hmmm that's interesting. as i understand it, the fuel pressure regulator (FPR) on the isuzu 3.2 V6 engine builds and maintains pressure in the fuel rail by acting on the *return* line, i.e. only allowing fuel above and beyond the pressure needed in the fuel rail to travel back to the tank. so when it fails, it allows too much pressure/volume to exit the fuel rail before it reaches the proper amount, or allows excessive bleeddown.scott wrote:I had a 99 amigo 3.2 that was doing the same thing with the gas. I replaced the pressure regulator, the fuel pressure in the rail would drop down after I turned the key off. It turned out the pump was bad and would bleed back through the lines and the pump after I turned off the ignition, replaced the pump and never had anymore problems.
thanks...yeah, i'd be interested in what it could be if anyone knows.scott wrote:After replacing the fuel pressure regulator, which I thought was the problem, I hooked up the fuel pressure guage and was only getting 42psi. As soon as I turned of the ignition the pressure would drop to zero in about 3 seconds. After I replaced the fuel pump, the fuel pressure was 53psi and the pressure held after I turned of the ignition. So something was worn inside the pump.
bigpoppax2 wrote:Sounds like you have two separate problems.
Both are easily fixable and not very expensive as well.
#1 The stalling, is the common intake manifold gasket problem. The
plastic intake manifolds crack and leak. They cost 40 bucks or so and you can replace them yourself in about 30-45 mins.
Some tell tale signs of the IMG leaking are a check engine light that will throw codes that say lean bank one, or lean bank two.
Add where you are located and you may have another Zu head that could help you out with the repairs.
#2 Having to wait to crank for a second is usually a sign that your fuel pressure regulator is not holding pressure and needs replaced.
Oh, and welcome to the Planet!
Posted: Wed Apr 09, 2008 9:39 am
Subject: Re: Gasket replacement Quote message
Did you replace the O2's and Fuel Filter?? Did it change anything.
Doing the intake gaskets is acutally easy. Even though I would not
replace them unless your 100% sure they are bad. I replaced mine
because I replace my thermostat and the manifold needed to come off.
I did it as part of a 50K maint and I thought it might be the reason my
truck takes so long to warm up. It did nothing and I feel like a dip for
wasting my time:)
The only hard part was the fuel lines. There is a small bracket in back of the manifold that is hard to get to. I removed the hoses from the line
which I think was a mistake (time wise). Other than that it was just
hoses and 8 (I think) long bolts.
After rereading your posts it does not seem the gasket is your problem.
Running lean on sensors 1 and 2 is a indication of a fuel problem.
Do some very simple stuff first.
1) Take off and inspect every vaccume line going to the manifold. This
should not take too much time and is FREE. Usually the smaller diameter
lines are your problem because they split eaisley. I had a split one
going to the FPR.
2) Remove your EGR Valve and inspect and clean. Make sure it is not
stuck open. If your EGR Valve is stuck open then it is putting Exhaust
Gas in the intake during idle which will kill the engine. Again this is super
easy. Maybe some PB Blaster on the two bolts if they are stuck. Before
you put the EGR back on check that you have vacume on the intake port.
There are two holes under the EGR valve. One for exhaust one for intake.
Plug the exaust hole (warning hot), and plug the intake. Start the truck
and make sure the intake has vacume by removing the plug. Should
make a loud sucking noise and motor might die so be quick.
3) PCV valve. If stuck open this will kill your engine at idle and give you
bank 1 and 2 lean. Just replace it with an ISUZU PCV vlave. You can
get these at a HONDA dealer. Just ask for one for a 00' PASSPORT.
4) For the ION sensing ignition use only the ND KPR plugs. According to your pictures you have this. Remove the IRIDIUMS.
5) Fuel filter. #1 problem when your truck stumbles when you first start
it. After it gets really clogged your truck dies.
6) Fuel Pressure Regulator. Cheep and easy to replace but I think the
fuel filter is more prevalent problem.
7) Remove + battery and unplug MAS sensor. If the MAS is bad then
unpluging it will cause the computer to go to a generic setting. Might have
to start your truck twice to keep it running. The MAS is a sensitive device
that can be ruined if you leave the battery connected. If the MAS sensor
is bad then after starting the truck for the second time the truck should
Cool Reset the computer by removing + battery cable for 30 min.
After all this then go to the gaskets. Reason being is that usually only one
side will go bad first. Just does not make sence not at least till 70K.
Usually when these start going bad the symptoms start slowly. For Eg
slightly eradic idle. Bizar highway crusing performance. Full throttle
acceleration is OK because low vacumme.
Anyway, I am still waiting for the new plugs. I got them for cheap from denso's website. 6.85 a piece.
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