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View Full Version : pinched fuel hose and pressure goes sky high??



cdn_w_sr20
08-02-2005, 02:33 PM
In my never ending pursuit of the problem i'm having with my engine i've come to the conclusion it has to be either ignition or fuel related. I blew the fuse out of my fuel pump 3 times in 1 day, hmmm something was wrong. until i put a 15amp fuse in there. it ran with the stock 10 amp fuse for over a year with no problems.

I was told that if i pinch the fuel return hose with a set of pliars and the fuel pressure goes up the FPR is bad, is that true? When i pinch mine maybe half closed the pressure goes from 40 psi to 65 psi. The car has been backfiring when i try to make it run past 3,500 rpm. Now here is the funny thing.

I disconnected the actuator from the turbo and the car acted the exact same way, well one difference i couldn't hear boost. but it happens right at the same rpm level.

Does that sound like a bad actuator? i'm going to re-wire the fuel pump tomorrow with a 30amp relay right to the battery..

GRRR will this never end!!

TS4l
08-02-2005, 02:55 PM
The fuel pressure should rise if you pinch the return hose. Sounds like it pefectly normal pressure. If you have low pressure you can try and pinch the hose and see if it goes up to see if your FPR is just not working or its the pump. The pressure seems normal though so I don't think its fuel pressure or pump related. I am sure you already said this in your other post but what do the plugs look like! Thats the first thing I always check to see if its just dumping fuel for some reason.

cdn_w_sr20
08-02-2005, 02:58 PM
Plugs looked black, very black. like burn fuel or something. The fuel pump doesn't sound like it used to either, does make the same high pitch sound.

I took my blow off valve off just now, its an apexi twin chamber. I swear i've been hearing some major "PSSSSH" sound when i shouldn't be. I poured some water into the blow off valve and slowly but surely it all leaked out. I'm thinking this should not be happening and would be cause for a boost leak which would cause me to run rich? i'm pretty sure its should be closed 100% right?

TS4l
08-02-2005, 03:05 PM
It sounds very likely it could be leaking. Hook the piping back up and get a funnel, and an air compressor. Push the air hose up to the funnel and push that into the coupler. Works goon enough to find leaks. But if you have a leak it will de exactly what your describing. My car had 6 leaks and at low boost it ran rich but still ran, higher boost it would buck like crazy and backfire. Hopefully you just found the problem.

Kingtal0n
08-02-2005, 08:11 PM
If you are suddenly blowing the fuel pump fuse out of nowhere, its because the fuel pump is suddenly working harder than it used to. possible causes are wiring is going south, or a crimped/clogged/crippled fuel line (return OR feed) or a fuel regulator diaphram going back (pull the return line and make sure the diaphram is not ripped, if it is fuel will come out of the regulator).

Fuel pumps usually work harder when the regulator begins restricting fuel flow to raise the pressure. if your pressure is normal, but the fuel pump is still working harder, then it sounds like a clog in the feed line or fuel filter, causing the pump to provide more pressure just to feed the regulator which further increases pressure and over-all kills your fuel volume (more pressure = less volume)-

That doesnt explain your rich situation, though... most def. check for boost leaks- though this would not make your fuel pump work harder and blow fuses.

cdn_w_sr20
08-02-2005, 08:35 PM
well i went over a really really bad bump. right after that the fuel pump fuse blew and then the motor started acting like crap, the bump did some damage by the looks of it, just a matter of what and why. To be precise they are doing some work on the train tracks and with no signs posted the tracks were hardcore to say the least.

MonkeyMagic
08-03-2005, 06:15 AM
damn train tracks. I feel your pain, the streets of my town look like they were set up so The Dukes of Hazzard could do their car chase scenes here.

Vapor
08-03-2005, 08:47 AM
as i said in the last post, you have a fuel supply problem. The FPR is performing as specified.

cdn_w_sr20
08-03-2005, 08:53 AM
Does anyone know which walbro fuel pump the one for the 240sx is? I went to a local part store and they had no part for it, just 200sx, nx2000 and sentra. Would these all cross over?

Would a stock fuel pump work okay for stock boost?