fuel pressure drops then car doesn't run

Put the fuel filter in, it was difficult to blow through, the new one was like blowing through a straw.

The pressure still drops to 21-22 psi but didn't go any further below that. I squeezed the out line of the fpr while running and it went to maybe 40 or so, when released it went back to 21-22 a most times and a few times like 18 but then crept up to 21-22, or the next time I squished and released the line. So wonder if that's an overpressure valve hanging up.

The pump does get buzzier when the pressure is at 21-22, than when first turned on cold. Does the pump wear out faster pushing through a clogged fuel filter. I'll replace the lines (minus the 4 fuel injector lines those look mean) as I have the kit and see what that does.

My rear fan in the trunk seems to have stopped turning on after I shut down and restart shortly thereafter, I had taped the wire hanging down to the sensor on the exhaust is that what controls it? It was worn through, perhaps in taping it I may have finished off the few strands that were making the connection.
 
The sensor,,

on the exhaust manifold is the o2 ( oxygen sensor ) or lambda sensor. The sensor for the cooling fan is on the opposite side of the FPR . It's raining pretty good here or I'd go get a better description for the fan sensor.
 
thanks, I just found a recent thread on it. Don't think that has anything to do with my fuel pressure, but I'm about to go out and find the sensor.
 
the wire you taped was for the O2 sensor...

the blower fan in the trunk is to cool the fuel rail and hoses that sit above the exhaust manifold and boil/bake.

That fan should kick on when the sensor reaches around 100* I believe.

The trunk FI cooling fan Thermoswitch is bolted underneath where you just put in the new FPR...
 
figures. This is why I like to do one thing at a time, and only when I absolutely have to. I swear I didn't break it!

I just looked and remember the wire in the way when I was trying to put the FPR in, but I just moved it, I swear:innocent:

OK, I'll get to that, it is a separate problem.
 
My recent saga, if it helps at all:
My pump started out not too loud, then became louder as the car warmed up, then it would quite down a bit again the next trip, this was only a few runs after I got it going. Then I pulled the line, cleaned the inlet, added a filter and it quieted down for about 60 miles, then started getting loud again, then I bit the bullet, pulled the tank, cleaned sealed and reinstalled, pump is happy to be feed gas from a nice clean tank. I did replace my engine bay filter just tonight, got one at Advance Auto for $27, which is too much but it was sitting right there and I wanted that piece of mind. The gas that came out of the old one looked alright though!. Maybe PO replaced it not long ago attempting to get the car going. I will say the car is running much much much better (but it wasn't running AT ALL a few weeks ago).

But, during my work getting it running again, I had about 33psi all the time, it would fall back to zero pretty quickly at first, then as the internal check valve in the pump starting behaving again (or so I assumed), it would take a good hour for it fall back down after shut down.
 
do you still have a filter before the pump, where did you put it, and is it the same size as the one past the pump?
 
kayaker37 said:
do you still have a filter before the pump, where did you put it, and is it the same size as the one past the pump?
Click to expand...

No, no more filter before the pump, as of Tuesday when I put the newly cleaned and sealed tank back in, I ran the line straight to the pump as OEM. I had added one there because I knew the tank was a rusty mess and serious crap was getting sucked into the pump. It was just a filter I had laying around, it was a big one with 3/8" nipples, I had to reduce the 12mm line from the tank, down to 3/8" then the filter than 3/8" into the pump. It was all temp and was only on a week before I pulled the tank. You can get filters (NAPA http://www.napaonline.com/Search/Detail.aspx?R=PSX23293_0242211138 ) that should fit that line decently but if your tank is crappy, bite the bullet and fix it it's a PITA but once done, done!
 
