The 4.8 in my '01 sierra I just bought seems to start hard after its sat a while... have to crank it a few seconds at a time about 3 times to get it to start. if its been running it doesn't take near as much time... Is this possibly indicative of the fuel pump? or just need a tune up. has 84k on most likely the factory plugs. it seems to run fine when it gets started.... but there ha been a few times where it seemed almost like it had a nearly un-noticeable miss.... I've only had 1 ls based motor so still new with these
CK5
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4.8 seems to start hard
- Thread starter shady
- Start date
On the earlier GM EFI setups long cranking was indicative of a failed fuel pump relay. I think the spec said somewhere around 10 seconds of cranking to get oil pressure up enough to close the switch.
Are the LS-series set up with a fuel pump relay and oil pressure switch?
Are the LS-series set up with a fuel pump relay and oil pressure switch?
Sounds fuel related, check your fuel pressure regulator and fuel pump.
A friend of mine has a 2000 Chevy pickup with the 5.3,and he was having difficulty getting it to start first thing in the morning,mostly when the temps were below 35 degrees out...
He replaced the fuel pump relay,fuel pump,and sending unit (gas gauge was not working all the time,so he did it while it was apart)..that failed to cure the hard starting/long cranking time problem though..once it started,it would fire up instantly the rest of the day as long as it did not sit more than 4-5 hours..however,as time went by,it started refusing to start on warm days too,and after not sitting long at all..
He also replaced a few sensors to no avail on the engine (coolant temp,and O2 sensors),and it wasn't until he was at a Chevy dealer buying some parts for another vehicle ,that he mentioned his problems to the parts guy,and he said "you should replace this harness--and he went and grabbed one off the shelf--he claimed many trucks were having the same trouble and this harness was found to be faulty"...
He bought it,it was about 35 bucks..it plugs in under the dash near the steering colum,I think it is part of the ignition switch harness...ever since he replaced that,it has fired up instantly regardless of the temperature...
So,you may want to look into that,as a possibility..
He replaced the fuel pump relay,fuel pump,and sending unit (gas gauge was not working all the time,so he did it while it was apart)..that failed to cure the hard starting/long cranking time problem though..once it started,it would fire up instantly the rest of the day as long as it did not sit more than 4-5 hours..however,as time went by,it started refusing to start on warm days too,and after not sitting long at all..
He also replaced a few sensors to no avail on the engine (coolant temp,and O2 sensors),and it wasn't until he was at a Chevy dealer buying some parts for another vehicle ,that he mentioned his problems to the parts guy,and he said "you should replace this harness--and he went and grabbed one off the shelf--he claimed many trucks were having the same trouble and this harness was found to be faulty"...
He bought it,it was about 35 bucks..it plugs in under the dash near the steering colum,I think it is part of the ignition switch harness...ever since he replaced that,it has fired up instantly regardless of the temperature...
So,you may want to look into that,as a possibility..
4xcrazy
3/4 ton status
Our Avalanche seems to have an extended start time if you hop in it and hit the key right away. I've gotten in the habit of turning the key to the on position for a few seconds to let the fuel pump pressurize and it's never gone into extended starter run time.
This thing is automatic, hit the key to start, it turns the starter over on its own until started or for a set time, then stops if the engine doesn't fire up. If it doesn't fire up you have to shut the key completely off and try again.
This thing is automatic, hit the key to start, it turns the starter over on its own until started or for a set time, then stops if the engine doesn't fire up. If it doesn't fire up you have to shut the key completely off and try again.
