suburban 3/4

[kaskirov]

my friend bought a gmc suburban at an auction last year. it seemed like a good deal but it needs work. i've been helping him with alot of it and i want to get the thing running good, so i thought i'd ask here for help. the current problem is hard starting when being used often. its weired; it it hasn't been ran for days it starts up no problem, go to a store come out and it takes like 10 secs and some gas pedal pumping to get going. i suggested injector cleaner, but i have no experience with this stuff and i'm unsure if it works. bottle of liquid that magically cleans your engine by putting it in your tank seems to good to be true, but i have seen people in magazines (articles not ads) say it works. the exaust also shoots some black smoke out when it starts.

its got the 5.7L (350) by the way.

any thoughts?

[CheapThrillB2]

your ign timing is off.....reason for hard start after warm-up......also if its fuel injected pumping the gas pedal doesn't do anything. But holding the pedal down causing the throttle to stay open will.

[kaskirov]

i'm not sure if hes pumping or holding... anyway, thanks for the help, i'll look into it

[Will]

Black smoke when starting? Starts after sitting? It's flooded. A leak into the intake manifold via the pressure regulator would be my first guess.

[gotmudd]

i would have to say check timing and knowing whether it is fuel injected or carbuerated would help also. the black smoke would indicate either flooding or too rich. had simular problem on my camaro. nocked my timing back and set my carb with a vacuum gauge solved problem

[kaskirov]

its fuel injected . 1999 GMC suburban k2500.

[CheapThrillB2]

are you getting a "service engine soon" light on the dash.....curious as to what the coolant temp sensor is reading

[kaskirov]

light is on, he got it checked for free at a dealer and they said O2 sensor

[pillen140]

if the o2 sensor is the one before the cat, it controls a/f mixture, or at least reads it, so the computer can make the changes, and that can make it run rich, thus, black smoke or flooding when starting. when it sits for a long time, the gas doesnt stay in the cylinder.

[Will]

Maybe, but the O2 sensor can also give a bad read if the flooding is for a different reason.

Cheaper to test the pressure regulator. I think I have a manual for that. I'll see what the pressure regulator is like on it.

[CheapThrillB2]

i can't say i have ever seen a pressure regulator go bad on this style FI set-up. I have seen p lenty of the assm seal leak, unplug the injecter pigtain on top of the intake and see if its wet with gas.

[kaskirov]

update: we rigged up dual batteries and it seems to start up no problem now... but time will tell.