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Roy, import/domestic specialest
Category: Car
Satisfied Customers: 5869
Experience:  ASE master tech for 40 years
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Isuzu Trooper: 2002 Isuzu Trooper. 3.5L, 6 cyl. Has been a

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2002 Isuzu Trooper. 3.5L, 6 cyl. Has been a great runner. Currently starts up, drives fine a little while then becomes jerky like no gas and dies. All the dash lights come on. I was able to restart in neutral on the move until recently. Now it won't start until it sits awhile. Have fuel and fuel is at test plug on fuel manifold. After twenty or so minutes it will start up again but will drive like it wants to stall. When I come to a stop I have to keep reving it up or it stalls. When it stalls now it has to sit for awhile. At the stop light If I'm lucky it starts and is jerky. I use alot of gas. It is my only transportation to get to work. Any help?
good afternoon my name is XXXXX XXXXX I will assist you today

First thing I would do is check the fuel pressure. you may have fuel at the test point but it needs a specific pressure to work. you can rent a gauge at a parts store to check. the pressure should be 48 to 55 lbs

is the check engine light on???

Customer: replied 3 years ago.

no, only when the motor stalls while in motion or at a stop

ok, I would start with fuel pressure check

Customer: replied 3 years ago.

O'rielly's next door does not have the fuel pressure gauge available today. It'll be a tomorrow thing. Although note my friend holding the valve open said there was good pressure coming out as I turned over the motor. I know that's not an absolute test. The fuel pressure valve is a much easier fix than the fuel pump. I'm guessing the fuel pump would not operate intermittingly?

you dont need to replace the pressure valve. the pump produces the pressure, the valve is a test point for actual pressure.

fuel pump can be intermittent. thats why we need to test it when the issue happens and see what the actual value is at the time

Customer: replied 3 years ago.

Ok, I'll see if I can get a test gauge on that fuel line near the intake. I guess I'll have to wait for a period of time until it starts to act up, yes? At this location in the diagnosis it includes the fuel pressure regulator valve and the fuel pump in the car tank. Can either one be the culprit? Is there another test fitting in front of the FPR valve to just test the fuel pump? thanks, Don

at the test point it will check the pressure from the pump. I would start there. dont replace anything yet till we confirm a failure

Customer: replied 3 years ago.

Hi Roy, a mechanic friend stopped by and ran a scan and determined it is the throttle control module. The car started right up and idled just fine for a short while. It started to stall and did then I started it again. It would gasp a few times while idling. He is very confident that that is the problem and he knows I have very little money and no current employment to continue to trade parts out. I sure hope this is the problem. Thanks,Don

ok, if this is the issue, then you would have a reduced engine power code and notification. I hope he is right but you will see if it works. please keep me updated.

dont forget to hit the smiley button so I get credit for my answers

Customer: replied 3 years ago.

He has put on a used throttle control module and a new inline gas filter. The car starts, idles for a bit then stalls. Starts up easily though. No codes show for the engine anymore but something is showing for the transmission. He is getting another analyser to verify. I'll keep you posted. Thanks, Don

ok. good luck
Customer: replied 3 years ago.

30-35 lbs is the fuel pressure

pressure is too low, it should be 48-55 lbs. this could be the reason for starting and stalling.



Customer: replied 3 years ago.

Is the problem with the fuel pressure regulator or the fuel pump. What do I next to check to eliminate either. Thanks, Don

in most cases, it is the pump that is the issue. you could block off the return line to the tank and re check the pressure. the regulator will release pressure back at about 60-65 lbs. I have replaced less than a hand full of regulators over the years for this.

Try closing the return line and see what the pressure does.

Customer: replied 3 years ago.

Fuel pump went in, pressure is up ,still stalls. What do you think? No
codes come out.

did you check the throttle body for any dirt around the plate??

Customer: replied 3 years ago.

It could have been a problem before but has now been replaced. The fuel pump has been replaced also. The problem stalling still exists. The motor runs like a kitten otherwise. Now my friend thinks it's the air control module near the air filter or even the computer. I told him I can't just keep throwing parts at this. I cannot afford it. I need Help!

I agree. there is an idle control motor in the throttle body that does control the idle speed. this can be removed and cleaned. try this . not a computer in my opinion at all.

did he check for any vacuum leaks???

Customer: replied 3 years ago.

The throttle body is the fixture in front of the intake manifold. He said it needed to be replaced and did. I had opened it up and cleaned it. It has just a butterfly valve in it. no other parts, no ports, electrical selinoid thing on top. the side panel has gears that were clean and nothing else. He said it was an electrical malfunction and had to be replaced. Afterward no codes were presented. He is thinking it's another piece nearer to the air cleaner, air control module?. It is inline with the the air hose just after the air filter box.

that is called the mass air flow sensor. does he have a scan tool???
Customer: replied 3 years ago.

A basic scaner, plug in dash type. Does he need another type of scanner? If so he can borrow it or O'rielly may have the loaner. I just need to know what it is. Thanks, Don PS: Does this even sound like a culprit?

Customer: replied 3 years ago.

he has a basic scaner, plug in dash type. , PO 452 evaporative emmission system presure sensor switch low is what he is chasing now from his most current scan ..........a small sensing switch on the side of the fuel pump?

has no effect on your issue. it is an evap code for fuel fumes.

I still think you have a vacuum leak somewhere that wont let it sustain an idle.

Customer: replied 3 years ago.

vacuum leak, ok........... idle until it warms up...........runs on the street maybe four blocks then I have to pump gas to keep it much of that and it stops in the street or the hiway until something clears.

have him look at all the hoses

Customer: replied 3 years ago.

thank you, XXXXX XXXXX you updated.

also, have him spray some car cleaner around the intake to see if the idle smooths out or gets rough

dont forget to hit the smiley button so I get credit for my answers

Customer: replied 3 years ago.

