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[SOLVED] hard start chevrolet

This is a discussion on [SOLVED] hard start chevrolet within the Automotive Support forums, part of the Tech Support Forum category. i am working on a 1998 k 1500 5.7 the truck is very hard to start but when it does


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Old 10-04-2007, 08:24 PM   #1
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i am working on a 1998 k 1500 5.7 the truck is very hard to start but when it does it runs fine.. good power and will start fine afterwards,,the problem i am having is when it sits for 2 days then once again it is very hard to start...
i have 55 lbs fuel pressure spark seems ok i even dropped the exhaust to see if it was restricted ng...
also installed fresh ac plugs coil cap wires also tried crank sensor.. again ng..
dosent seem to be flooded pulled plugs they were kinda black but not wet with fuel and it will not start wit ether HELLLLLP PLEASE
thanks in advance

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Old 10-05-2007, 05:03 AM   #2
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Good Evening island auto, that sounds really interesting.
Bearing in mind that a pre-programmed start cycle would be involved and that once it has been running it starts normally sounds very odd.

Low compression could be involved or moisture somewhere in the ignition components.

That is just a guess.

I can't think of anything else.

I think doing a complete compression test might be a good start for troubleshooting.

The compression will improve with thermal increase after it has been running, plus oil residue is greater. It may be simply at the point where compression is just too low.
One idea to prove this would be to remove all the sparkplugs and give a couple of CCs of oil down each plughole then refit them and see if it makes any difference after it has sat for a while. (cold)

I notice your nickname is "Island" you wouldn't be in a place with a salty misty spray kind of atmosphere by any chance. Saltiness and high humidity can be interesting together and have odd effects with ignition systems in some locations where moisture is attracted to crystalline material and is highly conductive but when dried loses that effect.

Have you tried spraying all the ignition components with a moisture inhibiting substance.

Others will have different ideas.

Cheers, qldit.

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Old 10-05-2007, 06:14 AM   #3
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Quote:
Originally Posted by qldit View Post
Good Evening island auto, that sounds really interesting.
Bearing in mind that a pre-programmed start cycle would be involved and that once it has been running it starts normally sounds very odd.

Low compression could be involved or moisture somewhere in the ignition components.

That is just a guess.

I can't think of anything else.

I think doing a complete compression test might be a good start for troubleshooting.

The compression will improve with thermal increase after it has been running, plus oil residue is greater. It may be simply at the point where compression is just too low.
One idea to prove this would be to remove all the sparkplugs and give a couple of CCs of oil down each plughole then refit them and see if it makes any difference after it has sat for a while. (cold)

I notice your nickname is "Island" you wouldn't be in a place with a salty misty spray kind of atmosphere by any chance. Saltiness and high humidity can be interesting together and have odd effects with ignition systems in some locations where moisture is attracted to crystalline material and is highly conductive but when dried loses that effect.

Have you tried spraying all the ignition components with a moisture inhibiting substance.

Others will have different ideas.

Cheers, qldit.
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Old 10-05-2007, 06:22 AM   #4
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good morning sir yes as the name states i live on an island a small one at that,, i will give the compression a check i just didint think of that cause the truck runs so good after it starts,,have you ever heard of the central cfi injectors causing this problem??? i was looking on alldata and there is a conversion kit available to make it a mfi system..
i will check compression too i have been in thi business for 20 years and this is a new one to me thanks
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Old 10-05-2007, 01:08 PM   #5
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i talked to a couple of techs and they seem to believe it may be the fuel pump,,the pressure bleeds off after a few minuits they also said that after a couple of days the fuel will drain back to the tank and that is maybe why it is so hard to start..also the pressure is at 60 lbs right at the minimum does this sound feesable to you??
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Old 10-05-2007, 04:24 PM   #6
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Good Morning island auto, well your mention of that kind of pressure does sound a bit high, but the gauge you are using may have an error, generally even if the fuel did drain back to the tank it only takes a few seconds to be replenished and even if the system contains air, I would expect some firing to happen initially.

The pressure relief valve on the end of the fuel rail is what actually controls the available pressure for the injectors and all excess returns to the tank so the available fuel for the injectors should remain relatively even independently of circumstances.

I expect you are measuring that fuel pressure on the rail using a "T" adapter and not "dead heading" the pump supply.

You will need to get the proper fuel rail pressure figures from the manual specific for that vehicle to really know.

