7.4 vortec fuel issue

[RawbDidIt]

Only thing I can see changing is the pcv
valve hose, looks a little rough. Think
that'll be enough to cause my issue?

Yes, that can cause issues. That stupid thing caused me the same headache. Trying to figure out why I had no acceleration under heavy throttle. Could do 80 on the freeway no problem as long as I didn't open the throttle more than 50%. Cracked PCV boot would hold vacuum under moderate acceleration, even had good vacuum pressure at idle and with no load. My fuel pressure was down too. Only difference is my fuel pressure was good with key on, engine off, it only showed low when I hit the throttle. With all the time and money you've thrown at it so far what's another 5 minutes and $20 for peace of mind?

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[RawbDidIt]

Is that the alternator voltage?

Is that the fuel pump voltage at the rear of the vehicle, near the tank?

That's pump voltage at tank. I'm assuming based on the location there, looks like it's under the bed.

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[Travon]

Is that the alternator voltage?

Is that the fuel pump voltage at the rear of the vehicle, near the tank?

Yes sir. Voltage coming directly from the connections.

 

[Travon]

Yes, that can cause issues. That stupid thing caused me the same headache. Trying to figure out why I had no acceleration under heavy throttle. Could do 80 on the freeway no problem as long as I didn't open the throttle more than 50%. Cracked PCV boot would hold vacuum under moderate acceleration, even had good vacuum pressure at idle and with no load. My fuel pressure was down too. Only difference is my fuel pressure was good with key on, engine off, it only showed low when I hit the throttle. With all the time and money you've thrown at it so far what's another 5 minutes and $20 for peace of mind?

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Ok cool! Thanks for shedding some light on this dark road. Fortunately I already have the
valve, just gotta get the hose in the morning.
True, I have too much involved not to enjoy
it at this point..

 

[n8pu]

I have the 5.7 V8, I hope you find and solve you issues quickly. Mine was the fuel pump, putting out around 45 PSI, I had it tested, it was also hard starting cold, warm not an issue. I was told that in my model year '98 that it had to be no less than 5 PSI from 60 PSI. If I slowly accelerated it would go down the road just fine, BUT if you put your foot down it would fall on it's face. I ended up taking it to the first place that was recommend to me, mistake. No their work was good, it's still using the pump they put in, but I think they saw a sucker walking through their door. I still wonder if they even charged me for every time the mechanic farted. It was a few dollars shy of a thousand. A couple years later I was talking to the garage I now go to, that bill would have been around $600 ish.

 

[Christian Steffen]

I have the 5.7 V8, I hope you find and solve you issues quickly. Mine was the fuel pump, putting out around 45 PSI, I had it tested, it was also hard starting cold, warm not an issue. I was told that in my model year '98 that it had to be no less than 5 PSI from 60 PSI. If I slowly accelerated it would go down the road just fine, BUT if you put your foot down it would fall on it's face. I ended up taking it to the first place that was recommend to me, mistake. No their work was good, it's still using the pump they put in, but I think they saw a sucker walking through their door. I still wonder if they even charged me for every time the mechanic farted. It was a few dollars shy of a thousand. A couple years later I was talking to the garage I now go to, that bill would have been around $600 ish.

I need to go into the business of replacing fuel pumps. lol It really isn't that hard, definitely not $1000 worth, or even $600 imo.. Hell i dropped my tank to fix the fuel pickup line on my truck while sitting on the side of a highway, probably took a half hour.

 

[RawbDidIt]

I need to go into the business of replacing fuel pumps. lol It really isn't that hard, definitely not $1000 worth, or even $600 imo.. Hell i dropped my tank to fix the fuel pickup line on my truck while sitting on the side of a highway, probably took a half hour.

I need some lessons from you. My bolts were all rusted though, that was most of my time there.

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[andy396]

What P/N and brand fuel pressure regulator did you put in? Any chance it was installed incorrectly or there's a vacuum leak at its port? Not fun to get to, but it seems you've eliminated most everything else.

 

[Travon]

I have the 5.7 V8, I hope you find and solve you issues quickly. Mine was the fuel pump, putting out around 45 PSI, I had it tested, it was also hard starting cold, warm not an issue. I was told that in my model year '98 that it had to be no less than 5 PSI from 60 PSI. If I slowly accelerated it would go down the road just fine, BUT if you put your foot down it would fall on it's face. I ended up taking it to the first place that was recommend to me, mistake. No their work was good, it's still using the pump they put in, but I think they saw a sucker walking through their door. I still wonder if they even charged me for every time the mechanic farted. It was a few dollars shy of a thousand. A couple years later I was talking to the garage I now go to, that bill would have been around $600 ish.

Thanks! Yeah, you gotta watch those shop prices!

 

[Travon]

What P/N and brand fuel pressure regulator did you put in? Any chance it was installed incorrectly or there's a vacuum leak at it's port? Not fun to get to, but it seams you've eliminated most everything else.

Regulator was PR217 Standard motors. Everything checked out during installation.