Tbi backfire through intake

[Rustjunky67]

Do you have system voltage at one wire to each injector when the key is turned to "Run"? If not, you've likely got a popped fuse.

When you have power to the injectors, install a 'noid light on one of the injector wire harnesses, see if it flashes. If it flashes, the injectors have signal to spray. If you have power to the injector, but no flashing--the computer is not commanding injectors to spray, or the wire harness is damaged.

Do you have spark? No injector spray, no spark = likely failed pickup coil or ignition module, or failed wire harness between module and ECM. Connect a scan tool and look for an RPM signal when cranking. No RPM when cranking = failed distributor parts, or failed wire harness.

All of that was good when checked before i fired it up the other day....I had it running....

I guess with every little thing I do I need to go back and check through the whole system at each step lol....
This thing is so frustrating...
Should my fuel pressure be dropping off as quickly as in this video?

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[PlayingWithTBI]

Should my fuel pressure be dropping off as quickly as in this video?

Yep, when you turn the key on, the pump will run for ~2 seconds, then shut off. TBI systems don't have a return check valve so, it'll bleed off almost immediately.

 

[Rustjunky67]

Yep, when you turn the key on, the pump will run for ~2 seconds, then shut off. TBI systems don't have a return check valve so, it'll bleed off almost immediately.

Yeah that was a brain fart...I knew that but still wasn't sure it should be that quick.....

 

[Rustjunky67]

Do you have spark? No injector spray, no spark = likely failed pickup coil or ignition module, or failed wire harness between module and ECM. Connect a scan tool and look for an RPM signal when cranking. No RPM when cranking = failed distributor parts, or failed wire harness.

I tested all this the other day and all checked out.....rpm i know is good because I have a tach (manual tranny)...tyranny....
Just checked CTS, TPS, IAC, EGR AND MAP again with multimeter and all check out good......
EGR valve itself is not holding vacuum as long as it should but I don't think that's a real issue here...
I'm honestly ready to just push it out in the road and leave it

 

[Schurkey]

I tested all this the other day and all checked out.....rpm i know is good because I have a tach

Doesn't matter what the instrument cluster receives for RPM signal. I want to know what the COMPUTER is getting for RPM signal. You'll need to check it with a scan tool.

Just checked CTS, TPS, IAC, EGR AND MAP again with multimeter

That's fine. What happens if the wire harness between the sensor and the computer is damaged? The sensor can be "perfect" and yet the computer doesn't get the signal. Use a scan tool to find out if the signal from each sensor is getting to the computer, and verify that the signal makes sense.

EGR valve itself is not holding vacuum as long as it should but I don't think that's a real issue here.

Be sure it's the EGR valve that's leaking, and not your vacuum tester. I had that problem with a Mityvac "Silverline" unit years ago. Needed a replacement check-valve in the pump.

Agreed that a leaking EGR valve is not causing a hard- or no-start condition.

 

[Rustjunky67]

Don't have a scan tool, won't be getting one, wouldn't know how to use it if I did.....
Here's the truck running at the last try.... why in the hell are both injectors dribbling so much? I could understand if it was one......
These were pulled from the treasure yard. Is there any chance they are a different injector? I will feel like an idiot if so. But the part numbers on them looked the same as my originals, best I can tell....

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[Rustjunky67]

So for some reason I have paid ZERO attention to this bugger...... the ESC module......
and it hasn't been mentioned in anything I've watched, read, or seen posted.....
But I disconnected it and truck crankeded up and was idling on point and just as smooth as you please..... for a minute that is....
So I suppose here I go having to learn about something else.....
Has ANYBODY got any advice whatever about what to do or how to test it, delete it, leave it alone, anything that can actually help me diagnose what's going on? This **** is insane the amount of people who have had basically the same symptoms over the years but different solutions..... there HAS TO BE a common denominator.... at any rate help is desperately appreciated......
Also here is video of it running for the longest I've had it going yet.... but I was holding throttle to it the entire time and as soon as I let off it dies every time..... video was taken before I "discover" the ESC module all sensors check out..... battery is not any good though I have to keep charger on it. Could that be an issue that would/could cause any of my issues?

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[Schurkey]

You'll need a (properly-functioning) ESC module to achieve proper spark advance/retard in combination with the knock sensor and computer-generated spark advance.

 

[Rustjunky67]

You'll need a (properly-functioning) ESC module to achieve proper spark advance/retard in combination with the knock sensor and computer-generated spark advance.

Yessir that's what I gather.... I've read some posts about bypassing it but not sure yet if that is actually a viable option......
So any clue as to why both injectors are streaming so?

 

[Schurkey]

So any clue as to why both injectors are streaming so?

Fix all known problems--ESC, battery, etc. Make the engine run as good as possible. You've verified fuel pressure...right? The fuel filter is not clogged...right?

If the injectors don't spray better with use, you'll maybe need some fuel detergent like Techron Complete Fuel System Cleaner, along with Top Tier gasoline...or you'll send 'em off to someone for thorough cleaning (or replacement.)