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HARD STARTING SUBURBAN

 
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mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/20/10
04:46 PM

1999 Suburban with 180k miles, 5.7 4wd.
starting a couple weeks ago it is hard to start first thing in the morning. once you get it started, it runs good all day and starts up just fine. leave it overnight and it is hard to start. initially it would just crank over for a few extra seconds and then start, but now it is taking about 10 minutes for it to start. you crank and crank and nothing happens, then it will kick over a time or two and then give a few light backfires and maybe even throw in one AWESOME backfire. eventually it starts. fuel pump is running when key is turned on. plugs and wires are good. not sure what i should be looking for?
any ideas?  

jgate-#002 jgate-#002
Guru | Posts: 953 | Joined: 06/07
Posted: 06/20/10
05:13 PM

Even though the pump is running, it might not be building the
pressure this 5.7 needs to stat and run. Could be the fuel
is draining back into the tank overnight, and not building pressure
fast enough to start and run.If you dont have anyway of installing a
fuel pressure gauge in the mornings, Something to try is to cycle the key
3 or 4 times before you try to start the engine, turn the key to the
run position wait for the pump to quit running, then turn the key off,
wait 5 seconds them do this again, for another 3 or 4 times, this should
build the 60psi you need to start the engine. I had to do this a few times
for weak fuel pumps.  

mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/20/10
06:10 PM

i tried that a couple times. it wasnt a fix. it MAY have helped a TINY bit. but not enough to notice. i think i have a gauge to check it. i will try hooking it up tomorrow. i am wondering if i left the key on overnight with a trickle charger hooked to the battery if it would start easy...... is there anything that would hurt?  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/20/10
07:19 PM

you might want to figure out which is the fuel pump relay under the hood in the relay box next to the master cylinder...

i just worked on a 98 5.7... i carefully took the fuel pump relay out of the box.. used a tiny screwdriver to pop the interior out of the case... and cleaned the relay contacts ...   spray cleaned it... put it back in..  gave it a squeeze to see if the fuel pump got power...  i then pulled it again and put the cover back on it...     i have a tiny screwdriver to burnish the contacts with the sharp flat edge of the tiny screw driver..  the contact faces are silver.. so they do tarnish..

cured the intermittent starting problem...

with the cover off.. you can squeeze the contacts closed to test the fuel pressure..  how fast it builds pressure... does it hold pressure...  

mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/21/10
04:55 AM

this morning, took about 10 minutes to start. after the first few times, you could smell gasoline. its almost like it is flooded, but not right away.......  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/21/10
06:21 AM

there is a chance that you have a bad fuel pressure regulator....

and that fouls the spark plugs...


got a timing light??????  hook it on the coil wire....  use tape on the trigger to keep it flashing.. aim it at you so you can see if its flashing when you are cranking the motor...

if it flashes a nice fast even pattern...  then  move it to one of the spark plug wires.. test again..

perhaps your cap and rotor have burned through....  they do go bad on these...

it takes torx screws on this model...  the screws are not captured like earlier models... the ones that hold the cap down... it is important when putting them back in.. with the new cap... that you turn the screw backwards until you feel it drop slightly...  WHY... the distributer housing is plastic... if you back the screw slightly and start it when it falls into the previous threads it won't strip the hole out..

test the fuel pressure.... if you have a harbor freight near by.. they have the proper tester for under 20 bucks..

the standard gm fuel pressure tester is an Sunpro CP7818 Fuel Pressure Tester Kit   usually around 25 to 30 bucks.. some stores get more for them... there are several brands of the exact same tester..

the electric fuel pumps on these models are almost 300 bucks... at the chain parts stores... even more for an original delco unit..  and they do go bad...


these trucks are equipped with anti theft systems that are hidden in the key and lock cylinder..  if it fails... or activates... it can lock you out from the car starting for 10 minutes.....

are you using an original key to start the truck??????

do you have any RFID keys on the same ring?????   or mobil speed passes... got any mini credit cards hanging on the key ring????? the ones you can just wave over the pad in the store????

is the security light on the dash flashing or ON when you are trying to start the truck?????  

mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/21/10
04:42 PM

i will check the things you mentioned. on this car, when the security system doesnt talk to the computer, it just plain wont start at all! it took me a week a couple years ago to figure that out. i bought another computer and that worked for about 3 months and then it did it again. i think there is a problem with the security system. i would like to just disable it. I ordered a computer with the programming changed to NOT require a valid passkey system to start. it also worked fine for about 4 months until this problem surfaced. what is weird to me is that once it is driven for a couple miles, i can park it for 2 or 3 hours and it will start right up. but overnight is apparently tooooo long. i dont think the cap or rotor is the problem because when they go bad, it starts fine, but runs rough as can be. right now if it starts, it runs smooooooooth and strong. just getting it started is the problem.  

mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/21/10
04:43 PM

oh btw,
original key, security light is almost always on(has been for years), no mini credit cards at all.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 06/21/10
07:00 PM

i am going to say.. take it in to a dealership... or a top line mechanic.. have the computer reflashed...

use the IATN.net shop finder to find a member shop near you... that might have the ability to do the job...

not all independent shops can do it...  takes some expensive gear...

just curious...

do you have a different GM car.. that might have a pass key????  inserting that incorrect key has been known to mess with the pass key programming..  

mrhoffer mrhoffer
New User | Posts: 11 | Joined: 06/10
Posted: 06/22/10
03:16 AM

i do have a saturn car, but the key is different enough that it doesnt fit. no idea if it even has the same passkey system.  

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