JoeBobJr

I posted a thread about installing a gauge to see the fuel pressure I'm getting and I'm not sure if I could post this into that thread or start a new one.

I have a 305 from an 89 Camaro RS with the 700r4 transmission installed in an 85 Chevrolet C10 Pickup.

I had to replace the fuel pump in order to get this truck running. A friend told me I should install a higher pressure fuel pump instead of using the cheapest one you can buy for TBI inline at autozone. He said a high pressure pump will guarantee that the max pressure needed will always be there instead of fluctuating.

I installed an 89 F150 inline fuel pump I think it was rated at 75psi or something closed and 40 psi open. I know the TBI has a built in regulator so I knew it would regulate down to what it needed.

Well even with the 4.3L injectors it's running super super rich. It's spraying entirely too much fuel. I noticed after I fight it for a while and get it warmed up it seems to straighten up quite a bit and actually start running half decent.

I was told it could be the Coolant Temperature Sensor. So I changed it with another one I had laying around. Not knowing for sure if it was working correctly or not. It was all I had.

I also changed the MAP sensor which I was told it could be also. With another laying around one I had on a shelf. Not knowing if it was good either. I also unplugged the O2 sensor to see if that would change anything. Nothing. I'm completely clueless as to why it's spraying so much fuel.

I was thinking too much fuel pressure but the regulator has been untouched and I even took it completely apart today and even adjusted the pressure down some to see if that might change it and still nothing. It's got me beat I need help bad!

EDITED: Is there a guide online or on this forum that teaches how to test each sensor on TBI? I've searched trying to get what I need to test the MAP sensor and coolant temp sensor and not able to find what I need. Someone should definitely compile a complete Sensor testing guide that tells shows you how to test every sensor on TBI/TPI. That would be really nice to have around.

JoeBobJr

Since there is no check engine light. I found some diagrams online that show what wire goes to the check engine light. I'm going to wire up a light soon and try to pull some codes from it and see what it's telling me. Might get some info to help from that.

ex-x-fire

Make sure the fuel return line is open, no restriction should be present.
Make sure the vacuum signal to the map is the same as manifold vacuum. Is the timing set right, does it advance when you rev it?
Get a dvom tester & test the continuity between the ecm connectors & sensors/grounds.

JoeBobJr

Is there a way to test the return fuel line to see if its flowing freely? It seems to pour a little gas out when I remove the line as if it's working.

I just sandblasted a TBI I had sitting around completely inside and out. So all vacuum lines and vacuum connections on the TBI are free flowing without a problem. I have replaced all vacuum lines with new ones just recently.

I'm not sure if the timing is set right at the moment. I know it was before I replaced all the lifters the other day. I cleaned under the intake and checked all intake ports and all that good stuff. It seems everything is clean and clear. Shouldn't be any reason the vacuum from the manifold and the vacuum to the MAP isn't the same but if I can find a vacuum gauge I'll try that soon.

Something I haven't checked yet is all the grounds but from what I remember when I was tracing down injector wires a while back all the grounds seemed to be intact.

JoeBobJr

Is there a guide online that teaches how to check all the sensors on the TBI engines? I'd like to test every sensor just to make sure they are all good. I have no idea if the MAP and Coolant Temp Sensor I put on my truck is even any good. It would ease my mind to know they are good.

JoeBobJr

I tested the Coolant Temp Sensor and it read 0 no matter what ohm setting it used. I did notice when I unplugged the sensor that the plastic turned about 1/4 of the ways around just unplugging. I grabbed it gently and was able to just spend it around in circles.

Does that mean it's just broken altogether?