View Single Post
Old 09-26-2017, 03:44 PM   #14
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 43,607
 

2003 L-Series 3.0L Sedan
Default Re: hard starting 2001 SL1

No dual circuit for fuel pump. It's one line, one circuit, period. One signal to run the for pump whether it's for two seconds or as long as the engine turns. The PCM detects whether the crank sensor signal is being sent to the pcm or not and determines either to run the pump for two seconds or have crank sensor signals allow it to run the pump for as long as crank sensor signals are being sent to the pcm. This isn't a pump or pump signal problem.

With mileage approaching 300k and replacing pump and filter, did you check fuel pressure? Don't assume, verify it. Guessing can be an expensive way to replace parts without determine what failed. With an intermittent starting problem, fuel and spark are the two main issues that must be verified at least once when problems don't go away. Yes, fuel and spark are there because the engine runs but no one can tell you why one or both aren't giving near instant starts which we're expecting. Starting requires instant full operating pressure from the fuel pump - that's where a fuel pressure gauge is needed to see actual pressure at ignition on time just before starting. Spark needs to be verified by a starting test in the driveway to verify spark at low starting rpm. When you verify both are consistent without problems, the next step would be a compression test. Lower than normal compression is only one reason for poor startups.

Chasing the egr and secondary air pump problems may be contributing to this issue. Addressing each problem requires eliminating one problem at a time as one or several problems can contribute to startup problems.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote