Bad regulator? Or leaky injectors?
07-16-2010, 05:42 PM
#1
TECH Resident
Thread Starter
iTrader: (7)
Join Date: Oct 2006
Location: Webster,Tx
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
Bad regulator? Or leaky injectors? Vehicle in question is a 2000 GMC Sierra with the 5.3. If the truck sits for a little while, it takes a second or two longer of cranking before its starts, and then bogs for a second, and then continues running fine. If you turn the truck off, then immediately crank it again, it will start with no problem, and again, drives completely fine.
I just went and put a pressure gauge on the fuel line to see what its doing. Turn the key to the run position and pressure instantly jumps up to what looked like ~50 psi (hard to see from in the cab), but quickly starts falling even if the key remains in the run position. When I turn the truck on it hold almost dead straight at 50 psi, and barely makes a drop in pressure with a rev.
Now I know that the regulators have been a problem on these trucks since almost forever, but nothing it did screams at me that the regulator is failing, and at about $50, not exactly something I want to blindly throw at the truck.
So other possibilities, leaky injector? Bad check valve at the pump?
I just went and put a pressure gauge on the fuel line to see what its doing. Turn the key to the run position and pressure instantly jumps up to what looked like ~50 psi (hard to see from in the cab), but quickly starts falling even if the key remains in the run position. When I turn the truck on it hold almost dead straight at 50 psi, and barely makes a drop in pressure with a rev.
Now I know that the regulators have been a problem on these trucks since almost forever, but nothing it did screams at me that the regulator is failing, and at about $50, not exactly something I want to blindly throw at the truck.
So other possibilities, leaky injector? Bad check valve at the pump?
07-16-2010, 05:45 PM
#2
Most likely it is a bad check valve in the fuel pump. Not that uncommon. Only way to fix it is to get a new pump (after you've verified that the fpr is good). Otherwise ignore it and prime the car twice before you start it after it sits for a while.
07-16-2010, 05:59 PM
#3
TECH Resident
Thread Starter
iTrader: (7)
Join Date: Oct 2006
Location: Webster,Tx
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
I pulled the vacuum line on the regulator and there was no gas in it, which from what Im reading around, is a sure sign its bad, but nowhere have a read that just because there isnt gas in it, that it good.
Im thinking the bog could be from the injectors leaking down, but if the pressure drops off that quickly, then its most likely not the injectors right?
Im thinking the bog could be from the injectors leaking down, but if the pressure drops off that quickly, then its most likely not the injectors right?
07-16-2010, 06:37 PM
#4
I pulled the vacuum line on the regulator and there was no gas in it, which from what Im reading around, is a sure sign its bad, but nowhere have a read that just because there isnt gas in it, that it good.
Im thinking the bog could be from the injectors leaking down, but if the pressure drops off that quickly, then its most likely not the injectors right?
Im thinking the bog could be from the injectors leaking down, but if the pressure drops off that quickly, then its most likely not the injectors right?
09-26-2010, 01:12 PM
#5
TECH Resident
Thread Starter
iTrader: (7)
Join Date: Oct 2006
Location: Webster,Tx
Posts: 785
Likes: 0
Received 0 Likes
on
0 Posts
Just thought Id update this real quick. I dont know if the check valve was bad or not, but when I pulled the fuel module, the plastic hose that from from the pump up to the hose, had a leak in it, so for sure that wasnt helping. Replaced the whole thing, problem solved.
