What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

my Blazer runs like *****TE!

K

kphx87blazer

Registered Member
Joined
Feb 2, 2009
Posts
26
Reaction score
0
Location
phx
Hey folks,

You folks always seem to answer my questions spot on....

I have a 87 K5. 350. Idles fairly good, you can feel a miss every now and then. When accelerating from a light for example in overdrive (the D with the ring around it, it runs through first and second gear okay, but in third gear, it really runs bad. No real power. That is until i take it OUT of overdrive (the D) then I have some power and it runs okay.

I checked the wires (as before they have touched the headers and melted) and they look and feel okay.

I changed the spark plugs, wires, cap, and, rotor about a year ago and have since put less than 5000 miles on it as it sits in the garage the majority of the time.

Any ideas as to what I can do?
 
New fuel filter might help. If that does not fix it maybe distributor module.
are you getting any trouble codes or check engine light?
 
The fuel filter was changed. A year ago when everything else was. Since, its been driven less than 500 miles.

Now, it only runs rough and misfires in OD, when I drop in down to drive, it runs fine.

No check engine light on.
 
I forgot to mention that I smelled fuel really bad teh other day. I stopped and checked for leaks from the pump, tank, filter and under the hood. I didnt see anything leaking. since then, the fuel smell has gone away.

I also recently change the MAP sensor and IAC valve.

Correction... It was the TPS i changed out.

Keep in mind, when I replaced the IACV and the TPS, i just literally switched out the two. I made to adjustments or anything. Pretty much plug and play.
 
kphx87blazer said:
Keep in mind, when I replaced the IACV and the TPS, i just literally switched out the two. I made to adjustments or anything. Pretty much plug and play.
Click to expand...

IACV and TPS are like that, you just install them. Computer takes care of the adjusting.
 
Ignition coil getting weak maybe??..sounds like spark failing under a load..maybe the EGR valve is opening too soon too?...
 
diesel4me said:
Ignition coil getting weak maybe??..sounds like spark failing under a load..maybe the EGR valve is opening too soon too?...
Click to expand...

Easy enough to test/isolate the egr system. Plug the vac line that goes from teh throttle body to a little black box on the passenger side top of the motor, on a 45˚ bracket. This will keep the egr system from working....but if its opening at the wrong times, it will cause a pretty big vac leak and affect performance.
 
Vacuum leaks??? My 91 was doing the same thing, I had a huge vacuum leak right at the throttle body, fixed the leak and it's gotten dramatically better, weather and lack of time have kept me from looking for others, but I'm pretty sure I have another smaller leak somewhere...
 
After you do the above checks (vac, etc), check your fuel pressure. Finally, after changing fuel pumps over the years that had just plain stopped pumping, I had one recently go bad...but was still pumping 4 -5 psi at the filter.
It ran a lot like you describe. Seemed rich just off idle and fell on it's face shifting gears. Finally got around to checking the pump after all the usual suspects... If you don't have the gauge set-up, go to Autozone and borrow it.
 
Folks... Thanks for the help.

I'll check the vacuum lines... again. this vacuum line crap is starting to tick me off.

I dont really understand how I check the egr valve. could you explain that again please. i dont get how i tell if its bad or not.

heck, im at a point that I might just put a new egr valve in. they are about 50 bucks at the zone.

this fuel pump tester, where do I hook it up at? if worse comes to worse and i need a new fuel pump, it is a real pisser to swap one out?

also, i think i read on here that the fuel pressure should be 13 psi. is that correct?

thanks again.
 
kphx87blazer said:
Folks... Thanks for the help.

I'll check the vacuum lines... again. this vacuum line crap is starting to tick me off.

I dont really understand how I check the egr valve. could you explain that again please. i dont get how i tell if its bad or not.

heck, im at a point that I might just put a new egr valve in. they are about 50 bucks at the zone.

this fuel pump tester, where do I hook it up at? if worse comes to worse and i need a new fuel pump, it is a real pisser to swap one out?

also, i think i read on here that the fuel pressure should be 13 psi. is that correct?

thanks again.
Click to expand...

I had the same thought about swapping the EGR for a good one, but once i did that, i did more diagnosis and found it was the EGR solenoid, not the valve, and that was more expensive.

To disconnect the egr system to test, follow the vac hose from teh egr valve. It hits a black box thing, which is the solenoid, with a couple wires connected to it. Mine is on the passenger side intake manifold (top of motor) on a 45˚ bracket. From that solenoid, there is a vac line going to teh throttle body. Unplug the vac line going to the throttle body at the egr solenoid, and plug it there.

If that solves the problem, replace solenoid.

For fuel pressure, these trucks don't have a test port. The "easy" way to check pressure is use a tester that "T" 's into where the fuel filter is. Basically you remove the filter temporarily to hookup the gauge. There is some trick adapter to hook up a gauge to a tbi that 4x4high has, but its about $100 to buy the adapter and hook it up. I say use the T setup at the filter for testing. Not idea, but should work.

