1998 Chevy Silverado vortec 5.7 wont start

Tiny
SICKCHEVY98
  • MEMBER
  • 1998 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 147,000 MILES
Well I believe I have 2 separate issues but too much info is better than too little

A couple months ago I started noticing a lack of power at heavy acceleration I could not get the engine above 3000 rpm except in park also could not get to go into passing gear (even manualy dropping to 3rd or 2nd) this got better as weather got warmer (felt normal with normal driving attitude)

My fuel pump has made a high pitched whine since I purchased vehicle 23000 miles ago (found that this can sometimes be normal)

Anyway what brings me to you is now the truck will not start I came home for a quick lunch about 15 minutes trying to leave the engine would just turn no start no cough quick troubleshoot found that I could not hear the pump whine

after replacing fuel pump truck started right up I let it run for a couple minutes called it good went to bed
overnight truck fired up in morning, again for a quick trip and again for lunch (about 9 milies driven)
upon my return the truck died in park and have not been able to start since I could not hear or see the fuel pump relay functioning could not hear pump (this one quiet) could hear pump running after jumpering relay pins 87 & 30
(constant 12v at 87 with 12v at pin 85 (relay terminal relay removed))
truck still would not start

I replaced the relay still nothing
I have not yet done the fuel pressure test or checked into my spark

I was wondering if you might have any other ideas before I throw a pressure regulator at it
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Sunday, April 25th, 2010 AT 9:58 PM

10 Replies

Tiny
RACEFAN966
  • EXPERT
OK first check for good spark if the spark is good then check the fuel pressure. I also would like you to check the cap and rotor, this type has a corrossion problem and I have had them toed to me to find it to be the cap and rotor. Let me know what you find.
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Tuesday, April 27th, 2010 AT 9:56 AM
Tiny
SICKCHEVY98
  • MEMBER
Carb cleaner wasnt enough to get it going but a quick shot of ether got it to turn over

found minor corrosion in relay sprocket not much but apparently enough to malfuction relay

got the pump going but could now hear it blowing bubbles in the gas tank (nylon tube lost its seat all no fuel was getting to the engine)

the truck starts and runs ok however it takes a little bit longer as though it is losing its prime

however the aforementioned problem is back as far as sudden acceleration (does not want to go above 3000 rpm or shift correctly) intermittant problem

I have not checked what psi the pump is putting out to engine now

thinking possibly dirty/clogged filter

Im pretty sure that its a HEI ignition under there but also sure the plugs could use a good cleaning or replacement
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Friday, April 30th, 2010 AT 8:46 PM
Tiny
RACEFAN966
  • EXPERT
OK you really need to check the cap and rotor for corrosion and not it is not HEI that was back a few years it is a electronic however. Also if you would check the fuel pressure need to know what it is. Let me know what you find.
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Saturday, May 1st, 2010 AT 9:23 AM
Tiny
SICKCHEVY98
  • MEMBER
Ok got the fuel pressures they are
60psi to prime and at start stays about
55 psi while idleing and fluctuates between 55 and 60 for everything else ( was unable to check pressure while driveing but did test with it in gear and brake on up too 1500rpm maxed)

At this point I had not pulled off EDI truck still working just harder to start and still falters on acceleration but working

I tried towing some vehicles with it with 97 cutlass had no other problems but with 92 s10 blazer about 20 miles out it started missing first just a pop maybe about twice a minute but eventually started sounding like popcorn I figured engine had pretty much had it so squeezed it as far as I could go as I got to a stop sign and let off accelerator the popping went away for the most part I still didnt have any power tho but it did make it back home

I pulled off EDI sure enough quite a bit of corrosion I changed the rotor and cleaned up the cap and changed the air filter so far still having the same problems allthough it is back to usual problems ( I can get it to miss sometimes if I put it in first and try to take off from there FYI first gear pedal to floor I can only do about 25mph at about 2700 rpm

In park I can hit 5000 rpm or higher with intermittant stumble about 4000 rpm
In neutral I can only get to about 3000 rpm

