1990 K5, Runs terrible: Need help

[nhoffman94]

Recently, I bought a 1990 K5 blazer with a 350 and 4 speed auto. Has only 112,000 miles and ran great when I bought it. I drove it about 20 miles and suddenly, when i stopped it began to run terrible, it now idles after i replaced the throttle body with a rebuilt one, the previous one was missing a few things so i just replaced it, i have replaced the coolant temp sensor, and the fuel filter. Nothing seems to work, it will drive, no more than 10 mph because it wont rev high enough. It surges at idle, and stumbles when driven, but can be revved in neutral.

 

[Old77]

Have you checked the distributor cap and rotor? How about spark plugs and wires?

BTW....welcome to the site

 

[dhamp]

Sounds like it could be the cat convertor too.

 

[89Suburban]

Is there an engine light coming on?

 

[towman]

you could try unplugging the egr valve and blocking the vacuum line

 

[HotRodPC]

Welcome to GMSB. Sounds like a great purchase. 90 K5 with only 112K three fitty and auto. Only thing woulda made it better for me is if it were a SM465 manual. Nonetheless, still a good purchase and happy to have you here.

Damn, what luck, after only 20 miles it jacked up like that??? Sorry to hear it. I'd suggest timing chain, but with only 112K, that's not it. So how about this, maybe someone tuned it up to get it ready to sell, didn't tighten down the distrubutor, and now the distrubutor just took a big jump out of time??? Worth a try. I see other suggestions above too. Keep us updated with what you're doing, trying and done, and we'll get you up and running in no time. I say its something simple since only 112K if its original motor and not a chop project.
Any idea if it sat for along time before you bought it? If so, the fuel pump diaphram could have dried out a bit, and after short usage, it tears and fuel pump is now junk. Do you have a fuel pressure guage??

 

[WHEELMAN]

if the engine fires up-with no problem-you do not have to crank on it.i would be looking at a fuel problem.you have on that vehicle.fuel pump relay--fuel filter and then your fuel pump.if there is no..check engine light on --on the dash...there will be no trouble codes..if check engine light is on.i would be looking at.a ...oxygen sensor and i have never had a vehicle,with the cats.stopped up..but.if any part of the exhaust system is closed up..that would make it.not want too run..some people have got a tank full of water.the last time they got gas..something to think about there..

 

[WHEELMAN]

anything goes bad electronic.it usually..makes the check engine light come on.a bad.
distributor module.will make the engine run like it is..running out of gas..and cut off at a red light..if you can go to a wrecking yard.you can strip off a lot of.parts.for a little bit of money..and try one thing at a time..until you find the problem.you got to get gas-it has to burn.with everything in time and then..whats burned.has to leave.the engine.and out the pipes.you got.crap.telling a stupid computer..what the engine is doing..if it does not like something.or gets a bad.message..the computer.can mess up the running.

 

[dhamp]

Have you put any gas in it since it started acting up? Try a bottle of dri-gas and put some fresh gas in there in hopes of diluting the old stuff. Might help. Or get a cheap siphon from Harbor Freight and suck the old gas out, then add 1/2 tank of the good stuff.

 

[nhoffman94]

Yep filled it up with gas. It was sitting for about 2 years with a brand new fuel pump and nearly empty tank. i believe when i let it idle for 10 minutes on three separate occasions before taking it to be filled up it may have burnt out the pump because the pump must have been very dry. Only has 5 psi of fuel pressure at the throttle body, will double check by the new fuel filter to be 100% sure. Should have 9-13 psi as many of you know so looks like i will be buying a new fuel pump. Thanks for the warm welcome and all the replies.

 

[nhoffman94]

I know it hasnt been messed with either, i know the people who serviced it and who i bought it from. They sold it to me for 800 bucks, and take half of my pay check every week until it is paid for. They are also taking off half the cost of any repairs to get it running from what i owe them.

 

[crazy4offroad]

It may be difficult to do, but it would be worth it to find out...drop the tank and take a peek inside. Steel tanks when left empty rust like a ****.

 

[HotRodPC]

Damn, you can't be a deal like that.
Yep, you have to lower the tank anyway to change the pump, so I'd be sure to check the tank for rust. Low fuel in the tank, means there was alot of bare tank wall to sweat and make water too. Water of course doesn't burn, and also mean possible rust in the tank.

 

[dhamp]

Keep us posted!

 

[Jims86]

I would suspect the fuel filter first...easy, and inexpensive to replace.