-2011, 01:44 PM   #4
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Re: 1985 s15 2.8 liter idle problem

ok pull the dist: out and the rotor is pointing at number one at the cap the truck is running and not back fire so set the timming at 10 deg bouth up the idle and running now but as soon as i put it into drive it dies . Its has a 2 barrel Vari Jet Rochester carburetor. there has been no backfiring.. New EGR valve what else has anyone had this problem is this Carb:Issue or should i look else where
fuel filter & pump where change by the other guy and they looks good i have the paper work for the fuel pump & filter.
Ya Mileage i just got it tow home so how can tell you about the Mileage
Old 10-16-2011, 03:50 PM   #5
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Re: 1985 s15 2.8 liter idle problem

no smoke or anything? Is it flooding itself out?
Old 10-16-2011, 09:44 PM   #6
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Re: 1985 s15 2.8 liter idle problem

If you hold the gas when you put it in gear, will it stay running or still die?
Old 10-16-2011, 10:54 PM   #7
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Re: 1985 s15 2.8 liter idle problem

Yes when i put one foot on the brake and one on the gas it will stay running i have to keep at high idle given it gas
and no its not flooding out
Old 10-16-2011, 11:57 PM   #8
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Re: 1985 s15 2.8 liter idle problem

my issue with the carb was that it had charcoal in the float bowl which clogged the pump jet and the off idle circuits. the charcoal canister float bowl vent purge valve was bad.

look down the bore of the primary of the carb and give the throttle a quick turn. you should see a nice stream of gas shoot out of the bore near the top about the 5 o'clock position. if you see anything less than a stream, then the pump plunger is bad or you have garbage in the carb.
Old 10-17-2011, 10:53 AM   #9
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Re: 1985 s15 2.8 liter idle problem

Quote: Originally Posted by tmans15
Yes when i put one foot on the brake and one on the gas it will stay running i have to keep at high idle given it gas
and no its not flooding out
Good. Next question... Does it shake like a dog in gear with the brake and gas pushed?
Old 10-17-2011, 12:39 PM   #10
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Re: 1985 s15 2.8 liter idle problem

Damax , Thanks for that i will check some time this week on the carb and look for that stream of fuel when i hit the gas . Ok talk about this charcoal canister float bowl vent purge valve was bad where is this located.

Ol Yaller no it doesnt shake like a dog in the rear why is this question ask i just want to under stand i may be missing some thing here as well ?
Old 10-17-2011, 12:40 PM   #11
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Re: 1985 s15 2.8 liter idle problem

You guys this some great stuff thanks a lot
Old 10-17-2011, 12:52 PM   #12
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Re: 1985 s15 2.8 liter idle problem

I believe Yaller is making sure the torque converter is working, whats your idle at? I had this problem before were my idle was about 300rpm below what it should have been and when ever you'd go into gear it would kill it
Old 10-17-2011, 03:07 PM   #13
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Re: 1985 s15 2.8 liter idle problem

Quote: Originally Posted by tmans15
Ol Yaller no it doesnt shake like a dog in the rear why is this question ask i just want to under stand i may be missing some thing here as well ?
I had a torque converter go bad on me and I had a tranny go bad on me. Both did what you describe. idled fine, but putting in gear bogged down the motor. If it shook, I was going to suggest a bad mount causing the engine / tranny centerlines to be at an angle. With no shaking, I'm thinking the engine is getting bogged down by the transmission.

the last question i was going to ask is if you drive with both feet - keeping gas on it while braking - does the truck drive or not?

If it does, I would suggest checking your torque converter out. If it doesn't drive, then I would suggest having the tranny checked out.
Old 10-18-2011, 03:58 AM   #14
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Re: 1985 s15 2.8 liter idle problem

sounds good i will steam clean the engine and trans this weekend and drop a new torque convertor in with a new seal whats an other 100.00 bucks.
I will keep you guys posted thanks so much
Old 10-24-2011, 10:14 AM   #15
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Re: 1985 s15 2.8 liter idle problem

ok well im back took my truck over to the transmission shop to have it check out for free well its not the torque convert every thing is work fine he said, have problem in the carb: so drove it home went bought a fuel mixture valve that sit on top of the carb 154.00 install that and it idles now doesnt die any more in drive.
But now it pop threw the carb now and then and more when i drive it under a load then dies ,then it start back up again and i drive it again
Old 10-31-2011, 11:10 AM   #16
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Re: 1985 s15 2.8 liter idle problem

There was another thread on here about a week ago where the carb was backfiring and it turned out two spark wires were switched (#5 and #3 I think). He chased all kinds of stuff till he found that.
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