Mechanics

BAD FUEL PRESSURE

1991 Toyota Camry

Engine Performance problem
1991 Toyota Camry 6 cyl Front Wheel Drive Automatic 202000 miles

I have rebuilt a dozen engines in my life and am a fair shade tree mechanic. My car occasionally sounds and feels like it is running out of gas. It sputters and once in a while stalls but starts again like nothing has happened. Sometimes when I stop at a stoplight and start to go it stumbles for a second or 2 and then moves right a long or just quits but restarts immidiately and off we go. In the mornings it is hard to start - sounds like it is trying to pump the gas and eventually starts and runs fine till it starts it's occasional sputter problem. I replaced the fuel pump, filter, and fuel regulator but no difference in the problem. Yesterday when I pulled off the fuel rail regulator there was no pressure. I talked to a couple of mechanics at the local Toyota dealer and they had no answer but Toyota dealer wants $90+ to diagnose my problems. I'm stumped. Any ideas?
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Thomasthomas1
November 28, 2009.




Hi there,

Thank you for the donation, the first thing to do is hook up a fuel pressure gauge and run the engine, check the pressure readings with the Toyota specs, let me know what you get.

Mark (mhpautos)

Mhpautos
Nov 28, 2009.
There is no place to attach a fuel flow meter. I will have to cut a hose and splice in the gauge. Lets assume I have intermittent low fuel pressure. I've replaced everything from the gas tiank to the fuel rail. What else can it be?

Tiny
Thomasthomas1
Nov 30, 2009.
The fuel pressure regulator will give this problem. And a leaking injector will drop static fuel pressure as well.

Mark

Mhpautos
Nov 30, 2009.
Thanks. I'll hook up a fuel pressure gauge tomorrow and ducktape it to my windshield and see what happens when the engine stumbles. It's late - take the rest of the day off!
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Tiny
Thomasthomas1
Nov 30, 2009.
O let me know how you get on, it's only 2 in the afternoon here, lots more to be done yet,

mark

Mhpautos
Nov 30, 2009.
I assume I am replying to your last reply - can't tell from this screen. I spliced a fuel pressure gauge between the fuel line from the tank and the fuel filter and drove the car. The gauge read 7 inches of something and remained steady even after the car warmed up and occasionally started to act like it was running out of gas. Apparently it isn't a fuel problem. I don't think it's a spark plug because it has stalled once or twice and one spark plug can't do that. I suspect the distruibutor cap and rotor. What do you think?

Tiny
Thomasthomas1
Dec 3, 2009.
Attached is a photo of the cheap Chinese vacuum/fuel gauge with numbers all over the place and no instruction in the pamphlet in 6 languages. the needle initially sat at 0 until I used the gauge and now it sits on 2 with no adjustments. When the gauge is hooked up to the car and running the needle runs counterclockwise to the just south of ther big number 6 on the left hand side of the gauge. I assume that is showing 22 on the inside gauge. I don't know what that means. My Toyota manual says "with the vacuum sensing hose attached . . . 33-37 psi. Does that mean I have low pressure? What would cause that? I have replaced everything in thee fuel line.


http://www.2carpros.com/forum/automotive_pictures/440856_File0009_1.jpg


Tiny
Thomasthomas1
Dec 3, 2009.
I finally got a fuel pressure gauge that works and set it up so I could read it while driving thee car. It read 40-50lbs depending on acceleration and did not drop when the car sounded like it was running out of gas. Since it has completely stopped a couple of times in the past I am ruling out a bad sparkplug and guessing I should change the distributor cap and rotor. I have never seen the check engine light come on. Whadaya think?

Tiny
Thomasthomas1
Dec 7, 2009.
Well it looks as if the fuel system is ok, I think that we are having ignition problems, coil may be breaking down under load, this will not throw a code either.

Mark (mhpautos)

Mhpautos
Dec 7, 2009.
Someone else mentioned the coil. I think I'll cruise over to PullAPart and get one of everything. This ranks high among all the mysteries I've had as a shadetree mechanic since I was 14 years old. Make me an offer and the car is yours.

Tiny
Thomasthomas1
Dec 7, 2009.

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