I have a 1999 Sierra Forged 370 cam,heads,headers,FLT 4L65E Well nothing is stock.LOL I am having a little trouble starting my truck. When I try to start it cranks for about 5 seconds then it fires up but it does not fire up strong it is a weak start up. Kind of hard to explain. So once it is finally turned on and driving in town it is fine but when I get on to the freeway it seems to lose power as I give it gas like it is losing fuel pressure. It will get up to speed just not as fast as it used to. Fuel pump that is just my guess. The fuel pump is a walbro with about 7,500 miles. Also no check engine light at all. Any ideas?

 

I would say fuel pressure regulator. Mine did that and once I changed it out it was fixed. Easy fix.

 

I am going to try the regulator I have to spare complete fuels with regulators on them. So Hopefully it wont cost me anything to fix. Worst case senario is fuel pump. Cool Thanks

 

Put a fuel guage on it. Otherwise, you're just guessing. Easy enough to do. You can even tape it to the windshield to watch during operation. BTW, it you're fuel pressure's down, you're probably running lean.

 

What is a normal psi for the fuel? At idle and driving in town. I don't think it could be running lean.

 

58 PSI at WOT, or at idle with the vac unplugged. Idle with the vac connect may be around 42.

 

Ok cool I will have to check fuel pressure. Let me see if I can find my gauge.

 

I just did this yesterday

 

I may have to do this as well. I have a fully forged high comp 370 and it started today. My CEL came on and said I was lean in bank 1, but it does that when I run with the cutout open...