DanS

iTrader: (1)

It's 1992 305 TBI, engine is stock.
Last year I installed a Walbro high volume fuel pump, which I am sure is way more than I need, but it seemed like a good idea for future mods. The car ran after installing the pump. Not the greatest, but it was drivable.

Well, I got distracted with other projects, and the car ended up sitting for almost a year. Now, I can't get it running again. It starts for a few seconds, if you play with the throttle, but then it backfires severely (shoots flames up through the throtte body) & dies.

I figured this was from sitting too long, so I tried all of the following:

Drained the old gas out of the tank & replaced it with new
Replaced fuel filter
Cleaned IAC
Cleaned throttle body & injectors, replaced all of the seals, gaskets in & o-rings (the ones found in a throttle body repair kit)
Replaced spark plugs, distributor cap & rotor

Still getting same results, so I installed a fuel pressure gauge under the hood, in the rubber part of the fuel feed line. It shows I'm only getting around 4psi fuel pressure. So, I thought maybe the filter had become plugged again. I disconnected the battery, removed the gas cap (to relieve pressure), and started to remove the fuel filter. Approx 2-3 quarts of fuel ran out of the exit side of the filter (with the enter side still connected). This seems like a lot of fuel to me, especially if I'm only getting 4 psi at the gauge.

So, now I'm guessing there is a restriction in the fuel feed line. Would this be a good guess? Or am I missing something? Any other ideas?

Sorry for the long explanation, but I hope the detail helps. Please help me diagnose this problem.

dimented24x7

iTrader: (2)

Stupid question, but what line is the fuel pressure gauge installed on? The larger of the two lines?

It could be a restriction as you say, loose or leaking hose on the fuel pump assembly, faulty pump, just to name a few. Have you made any adjustments to the fuel pressure regulator? How does the pump sound when its running?

DanS

iTrader: (1)

Thanks for the reply.
Fuel pressure gauge was installed on the upper, larger, hose. Which should be the feed line. Correct?
Pump sounds fine (to me anyway). It makes a whining sound.
I performed the mod to make the fuel pressure regulator adjustable. I tried it in several positions, adjusting as far as it would go it either direction, and there wasn't any change.
The fact that so much fuel comes out when disconnecting the filter, leads me to believe that the problem is between the filter and the guage. Does this sound like a good assumption? What would you suggest next?

dimented24x7

iTrader: (2)

Turn on the pump with the engine off and see what the pressure is with no load. If it hits 12 PSI or so, then there is a restriction. If its still low then it could be a faulty or incorrectly assembled FPR, or the hose that connects the pump itself to the pump/sender unit split, or the gauge itself could be faulty (sudden pressure spikes will damage the gears in the gauge), assuming the pump is still good.

boogie

What should the pressure read with the key on/engine off?