5.7 TBI loss power

[efipaneltruck]

hi guys
i got old truck that has been sitting
with a 5.7TBI with a 700r4
tires are 35/12.5/15

at first when i got it
like most people with a 700r4 is to test it out if it shift right and goes into OD
I only drove it around the block , the streets are not long enough to push it
i could get the tranny to shift 2nd and 3rd but not OD
its when i decided to took it on the highway
that i noticed the truck wont go over 50 mph
and struggle on hills as well
and to get to 50mph I floor it
truck struggle to go over 2500rpm

the truck - cold start - in park it idle very good and start right away
when i drove it around the block for a little and get warmed up , truck stall at stop sign ,
the rpm goes lower and lower until it dies ,

beside not going over 50 mph....around the block truck feel fine .

what ive done so far
yes there is fluid in the transmission
i tested the tps and get 0.72 to 4.46 WOT
vacumm gage read 21hg constant
fuel pressure is 12psi
i test the coil 11k ohm
spark plugs look very clean


i installed new injectors
new fuel filter

i really like to be able to get at leat at 70mph.....ahaha

what left that i didnt look?
i never had a TBI

thanks a lot

 

[RawbDidIt]

hi guys
i got old truck that has been sitting
with a 5.7TBI with a 700r4
tires are 35/12.5/15

at first when i got it
like most people with a 700r4 is to test it out if it shift right and goes into OD
I only drove it around the block , the streets are not long enough to push it
i could get the tranny to shift 2nd and 3rd but not OD
its when i decided to took it on the highway
that i noticed the truck wont go over 50 mph
and struggle on hills as well
and to get to 50mph I floor it
truck struggle to go over 2500rpm

the truck - cold start - in park it idle very good and start right away
when i drove it around the block for a little and get warmed up , truck stall at stop sign ,
the rpm goes lower and lower until it dies ,

beside not going over 50 mph....around the block truck feel fine .

what ive done so far
yes there is fluid in the transmission
i tested the tps and get 0.72 to 4.46 WOT
vacumm gage read 21hg constant
fuel pressure is 12psi
i test the coil 11k ohm
spark plugs look very clean


i installed new injectors
new fuel filter

i really like to be able to get at leat at 70mph.....ahaha

what left that i didnt look?
i never had a TBI

thanks a lot

You said around town and idling is fine, but when you push it, it's struggling. Had the same problem when I got mine. For me it was the fuel filter. Had decent pressure at idle, but couldn't flow enough for actual acceleration, it would fall on its face. Test fuel pressure during hard acceleration. If that holds up, test vacuum the same way. If the problem only arises while driving, not at idle, your tests can all look good, but be below spec under load.

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[Reecek]

Catalytic converter may be plugged.

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[efipaneltruck]

Catalytic converter may be plugged.

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truck doesnt have a Catalytic converter

 

[Schurkey]

Connect a scan tool and see what the data stream says.

Restricted exhaust is still a likely possibility. Partially-plugged injectors. Misadjusted throttle cable. Weak spark or other fault on the secondary ignition side. Poor compression. Wiped camshaft. There's plenty of possibilities.

 

[alpinecrick]

Muffler may be plugged/collapsed.

If the fuel filter turns out to be the culprit, expect your fuel pump to die within the next few months. Plugged/partially plugged fuel filters kill fuel pumps.

 

[victor II]

Did you change all fluids, dist. Cap and rotor? I would also put in new plugs and wires. Outside of that, yeah, get it scanned.

 

[2001ZR2]

what about the gas in the tank did you drain it and put in fresh?
Check the fuel lines to make sure there aren't any kinks or bad rubber hose.
Double check the exhaust

Is dropping the transmission pan and changing the filter an option? I don't think it's that bad but not going into OD is a concern.

 

[efipaneltruck]

Did you change all fluids, dist. Cap and rotor? I would also put in new plugs and wires. Outside of that, yeah, get it scanned.

i didnt change cap and rotor yet .
i check all the spark plugs and they look really good
compression test later...when i will have time...truck has headers and it make hard to access..i have to remove yhe headers on order to do it

scan test..yes..an other issue.. i have a innova 3140g...and pcm doesnt communicate at all....

 

[long_bed]

Any idea what gears you're pushing those 35's with?

You can scan for codes by jumping two terminals on the diag port with a paper clip by reading blinks on the Check engine light.

Otherwise, engine warm, Make sure the ignition timing is set at 0deg btdc with the advance wire unhooked.
Check / replace Coolant temp sensor.
Change fuel filter, clean and rebuild throttle body (including screens and filters on injectors).
Make sure kickdown & throttle cable are lubed and adjusted properly.
Check for vacuum leaks, replace any leaking hoses.
Check the EGR system.