I should be changing plugs and wires sometime this week

also truck dies as soon as I pull the air cleaner off
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Saturday, May 8th, 2010 AT 11:06 PM
Tiny
RACEFAN966
  • EXPERT
OK the dieing when you remove air filter is ok shouldn't run without one anyway. I would like you to clean the mass air flow unit with mass air flow cleaner nothing else. Also check that cap and rotor if you haven't already. Once you do that and the wire let me know how it runs. If there is still a problem then you will need a digital multi meter so we can check the Mass Air Flow sensor.
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Tuesday, May 11th, 2010 AT 9:23 AM
Tiny
SICKCHEVY98
  • MEMBER
I went ahead and changed the fuel filter first time ive ever seen black gas that ended up helping alot

also got wires and plugs changed ( changed rotor and checked cap prior to last post)

allthough it is still slightly hard to start a little slugish and lacking some torque It does now go above 3000 rpm for the most part the engine sounds healthy have heard or felt anymore misses from it

right now its acting like it is low on transmission fluid allthough it is not but it is definatly due for fluid flush and filter change in tranny, its getting pretty dark

ill get some mass air sensor cleaner tomarrow starting to feel like an idiot as most of this is just lack of routine maintenance
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Wednesday, May 12th, 2010 AT 11:34 AM
Tiny
SICKCHEVY98
  • MEMBER
Sorry have NOT heard anymore misses from it
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Wednesday, May 12th, 2010 AT 11:36 AM
Tiny
RACEFAN966
  • EXPERT
Ok after you clean the mass air flow unit let me know how it runs and we will go from there. Don't feel bad we all get busy and forget the basic maintenance stuff.
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Thursday, May 13th, 2010 AT 10:41 AM
Tiny
SICKCHEVY98
  • MEMBER
Well Ive cleaned the mass air flow havent drove much to say if it did any difference

however all previous symptoms are back plus more

anyway the truck idles fine
with slow application of acceleration rpm increases with hesitation or stumble every now and then

with quick acceleration massive hesitation plus backfire almost continueously (hasnt blown air cleaner off but I can see the hose stretch between maf sensor and throttle body)

after release of accelerator rpm increases back to about 900 rpm and it idles smoothly

(it was idleing at about 600 before plug and wire change)

now for the new I drove up to school about 20 minute drive went back to truck after getting directions to class the truck would not start back up (nowadays normal to fire up just at second crank) after about 5 attempts the battery was too discharged to turn engine I ended up getting a jump but still had to spray carb cleaner in to get it running in cab voltmeter showed 14 volts

the backfires started on my way home the next morning battery could only turn engine 2 start attempts

now I mentioned this because this has kinda happened before when I was trying to pull that blazer 2 weeks ago I pulled over because I had to restrap the tires on blazer I shut the truck down out of habit but could not start it again until I got a jump (engine would still turn but very slow when jump vehicle arrived) then after about 20 minutes of driving the backfires started

(I know I said misses sorry that was just wishful thinking and denial)
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Thursday, May 20th, 2010 AT 4:45 PM
Tiny
SICKCHEVY98
  • MEMBER
Well I rechecked fuel pressure before the new problem was still at 60 psi to prime but would drop to 50 while running with slow acceleration pressure continued dropping got to about 35 psi at about 5000 rpm no longer backfires with quick acceleration just dies

now new problem on way home from work I could not touch accelerator without it stalling out it eventually died anyway could get it restarted for a bit with carb cleaner I got about 20 feet before it died again

I cranked the engine it turned ok but no start went to crank again and as soon as I got to run position all power went out dome lights everything

pulled and checked fuses they all looked good truck magically had power again truck started died then same power problem

in run and start I had absolutly no power at all accessory position worked

anyway pretty much nothing works accessory too

battery is just above 12 volts all fuses good the light on my cell phone charger is on and with the key in run position the gear indicator light comes on that is it no domes no brake lights nothing else

Does that all run through the vehicle control module?
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Sunday, May 23rd, 2010 AT 9:59 PM

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