Are you using new hose clamps?



-Ted

 

I would think there would have to be something clogging the lines somewhere. I can't see why that would be happening.

 

Brad,

Have you tried putting a fuel pressure gauge on it to see how much the pump is putting out? If that's in spec, it sounds like the regulator isn't letting anything flow back into the tank.

 

Just took a look... the book says if the pressure is higher than specified to change the fuel pressure regulator. I don't think there is a way to test it off the car, but if you short the yellow 2 pin test connector on the passenger side of the engine compartment and key on, you'll hear a hiss coming out of the pressure regulator. That's the excess fuel flowing back in. That only tells you something is going back, not how much obviously. Best bet is to put a fuel pressure gauge on the main fuel line coming in and do the test connector shorting. Your pressure should be 34 to 39 in the system, 64 to 85 coming right off the pump. The system pressure sounds like the one you need to be concerned about, so you need to tee into the line. I'd guess what's happening is the regulator is stuck closed so nothing flows back. Obviously, be careful as hell if you're blowing fuel. If it were me, I'd just replace the regulator. Spraying fuel scares the hell out of me. I think cost is about $90 at an auto parts store.

 

Guys,

I don't think that the fuel injection lines should bust even if the pressure regulator is bad. I don't think the stock pump can go THAT high. Is this the stock pump? Where did you get this line and what is the working pressure for the line you are using. I used "high pressure fuel injection hose" for mine....like $4.00 for a foot of it. If I was having the problems you are having i'd go to a Mazda dealer and get the little section of hose and the factory clamps (I wouldn't think they would be more than a few bucks).

Todd

 

Y'know, that's a good point akageals made... now that I think about it, when I tested the pressure off the pump in my car I ran it directly to the fuel gauge at 90 pounds and that didn't blow. Is the hose you're using specifically for fuel injected cars? Regular fuel hose isn't rated for that high of pressure. I think it says right on it if it is. Also, is it actually blowing the hose or blowing it off the rail?

 

Brad,

Do you have a fuel pressure gauge? It would be good to see how much pressure is coming off the pump.

 

One other thing. If the pressure in the lines is high enough to blow that hose then your car should be running VERY rich I would think. You must be running over 100 PSI if that hose is busting and the pressure reg. normally keeps it around 40 PSI if I remember the spec. correctly. I think that much pressure would make the car run rich enough that it might not run at all (maybe someone knows what the increased pressure would do).

Todd

 

Brad,

The fuel pressure gauge is a little bit of a bitch. The only ones I could find when I bought mine are meant for American cars where there's a fitting on the rail. If that's all you can find, you have to make your own T setup out of fittings and fuel hose. Maybe one of the other guys here knows where you can buy one that comes with those fittings. What part of Indiana are you in? I'm near Chicago. I'll help you out if I can.

Did you try shorting the test connector with the key on, engine off to see if you could hear hissing through the regulator?

I guess what bothers me now is what akageals mentioned. I don't get how it can build up enough pressure to blow the hose. If the pump can only put out 90 lbs it shouldn't exceed that even if the regulator is totally closed, right? Anyone?

 

Carefull with those aftermarket clamps, they cut into the hose if you over torque them. I use the mazda factory fuel line clamps and double clamp each end.

 

Even if there were a clog, most "fuel injection fuel hose" are rated up to 150-200psi of pressure.

I would just double check to make sure it is the high pressure hose that you're using...



-Ted

 

To reiterate what cymfc3s mentioned about the hose clamps.......DO NOT USE THOSE SCREW-TYPE HOSE CLAMPS!!

I had my intake off and decided to replace all of the fuel lines and vacuum hoses while it was apart. I bought all new screw-type hose clamps thinking that they would be a little more sturdy than those spring loaded OEM clamps. Two days after I got everything back together I had a fuel leak all of the way down under the intake. I took it all apart again....no easy chore....and tightened the clamps up. I manually pressurized the fuel lines by jumpering the yellow connector before replacing the intake and had no leaks. So....I put everything together and a few days later it started leaking again!! Right where the hoses slide onto the fittings. I had to disassemble everything AGAIN, and this time I put the old spring-type OEM clamps on and have not had a problem since.

Those clamps are too easy to over-tighten causing the fuel line to split, or to under-tighten allowing a leak. I guess the spring clamps keep a constant pressure around the hose to keep a tight seal with the expansion and contraction from hot and cold temps under the hood.