TBI guru's / 4x4high

[jekquistk5]

I just got my truck running this last weekend, everything was running great smooth Idle, started right up, great throttle response. I noticed i had no gauges so I just through on a set of mechanical gauges I had to verify I had oil pressure before I got to into it. I had good pressure, temp was holding, and my Alternator was putting out good voltage. Its a 350 with edelbrock intake, original heads ported to match intake, and headers, hooker long tubes, 3 wire o2 sensor. I ran it up the road about 5 miles, and back, let it idle for 5 to 10 min to see if I was leaking anything turned around to park it and work on it tomorrow when it died and wouldn't start. It ran really great on the road, had plenty of power, exactly what I expected. I tried cranking it again, and it looked like one injector was dumping way, way to much fuel. This is where I think the problem is, because I can turn the fuel pump off and she will fire in about 2 cranks and then die when it runs out of fuel. The second I turn the pump on it will not fire. I think I may have a stuck injector because the left injector after 3 cranks had a puddle of gas stuck on the butterfly, but the right had just a light coating. Do you think that is my problem? or is it an O2 sensor not reporting correctly causing a lean condition? I guess I should run the codes tomorrow see what they are. Just trying to get a game plan together!

 

[4X4HIGH]

Sounds like you might have a bad injector. The spray pattern should be a nice conical pattern and once it died it sound like you now have the one injector leaking somewhere. I recently replace an injector for a buddy that was an aftermarket injector and it was leaking severely from the top of the injector where the wire clips on.

You should hold the throttle wide open and try to start it again but don't let up on the throttle until it starts. If it will run long enough for you to get back up front to check the spray pattern or to see if the injector is leaking anywhere obvious other than the nozzle. How long did this rig sit for?

If you know which injector seems to be giving you problems you could always swap them and see if the problem follows the swap.

 

[jekquistk5]

The tbi unit was bagged in my barn for about 5 months, so quite awhile. The thing that gets me is it was running so well. I will swap the injectors tomorrow, and maybe grab an extra tbi unit from the scrap yard as well.

 

[4X4HIGH]

How old is the fuel in the tank? Gas starts to go bad after 6 months and turns into a varnish which like to make things such as valves and injectors stick. This could be your problem. The only real cure is to drain the tank and have it boiled out. Some people try to just drain and refill and some people are successful but it's not a 100% guarantee like boiling the tank clean.

 

[jekquistk5]

That could be it. I'll drain it, and try putting some new stuff in there. If that doesn't work I'll have it boiled. I never even thought of fuel, thanks scott!

 

[dyeager535]

Another thing, is there any reason you simply can't swap the wiring to the injector, not the injector itself? (IE swap the injector connector from one injector to the other)

 

[Fabrimacator21]

I don't remember how the stock injectors mounted but if its anything like the holley injectors then theres a plate that holds them down into the pods. Not sure if thats how the stockers work but if it is then check the plate that holds them down... they like to get bent and not provide enough down pressure to hold both injectors in well enough. Either that or it could be loose.

I would check your injectors before you pull the tank. That is a PITA compared to checking your injectors.

Did it look like one of them was spraying enough fuel? It doesn't take much to let it idle.

 

[4X4HIGH]

The reason i said to swap the injectors is because then he can also see if there is a piece of crap hung up in the injector pod as well.

 

[dyeager535]

The reason i said to swap the injectors is because then he can also see if there is a piece of crap hung up in the injector pod as well.

Gotcha. I was thinking along the lines of a shorted wire, which would follow the lead, not the injector.

 

[jekquistk5]

It is a fuel issue for sure, It is spraying way to much fuel for some reason. I can start it when it isn't flooded by holding the throttle wide open. Then let it warm up then slowly let off the gas till the computer adjusts and kicks the idle up. Its idling at around 800-900 RPM's once it is warm and the computer adjusts everything. Both Injectors are spraying the same amount. I'm going to clean everything tomorrow. But I ran it around today for 30 min or so, and is definitely running rich. Helps me find little exhaust leaks Thanks for all the help guys, I'll keep ya updated.

 

[Wildman III]

Check the temp sensor you can ohm it out and see if it is reading corectly
if it reads too cold when your engine is warm it will cause it to run rich
Here is how the tbi system works
It reads the engine coolant temperature and controls the fuel mixture
when the vehicle reaches operating temp it will go in to open loop and run on the raw sensor data in closed loop it runs off a preprogrammed fuel map in the prom .

 

[4X4HIGH]

Check the temp sensor you can ohm it out and see if it is reading corectly
if it reads too cold when your engine is warm it will cause it to run rich
Here is how the tbi system works
It reads the engine coolant temperature and controls the fuel mixture
when the vehicle reaches operating temp it will go in to CLOSED loop and run on the raw sensor data in OPEN loop it runs off a preprogrammed fuel map in the prom .

There, fixed it for you.

 

[jekquistk5]

I'll try putting a new sender in, that could be it cuz it's not registering.

 

[dyeager535]

Temp sender?

Sender has absolutely nothing to do with one injector giving more fuel than the other, assuming you are confident that is what is happening. A temp sender will not stop a vehicle dead in its tracks.