Fuel Injector Hose Leaking!

[Gilzee]

My '78 280z was running fine until I decided to remove the fuel rail and change the incorrect hose clamps on the fuel injectors to the proper type fuel injector hose clamps. To make a long story short, I have removed the fuel rail three times due to the same hose leaking upon reassembly and cranking the motor! I am using 1/4 inch fuel injected hosing at 400 PSI. The leaky hose in question is the second injector nearest the radiator. Yes, I have switched injectors to no avail...the same situated hose still swells up and starts to leak. Someone suggested changing the fuel pressure regulator which I currently have on order. Could this be the problem? It appears that all injectors are firing up and the engine purrs smooth before the FI hose bursts. Any input appreciated.

[ALT_255]

is the hose bursting? i.e. is the side blowing out? or is it leaking from the top or bottom?

if it is leaking is it leaking from the top (nearest the fuel rail) or the bottom? if you dont have on on there you need a clamp on the top and their should be a washer type thing on the bottom.

[Gilzee]

The last two times the hose swelled up and began leaking from the hose itself. The leak did not come from the top or bottom clamps but from the damaged hose.

[Gilzee]

I think what I'm going to do when I install the rail (for the third time) with the repaired FI hose and new fuel regulator is to use regular fuel line hose on one end of the fuel regulator. That way if it springs a leak with the weaker regulator hose (fire extinguisher in hand), it would be an easier repair without having to remove the entire fuel rail again....that is provided the problem is not in the injectors or fuel rail itself.

[sblake01]

Is there a sharp edge on the barb that goes into that particular hose? Or is it bent? Otherwise, I'm having a problem figuring out why it blows just that one. If the fuel pressure was too high, I would think more that one hose would be affected. I've changed hoses on both my F.I. cars and have never experienced that.

[Gilzee]

I didn't notice any sharp edges on the affected barb and the clamps are all new. I also switched injectors and still the same located barb caused the hose to swell and leak. Well, we'll see what happens this weekend when I reinstall the rail for the third time!

[webdawg1]

Could be the hose size! (1/4" ??) I'm no expert by a long shot, but I'm showing 5/16' ID (EFI hose) to be the correct size hose. Also how far from the end of the hose are you clamping the clamps? What name brand hose are you using? According to the service manual I have for my 75 Z it's saying to use 13.5 mm (0.531 in) hose clamps on the injector and fuel pipe side. 15 mm (0.591 in) all other positions) Insert approx. 20 mm and clamp 3 mm from the end. Has a "WARNING" about not clamping on the bulged portion of the fuel pipe also...

[Gilzee]

I've always wondered whether or not to use 1/4 inch or 5/16 inch on the injectors themselves. If you click on the following link, the author suggests using 1/4 inch on the injectors and 5/16 inch on both ends of the fuel pressure regulator. Victoria British (I know, not OEM) sent me the 1/4 inch fuel injector hose. (I believe Motorsport uses the 5/16 inch). Life would be much easier using 5/16 since the 1/4 inch scrapes the skin off my fingers squeezing them into the rail. Anyways, if the manual suggests 5/16 inch, so be it. I will change my hoses/clamps over to the recommended size and see what happens, thanks for everybody's responses!

http://people.ucsc.edu/~penniman/injectho/IHR.htm

[Gilzee]

Well, if you've been following this thread, you're probably wondering if I resolved the leaky injector hose issue. Well I ended up installing a brand new fuel pressure regulator and used fuel rail from a non-running zx. To my dismay, two more FI hoses sprung a leak! After removing the rail for the upteenth time, I then decided to install 5/16th inch hose from Motorsport (instead of the 1/4th inch) on the fuel injectors *and* to try a different set of fuel injectors. Well it's been two days of testing without any of the injector hoses busting and I believe that my original fuel injectors were defective. Knock on wood I hope I fixed the problem. My next question is why the engine dies when it's cold? It runs beautiful warm, but when it's cold it keeps dying on me. I understand that the cold start valve and thermotime (sp?) switch have something to do with cold starts, right?

[TomoHawk]

The cold start valve is controlled more or less by the thermotime switch. The thermotime switch senses the coolant temperature and until the coolant reaches a certain temperature, the cold start valve will inject fuel, richening the mixture.

An open cold astart valve seems to be a problem on many Zeds with a rich mix.

[TomoHawk]

In addition to the cold-start injector, there is an Auxilair Air Valve that bypasses the throttle-body to let a little extra air into the intake, simulating a partially-open throttle. It's supposed let the engine run better when cold, and the valve closes off after a few minutes ( don't know exactly how long).

[TomoHawk]

I was reading the FSM, and it tells you the factor spec on fuel pressure is 36 psi(and may fluctuate a little higher or lower), so it looks like 90 psi hose might be a little overkill, but not a bad idea for safety.

thx