Mystery problem...

[BlazerLT]

Aight, I am stumped seeing I don't know the TBI engine as well as my CPI and the CSFI system.

Anyone know where the hose with the screw it in goes?

[hunter01]

I can't be certain without looking at my other truck which isn't here right now, but according to my book it looks like the hose that goes to the temperature sensor in the air cleaner assembly that controls the damper in the pre heater.

[flipster125]

Nope, that's the yellow one... (I put a blocked hose on it while the air cleaner is off so I don't have a vacuum leak...)

[Rmbodie]

Where can you get a carb for that price . I have the samr year with similar problems and I am going to put a carb on it . Is that a used one ? how are you going to make it fit ? I finally have mine idling all the time but I have the IAC unplugged and the Mechanical adjust screw doing the job .

[Allbert]

If it still might be some help, I found a web page with some info on how to use a vacuum gage: http://www.free-ed.net/sweethaven/Me...?iNum=01030305

[flipster125]

Rmbodie, a friend of a mechanic friend... heck, don't even know what the going rate is for carbs

Allbert, Thanks, I'll try and see if I can find a vacuum gage sometime tommorow (got a final exam for uni today :| )

[hunter01]

I finally got a chance to look under the hood of my 91 blazer yesterday and that line goes to a small check valve then a T behind the distributer. One side goes to the vacuum ball, the other goes to another T with one line going along the firewall over to the drivers side the other going along the firewall to the passenger side. Sorry I couldn't be more specific I was pressed for time. I'll be going back next week and I'll try to take a picture if I can.

[BlazerLT]

Originally Posted by hunter01

I finally got a chance to look under the hood of my 91 blazer yesterday and that line goes to a small check valve then a T behind the distributer. One side goes to the vacuum ball, the other goes to another T with one line going along the firewall over to the drivers side the other going along the firewall to the passenger side. Sorry I couldn't be more specific I was pressed for time. I'll be going back next week and I'll try to take a picture if I can.

That makes sense.

[flipster125]

Thanks for the location... all hooked up now. However, still running like a bag of crap. once it's warm it will idle and for the most part will accelerate well enough, but will still hesitate at higher throttle openings. (such as highways) I've also run it enough now to notice an EXTREMELY low gas millage (I don't have an exact mesurement, but approximately 10 miles/gallon) In addition, when cold, it will search for idle (high/low, but mostly low), stall, and hesitate over 10% throttle. any thoughts?

[Rmbodie]

Flipster , the hose plugged with the screw goes to a multidistribution vac near the distributer at the firewall . the peice of hard plastic tubing coming thru the firewall behind the transmission dipstick is supposed to be connected to it as well. Along with a line running to the back of your transmission , unless you have 2 wheel drive. I assume your vents don't change from floor to dash or windshield.
Your description of your problems sounds like what I have been fighting for six months now. I have my IAC solenoid unplugged and the plunger screwed out to close the hole and the mechanical idle set screw holding the idle . My 89 would randomly idle high/low, stumble, studder, stall, running hot ,and was getting bad gas mileage . I had no codes except lean O2 senser . Now I can drive it with no real problems except hills . It will surge or hesitate when starting on even low grade hills.With all new ignition and fuel components , The only thing not replaced is the computer.

[flipster125]

ok, fixed the vacuum hose...

Also got a theory as to why it's running like crap... thought maybe you guys would know more...

When I got the truck, the fuel tank/sending unit was garbage, so I replaced them with scrap yard parts from a mid 90's one... now, according to my manual, the fuel pressure should test at 9-13 psi for my TBI, however, for the newer models it says 55-61psi, could it be the fuel pump I have is supplying too much fuel pressure? keeping in mind that my setup has a presure bleed off, and I don't know how that would affect fuel pressure. Basically, has there been a change in fuel pump since 89? And could this be the problem?

PS, I don't have access to a fuel pressure gauge (aside from bringing it to the garage, but I'd like to avoid that cause I'm broke)

Thanks, Thomas

[blazee]

That is most likely the problem.

[flipster125]

what I'm wondering though, is is there a difference in the actual fuel pump from 89 to early-mid 90s? Also my TBI has a fuel presure regulator... and the pump I put in did look the same as the one that was in it before...

[rbuck]

Check your intake gasket, and also your tbi gasket can of starting fluid sprayed at each engine should not speed up any, if it does tighten or replace.

[holt01]

your egr is sticking. it might be the solenoid that controls it or both. get a new egr and clean the passageway. also check your map sensor. my pickup acted similarly and it was both items acting up. The GM garage had too replace both eventually.