We've been having on-going problems with my wife's 2001 Rodeo with the 3.2 V6. It has about 95k miles on it, and the extended warranty will be expiring soon.

The power is low, especially under moderate acceleration (1/4 to 2/3 throttle - on the floor it is better, but still not like it should be), it bogs, and it sometimes surges. I checked the fuel pressure and it is 37 PSI at idle - the Haynes manual (all I could find) shows the specs as 44-55.

If I pull the vacuum hose off what I *believe* is the fuel pressure regulator (on the back of the fuel rail on the driver's side of the engine, hidden by a bracket with vacuum solenoids), the PSI jumps to 44. Pinching the return line causes the pressure to hit 70+ PSI. Using the process outlined in the Haynes manual, the problem seems to be the regulator or vacuum switching valve.

After multiple trips to the dealer, even armed with the above information, they insist nothing is wrong and the truck is running like it is supposed to. They also claim 37 PSI is within spec with the engine running. Obviously, SOMETHING is not right - moving the accelerator pedal from 1/4 to 2/3 should result in at least SOME increase in power - but I hate to start throwing parts at it.

Now, if I'm looking at what really is the fuel pressure regulator, it appears to be part of the fuel rail, and I don't see any way to separate it from the rail. Does it have to be replaced as an entire assembly, or am I looking at something else? If this isn't the regulator, where is it???? There is very little room to see the back of the engine since it's so tight against the firewall....

Thanks!

It can be replaced seperatly. Sounds like you are looking at the right part from your description. Apparently the screws are really tough to get to though. I know Mike (protetype) on planetisuzoo.com just replaced the one on his '01 rodeo recently. You could pm him there for more info.

I've never done one so cant offer much help. Here is a pic of it I took for someone else though if it helps any..

Thanks - that's what I was looking at, but couldn't get a really good look to see how it comes off the fuel rail. Good to know it can be replaced without messing with the whole unit....

I'll bookmark the other website, too. Thanks!

I really hope there's an easier way than what I had to do.

Since the rear bolt holding the black cover over the FPR isn't exactly accessable (atleast I didn't have the tools to do it.) I took the bolt facing the driver side off, and used a small pry bar to aim the cover so I could access the FPR a little better. I'm a short mofo, and my Rodeo is lifted so I basically had to climb up on top of the engine to get into the FPR. It's held in by a snap ring/c-clip. My snap ring pliers wouldn't work on it, so I used a knife tip to pry the snap ring in and put a small screw driver under the snap ring to push up. then just worked it off.

Make sure you relieve the pressure first by removing the fuse for the fuel pump and letting the truck run before you attempt removal. After that, disconnect the battery! There will still be some pressure in there, so just wrap the fpr in a rag before you pull it off. If you pull it off slowly, you can relieve the pressure that way so it doesn't spray everywhere.

replace, repeat in reverse. i still have those same symptoms occasionally after replacing mine.

If you have 37psi fuel pressure with the vacuum hose attached
and 44 not attached, I don't think you're problem is the fuel pressure regulator. That's exactly how it should work.

Have you checked your fuel filter?

You also might want to check your EGR and make sure it's not
plugged up. It will cause a loss of power if it gets plugged and doesn't function properly.

protetype - Thanks for the added info! I'm another short mofo, which was why I was having such a hard time seeing the stupid thing....

litnin - The Haynes manual doesn't give separate specs for with the hose attached or not, just 42-55 PSI for 1996 and up (it does show different specs for having the vacuum hose attached or not for 1995 and back, though). That was all I had to refer to, so that's what I was going by. If you have a manual that shows otherwise, please let me know - I really want to figure this thing out.

The fuel filter was replaced about a month ago - PSI was unchanged. EGR valve was replaced less than a year ago when the dealer first started trying to diagnose this problem. $300, didn't make any difference.....

Dan,
do not waist time replacing the regulator.
37 @ idle with the vacume on it & 44 with vacume off is perfect (forget about Hayens).
According to Jerry Lemond and his Isuzu Factory Repair Manual that's what it should be (if any thing it's even a little higher).

I went through a lot of grief after bumping my fuel pressure up (did you know you can adjust it on ours?).

Normal pressure should be 34-35 PSI with vacume on & 44-45 PSI with vacume off.

My suggestion is change the fuel filter & check to see how's the air filter.

If it dosn't help let me know & i'll tell you what to check next (but it should do the trick <img src="/forums/images/graemlins/smile.gif" alt="" />).

Just my $.02

Thanks - the Haynes and Chiltons manuals aren't the best, but that was all I had to work from. If the factory manual says 37 PSI is good then I won't mess with the regulator.

The fuel and air filters are new (fuel less than a month old, air a few months, no change when either was replaced). I've doused the area around the intake manifold with carb cleaner and noticed no change in the idle, so I don't think it's an intake gasket. I'm not sure where to go next. The check engine light isn't on, and no codes are stored. It just passed the OBDII smog check. But, nobody can figure out why this thing runs like crap. Any ideas would be greatly appreciated - we're tired of dealing with the problems, but financially can't replace it right now.

One thing comes to mind from reading the symptoms (and it's not a chip fix by a long shot).
Sounds like you'r fuel pump , altho having enough pressure, dosn't supply enough volume of gas.

One other thing, but you better confirm it with Jerry, it may be you'r TPS on the pedal assembly (not the one in the TB). Try cleaning it with some contact cleaner & see what happens.

Get back here with the results.