Some vehicles only operate with as low as 10-15 PSI whereas others really have high pressure in the rail.

As mentioned previously on this site, some people have experienced where only 5 to 10 PSI low caused starting problems on higher pressure systems.

But this problem clears when the vehicle has been run, so that makes that kind of thing less probable.

Problems where the fuel pump relay occasionally doesn't operate have happened but this happens at all kind of odd times and doesn't fit your symptom.

Is this problem evident when the fuel tank is filled completely?
In some cases the pump pick-up could be involved.

It is possible that you could have "dribbly" injectors that are not shutting off properly, that could cause odd effects, in many cases putting injector cleaner in the tank helps that problem after a week or so operating.

It is an interesting exercise to remove and test them on the bench with a simple kind of test rig and actually watch the spray and shutoff, but usually anytime you remove injectors you need to replace all the seals, so I practice the TFN rule. (Touch Nothing) Unless a problem is obvious.

So if we consider that fuel and all other items are good we have the "actual engine condition" that is why I was thinking compression.

Sorry not much help there.

Others will have different ideas.

Cheers, qldit.
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Old 10-05-2007, 06:38 PM   #7
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good evening
i have aldata access and the fuel pressure specs are 60=65 psi so i am in range also i am using the test port on the fuel line i pinched off the return line and it boosted pressure to 100 lbs so pump should be ok
i also check compression have 175 lbs on all cyls..but when i removed plugs they were wet with fuel and also black...but the truck has never run with these plugs just cranked 100000 times hahha
also i have a strong spark at coil so my next step is i am hoping faulty cap n rotor
this type of ignition syst has the horizontal cap...did ohm ck cap 8 oms on all towers gotta chek if any specs on that thans for all your input
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Old 10-05-2007, 08:36 PM   #8
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Good Afternoon well that becomes more interesting, compression is definitely good, fuel is definitely good and I really would suspect there is nothing really wrong with your ignition.

I do know that some of those injectors leak and it may well be an overfuelling problem where there is insufficient available air.

There was a previous chap with a similar problem but the engine wouldn't run all that well.
You might try starting with the throttle held fully open and see if that has any effect, if it does you might read his posts.

He found the injectors were faulty and leaking and also that the computer had a problem etc.

It was a similar system with just the two injectors as it appears is yours.

His post also involved a Chevy and his name was "dgoad".

This is the URL, You might find his approach very interesting. http://www.techsupportforum.com/f155...es-179014.html

Cheers, qldit.
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Old 10-05-2007, 09:10 PM   #9
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PS I forgot, notice especially his finding with one injector disconnected!

BTW, I don't know that much about different type injectors so cannot advise on them.

I only ever use identical replacements.

Cheers, qldit.
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Old 10-06-2007, 08:46 AM   #10
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Mornig Sir
Problem Solved Yahooooooooo As We Say In The South ..
The Problem Was Faulty Dist Cap And Rotor Ohms On Old Cap 8 New One Is 4 Oh Well Next Time I Know Only Buy #1 Quality Parts Brass Terminals On Cap....thanks Again For All The Input Maybe Thiss Will Help Somebody Else Just Rmember This Engine Has 8 Injectors Poppet Valve Type
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Old 10-06-2007, 03:40 PM   #11
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Good Morning island auto, well done, duh, I was thinking that was the two injector type.

Cheers, qldit.
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Old 10-06-2007, 04:48 PM   #12
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Thanks Again,
Nice To Have I (wanna Say Talked To Ya...) I Guess You WoulD Say Forumed You Haha If I Ever Get To The Land Down Under Ill Look You Up Have A Blessed Day..
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Old 10-06-2007, 05:07 PM   #13
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Good Morning Again island auto, thanks and nice to meet you.

By the way, I do a few odd jobs from time to time in odd places and on one of these occasions did a bit of work on the island of Nauru, (small island on the equator) this is entirely phosphate and about 5 miles or so in diameter, but the breeze blows from the ocean constantly, and the main perimeter reef is only a hundred yards or so from the shore with ever crashing surf, so the breeze is heavilly salt-laden, it is amazing to see people continually pouring oil over their vehicles to try to combat the effects of corrosion and salt!

The majority of vehicles there have aluminium bodies (old Land Rovers) but their chassis all rust incredibly.

Often pulling distributor caps is an exercise in pure physics as to how salty ingress can enter the most protected areas.

