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Billy
Billy, Trainer/Master tech.
Category: Car
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Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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95 trooper: 3.2 sohc a/..rough..acceleration..smooth..fuel pressure

Customer Question

95 trooper 3.2 sohc a/t

Idles rough an has no acceleration. While in park above 2000rpms it gets smooth an sounds fine but put it in drive an it has no power will not even go up a small hill. I'm getting good blue fire to all 6 plugs plus fuel pressure is good to around 40psi. Also getting around 130 psi on all six cylinders. Timing shows 5 degrees bdc. The computer shows code 12 nothing else.

Here is what I've do so far new fuel pump & filter, had fuel injectors checked an cleaned, new IAC, MAP, TPS, PVC, CPS, plugs plus wires, new coil packs, Oxygen sensor, ECM, cleaned EGR an valve is moving up an down as engine accelerates. I removed catalytic converter thought maybe stopped up but made no difference.

Note when it first started you could be driving along an all of a sudden it would be like you was running out of gas the engine would loose all power but you could start pumping the gas an it would pickup an start going again an a few miles down the road it would do it again but engine would never die it would just go down to an idle, start pumping the gas an it would pick back up again. This has changed some what with all the parts I've add now it doing what I stated above. I'm out of hair I've pulled it all out! Please help! Tony
Submitted: 4 years ago.
Category: Car
Expert:  Tim's Auto Repair replied 4 years ago.

tims auto repair :

is the fuel pressure below 40psi?

Customer:

Its around 42psi

tims auto repair :

ok

tims auto repair :

when you give it throttle,,does the pressure rise?

Customer:

maybe a little

tims auto repair :

the reason i am asking,is that the fuel pressure is border line

tims auto repair :

these should have no less than 41psi

tims auto repair :

and should rise to around 46psi when you give it throttle

Customer:

the book say 40 to 45 I can raise it I put a self ajust regular with gage on it

tims auto repair :

ok

tims auto repair :

1995 Isuzu Truck Trooper 3.2L MFI SOHC 6cyl




The Fuel System Pressure


41-46 PSI (Pounds per Square Inch)

Vent the fuel tank vapors by loosening the fuel cap.Remove the electric fuel pump relay and start theengine. Allow the engine to idle until it runs outof fuel and stalls.After spinning the engine over for a period of (3) to(5) seconds, turn off the ignition switch and installthe electric fuel pump relay. Next, install afuel pressure gauge in the fuel rail supply line, andsecure the fuel tank cap.With the ignition key in the on position, and thevacuum hose for the fuel pressure regulator plugged,verify that no leaks are present and start the engine.Visually verify the PSI reading on the gauge.



tims auto repair :

does it idle well?

Customer:

I'll try this an see

tims auto repair :

ok

tims auto repair :

let me know

tims auto repair :

the fuel pump may be weak

tims auto repair :

Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my answer.it does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.if i have sent any diagrams,please print them.they will only stay on here for an hour or so.PLEASE ASK IF YOU NEED MORE HELP

Customer:

The fuel pump is new....

tims auto repair :

ok

tims auto repair :

unbolt the exhaust from the manifold and see if it has power then..the catalyst may be clogged

tims auto repair :

make sure the fuel pressure rises when you give it throttle

Customer:

I took the catalyst off still no change

tims auto repair :

ok..but it does idle well right?

Customer:

no it has a rough idle

Customer:

Please read my post it tells what all I've done

tims auto repair :

ok tony......i will opt out,,maybe one of the other guys has an idea of what is going on here,,,someone will be with you shortly





Expert:  Billy replied 4 years ago.
Hello Tony,

I'm Billy and will try to help as this seems to be challenging.

First i need you to do the following:
- when the engine is rough idling, try and close the return line on pressure regulator with some pliers, and if idle returns to normal, change the regulator.
- remove engine ground cable, clean contacts and refit, you might want to reinforce engine ground with extra cable.

Perform these checks, and get back to me.

Regards,
Billy
Customer: replied 4 years ago.
Hi Billy

Sorry about being late getting back to you was gone over the weekend. Ok I did what you said the idling is not that bad my bigest problem just no acceleration lack of power when pulling out or going up hill. I'm talking about 10 mph up hill. I took some pliers an closed off the return line an when I do this the engine die's. I have a new ajustable regulator I have it set at 45 psi. As for the engine grounds they are all clean.

Thanks Tony
Expert:  Billy replied 4 years ago.
Hi again,

Hope all is well...

All i can suggest know is for you to check the timing, and for that i will attach the timing belt diagram that will show you all the marks.
graphic

Regards,
Billy
Customer: replied 4 years ago.
Hi Billy

I put a new timing belt on about 2 years ago. I check the timing with a light its around 5 degrees BTDC. Do you think its jumped a notch on the belt? Also should the engine die when you close off the gas return line from the regulator?

Tony
Expert:  Billy replied 4 years ago.
Hello Again,

The timing on your vehicle as per data should be:
16 degrees BTDC (before top dead center) at 750 rpm (idle).
So yes i think it did jump a notch, as it is 5 degrees.

And no, the engine should not die, if the regulator is faulty and leaking through the return line, the engine would idle better when you close the regulator's return line.

Regards,
Billy
Customer: replied 4 years ago.
Ok Billy I'll check the timing belt as for the engine dying when I pinch off the return line what would cause that? Would the timing have something to do with that?
Expert:  Billy replied 4 years ago.
Hello Tony,

If the regulator was leaking then pinching the return line would have caused the engine to work normally, thus confirming that regulator is defective. But since your regulator is good (45 PSI is very good pressure on this system) forget about the pinching (it would make the mixture very rich so the spark plug will not be able to burn it, thus the engine would turn off).
Check the timing for now (a notch skipped is most probably your case), and by the way check your coil (good ground and check if it is leaking, you might spray some water on it so if it is leaking it will leak more and engine will stall).

Regards,
Billy
Billy, Trainer/Master tech.
Category: Car
Satisfied Customers: 3279
Experience: Trainer 8+ years, master tech. 10+ years, SAE member
Billy and 4 other Car Specialists are ready to help you
Customer: replied 4 years ago.
Ok Billy it was the timing..............Off 2 or 3 notches. Have not put it back together yet. Should get it done tomorrow.

Thanks Tony
Expert:  Billy replied 4 years ago.
Hello Tony, Congratulations!!!

Here are the removal and installation instructions in case you need them:

- first the special precautions:
graphic

The removal instructions:
graphic

The installation:
graphic

Good luck! Get back to me if anything goes wrong during the fix.

Regards,
Billy

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Trainer 8+ years, master tech. 10+ years, SAE member