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Username Post: fuel pressure not holding
george88gta
"16th Year" Silver Supporting Member
Posts 2006
george88gta
08-28-19 02:59 PM - Post#2774325    

2001 s-10 4.3l 135000 mi. Friends truck. It has slow start and stumbling. I havent really dug in to this yet, but an initial check of the fuel pressure shows that as soon as the pump stops (just turning the key on/off, not starting the engine) the pressure goes to zero. With the pump running, the fuel pressure is around 55-60 psi. Not familar with these fuel systems, but I know that on my TPI engines, the fuel pressure holds for a long time. If it dropped, we would change out the pressure regulator. Same rule here or does this system work differently? Plan is to go over the entire system to look for leaks, etc. There is no smell of fuel anywhere, not even in the engine oil. If it was a defective injector, shouldnt we be seeing exhaust smoke of fuel in the oil?
Truck acts strange, gauges move erractically and he occassionally gets a low fuel light with a full tank of fuel. Truck is rusty, plan is to go over all the grounds to see if corrosion is a factor. I will check the fuel filter. He said the fuel pump was replaced a few years ago, so hopefully that is not a contributing factor. Not much to go on, but any ideas as to where to start? We will be looking at this over the weekend ( time permitting).
gchemist
Member #271 Senior Chevytalk Moderator
Posts 25038
gchemist
08-30-19 03:34 AM - Post#2774456    

It should hold pressure after shutting down. The fuel pressure regulator is bad. Is the fuel pump original? It may be time for a new one.
You can unbolt the bed for tank access.
'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles

george88gta
"16th Year" Silver Supporting Member
Posts 2006
george88gta
08-30-19 03:38 AM - Post#2774457    

Yes, I am of the same opinion, defective regulator. Pump was replaced. I was kinda hoping for a little less work, this regulator isnt an easy swap like my TPI or LS engines. Thanks for the response.
gchemist
Member #271 Senior Chevytalk Moderator
Posts 25038
gchemist
08-30-19 06:58 PM - Post#2774532    

I’ve replaced a few fuel pumps just to replace a bad fuel regulator. I tell friends for labor costs, it’s the same either way. Cheap fuel pumps just don’t last.
'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles

george88gta
"16th Year" Silver Supporting Member
Posts 2006
george88gta
08-31-19 03:40 AM - Post#2774540    

We went with an Airtex pump. The original pump was getting very noisy.
gchemist
Member #271 Senior Chevytalk Moderator
Posts 25038
gchemist
08-31-19 04:27 AM - Post#2774546    

How's it running now?
'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles

george88gta
"16th Year" Silver Supporting Member
Posts 2006
george88gta
08-31-19 09:31 AM - Post#2774566    

OK, confusing reply on my part. When the pump was replaced, a while back, we installed an Airtex. Waiting for a regulator and setting aside some time to change it. Will post up results, but it will be a while before we can coordinate schedules.
george88gta
"16th Year" Silver Supporting Member
Posts 2006
george88gta
09-06-19 02:43 PM - Post#2774958    

Update, I kind of moved this to the Chevy High Performance forum. Please check there for new info. We started the process yesterday and are at the point where the fuel lines are all connected and the plan is to do a pressure test tomorrow before finishing the job. Fire department is on speed dial. Thanks for the help.
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