Water is all desal so is precious, and it is really impossible to wash vehicles.
So everything develops an ever growing layer of salt!

Keeping a clean windscreen is a problem!

Look forward to seeing you down here sometime.

Cheers, qldit.
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Old 10-07-2007, 09:21 AM   #14
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Goon Morning,
I Remembered A Tsb I Read Abot Repeated Dist Cap Failure On This Type Of Truck..the Low Side A/c Line Passes Right Over The Distributor So Guess What When It Sweats It Drips On Cap....
Fix Is To Use Foam Insulation Tube For Plumbing And Put It On The Line ,,
Had This Problem Happen At My Other Job With The Local Government Here..
With A 2001 1500 Pickup Funny How Now After Quie A Few Wasted Hours I Finally Put 2 N 2 Together,,,
Oh Well Must Be Getting Old..hahaha
Have A Great Day

P/s We Dont Have Such A Severe Problem With Salt Air As You Described But You Stll Kinda Need To Do A Little More Pm. Than Normal
See Ya
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Old 10-10-2007, 04:33 PM   #15
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Just a note if you happen to check back, rule of thumb with this style gm ign. Ever 50 - 70,000 kms you'll need cap, rotor & wires. very expensive and a big pain.
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Old 05-03-2009, 11:00 AM   #16
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I have a 5.7 litre chevy suburban 1996. It has a hard starting problem. I have to crank for a minute or two, several tries and it finally catches and runs perfectly after it starts, no coughs, no stutters. I have been told that it isn't the fuel pump, because a fuel pump either works or doesn't. It is like the fuel drains back down the line to the tank and it takes a lot of cranking to bring it back up the line to the engine. I replaced the fuel pump about 60K miles ago. Could I have a working fuel pump that just doesn't provide enough fuel pressure for normal starting. I just replaced the fuel filter and I made no difference. Your idea about replacing distributor cap and wires is interesting.
I'll check into that. Thanks.
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Old 05-03-2009, 05:08 PM   #17
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also check the cap and make sure it has the copper terminals on it i also had a chevrolet that had the same problem and that was the fix cheaper is not better in this case please let me know if this fixes the problem
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Old 05-04-2009, 04:21 AM   #18
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Not so that a fuel pump "works or it doesn't". Pumps can fail gradually and start getting weak, as in putting out lower than spec pressure. A weak pump can cause this hard starting problem ibecause it puts out lower psi on battery volage during start (nominal 12v but pulled down below that by the starter) than it does once the motor is running and the alternator is pumping out 13-14v. Not saying this is your problem but it is very possible and some fuel injection systems are more sensitive to low fuel pressure than others. So make sure to do the easy key on, engine off, fuel pressure test.

Quote:
Originally Posted by chelsearose View Post
I have a 5.7 litre chevy suburban 1996. It has a hard starting problem. I have to crank for a minute or two, several tries and it finally catches and runs perfectly after it starts, no coughs, no stutters. I have been told that it isn't the fuel pump, because a fuel pump either works or doesn't. It is like the fuel drains back down the line to the tank and it takes a lot of cranking to bring it back up the line to the engine. I replaced the fuel pump about 60K miles ago. Could I have a working fuel pump that just doesn't provide enough fuel pressure for normal starting. I just replaced the fuel filter and I made no difference. Your idea about replacing distributor cap and wires is interesting.
I'll check into that. Thanks.
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Old 05-04-2009, 07:17 AM   #19
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My engine is the '96 Chevy 5.7 with throttle body fuel injection. Is there a port to plug a tester into for measuring fuel pressure. My mechanic showed me where he could test it on another engine because it was port injection and had a test valve, but says no place on mine. Is there a place on my engine to get a reading???
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Old 05-04-2009, 11:48 AM   #20
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That doesn't make any sense. If you have fuel injection and an in-tank pump there has to be a test port. My 1994 camaro 5.7L port F.I. and my now-gone 1994 S10 pickup 4.3 L CPI both have the same kind of schraeder valve test port. Just follow the fuel lines back from the fuel rail, or CPI manifold, or throttle body (if you have TB injection) to the firewall and you should find the port, probably on the driver's side. Has a plastic valve cap on it... take that off and screw on the test gage hose. When you are done make sure to vent the pressure off and catch the vented gas in a container before undoing the test gage conection. There should be a little button on the test gage hose to vent it.

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