And if you have to change fuel pumps, have fun. Never done it, but you have to drop the tank.
 
sonofva pup. the fuel pump... I just filled this bastard with 30 gallons of fuel!

Anyways,

i'll try the test.

What should be my fuel pressure?


":whistle: ignition module "

What makes you think it's the ignition module??

In fact, what makes you think its the EGR valve Solenoid? I was under the impression that either these parts work or they dont, there's no in between.

I think my plan is this....

Start tomorrow, I'll replace the wires (they LOOK okay) but hell, I have a spare set. Take out and replace teh plugs (have spares also). I want to check to see if they were gaped correctly.

If I was a bettin' man, I'd have to say they were NOT gapped correctly.

The vacuum lines APPEAR to be good. No apparent leaks. I started the truck, and sprayed carb cleaner into the TBI module, it didn't stall, so I assume there were no leaks.

I'll take a closer look at the cap and rotor.

I'll test the fuel pressure. What should the pressure be?

Then I'll test the EGR valve/ solenoid.

Hopefully, god willing... The problem will be fixed. If it isn't, I'll need a new windshield.
 
kphx87blazer said:
In fact, what makes you think its the EGR valve Solenoid? I was under the impression that either these parts work or they dont, there's no in between.



The vacuum lines APPEAR to be good. No apparent leaks. I started the truck, and sprayed carb cleaner into the TBI module, it didn't stall, so I assume there were no leaks.

I'll take a closer look at the cap and rotor.

I'll test the fuel pressure. What should the pressure be?

Then I'll test the EGR valve/ solenoid.

Hopefully, god willing... The problem will be fixed. If it isn't, I'll need a new windshield.
Click to expand...

I just threw EGR solenoid out there, cause i had some weird conditions that seemed like an inconsistent vacuum leak. Anyways, its a 30 second test, and free, so you might as well check it. That was my main reasoning, to eliminate one more possibility.

Spraying carb cleaner down teh TBI isn't a good idea, and doesn't check for leaks. Pretty sure those injectors are sensitive to Carb cleaner, and there is a TBI specific cleaner out there. The idea was to spray cleaner slowly around the base of the tbi from the outside, and at all teh vac lines/connections. If there is a vac leak, it will suck carb cleaner in through the leak, and the cleaner will cause it to stumble.
 
Book says fuel pressure should be 9 to 14 psi. Check your local auto parts store for the fuel pressure test kit. The one I borrowed had been checked out twice by the same guy in three years... It was like new. The instruction book showed exactly which fittings to use and pictures of how to hook it up.

Do all the cheap checks before you go throwing dollars at it!

Check for codes.

When you're checking for vac leaks, don't forget that big hose that goes to the brake booster.

Ignition module can cause same symptoms, too. They're fairly cheap and easy to replace. Put it on the front end of the stuff you do, when you start spending money....or take it out and have the auto parts store test it.

If it is the fuel pump... Yeah it's a pita. Drop your tank or cut a hole in your floor.... I did mine the drop-the-tank way. If you have a reese style hitch, it really is worth pulling the four bolts out and dropping it, when you're putting the tank back up... Trust me on that one. Siphon the gas out before you drop it. I used my buddy's transmission jack, but a floor jack can be used if you're adventurous. Go ahead and buy new hose clamps for the fill hose.

Have fun!
 
any updates on this one? was wondering if the problem was found?
 
Hello,

Sorry be real busy the last couple weeks...

anyways...

I replaced the egr valve. I also checked the fuel pressure. It has enough pressure.

Update: It still runs the same. No improvement.
 
I can't believe it, but I have been having similar problems, and no better luck than you at finding a solution.... As a matter of fact mine had been stalling more and more. Out of desperation last Saturday, I bought a can of seafoam and added the entire can to my gas tank when I filled up. Drove about 20 miles with no real difference. Came out of the store and when I started her back up I had what sounded like an exhaust leak which quickly turned into a loud popping everytime one of the cylinders fired!!! I thought oh crap, my engines toast... It's just getting louder and louder, then just slowly stops doing it and the idle smooths out. Throttle response is back, idles great, and the more I've driven it the better it gets!!! 140 miles and I'm still at 2/3 a tank. She actually spun the tires leaving work tonight!!! I'm still nervous though, I think it's cleaning the crud out of my injectors as well as the carbon and crap off the valves etc... I just hope it doesn't mess something up!!! I'll keep you posted...
 
i dont think its your motor!

if you dont throw codes and you have a 700 r4 -and it only happens in od its your torque converter lock-up-- happening too early-they make a kit you can make it wait until 50 mph to go 1to1 by then you have enough go to get past that [power loss feel] i think its a rostera lock up kit? check it out....
 
You must log in or register to reply here.

Latest Posts

Top Bottom