Fuel pressure test results (need some help here)

[j cAT]

Originally Posted by C.Steele

Ok I went and drove it with the guage taped to the windshield and here is what I found:

Idle: 49psi
Driving around town: 52-54psi
Accelerating: 56ish
Going up a long steep hill where it bogs down: 60psi

The pressure never went below 48 even when I stepped on it hard. It actually shot up to 56 or so and held there the whole time I stayed on it.

The hill I go up everyday to work is where I really notice problems. I can be crusing at 50+ mph and just starting up the hill it bogs right down. I can put my foot all the way down to the point where it's about to shift into passing gear and the engine doesn't change at all. It's like there is nothing for several inches of pedal. I have to shift into passing gear then it goes ok but wants to shift right out. When it does it's back to bogging.

Also, I took it to a tranny shop today and had them do a full check on the tranny including road test and they said the tranny is solid and hitting all the shift points perfectly.

So what do you guys think based on this new info?

the testing of fuel pressure when operating the vehicle is the correct test to be sure...the lower than normal pressures at idle may mean that the voltage generated by the alternator are low ,,since at idle you will get lower amps out from the alternator at idle..normally..

check the voltage at idle should be 13.5-14.5 volts dc..
if lower than 13 volts this will need an alternator check..

loss of power on acceleration / up hills etc may mean a restricted exhuast.. this can be checked by removal of the upstream O2 sensors and leaving these holes open ,,,so exhaust can escape..if the problem lessens greatly , then you know it's the exhaust thats at issue..

normally this will throw dtc's miss fires etc...

[C.Steele]

Ok, I like the "yank the O2 sensors" idea much better than the $45 I was going to pay for a back pressure test. I will pull them tomorrow and report back.

This won't hurt anything or cause it to run bad?

And hey guys - you have been a tremendous help already. I really appreciate everyone taking the time to try and help me out.

[j cAT]

Originally Posted by C.Steele

Ok, I like the "yank the O2 sensors" idea much better than the $45 I was going to pay for a back pressure test. I will pull them tomorrow and report back.

This won't hurt anything or cause it to run bad?

And hey guys - you have been a tremendous help already. I really appreciate everyone taking the time to try and help me out.

just be sure the wires are not going to be damaged,, they will melt on the exhaust pipes...

remember your going for a test run ...not going to operate all day with them removed...it will be loud ..but it should reveal if it is the cat converter or possibly the muffler..droping the exhaust will reveal all this if it is the reason of your power loss up hills....

[danielsatur]

You can borrow a compression guage tool at the local Auto parts store for free!

Do a google ''youtube catalytic converter back pressure''

I use the upstream HO2 sensor holes for the short!

[C.Steele]

Compression guage tool? Checking compression wouldn't tell anything about exhaust would it?

[old_master]

Nope.

[j cAT]

Originally Posted by C.Steele

Compression guage tool? Checking compression wouldn't tell anything about exhaust would it?

checking the compression would be a good check after the exhaust is checked for restriction...

question is IS YOUR ENGINE IN GOOD RUNNING CONDITION ?

does it use oil beteen oil changes , smokes out the exhaust , hard to start, idles ruff unevenly, uses a lot more fuel , noisy...this would indicate a worn low compression engine....worn rings. valve springs, piston bore.

also main bearings worn ....

[C.Steele]

It runs good other than the slight idle stumble I feel constantly. It only has ~90k on it and has been well taken care of. No smoke, no noise, no codes, 17+mpg, nothing pointing to anything "major"....at least I don't think so.

[danielsatur]

A plugged catalytic converter will choke your engine out!

[j cAT]

Originally Posted by C.Steele

It runs good other than the slight idle stumble I feel constantly. It only has ~90k on it and has been well taken care of. No smoke, no noise, no codes, 17+mpg, nothing pointing to anything "major"....at least I don't think so.

if thats the case then compression should be fine..it would take a very very worn out engine to loose power with your issue..

[Rugerlab]

I am not sure if this is the answer for you or not but I have a 99 with 156000 miles on it and it was experiencing almost identical symptoms as your truck. I thought for sure it was the fuel pump as well, but turns out it was a stopped up cat and leaking intake gasket. Had the Intake Manifold Gasket and one of the Catalytic Converters replaced on it and it is running like new again.