TBI injection

[DFord]

I have a 79 CJ5 w/ AMC 304 that I have installed Howell TBI kit (http://howellefi.com/tbi-kit-1972-93-304-360-401-v-8-jeep-amc-emissions-legal.html), the problem that I have is that the fuel pump went out which I replaced with an off the shelf pump that has a discharge pressure of 100 PSI(kit pump output approximately 50 PSI) and got a kit and rebuilt the throttle body. I contacted Howell and they told me that this pump will work with the kit and to adjust the regulator all the way clockwise then 8-10 turns back. I have done that and adjusted it from the 10 turns to 1 turn and still cant get it to run. If I pull the fuel pump fuse it will run as long as the fuel, if I start it and then install the fuse it will die and not restart. I am trying not to have to by another pump ($135) and keep the cost down. Any insight would be appreciated.

 

[Torxhead]

The way I see it, you burnt up a fuel pump because it was not getting enough fuel to it, This could mean a poor vent system or a blockage prior to the pump. I really don't understand your adjusting fuel pressure by the amount of turns on the regulator which I assume is the one in the tbi unit and not an external one. I set my pressure with a gauge hooked up inline just before the fuel line goes into the tbi on the low side of the Howell spec of 10-12 psi. I have also installed a fuel pump designed for the low pressure that the system requires so that the fuel pump will work a lot easier and let the alternator charge the battery instead of pumping a lot of fuel back thru the return line.

 

[DFord]

Your right in that it failed because of blockage (the fuel line broke down and plugged the filter). Understanding that the TBI only needs 13 psi to operate but even the kit pump supplied 40-60 psi, so that needs to be regulated somewhere (hence the TBI pressure regulator) but since the off the shelf fuel pump is 1.5x the pressure and from the conversion I had with Howell I was under the impression that the TBI fuel regulator would handle the added pressure. I am 90% sure that the engine is flooding and wanted to see if any one was able to overcome this w/o adding an external regulator.

 

[Torxhead]

I once had Howell send me a fuel pump that was probably twice as big as the one that came in the kit, this was the Airtex E2000. I got it to work fine with the internal tbi regulator, but gave it to a buddy with a 350 chevy. If you want to have less gas coming in for set up purposes, unplug one of the injectors until you get your pressure down. A clogged up fuel return line will give you excessive fuel pressure btw.

 

[jdarg]

There's indeed a point where too much fuel pressure at the pump will overcome the built-in TBI regular. The only solution AFAIK is an external regulator or different pump. Probably cheaper and easier to just use a different pump. I'm using the stock MPFI pump off a 94 wrangler for my 350/TBI setup. Works fine, pressure is ~ 40PSI, and it works just fine w/ the TBI setup.

Disconnecting one injector might not be a good idea - depends on the intake.

The only way to properly adjust the pressure is using a gauge. I wouldn't mess with it too much without one otherwise you are totally guessing. Backing out the adjustment all the way has a limit and you might need a weaker spring to get where you need to be (or replace the pump.)

I'm guessing the Howell setup wants about 12-14psi but you should check with them. Note this PSI is marginal for a 350 even w/ the proper 65/lb injectors anyways. It will likely be lean at WOT.