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91 Suburban V2500 - Tow/Weekend Rig - Build Thread

Drove the 91 all day yesterday, no issues. Hopefully its back on its feet for good.

Although, i think its getting awful mileage.

Any ideas on why it would start getting 1/2 the MPG it used to?
 
Just a note:

My 83 had intermittent ECM issues. Sometimes it would start up, sometimes not, some times just die while driving. I replaced the coil, cap, rotor, pick up unit(twice) and still had issues. The thing that kept me from getting to the ECM was at times changing the other parts and it would start running again.

I didn't even know they had ECMs in 83 until someone on this site told me. Changed it out and never had an issue since.
 
And guess what time of year it is!!!

30.jpg
 
cuervo said:
Just a note:

My 83 had intermittent ECM issues. Sometimes it would start up, sometimes not, some times just die while driving. I replaced the coil, cap, rotor, pick up unit(twice) and still had issues. The thing that kept me from getting to the ECM was at times changing the other parts and it would start running again.

I didn't even know they had ECMs in 83 until someone on this site told me. Changed it out and never had an issue since.
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Had all sorts of stumbling issues that i swapped an ECM for about 6 months ago. New delco unit is installed.
 
cuervo said:
And guess what time of year it is!!!

30.jpg
Click to expand...

Forgot you upgraded! Had mine out for a day in feb, driving up to Shasta to test drive a VLX with a friend tomorrow, and Chief Driver for a college tournament next weekend! Definitely that time again!
 
Well, the good news is the truck runs. Drove up to Shasta and back today.

The bad news is its getting 8.5mpg at 70-75 on flat freeway.

Afraid i have to tear off the Intake Manifold again. Thought i did an excellent job sealing it, but it idles REALLY bad at startup, and flutters a bit once warmed up.

Thinking bad exhaust leak.

Any other ideas?
 
Not much help I guess but an exhaust leak really should have any effect on a cold start. When It's cold It's not "listening" to the o2s since It's in open loop. Once it goes into closed loop after its ran for several minutes, then an exhaust leak could effect it. So that could be your bad highway mpg. Other then that for the cold start, I guess either a vacuum leak, fudged up injector,or messed up iac. Maybe even sticking egr valve.
 
y5mgisi said:
Not much help I guess but an exhaust leak really should have any effect on a cold start. When It's cold It's not "listening" to the o2s since It's in open loop. Once it goes into closed loop after its ran for several minutes, then an exhaust leak could effect it. So that could be your bad highway mpg. Other then that for the cold start, I guess either a vacuum leak, fudged up injector,or messed up iac. Maybe even sticking egr valve.
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EGR isn't sticking, cause the solenoid is disconnected.

Injectors sprayed good the last few times i checked them.

Was getting an intermittent Check Engine light, will inspect further and see what happens. For the time being, i need to drive it a bit, and get some repairs done on the BMW.

My commute recently was reduced from 2-3 hrs to a mile....so the 8.5mpg won't hurt too bad.
 
eclipse85k10 said:
I just noticed your DD is what I want for a DD. hows your mileage on that 540
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Not great. Was getting 22 combined in Sacramento traffic, more like 18-20 in bay area traffic. Have seen 23-24 on long drives....but really, a heavy foot normally kills that.

Running on Premium. Normally they require 89, but mine has a chip in it that requires 91
 
Ok....its good to be back in the old rig.

To do:
Reseal Intake
Change Ign Coil, IAC, and MAP sensor plugs
Door hinge bushings / pins / strikes
Rebleed brakes for the 1000th time. They get air in them from driving...no idea how. No leaks, new MC/Calipers/Cylinders/Rubber lines. Some hard connection somewhere is leaking. While truck sat for a month, no change in pedal. 1 wk of driving, and pedal is getting softer.
 
Yep, def air leak. I had the same issue with my clutch m/c. Would bleed and bleed and get no air out, but pedal sucked. Replace the m/c and the prob went away...

Any chance you got a bunk brake m/c?

Sent from one a dem der smart phones
 
COCHEV said:
Yep, def air leak. I had the same issue with my clutch m/c. Would bleed and bleed and get no air out, but pedal sucked. Replace the m/c and the prob went away...

Any chance you got a bunk brake m/c?

Sent from one a dem der smart phones
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Been through a number of MC's, really doubt its the MC. They've all been brand new too. The pedal feel is awesome after a fresh bleed.
 
Hmmm, slow leaky wheel cyl? Don't know otherwise unless. Usually you'll see fluid leaking unless the air leak is up high (like the mc) frustrating, i'm sure

Sent from one a dem der smart phones
 
COCHEV said:
Hmmm, slow leaky wheel cyl? Don't know otherwise unless. Usually you'll see fluid leaking unless the air leak is up high (like the mc) frustrating, i'm sure

Sent from one a dem der smart phones
Click to expand...

Problem has been pretty consistent through replacement of all parts....so its gotta be a connection / line somewhere.

I'll keep bleeding it til i find it.
 
Ok, redid the intake gasket over the last few nights.

Replaced it a couple months ago, and seem to have a vac leak somewhere, and lost significant MPG, as well as running awful on startup.

Decided to try again. Nothing to be found in terms of unsealed areas, but it definitely idles better now. We'll see what the mileage looks like over this weekend.

Also spent another couple hours fixing and resheathing wiring on the back of the motor. Ign coil wire, plus about 8 other wires had 1" or more of bare wire. Fixed/heat shrunk here and there, as well as replaced coil, MAP, and IAC plugs (that had broken clips).

Can't even believe the condition of the wiring some of you with older trucks must be dealing with!
 
Well, its running. Need to get it in for a real alignment. Checked via tape measure, and everything seems close, but i'm getting BAD outside wear on the front tires, and feel like the vehicle is pushing the front tires more than necessary. Hopefully its out of alignment, and that is also causing the increased fuel consumption.

Brakes need to be bled before i put many more miles on it.

So...overall, its running. But not great.
 
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