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Tbi help needed

83ChevyK5Blazer

83ChevyK5Blazer

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McHenry Mississippi
So, my burb has twice left me on the side of the road and I'm about at wits end with it.

The issue- starts fine, seems like it surges when under load at low speed. When i get out on the highway it will run decent, with my gearing and trans, rpm is 3k at highway speed.
It has started to lose power intermittantly and will start to stumble and then cut off.

It did it once about 1.5 hours into a trip on the interstate, it restarted and finished the drive with out issue, on the way home about the 3 hr mark, it did it again and after a 45 min cool down it restarted and we got home.

I changed the ICM in the dizzy, along with the cap and rotor for good measure.
All the signs feel like it's an ignition problem, I'm just not sure abs don't want to throw parts at it.

Also it's running way rich and fuel is 10.5 to 12 psi before the regulator in the throttle body.

the system is the stock throttle body, and computer with an adapter onto a edelbrock performer intake, on a goodwrench crate engine, with non tbi heads. I'm using a heated 02 sensor in the collector on the driver's side.

Any help is appreciated.
thanks.
 
Couple observations:

10-12 psi is fine, maybe a tad low on a modified engine, so being rich to me indicates not burning what is going in. I see the ICM was changed, but no mention of coil

The adapter plate on both of my conversions at some point screwed me over.
If you can, check with a vacuum gage and make sure you have normal vacuum, ~15-18"
If not, use the propane or carb cleaner method to look for a vacuum leak


A few years back @onetonbb74 had very similar problems in Moab.
He ended up finding some damaged wires in the harness, but I don't recall exactly where
 
I had a similar problem on my 94 1500 coil was taking a poop when it got hot.
 
I'm going to ohm the pick up in the dizzy, and i think the parts store can check the coil, all parts were new 2 years ago also. I'm putting off changing the pump until i can swing a better system.
 
I probably wouldn't worry about that pump. Not thinking it is an issue, unless you see it loosing pressure while running
 
It's no fun waiting to let it leave you stranded, but next time it does it, immediately check for fuel and spark. By yourself checking for fuel with TBI could be tough, but power the pump relay and make sure the pump at least runs.

I had (Well, still have) a fuel pump that left me stranded a few times, until I got a chance to test things when it stalled. It definitely felt and acted like ignition, but honestly at this point I think the manual trans made it seem like it was trying to run, when it was just being forced to turn over at 65MPH.

Thing will still randomly start, even though the pump has played dead for hours or days at a time, going on a year and a half from onset of the issue.

Not saying yours is the pump, but narrowing it down to fuel or spark will make a difference in helping diagnose.

I also had the ubiquitous split fuel hose that allowed the truck to run for a long time, but caused all sorts of lack of power/stalling issues, but intermittent. Probably related to fuel level if I had figured out what was going on soon enough to pay attention to when it occurred.
 
Good. As long as the injector spray is strong and cone shaped, should be GTG with fuel and the pressures you posted.
 
Sorry, but as a EE I have problems with people using ‘ohm’ as a verb. You measured a resistance of 1016 ohms between the leads. :waytogo:
If you were measuring the voltage of a battery would you say “I volted at 12 across the terminals”?
 
Mine did that to me recently, I found several bad plug wires (burnt boots), rotor looked burnt, I changed the ICM just because, and found a vacuum line on the base of the TBI was burnt through, it was a plugged off vac line. So no help but that is what I found on mine, Oh and my positive battery cable was loose in the bung.
 
I was just going there...how about checking that ALDL feed and seeing what's happening when it's losing power. I have an old laptop that I don't care if it gets stolen, and when I have an issue, I just leave it on datalog when I'm driving, most times if it dies, I can tell what happened from looking at the logs just prior.
 
I don't think the CEL works anymore, I took it to work and it died after about 20 min on the highway, cooled down 5-10 min, restarted and finished the drive.

I went ahead and threw a new coil, plugs and wires at it, it idles better, but i haven't had a chance to road test.

Plugs didn't look atrocious for being in there a couple years with it running rich.
20200723_191148.jpg
 
were you able to check anything when it quit? I suspect the fuel pump is laying down, when it gets hot. I hate TBI for not having a fuel pressure test port
 
did it stumble run rough and die or just up and quit? Did your speed change, like above 40 mph to 5 10 mph ?
 
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