I haven't forgotton about smiley. I just didn't want to hit it and I loose your contact. I sprayed the throtle cleaner around at first try but sparingly and got no sound change. I didn't saturate totally thinking I'd need an extinguisher close by just in case. Hoses, intake maniold. If not then what? EGR? Somehow I thought that was in the throttle body. Thanks,Don

egr is a good possibility if it is not seating correctly.

you can contact me anytime after rating me. i will continue to answer as long as you contact me

Customer: replied 3 years ago.

Could it be some sort of electrical sensor or fuse. It's fine until it warms up. If so where do I look. I'll check for a vacuum leak again. And have him do the scan thing again, Thanks,Don

sensor or fuse

look for vacuum leak.

Customer: replied 3 years ago.

Looked for the vacuum leak and found none. Sprayed carberater cleaner on hoses and manifold gaskets. No changes. Again tonight barely made it home from a three block test run. Ran fine three blocks just fine then died and was hard to start. Stuck on the street for about 10-15 minutes before it would start again and learched for one block each time. Runs fine until it warms up. Scan: PO 1125 DTC definitions...............PO 452 evaporative emission system sensor switch low.............P1295 DTC refer to vehicle manual are the

here is the description for 1295 which pertains to the throttle body. the used throttle body may be the issue but have him check this out.


Circuit Description
The throttle position (TP) sensor circuit provides a voltage signal relative to throttle position (blade angle). The throttle blade angle will vary about 8 % at closed throttle to about 92 % at wide open throttle (WOT).
The DC motor circuit provides a voltage signal relative to command throttle position (blade angle).
The mass air flow (MAF) sensor measures the amount of air which passes through it into the engine during a given time. The powertrain Control Module (PCM) uses the mass air flow information to monitor engine operating conditions for fuel delivery calculations. A large quantity of air entering the engine indicates an acceleration or high load situation, while a small quantity or air indicates deceleration or idle. The MAF sensor produces a frequency signal which can be monitored using a Tech 2. The frequency will vary within a range of around 4 to 7g/s at idle to around 25 to 40g/s at maximum engine load.
This DTC detects that if the system is in Power Management Mode. (Fail safe Mode)
Conditions for Setting the DTC
The ignition is "ON".
Power Management Mode is active. (Fail safe Mode)
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) the first time the fault is detected.
The PCM calculates an air flow value based on idle air control valve position, throttle position, RPM and barometric pressure.
The PCM will store condition which were present when the DTC was set as Freeze Frame and in the Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn the MIL "OFF" on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
A history DTC P1295 will clear after 40 consecutive trip cycle during which the warm up cycles have occurred without a fault.
DTC P1295 can be cleared using the Tech 2 "Clear Info" function or by disconnecting the PCM battery feed.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at PCM - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals,And poor terminal to wire connection.
Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the TP sensor 1, TP sensor 2 display on the Tech 2 while moving connectors and wiring harnesses related to the sensor.
A change in the display will indicate the location of the fault. If DTC P1295 cannot be duplicated, the information included in the Failure Records data can be useful in determined vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently, performing the DTC
P1295 Diagnostic Chart may isolate the cause of the fault.
Roy and other Car Specialists are ready to help you
Customer: replied 3 years ago.

Well......................I don't know...... on a small 4-5 block test run it did not stall. Tomorrow I'll take it on a 15-30 minute run and see what happens. My friend thought it was another sensor. When the engine heats up it stalls. He pulled the sensor near the crank shaft out and ground down the end a bit just to clean it up. It has a magnetic tip. His thinking is when the engine heated up that the sensor with debris on it wasn't sending the right signal to the computer and the the motor would stop until it cooled down a bit but then reoccur as it heated up again. What do you think? Don

that is the crank sensor. there is a specific gap required so tell him to be carefull cleaning the end. He is correct with the operation.

I will offer you an additional service where we can talk to each other on the phone if you like.

Customer: replied 3 years ago.

Hi Roy, Well, so far so good. Yesterday I was cautiously optomistic and after a couple of road runs the longest being 40 min out I think the fear of loosing my life-support transportation has resided. Thank you ever so much for your online support. You were a big help in just having some one in the know as back up. It's unfortunate that the crank sensor could not have been the first choice for the remedy but my mechanic assured me that the other work was needed also. I have avoided normal maintenance for a long time doing only that which is needed to keep it running just to get to work and a few errands close to home. I see on the internet that others have had the same problem and their mechanics have replaced everything it seems chasing the problem. Sad. Stories of thousands spent and to still have the stalling problem. I have dropped a comment on a few. In the very beginning of this ordeal I attempted to get an in depth diagnostic test from a local auto parts store. The $100 was quite a commitment on my part being currently unemployed and without unemployment insurance. If they could pin point the problem in the beginning maybe I could avoid a larger expense repair bill until I was back on the job and better able to handle it. Unfortunately the test was inconclusive for whatever reason, lack of technical experience with the diagnostic machine or my car problems. I was not charged the $100 nor did I get any answers. Whew, in one breath, and uh oh with the next. Thanks again for your help and I hope this correspondence will help others. I won't leave my phone number but I can be reached at [email protected], thank you so much again, Don Anderson

good glad to hear it is solved.


make sure you hit the smiley button so I get credit for my answers.



Customer: replied 3 years ago.

I'll hit smiley again. Maybe you'll get a two-fer credit. I see the email was gleaned. OK,.....hmmm.......lake tahoe don at g mail. com is another possibility. Thanks again, Don

have a great day
Customer: replied 3 years ago.

lake tahoe don at g mail com

good luck