I knew mine was shot by the plugged pump, then the plugged filter I put before it, I drained some gas out and looked at it and let it dry out, leaving brown rust powder behind. I ran some through a coffee filter and it only flowed for a couple seconds before it clogged with rust powder. That settled it. I couldn't believe the car ran at all. After the tank is out, then you can look inside. I found my treble light with a smallish CFL bulb would slip into the hole where the sender goes, then you can look through the filler hole. But DON"T stick any bulb in there until long after the gas is gone and fumes have left (tank has been flushed with tons of water several times) or you will blow up and die. (I got careless and broke the CFL bulb while taking it out, that could have killed me).
Here's the thread on it, there's a link there to pictures of the flotsam on my driveway, I was amazed.
http://xwebforums.com/forum/index.php?threads/8205
I'm not sure this is your problem, but it could be I suppose. Or it could be A problem and not THE problem.
 
O2 sensor could be causing some issues..

if that wire is indeed damaged/shorted out where you taped it. I don't know that it would cause the fuel pressure drop like that, but seems like a quick thing to repair and see if any help.
 
But not this issue...

The O2 sensor is a sensitive thing, and relies on millivolts of voltage to tell the ECU how much to pulse the injectors, but has nothing to do with the fuel pump power or fuel pressure.

The car will actually run pretty good with it unplugged as long as the CO% screw is set correctly.
 
Tank peek.

I used a miny flashlight to check mine. One from the dollar store with the flex wire. A small one works at the hole also and just line up with the beam and move around. Works best in low light conditions as in a garage or at dusk so your eyes can adjust. Works surprisingly well.
 
pics of new pump, prefilter, filter, SS lines, pressure still drops but runs

so with the new prefilter, pump, filter, pressure regulator, SS lines (minus the five little ones on the rail), pressure still drops but at least I was able to take it out for a brief run with a gallon in it to check for leaks. Got back and it was at 24 psi, although I have read that liquid pumps can drop as they warm up. I'll fill it with more gas next weekend and take it out again and see how he does ( I think I've decided it's a boy, to angular to be a girl).

I'll consider dropping the tank at a later date, to see whats in there. I'll pull the prefilter at some point and see how it's doing. Think I'd prefer to drop the tank before I tackle the fuel rail hoses.

P1010409.jpg

P1010410.jpg

P1010412.jpg

P1010413.jpg
 
So, is it still running badly after pressure drop? Maybe it's running badly for some other reason? If it runs decent, just drive it pressure be damned. Could be the gauge isn't calibrated right either. Good work BTW, looks good!
 
No it ran fine today on the short drive. The gauge may be indicating somewhat lower when it gets hot, so I'll drive it and see what happens. But when it has shown 18 and below in the past the car was running bad. So I believe the problem is pressure related, but the gauge may just fluctuate.

I looked in the archives and saw some disassembled tanks, and under the baffle and around the end of the pipe that goes to the pump is a sock. I'm wondering if that sock is picking up crap when it runs and is slowing things down? In other words reduced flow, even though there may be not a lot of rust coming out.

jvandyke said:
So, is it still running badly after pressure drop? Maybe it's running badly for some other reason? If it runs decent, just drive it pressure be damned. Could be the gauge isn't calibrated right either. Good work BTW, looks good!
Click to expand...
 
Looks like you did quite a bit of work!

This line does not look good, definitely would consider a larger or more rigid line here, and from a safety perspective, it looks really low!

P1010410.jpg
 
that is the 3/8" line that came with the SS kit. Was barely able to get it over the tank pipe (there is no bulge on the end, it is a straight pipe, and not quite slid all the way on), and a bear of a time to get it on the opposite side you point to because of the bulge on the prefilter inlet. I think this is supposed to be a metric line, it is temp as I will remove and check the prefilter in a month or so. Basically until I find a better fitting line. I had applied some 3 in 1 oil to the inside of the tube and to the pipe ends as well.

Also that picture does not show the plastic shield installed which pushed everything up higher.
 
Last edited:
does anything change if you loosen/remove gas cap?

does the pressure change... or after you shut off, if you open the cap, any pressure or suction release?

I believe that sock is a known clog point as well..
 
You must log in or register to reply here.
Back
Top