midnight rumbler

I have an '89 chev with a 350 and recently replaced the fuel lines (Both feed and return) due to previous lines being rotten. I replaced the fuel filter at this time as well even though it was only 8 months new previously.

I am having an issue where the truck seems to not be getting enough fuel or possibly even too much. The truck is very hesistant and bogs down when I apply the fuel peddal or going up hill. It does not seem as if it wants to stall but mearly stumbles.

I had only started to notice the stumbling/bogging issue after the fuel line installation.. I took a reading of the fuel pressure and I am at 17-18psi which I have read is too high. When I pinch the return line, the pressure jumps to 22-24psi.

The truck is running rich as it smells like fuel out the exhaust.

I have cleaned out the TBI including injectors incase any debris got into these after the new line installation and have inpsected all lines to see if they were pinched which they are not.

Any ideas would be great!!!!!


Ok, Just to rule things out here I just finished disconnecting the fuel return at the throttle body to rule out blockage within this line causing the high pressure. With the line disconnected leading into a container, the pressure is still at 18psi leaving out the possibility of a blocked line even though it was just replaced.

I also replaced the entire upper portion of the TBI unit which consisted of new injectors and pressure regulator so that leaves those out.

What could be causing the higher fuel pressure reading and the stumbling/bogging issues. I have seen some people say that 12-15psi is average fuel pressure where some asy 14-18psi is average. Maybe I am in the aveage range but looking at the wrong problem.

The truck is an '89 but it only has 20,000 original miles.


Just to throw you off a bit, I checked my vacuum line leading into the EGR, I do not seem to have any suction or air flow at all coming from this line at idle or accelearation. When I press on the diaphram, the engine will bog down.

The funny thing is there is a little bolt on the side of the TBI unit and if I remove this bolt, the truck is losing vacuum but seems to run better but idles higher a little higher. The reason I had done this is because that is where I tapped a vacuum gauge into and by removing the vacuum line, it allowed pressure to be lost but makes the truck run better. If I plug the hole with my finger while exposed, the truck will stumble/bog down again.


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