Possible cause for high fuel pressure during cold start up cycle

[bigbreak_2000]

I'm experiencing an issue I hope someone can help pinpoint to a probable cause. I have the stock fuel rail from a 280zx Turbo, and then also a stock pressure regulator that (has 2 inlets/1 outlet and a vacuum connection) and fits right into the stock fuel rail. Also uses the 280zx turbo injectors. There is no cold start injector (the intake is modified to accommodate a MAP sensor). The engine had been running well for past 3-4 years since I had it installed. Recently, occasionally (I will explain this more), soon after start up fuel will spout out past the connections to the pressure regulator. I assume something is causing a pressure built up. Switching engine off, let is rest, then restart may cure the problem. What can be going on here? Had anyone seen this problem with a faulty pressure regulator, or could it be a clogged injector causing a spike in pressure, what else?

 

Background: It always smelled a little heavy of fuel during the cold start up cycle, which I thought was rich tuning, combined with a by-result of running an open crank vent system (tube on block vents to atmosphere via catchcan). The other morning about 1 mile into driving I experienced an engine fire - it was driving fine but I started to smell rubber burning and could see black smoke coming from the engine. Some wire loom got melted. Could not see where fuel was leaking from, however stain marks on the block pointed to a few manifold bolts that felt a bit loose and thought perhaps fuel/oil mist from the intake could be seeping out onto the hot header. After tightening those, I drove the car a couple times and did not experience any further issue. You can switch to the On position, with pump running, and no fuel will leak. Subsequently I also got my insurance to inspect it and they paid me to get the melted wiring replaced. Yesterday after the car had been sitting for a week, I wanted to take her out for drive. I started the engine, popped the hood to see if everything still looked ok, and to my dismay saw fuel streaming out from the fuel rail. Now I know where it is leaking from. In the pictures I show the pressure regulator so you can see the style, the other shows the top side of one of the fuel hose connections and it appears a little swelled at the top section, and the other picture shows where the hose pushed with my finger upwards, it felt very soft and thin and you can see how easy it deforms just by the slight pressure of my finger. These are fuel hoses supplied by Nissan. Could they have gone bad (were new 4 years ago)? Perhaps the heat exposure from the header made then soft? In the picture you can see I recently installed my own fabrication of a modded stock heat shield plate, covered with a layer of thermo-tec header blanket material.This was installed after the first fire incident.

Edited December 31, 2011 by bigbreak_2000

[NewZed]

You should take an actual measurement of the fuel pressure to see if it's really abnormally high or if you just have leaking lines.

 

Edit - I see that you put new lines on 4 years ago. Maybe you got a bad mechanic and they put the wrong lines on (regular fuel line instead of fuel injection line - the lines should not swell like that). Plus those aren't the best hose clamps for fuel injection line.

 

p.s. Your pictures are way too big.

Edited December 31, 2011 by NewZed