midnight rumbler

I replaced the fuel lines on my truck equipped with the 5.7 350 and I installed an aftermarket fuel filter which appears to be a little smaller than stock but has the same 3/8" inlet/outlet. I am not sure if this would effect the fuel flow through this filter.

All lines are to manufacturers specs and are not pinched or crimped. and lead from just outside the tank all the way up to the TBI.

I had to install an aftermarket fuel filter which as stated is a little smaller as I did not have the flange tool to create the stock fuel line flanges.

The problem I am having is that the truck seems to be sluggish upon start up as if it has a misfire and after it reaches normal operating temp it is fine until I start putting it under load going up hills etc.

What might the problem be?

I pulled the TBI apart today and cleaned up everything including injectors just incase any dirt got through from cutting the old lines.

The stock feed line was 3/8" and the return was 5/16" with the smog line 1/4".

Any help would be great

thanx

jeffs_62

We might need a little more information.
What prompted you to change the lines?
What year is it?
Have you checked the fuel pressure?
I the flow arrow on the filter pointing towards the motor?
Did it run fine before?
Have you checked the computer for faults?

midnight rumbler

What prompted you to change the lines? Lines were rotted

What year is it? 1989

Have you checked the fuel pressure? Yes

Is the flow arrow on the filter pointing towards the motor? Most definately

Did it run fine before? Yes

Have you checked the computer for faults? Yes

jeffs_62

I was hoping the answer was in there somewhere.

You cleaned out you're injectors, and all the rest of the stuff was okay?

It is definateley wierd that it happened all of a sudden.

Sounds like it is running just like my Suburban did just before I found out the head gasket was blown.

I'll have to consternate on this one.

shawnvw

You say you checked fuel pressure....what is it at idle? at start-up? while driving?
Sounds like a one of a couple things.

Wrong flow through the fuel filter. Take it out and put a piece of hose in and take it for a quick boot to see if the problem is gone.

Your fuel pump was used to pushing against a clogged fuel filter, and now that its free flowing it has fallen on its face. how bad was the old filter?

you got a piece of dirt in the injector. But you already said you cleaned it

I have done this before, and it took a couple days of running like **** to figure it out....where the steel lines meet the rubber hoses at the tank, make sure either line is not pinched. You already said its not, but double check it.....I didn't think it was pinched either.

midnight rumbler

how bad was the old filter? I just replaced the filter previously about 8 months ago but as stated, could not use this due to not having the tool to create factory flanges in the fuel lines.

I went and double checked the lines at the tank and it appeared that the 3/8" line was slightly pinched. This must have occured over the past few days from diriving so I have since put in a 3/8" rubber fuel line to correct this. The pinch was not significant to me but I guess it may have been for the truck.

I will be doing some good driving tomorrow so we will see if this was the culprit. If not, I will remove the fuel filter and put in a rubber feul line to narrow things down and go from there.

Thank you