1998 5.7 k1500 bogging out at 2500 rpms

[Tracto-man]

Good evening gentlemen,

 

I recently purchased a 1998 Chevy K1500 extended cab short bed 4x4 Silverado with 290,000 miles, (I know that's high, but the truck is almost rust free)

 

Ran and drove fine, only issue I noticed is lower oil pressure, (45 cold, 20 hot) which I would expect from a high mileage car, if I have to put a crate motor in in a year or 2, that's okay.

 

Anyway, it's started bogging at any hard acceleration, or consistently at 2500 rpms and up, will about die and starts backfiring if I don't let off the pedal.

 

Checked fuel pressure, it tested good while running, and while the engine bogged fuel pressure didn't go down. scanned for any codes, seemed like clogged exhaust, cut the exhaust, no difference. (Cats have already been removed by some owner in the past) tested EGR valve, it tested good, cleaned throttle body, no difference. Went ahead and spent almost 200 on good cap, AC Delco plugs, wires, rotor, still no difference, bogs just the same.

 

I've been looking all over the internet and seen this is a fairly common problem but haven't really found any answers.  Where should I go from here? I'm not the kind of guy that just replaces things until it runs... I always work on my own stuff but this really has me stumped.

 

Thanks in a advance for any help I can get!

[barry G]

take lid off of air cleaner box.

 

live data map sensor,

 

check coil for old and swollen..

 

check plug wires, they like to attack each other at the last 3 cylinders  on passenger head before any other spot.

 

check engine ground while in that area.

 

there is other things, but under load weirdness, I go for electrical first.

 

 

in michigan?

that IAT will climb just 10F beyond outside air.

you get 20 below like maine, it is going to do something not friendly eventually.

 

I found the radiator doe snot need to flow for several weeks here..

that spell ids finally broken just this past weeks. It has been 8 weeks this year.

 

my truck is at 369k.

it has had a damn good engine replacement at least once (I think it is on its third, I have clues, no facts).. but used older gadgets from prior engine.

I am willing to bet you got the same thing.

 

my backfire spell was just recent.

it was coil.

I also blamed salt for keeping a freakishly dry high static engine bay.

electric does not like that.

 

0% humidity.. that needs to stay in so cal.

[silveradosid]

that mileage and age would be checking intake gaskets

[Tracto-man]

Replaced the fuel pump and it's running great. Guess my fuel pressure gauge was off, took it to a mechanic and his pressure tester showed the highest psi the fuel ever got to was 55

[Rob Okray]

Good news! i had a 1991 5.7 with over 200k behaving the same way. Turned out the tank, sending unit, pump and lines were all rotten.